text: Rootless cones, also called pseudocraters, are volcanic cones that are not directly associated with a conduit that brought magma to the surface from a deep-seated magma reservoir. Generally, three types of rootless cones, littoral cones, explosion craters, and hornitos are recognized. Littoral cones and explosion craters are the result of mild explosions that were generated locally by the interaction of either hot lava or pyroclastic flows with water. Littoral cones typically form on the surface of a basaltic lava flow where it has entered into a body of water, usually a sea or ocean. Explosion craters form where either hot lava or pyroclastic flows have covered either marshy ground or water-saturated ground of some sort. Hornitos are rootless cones that are composed welded lava fragments and were formed on the surface of basaltic lava flows by the escape of gas and clots of molten lava through cracks or other openings in the crust of a lava flow.

text: Rootless cones, also called pseudocraters, are volcanic cones that are not directly associated with a conduit that brought magma to the surface from a deep-seated magma reservoir. Generally, three types of rootless cones,

entity_name: Littoral cone

text: littoral cone

text: s, explosion craters, and hornitos are recognized. Littoral cones and explosion craters are the result of mild explosions that were generated locally by the interaction of either hot lava or pyroclastic flows with water. Littoral cones typically form on the surface of a basaltic lava flow where it has entered into a body of water, usually a sea or ocean. Explosion craters form where either hot lava or pyroclastic flows have covered either marshy ground or water-saturated ground of some sort. Hornitos are rootless cones that are composed welded lava fragments and were formed on the surface of basaltic lava flows by the escape of gas and clots of molten lava through cracks or other openings in the crust of a lava flow.

text: The Grotta Bianca ("white cave") is located on the island of Capri, Italy. It derives its name from white incrustations of calcareous matter upon its sides, and from clusters of white stalactites which hang from the roof and fringe the entrance. The cave faces east, and is situated near the Punta della Chiavioa. The entry, about  high, leads into upper and lower caves, of which the former is not easily accessible. The lower cave can be entered by boat for a short distance. Unlike most other caves at the water-level, it is much broader at approximately  above the water than actually at the surface. The total height is no more than . The upper erosion line is clearly marked near the cave and within it. The upper cave seems to belong to an earlier period.

text: The Grotta Bianca ("white cave") is located on the island of

entity_name: Capri

text: Capri

entity_name: Italy

text: Italy

text: . It derives its name from white incrustations of calcareous matter upon its sides, and from clusters of white

entity_name: Stalactite

text: stalactite

text: s which hang from the roof and fringe the entrance. The cave faces east, and is situated near the Punta della Chiavioa. The entry, about  high, leads into upper and lower caves, of which the former is not easily accessible. The lower cave can be entered by boat for a short distance. Unlike most other caves at the water-level, it is much broader at approximately  above the water than actually at the surface. The total height is no more than . The upper erosion line is clearly marked near the cave and within it. The upper cave seems to belong to an earlier period.

text: The Punkva Caves (Czech: Punkevní jeskyně), are a cave system of the Czech Republic located north of the city of Brno, near the town of Blansko. The Punkva River flows through it. Part of it is the Macocha Gorge, its sinkhole is about 138.7 meters deep and also the deepest of its kind (light hole type) in Central Europe. It is a popular tourist attraction for casual visitors to the region, in addition to cavers and advanced technical divers.

text: The Punkva Caves (

entity_name: Czech language

text: Czech

text: : Punkevní jeskyně), are a

entity_name: Cave

text: cave

text: system of the

entity_name: Czech Republic

text: Czech Republic

text: located north of the city of

entity_name: Brno

text: Brno

text: , near the town of

entity_name: Blansko

text: Blansko

text: . The

entity_name: Punkva

text: Punkva River

text: flows through it. Part of it is the

entity_name: Macocha Gorge

text: Macocha Gorge

text: , its sinkhole is about 138.7 meters deep and also the deepest of its kind (light hole type) in

entity_name: Central Europe

text: Central Europe

text: . It is a popular

entity_name: Tourist attraction

text: tourist attraction

text: for casual visitors to the region, in addition to

entity_name: Caving

text: caver

text: s and advanced

entity_name: Technical diving

text: technical diver

text: s.

text: When affected by moving water or wind, particles that are eroded and held in suspension will increase the erosive power of the fluid that holds them by increasing the average density, viscosity and volume of the moving fluid.

text: The course of the Brahmaputra River has changed dramatically over the past 250 years, with evidence of large-scale avulsion, in the period 1776-1850, of 80 km from east of the Madhupur tract to the west of it. Prior to 1843, the Brahmaputra flowed within the channel now termed the "old Brahmaputra". The banks of the river are mostly weakly cohesive sand and silts, which usually erodes through large scale slab failure, where previously deposited materials undergo scour and bank erosion during flood periods. Presently, the river’s erosion rate has decreased to 30m per year as compared to 150m per year from 1973 to 1992. This erosion has, however, destroyed so much land that it has caused 0.7 million people to become homeless due to loss of land.

text: Some areas of Mars show inverted relief, where features that were once depressions, like streams, are now above the surface.  It is believed that materials like large rocks were deposited in low-lying areas.  Later, erosion (perhaps wind which can't move large rocks) removed much of the surface layers, but left behind the more resistant deposits.  Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.  On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces.  Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River, Utah.  Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.

text: Some areas of Mars show

entity_name: Inverted relief

text: inverted relief

text: , where features that were once depressions, like streams, are now above the surface.  It is believed that materials like large rocks were deposited in low-lying areas.  Later, erosion (perhaps wind which can't move large rocks) removed much of the surface layers, but left behind the more resistant deposits.  Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.  On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces.  Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River,

entity_name: Utah

text: Utah

text: .  Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.

text: They also found evidence for underground passages and chambers, and drains for spring water. Additionally, they discovered at the site formations of travertine, a form of calcite created when water flows through limestone and dissolves calcium carbonate, which is later redeposited. Further investigation revealed that deep beneath the Delphi region lies bituminous deposit, rich in hydrocarbons and full of pitch, that has a petrochemical content as high as 20%. Friction created by earthquakes heat the bituminous layers resulting in vaporization of the hydrocarbons which rise to the surface through small fissures in the rock.

text: They also found evidence for underground passages and chambers, and drains for spring water. Additionally, they discovered at the site formations of

entity_name: Travertine

text: travertine

text: , a form of calcite created when water flows through limestone and dissolves

entity_name: Calcium carbonate

text: calcium carbonate

text: , which is later redeposited. Further investigation revealed that deep beneath the Delphi region lies

entity_name: Asphalt

text: bituminous

text: deposit, rich in

entity_name: Hydrocarbon

text: hydrocarbons

text: and full of pitch, that has a petrochemical content as high as 20%. Friction created by earthquakes heat the bituminous layers resulting in vaporization of the hydrocarbons which rise to the surface through small fissures in the rock.

text: The European perch lives in slow-flowing rivers, deep lakes and ponds. It tends to avoid cold or fast-flowing waters but some specimens penetrate waters of these type, although they do not breed in this habitat.

text: By early 1964, though, the continuing eruptions had built the island to such a size that sea water could no longer easily reach the vents, and the volcanic activity became much less explosive. Instead, lava fountains and flows became the main form of activity. These resulted in a hard cap of extremely erosion-resistant rock being laid down on top of much of the loose volcanic pile, which prevented the island from being washed away rapidly. Effusive eruptions continued until 1965, by which time the island had a surface area of .

text: By early 1964, though, the continuing eruptions had built the island to such a size that sea water could no longer easily reach the vents, and the volcanic activity became much less explosive. Instead,

entity_name: Lava

text: lava fountain

text: s and

text: flows

text: became the main form of activity. These resulted in a hard cap of extremely erosion-resistant rock being laid down on top of much of the loose volcanic pile, which prevented the island from being washed away rapidly. Effusive eruptions continued until 1965, by which time the island had a surface area of .

text: The Chañares Formation represented an extremely thick accumulation of volcanic tuffs that were deposited in wither eolian or lacustrine settings. The lack of stratification prompted Romer to further conclude that deposition in water was unlikely. Instead, Romer envisioned the Chañares landscape “with tremendous quantities of volcanic ash in Pompeii-like fashion”. The formation included deposits of muddy streams transporting abundant volcanic detritus. Ash-flow sheets potentially were emplaced as mass flows on sub alluvial surfaces and in lakes that occupied the Ischigualasto-Villa Únion Basin.

text: The Chañares Formation represented an extremely thick accumulation of volcanic tuffs that were deposited in wither

entity_name: Aeolian processes

text: eolian

text: or

entity_name: Lake

text: lacustrine

text: settings. The lack of stratification prompted Romer to further conclude that deposition in water was unlikely. Instead, Romer envisioned the Chañares landscape “with tremendous quantities of volcanic ash in Pompeii-like fashion”. The formation included deposits of muddy streams transporting abundant volcanic detritus. Ash-flow sheets potentially were emplaced as mass flows on sub alluvial surfaces and in lakes that occupied the

entity_name: Ischigualasto Provincial Park

text: Ischigualasto

text: -Villa Únion Basin.

text: The rate of flow of rivers depends mainly upon their fall, also known as the gradient or slope. When two rivers of different sizes have the same fall, the larger river has the quicker flow, as its retardation by friction against its bed and banks is less in proportion to its volume than is the case with the smaller river. The fall available in a section of a river approximately corresponds to the slope of the country it traverses; as rivers rise close to the highest part of their basins, generally in hilly regions, their fall is rapid near their source and gradually diminishes, with occasional irregularities, until, in traversing plains along the latter part of their course, their fall usually becomes quite gentle. Accordingly, in large basins, rivers in most cases begin as torrents with a very variable flow, and end as gently flowing rivers with a comparatively regular discharge.

text: The

entity_name: Volumetric flow rate

text: rate of flow

text: of rivers depends mainly upon their fall, also known as the gradient or slope. When two rivers of different sizes have the same fall, the larger river has the quicker flow, as its retardation by friction against its bed and banks is less in proportion to its volume than is the case with the smaller river. The fall available in a section of a river approximately corresponds to the slope of the country it traverses; as rivers rise close to the highest part of their basins, generally in hilly regions, their fall is rapid near their source and gradually diminishes, with occasional irregularities, until, in traversing plains along the latter part of their course, their fall usually becomes quite gentle. Accordingly, in large basins, rivers in most cases begin as

entity_name: Stream

entity_section: Intermittent and ephemeral streams

text: torrent

text: s with a very variable flow, and end as gently flowing rivers with a comparatively regular discharge.

text: The original land surface was around  above the current sea level. The surface had sandy deposits from an ancient sea, laid over sedimentary clay (this is the blue London Clay). All the erosion down from this higher land surface, and the sorting action by these changes of water flow and direction, formed what is known as the Thames River Gravel Terraces.

text: The original land surface was around  above the current sea level. The surface had sandy deposits from an ancient sea, laid over sedimentary clay (this is the blue

entity_name: London Clay

text: London Clay

text: ). All the erosion down from this higher land surface, and the sorting action by these changes of water flow and direction, formed what is known as the Thames

entity_name: Fluvial terrace

text: River Gravel Terraces

text: Florida Caverns is unusual for the state.  The limestone caverns were formed over time, as water seeped into and dissolved local bedrock, forming stalagmites, stalactites and flowstones.  The same phenomenon is occurring in many other locations throughout Florida; as years pass, local fissures may turn to holes, and holes into caves.  However, the vast majority of Florida's groundwater erosion formations have stopped at the sinkhole stage and have not developed further into caves.

text: Florida Caverns is unusual for the state.  The

entity_name: Limestone

text: limestone

text: caverns were formed over time, as water seeped into and dissolved local

entity_name: Bedrock

text: bedrock

text: , forming

entity_name: Stalagmite

text: stalagmite

text: s,

text: stalactites

text: and

entity_name: Flowstone

text: flowstone

text: s.  The same phenomenon is occurring in many other locations throughout Florida; as years pass, local fissures may turn to holes, and holes into caves.  However, the vast majority of Florida's groundwater erosion formations have stopped at the

entity_name: Sinkhole

text: sinkhole

text: stage and have not developed further into caves.

text: The aim of the majority of soil erosion models is to predict average rates (often an annual average rate) of soil loss from an area such as a plot, a field or a catchment/watershed under various land management techniques. Some erosion models are purely statistical, others more mechanistic (or physically based). Two of the more widely used soil erosion models in North America are the Revised Universal Soil Loss Equation (RUSLE) and the Water Erosion Prediction Project erosion model (WEPP). Much of the mineland erosion literature is solely focused on fitting or improving RUSLE parameters. Few soil erosion models consider gully erosion, mostly due to difficulties in modelling these large erosional features.

text: The aim of the majority of soil erosion models is to

entity_name: Prediction

text: predict

entity_name: Average

text: average

text: rates

text: (often an annual average rate) of

text: soil loss

text: from an area such as a

entity_name: Quadrat

text: plot

text: , a

text: field

text: or a

entity_name: Drainage basin

text: catchment/watershed

text: under various

entity_name: Land management

text: land management

text: techniques. Some erosion models are purely

entity_name: Statistics

text: statistical

text: , others more mechanistic (or

entity_name: Physics

text: physically based

text: ). Two of the more widely used soil erosion models in

entity_name: North America

text: North America

text: are the

entity_name: Universal Soil Loss Equation

text: Revised Universal Soil Loss Equation

text: (RUSLE) and the

entity_name: WEPP

text: Water Erosion Prediction Project erosion model

text: (WEPP). Much of the

entity_name: Mining

text: mineland

text: erosion literature is solely focused on fitting or improving RUSLE parameters. Few soil erosion models consider

entity_name: Gully

text: gully

text: erosion, mostly due to difficulties in modelling these large erosional features.

text: At least three phases of eruptive activity have been recognized at Mount Fee. The only exposed remnant of Fee's earliest volcanic activity is a minor outcrop of pyroclastic rock. This is evidence of explosive eruptions during Fee's eruptive history, as well as its first volcanic event. The second volcanic event produced a sequence of volcanic rocks on Fee's eastern flank. This volcanic material was likely deposited when a sequence of lava flows and broken lava fragments erupted from a volcanic vent and moved down the flanks during the construction of the ancestral Mount Fee. Following extensive dissection, renewed volcanism produced a viscous series of lavas on its northern flank. The U-shaped crevice separating the two main summits of Mount Fee separates this lava flow from the main volcanic ridge. The conduit from which these lava flows originated was likely vertical in structure and intruded through older rocks deposited during Fee's earlier volcanic events. This volcanic event was also followed by a period of erosion, and likely one or more glacial periods. Extensive erosion following the last volcanic event at Mount Fee has created the rugged north-south trending ridge that currently forms a prominent landmark.

text: At least three phases of eruptive activity have been recognized at Mount Fee. The only exposed remnant of Fee's earliest volcanic activity is a minor outcrop of pyroclastic rock. This is evidence of

entity_name: Explosive eruption

text: explosive eruption

text: s during Fee's eruptive history, as well as its first volcanic event. The second volcanic event produced a sequence of volcanic rocks on Fee's eastern flank. This volcanic material was likely deposited when a sequence of lava flows and broken lava fragments erupted from a volcanic vent and moved down the flanks during the construction of the ancestral Mount Fee. Following extensive dissection, renewed volcanism produced a viscous series of lavas on its northern flank. The U-shaped crevice separating the two main summits of Mount Fee separates this lava flow from the main volcanic ridge. The conduit from which these lava flows originated was likely vertical in structure and intruded through older rocks deposited during Fee's earlier volcanic events. This volcanic event was also followed by a period of erosion, and likely one or more

entity_name: Glacial period

text: glacial period

text: s. Extensive erosion following the last volcanic event at Mount Fee has created the rugged north-south trending ridge that currently forms a prominent landmark.

text: For slow swimmers, low Froude number, the Lighthill−Whitham geometric argument that the opening of the Kelvin chevron (wedge, V pattern) is universal goes as follows. Consider a boat moving from right to left with constant speed v, emitting waves of varying wavelength, and thus wavenumber  and phase velocity , of interest when < v for a shock wave (cf., e.g., Sonic boom or Cherenkov radiation). Equivalently, and more intuitively, fix the position of the boat and have the water flow in the opposite direction, like a piling in a river.

text: For slow swimmers, low Froude number, the Lighthill−Whitham geometric argument that the opening of the Kelvin chevron (wedge, V pattern) is universal goes as follows. Consider a boat moving from right to left with constant speed v, emitting waves of varying wavelength, and thus wavenumber  and phase velocity , of interest when < v for a shock wave (cf., e.g.,

entity_name: Sonic boom

text: Sonic boom

text: or

entity_name: Cherenkov radiation

text: Cherenkov radiation

text: ). Equivalently, and more intuitively, fix the position of the boat and have the water flow in the opposite direction, like a piling in a river.

text: The head of the river is located on moorland and the river character is affected by the run-off levels from the three reservoirs. The upper valley is primarily millstone grit with fluvio-glacial deposits. The overlaying soil is prone to water-logging due to its slow permeability, being composed of loamy soils on top of clay with peat on the top layer. Around Lofthouse there are outcrops of Upper Yoredale limestone, which is more permeable than millstone grit and has created the Nidderdale Caves, where the river flows underground.

text: The head of the river is located on moorland and the river character is affected by the run-off levels from the three reservoirs. The upper valley is primarily

entity_name: Millstone Grit

text: millstone grit

text: with fluvio-glacial deposits. The overlaying soil is prone to water-logging due to its slow permeability, being composed of loamy soils on top of clay with peat on the top layer. Around Lofthouse there are outcrops of

entity_name: Yoredale Series

text: Upper Yoredale

text: limestone, which is more permeable than millstone grit and has created the

entity_name: Nidderdale Caves

text: Nidderdale Caves

text: , where the river flows underground.

text: Geologic evidence supports the view that the slide occurred 13,000 to 15,000 years ago as the result of undercutting which occurred during the Missoula Floods associated with the retreat of glaciers during the last ice age. Water flowing through the Channeled Scablands split into two streams just upstream of the Corfu Slide, with part flowing to the east to pass over the low end of the Saddle Mountains and part flowing westward to pass through Sentinel Gap in the Saddle Mountains. The force of the water diverted to the west impinged on the base of the Corfu Slide area, causing erosion. At least some of the slide occurred before the final Missoula Floods as the older landslide debris has been eroded and smoothed by water flow.

text: Geologic evidence supports the view that the slide occurred 13,000 to 15,000 years ago as the result of undercutting which occurred during the

entity_name: Missoula Floods

text: Missoula Floods

text: associated with the retreat of glaciers during the last

entity_name: Ice age

text: ice age

text: . Water flowing through the

entity_name: Channeled Scablands

text: Channeled Scablands

text: split into two streams just upstream of the Corfu Slide, with part flowing to the east to pass over the low end of the Saddle Mountains and part flowing westward to pass through

text: Sentinel Gap

text: in the Saddle Mountains. The force of the water diverted to the west impinged on the base of the Corfu Slide area, causing erosion. At least some of the slide occurred before the final Missoula Floods as the older landslide debris has been eroded and smoothed by water flow.

text: In 1992, a well was plugged in Fort Sam Houston that had been used for irrigation for farmers. The well had maintained the ecosystem of the creek since a decline in the number of springs that had fed it. In 1995, plans to revitalize the creek began. Groups such as the Salado Creek Foundation began work to restore the historic significance of the creek as a link of Northern Bexar County to the missions in the South. The creek was affected by the Floods of 1998 causing property damage and unconstructive erosion to the creek bed. In March 2001, the San Antonio Water System's Salado Creek WRC began using recycled water to help the creek flow regularly for the first time in almost ten years.

text: In 1992, a

entity_name: Water well

text: well

text: was plugged in

entity_name: Fort Sam Houston

text: Fort Sam Houston

text: that had been used for

entity_name: Irrigation

text: irrigation

text: for

entity_name: Farmer

text: farmers

text: . The well had maintained the

entity_name: Ecosystem

text: ecosystem

text: of the creek since a decline in the number of springs that had fed it. In 1995, plans to revitalize the creek began. Groups such as the Salado Creek Foundation began work to restore the historic significance of the creek as a link of Northern Bexar County to the

entity_name: Spanish missions in Texas

text: missions

text: in the South. The creek was affected by the

entity_name: Floods in the United States: 1901–2000

entity_section: Central and South Texas Flood of October 1998

text: Floods of 1998

text: causing property damage and unconstructive

entity_name: Erosion

text: erosion

text: to the creek bed. In March 2001, the San Antonio Water System's Salado Creek WRC began using

entity_name: Reclaimed water

text: recycled water

text: to help the creek flow regularly for the first time in almost ten years.

text: A serious and long-running water erosion problem occurs in China, on the middle reaches of the Yellow River and the upper reaches of the Yangtze River. From the Yellow River, over 1.6 billion tons of sediment flow each year into the ocean. The sediment originates primarily from water erosion (gully erosion) in the Loess Plateau region of northwest China.

text: A serious and long-running water erosion problem occurs in

text: China

text: , on the middle reaches of the

text: Yellow River

text: and the upper reaches of the

text: Yangtze River

text: . From the Yellow River, over 1.6 billion tons of sediment flow each year into the ocean. The

text: sediment

text: originates primarily from water erosion (gully erosion) in the

text: Loess Plateau

text: region of northwest China.

text: At each end of the shell, a sheet of sufficient thickness usually made of stainless steel is provided, with holes for the tubes to be inserted and rolled. The inlet end of each tube is also bellmouthed for streamlined entry of water. This is to avoid eddies at the inlet of each tube giving rise to erosion, and to reduce flow friction. Some makers also recommend plastic inserts at the entry of tubes to avoid eddies eroding the inlet end. In smaller units some manufacturers use ferrules to seal the tube ends instead of rolling. To take care of length wise expansion of tubes some designs have expansion joint between the shell and the tube sheet allowing the latter to move longitudinally. In smaller units some sag is given to the tubes to take care of tube expansion with both end water boxes fixed rigidly to the shell.

text: At each end of the shell, a sheet of sufficient thickness usually made of

text: stainless steel

text: is provided, with holes for the tubes to be inserted and rolled. The inlet end of each tube is also bellmouthed for streamlined entry of water. This is to avoid

text: eddies

text: at the inlet of each tube giving rise to erosion, and to reduce flow friction. Some makers also recommend plastic inserts at the entry of tubes to avoid eddies eroding the inlet end. In smaller units some manufacturers use ferrules to seal the tube ends instead of rolling. To take care of length wise

text: expansion

text: of tubes some designs have expansion joint between the shell and the tube sheet allowing the latter to move longitudinally. In smaller units some sag is given to the tubes to take care of tube expansion with both end water boxes fixed rigidly to the shell.

text: The canyon of the Saint-Charles river was formed after the glacier's retreat, by the erosion caused by the flowing of water from the Saint-Charles lake. The latter was formed of hard and resistan rocks, gneiss, covered by much less resistant calcarous rocks. Consequently the water eroded the calcarous rocks until it attained the resistant gneiss which resulted in the Waterfall and 42m high canyon. The rate of erosion of the canyon was an estimated 3.33mm per year.

text: The canyon of the Saint-Charles river was formed after the glacier's retreat, by the erosion caused by the flowing of water from the Saint-Charles lake. The latter was formed of hard and resistan rocks,

text: gneiss

text: , covered by much less resistant calcarous rocks. Consequently the water eroded the calcarous rocks until it attained the resistant gneiss which resulted in the Waterfall and 42m high canyon. The rate of erosion of the canyon was an estimated 3.33mm per year.

text: Lake Urema is located in the middle of the valley, about three-quarters of the way down from the Park's northern boundary. The Muaredzi River, flowing from the Cheringoma Plateau, deposits sediments near the outlet of the lake slowing its drainage. This "plug" causes the Urema River to greatly expand in the rainy season.  Water that makes its way past this alluvial fan flows down the Urema River to the Pungue and into the Indian Ocean. In the flooded rainy season, water backs up into the valley and out onto the plains, covering as much as 200 square km in many years. During some dry seasons, the lake's waters shrink to as little as 10 square km. This constant expansion and retraction of the floodplains, amidst a patchwork of savanna, woodland, and thickets, creates a complex mosaic of smaller ecosystems that support a greater abundance and diversity of wildlife than anywhere else in the park.

text: Lake Urema is located in the middle of the valley, about three-quarters of the way down from the Park's northern boundary. The

text: Muaredzi River

text: , flowing from the Cheringoma Plateau, deposits sediments near the outlet of the lake slowing its drainage. This "plug" causes the

text: Urema River

text: to greatly expand in the rainy season.  Water that makes its way past this

text: alluvial fan

text: flows down the Urema River to the

text: Pungue

text: and into the

text: Indian Ocean

text: . In the flooded rainy season, water backs up into the valley and out onto the plains, covering as much as 200 square km in many years. During some dry seasons, the lake's waters shrink to as little as 10 square km. This constant expansion and retraction of the floodplains, amidst a patchwork of

text: savanna

text: woodland

text: , and thickets, creates a complex mosaic of smaller ecosystems that support a greater abundance and diversity of wildlife than anywhere else in the park.

text: Like many other waterfalls in Wells Gray Provincial Park, Mahood Falls owes its formation to the deposits of volcanic rock in the Wells Gray-Clearwater volcanic field. Layer upon layer of fresh lava created flat areas, over which enormous floods flowed at the end of the last ice age. These floods carved the canyons below Mahood Falls and Canim Falls. Erosion by wind and rain created a natural bridge in the cliffs beside the trail, one of only three in Wells Gray Park.

text: Like many other waterfalls in Wells Gray Provincial Park, Mahood Falls owes its formation to the deposits of

text: volcanic rock

text: in the

text: Wells Gray-Clearwater volcanic field

text: . Layer upon layer of fresh

text: lava

text: created flat areas, over which enormous

text: flood

text: s flowed at the end of the last

text: ice age

text: . These floods carved the canyons below Mahood Falls and Canim Falls. Erosion by wind and rain created a natural bridge in the cliffs beside the trail, one of only three in Wells Gray Park.

text: Environmental issues can include erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to create space for the storage of the created debris and soil. Contamination resulting from leakage of chemicals can also affect the health of the local population if not properly controlled. Extreme examples of pollution from mining activities include coal fires, which can last for years or even decades, producing massive amounts of environmental damage.

text: Environmental issues

text: can include

text: erosion

text: , formation of

text: sinkhole

text: s, loss of

text: biodiversity

text: , and

text: contamination of soil

text: groundwater

text: and

text: surface water

text: by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to create space for the storage of the created debris and soil. Contamination resulting from leakage of chemicals can also affect the health of the local population if not properly controlled. Extreme examples of pollution from mining activities include

text: coal fires

text: , which can last for years or even decades, producing massive amounts of environmental damage.

text: The Via Doloroso leads down a steep path to the bottom of the sinkhole containing the Schnurbusch Karst Window. The shrine features a statue of the Blessed Virgin Mary as Our Lady of Grace, a small altar for Masses, and amphitheater. A small waterfall flows out of the cave, and its water flows before the altar, under the stone bridge, and back into the cave.

text: The Via Doloroso leads down a steep path to the bottom of the

text: sinkhole

text: containing the Schnurbusch Karst Window. The shrine features a statue of the Blessed Virgin Mary as Our Lady of Grace, a small altar for Masses, and amphitheater. A small waterfall flows out of the cave, and its water flows before the altar, under the stone bridge, and back into the cave.

text: By the mid-1990s a push into the central Yucatán Peninsula by dedicated deep cave explorers discovered a large number of deep sinkholes, or pit cenotes, such as Sabak Ha, Utzil and deep caves such as Chacdzinikche, Dzibilchaltun, Kankirixche that have been explored and mapped. To this day these deep caves of the central Yucatán remain largely unexplored due to the sheer number of cenotes found in the State of Yucatán, as well as the depth involved that can be only tackled using technical diving techniques or rebreathers. In the end of the last millennium closed circuit rebreather (CCR) cave diving techniques were employed in order to explore these deep water filled caves.

text: Within the territory of Corleone, a short walk from the historic center of the city is the " Natural Park of the cascade of two fortresses ." After going through a series of narrow streets in the district San Giuliano you come in front of a small church dedicated to Our Lady of precisely two fortresses . To the left of this church ' winds a path that leads between the poplars, willows and elms to the falls. Comfortably seated on the ancient square blocks in the shade of mulberry trees, nuts and frassinisi can see the enchanting view of the waterfall. The jump of the water of the river has, with its erosive action, formed a large puddle among rocks calcoarenitiche . The water gets frothy considerable steam that turns into the sun shimmering rainbows . All around the rocks glauconitic, brought to life by the erosion in their yellow- green, are occupied by rocky vegetation . Looking good the walls are the remains of an ancient aqueduct. Before you jump into this point, the river upstream has exerted a strong action of excavation along the rocky sides forming the canyon. "( From Corleone SottoSopra )climate

text: Water flow is the key factor in lotic systems influencing their ecology.  The strength of water flow can vary between systems, ranging from torrential rapids to slow backwaters that almost seem like lentic systems.  The speed of the water flow can also vary within a system and is subject to chaotic turbulence. This turbulence results in divergences of flow from the mean downslope flow vector as typified by eddy currents.  The mean flow rate vector is based on variability of friction with the bottom or sides of the channel, sinuosity, obstructions, and the incline gradient.  In addition, the amount of water input into the system from direct precipitation, snowmelt, and/or groundwater can affect flow rate.  Flowing waters can alter the shape of the streambed through erosion and deposition, creating a variety of habitats, including riffles, glides, and pools.

text: Water flow is the key factor in lotic systems influencing their ecology.  The strength of water flow can vary between systems, ranging from torrential rapids to slow backwaters that almost seem like lentic systems.  The speed of the water flow can also vary within a system and is subject to chaotic turbulence. This turbulence results in divergences of flow from the mean downslope flow vector as typified by eddy currents.  The mean flow rate vector is based on variability of friction with the bottom or sides of the channel,

text: sinuosity

text: , obstructions, and the incline gradient.  In addition, the amount of water input into the system from direct precipitation,

text: snowmelt

text: , and/or groundwater can affect flow rate.  Flowing waters can alter the shape of the streambed through erosion and deposition, creating a variety of habitats, including

text: riffle

text: s,

text: glides

text: , and

text: pools

text: Some prominent delta deposits, such as those on Huron River just east of Ypsilanti, on Rouge River at Plymouth, and on Clinton River below Rochester, belong to Lake Maumee, at its lowest stage. The valleys of incoming rivers had deepened and widened during Lake Arkona. When the ice sheet advanced and the water levels rose, the lower courses of the streams became drowned and were turned into dead-water estuaries. Thus stream deposits would start at the head of these estuaries.  Only once they had completely filled the estuary would a Lake Whittlesey delta form. The deltas of Lake Whittlesey are inset and exist within the estuaries general shoreline. Recent erosion during the modern Lake Erie period has deepened these stream beds, removing most of the estuarine deltas. Only fragments remain as gravel terraces along the back areas of the old estuaries. The best remaining terrace is along the Huron River below Ypsilanti.In New York there is one delta, which is a deposit in Lake Whittlesey.  It buries the eastward ends of the Arkona beach ridges a mile or two east of Alden. The river, which built this delta, flowed westward along the front of the ice when the front was on the Alden moraine. It flowed in a valley, which had not been deepened during the time of Lake Arkona, and it is therefore an exception to the inset deltas of Lake Whittlesey. This delta is not large, but its relation to the Arkona beaches establishes the time at which it was built.In Ontario there are three Whittlesey deltas, each larger than any on the American side. One appears on Grand River between Paris and Brantford, another on Thames River between Komoka and London, and another on a large glacial river, which came from the northeast along the ice front and entered the Au Sable Bay of Lake Whittlesey a few miles northwest of Clinton. The first two are inset deltas like those in Michigan. The third, like the one near Alden, New York, was built by a river flowing along the ice border. Another smaller delta, formed, by a river flowing along the ice border, occurs near Guelph, Junction, Ontario. The fourth and only other place where such a delta could occur is occupied by the Ubly outlet in Michigan.

text: Some prominent delta deposits, such as those on

text: Huron River

text: just east of

text: Ypsilanti

text: , on

text: Rouge River

text: at

text: Plymouth

text: , and on

text: Clinton River

text: below

text: Rochester

text: , belong to

text: Lake Maumee

text: , at its lowest stage. The valleys of incoming rivers had deepened and widened during

text: Lake Arkona

text: . When the ice sheet advanced and the water levels rose, the lower courses of the streams became drowned and were turned into dead-water

text: estuaries

text: . Thus stream deposits would start at the head of these estuaries.  Only once they had completely filled the estuary would a Lake Whittlesey delta form. The deltas of Lake Whittlesey are inset and exist within the estuaries general shoreline. Recent erosion during the modern

text: Lake Erie

text: period has deepened these stream beds, removing most of the estuarine deltas. Only fragments remain as gravel terraces along the back areas of the old estuaries. The best remaining terrace is along the Huron River below Ypsilanti.In

text: New York

text: there is one delta, which is a deposit in Lake Whittlesey.  It buries the eastward ends of the Arkona beach ridges a mile or two east of

text: Alden

text: . The river, which built this delta, flowed westward along the front of the ice when the front was on the Alden moraine. It flowed in a valley, which had not been deepened during the time of Lake Arkona, and it is therefore an exception to the inset deltas of Lake Whittlesey. This delta is not large, but its relation to the Arkona beaches establishes the time at which it was built.In

text: Ontario

text: there are three Whittlesey deltas, each larger than any on the American side. One appears on

text: Grand River

text: between

text: Paris

text: and

text: Brantford

text: , another on

text: Thames River

text: between

text: Komoka

text: and

text: London

text: , and another on a large glacial river, which came from the northeast along the ice front and entered the Au Sable Bay of Lake Whittlesey a few miles northwest of

text: Clinton

text: . The first two are inset deltas like those in Michigan. The third, like the one near Alden, New York, was built by a river flowing along the ice border. Another smaller delta, formed, by a river flowing along the ice border, occurs near

text: Guelph, Junction, Ontario

text: . The fourth and only other place where such a delta could occur is occupied by the Ubly outlet in Michigan.

text: Hard water also forms deposits that clog plumbing. These deposits, called "scale", are composed mainly of calcium carbonate (CaCO), magnesium hydroxide (Mg(OH)), and calcium sulfate (CaSO). Calcium and magnesium carbonates tend to be deposited as off-white solids on the inside surfaces of pipes and heat exchangers. This precipitation (formation of an insoluble solid) is principally caused by thermal decomposition of bicarbonate ions but also happens in cases where the carbonate ion is at saturation concentration. The resulting build-up of scale restricts the flow of water in pipes. In boilers, the deposits impair the flow of heat into water, reducing the heating efficiency and allowing the metal boiler components to overheat. In a pressurized system, this overheating can lead to failure of the boiler. The damage caused by calcium carbonate deposits varies on the crystalline form, for example, calcite or aragonite.

text: Hard water also forms deposits that clog plumbing. These deposits, called "

text: scale

text: ", are composed mainly of

text: calcium carbonate

text: (CaCO),

text: magnesium hydroxide

text: (Mg(OH)), and

text: calcium sulfate

text: (CaSO). Calcium and magnesium carbonates tend to be deposited as off-white solids on the inside surfaces of pipes and

text: heat exchanger

text: s. This precipitation (formation of an insoluble solid) is principally caused by thermal decomposition of bicarbonate ions but also happens in cases where the carbonate ion is at saturation concentration. The resulting build-up of scale restricts the flow of water in pipes. In boilers, the deposits impair the flow of heat into water, reducing the heating efficiency and allowing the metal boiler components to overheat. In a pressurized system, this overheating can lead to failure of the boiler. The damage caused by calcium carbonate deposits varies on the crystalline form, for example,

text: calcite

text: or

text: aragonite

text: The second main point about the regular spacing of cusps is that negative feedback will decrease the amount of net erosion and deposition within a well-formed cusp. As the wave strikes the beach, it will first come into contact with the cusp horns, which will slow the water down. This causes it to lose energy and some of the heavier sediment that it is carrying will be deposited.  The loss of this sediment, however, gives the water extra energy, and it uses this to remove sediment from the embayment on the backwash.

text: A grassed waterway reduces soil erosion and captures most nutrients and pesticides that would normally wash out of crop fields and into major waters. These waterways help to carry surface water at a non-erosive velocity to an area where it will have a stable outlet.  Outlets must be adequate enough to allow water to drain without ponding or flooding the area being protected, while also preventing erosion of the water into the outlet which can be accomplished through the use of riprap.  A limitation is during large runoff events, when soil is saturated, grassed waterways will have a very concentrated flow of water making them not as effective during high rainfalls. Grassed waterways require very little maintenance once they are introduced with major upkeep being mowing of the grass and reseeding. Farm machinery and cattle can cross these waterways but it may be hazardous during wet periods. One of the major disadvantages of waterways are actually getting them established. A late summer or early fall seeding when rainfall is minimal is recommended to allow the seed to have the best chance at establishing a root system.

text: A

text: grassed waterway

text: reduces soil erosion and captures most nutrients and pesticides that would normally wash out of crop fields and into major waters. These waterways help to carry surface water at a non-erosive velocity to an area where it will have a stable outlet.  Outlets must be adequate enough to allow water to drain without ponding or flooding the area being protected, while also preventing erosion of the water into the outlet which can be accomplished through the use of

text: riprap

text: .  A limitation is during large runoff events, when soil is saturated, grassed waterways will have a very concentrated flow of water making them not as effective during high rainfalls. Grassed waterways require very little maintenance once they are introduced with major upkeep being mowing of the grass and reseeding. Farm machinery and cattle can cross these waterways but it may be hazardous during wet periods. One of the major disadvantages of waterways are actually getting them established. A late summer or early fall seeding when rainfall is minimal is recommended to allow the seed to have the best chance at establishing a root system.

text: In geology, physical geography, and sediment transport, fluvial processes relate to flowing water in natural systems. This encompasses rivers, streams, periglacial flows, flash floods and glacial lake outburst floods. Sediment moved by water can be larger than sediment moved by air because water has both a higher density and viscosity. In typical rivers the largest carried sediment is of sand and gravel size, but larger floods can carry cobbles and even boulders.

text: In

text: geology

text: physical geography

text: , and sediment transport,

text: fluvial

text: processes relate to flowing

text: water

text: in natural systems. This encompasses rivers, streams,

text: periglacial

text: flows,

text: flash floods

text: and

text: glacial lake outburst flood

text: s. Sediment moved by water can be larger than sediment moved by air because water has both a higher

text: density

text: and

text: viscosity

text: . In typical rivers the largest carried sediment is of

text: sand

text: and

text: gravel

text: size, but larger floods can carry

text: cobbles

text: and even

text: boulders

text: Prior to its final drawdown, the first major outburst of Lake Agassiz occurred around 12.9 ka calendar years and involved the routing of water east into the Great Lakes and the St. Lawrence. Assuming this occurred over a one-year period, the flux was 0.30 Sv. Then, another outburst took place around 11.7 ka calendar years and contained two events total. First, water flooded southward through the Mississippi River Valley and into the Gulf of Mexico. Within a few years, flood water flowed to the northwest and into the Arctic Ocean. These two stages resulted in a total flux of 0.29 Sv (again, over one year). The fourth major flooding event that preceded a cooling period occurred about 11.2 ka calendar years. In this event, water flowed to the south and then the northwest, resulting in a flux of 0.19 Sv over one year. This event probably would have spanned more than a year, reducing the estimated flux, because of erosion to outflow channels due to the first two major fluxes. Subsequent flooding occurred after these three events and before the final outburst, but they are not considered, as their resultant fluxes were generally weaker and did not precede substantial cooling.

text: Prior to its final drawdown, the first major outburst of Lake Agassiz occurred around 12.9 ka calendar years and involved the routing of water east into the

text: Great Lakes

text: and the St. Lawrence. Assuming this occurred over a one-year period, the flux was 0.30 Sv. Then, another outburst took place around 11.7 ka calendar years and contained two events total. First, water flooded southward through the Mississippi River Valley and into the Gulf of Mexico. Within a few years, flood water flowed to the northwest and into the Arctic Ocean. These two stages resulted in a total flux of 0.29 Sv (again, over one year). The fourth major flooding event that preceded a cooling period occurred about 11.2 ka calendar years. In this event, water flowed to the south and then the northwest, resulting in a flux of 0.19 Sv over one year. This event probably would have spanned more than a year, reducing the estimated flux, because of erosion to outflow channels due to the first two major fluxes. Subsequent flooding occurred after these three events and before the final outburst, but they are not considered, as their resultant fluxes were generally weaker and did not precede substantial cooling.

text: The three caves of the Monument that are tourable are: Hansen Cave, Middle Cave, and Timpanogos Cave. The three caves are connected by manmade tunnels blasted in the 1930s by the Works Progress Administration . The average temperature in the caves is 46 degrees Fahrenheit. Many colorful cave features or speleothems can be seen. Among the most interesting are the helictites, which are hollowed, twisted, spiraling straws of deposited calcite or aragonite. They are formed when water travels through the tube and then evaporates, leaving a trace mineral deposit at the end. Other speleothems found in the cave include: cave bacon, cave columns, flowstone, cave popcorn, cave drapery, stalactites and stalagmites.

text: The three caves of the Monument that are tourable are: Hansen Cave, Middle Cave, and Timpanogos Cave. The three caves are connected by manmade tunnels blasted in the 1930s by the

text: Works Progress Administration

text: . The average temperature in the caves is 46 degrees Fahrenheit. Many colorful cave features or

text: speleothem

text: s can be seen. Among the most interesting are the

text: helictite

text: s, which are hollowed, twisted, spiraling straws of deposited

text: calcite

text: or

text: aragonite

text: . They are formed when water travels through the tube and then evaporates, leaving a trace mineral deposit at the end. Other

text: speleothems

text: found in the cave include: cave bacon, cave columns,

text: flowstone

text: cave popcorn

text: cave drapery

text: stalactite

text: s and

text: stalagmite

text: s.

text: In the upper portion of the watershed, spectacular erosion-related events have occurred at English Canyon Creek, where water flowing at high velocity around a bend during a flood caused several landslides in the 1990s.

text: In the upper portion of the watershed, spectacular erosion-related events have occurred at

text: English Canyon Creek

text: , where water flowing at high velocity around a bend during a flood caused several landslides in the 1990s.

text: In freshwater ecology, upland rivers and streams are the fast-flowing rivers and streams that drain elevated or mountainous country, often onto broad alluvial plains (where they become lowland rivers). However, altitude is not the sole determinant of whether a river is upland or lowland. Arguably the most important determinants are that of stream power and course gradient. Rivers with a course that drops in altitude rapidly will have faster water flow and higher stream power or "force of water". This in turn produces the other characteristics of an upland river - an incised course, a river bed dominated by bedrock and coarse sediments, a riffle and pool structure and cooler water temperatures. Rivers with a course that drops in altitude very slowly will have slower water flow and lower force. This in turn produces the other characteristics of a lowland river - a meandering course lacking rapids, a river bed dominated by fine sediments and higher water temperatures. Lowland rivers tend to carry more suspended sediment and organic matter as well, but some lowland rivers have periods of high water clarity in seasonal low-flow periods.

text: In freshwater ecology, upland rivers and

text: stream

text: s are the fast-flowing rivers and streams that drain elevated or mountainous country, often onto broad

text: alluvial plain

text: s (where they become lowland rivers). However, altitude is not the sole determinant of whether a river is upland or lowland. Arguably the most important determinants are that of stream power and

text: course gradient

text: . Rivers with a course that drops in altitude rapidly will have faster water flow and higher stream power or "force of water". This in turn produces the other characteristics of an upland river - an

text: incised course

text: , a

text: river bed

text: dominated by

text: bedrock

text: and coarse sediments, a

text: riffle

text: and pool structure and cooler water temperatures. Rivers with a course that drops in altitude very slowly will have slower water flow and lower force. This in turn produces the other characteristics of a lowland river - a meandering course lacking rapids, a river bed dominated by fine sediments and higher water temperatures. Lowland rivers tend to carry more suspended

text: sediment

text: and organic matter as well, but some lowland rivers have periods of high water clarity in seasonal low-flow periods.

text: This implies that a potential flow is an irrotational flow. This has direct consequences for the applicability of potential flow. In flow regions where vorticity is known to be important, such as wakes and boundary layers, potential flow theory is not able to provide reasonable predictions of the flow. Fortunately, there are often large regions of a flow where the assumption of irrotationality is valid, which is why potential flow is used for various applications. For instance in: flow around aircraft, groundwater flow, acoustics, water waves, and electroosmotic flow.

text: This implies that a potential flow is an

text: irrotational flow

text: . This has direct consequences for the applicability of potential flow. In flow regions where vorticity is known to be important, such as

text: wake

text: s and

text: boundary layer

text: s, potential flow theory is not able to provide reasonable predictions of the flow. Fortunately, there are often large regions of a flow where the assumption of irrotationality is valid, which is why potential flow is used for various applications. For instance in: flow around

text: aircraft

text: groundwater flow

text: acoustics

text: water wave

text: s, and

text: electroosmotic flow

text: Glacial plucking is the main mechanism of other small scale mechanical glacial erosion such as striation, abrasion and glacial polishing. The heavier the sediment load, the more extreme the erosion of the downhill landscape. Erosion is largely dependent on the amount of water flow and its velocity, the clast size and hardness with relation to the stability of the slope.

text: Glacial plucking is the main mechanism of other small scale mechanical glacial erosion such as

text: striation

text: abrasion

text: and

text: glacial polish

text: ing. The heavier the sediment load, the more extreme the erosion of the downhill landscape. Erosion is largely dependent on the amount of water flow and its velocity, the clast size and hardness with relation to the stability of the slope.

text: Flow in culverts, over dams, and around bridge piers can cause erosion of the bed. This erosion can damage the environment and expose or unsettle the foundations of the structure. Therefore, good knowledge of the mechanics of sediment transport in a built environment are important for civil and hydraulic engineers.

text: A bluff will be more susceptible to erosion if the sediment is unconsolidated, and more resistant in crystalline rocks, like granite. Rocks that are heavily fractured are also very likely to suffer from erosion because the water can flow between the cracks to speed up the process. A bluff will retreat towards land as the erosion processes continue.

text: The lava flows formed the conditions for creation of Lake Superior agates. As the lava solidified, water vapor and carbon dioxide trapped within the solidified flows formed a vesicular texture (literally millions of small bubbles). Later, groundwater transported ferric iron, silica, and other dissolved minerals passed through the trapped gas vesicles. These quartz-rich groundwater solutions deposited concentric bands of fine-grained quartz called chalcedony, or embedded agates.

text: The lava flows formed the conditions for creation of Lake Superior agates. As the lava solidified, water vapor and carbon dioxide trapped within the solidified flows formed a

text: vesicular texture

text: (literally millions of small bubbles). Later, groundwater transported ferric iron, silica, and other dissolved minerals passed through the trapped gas vesicles. These quartz-rich groundwater solutions deposited concentric bands of fine-grained

text: quartz

text: called

text: chalcedony

text: , or embedded agates.

text: Copper water tubes are susceptible to: cold water pitting caused by contamination of the pipe interior, typically with soldering flux; erosion corrosion caused by high speed or turbulent flow; and stray current corrosion, caused by poor electrical wiring technique, such as improper grounding and bonding.

text: Copper water tubes are susceptible to:

text: cold water pitting

text: caused by contamination of the pipe interior, typically with

text: soldering flux

text: erosion corrosion

text: caused by high speed or turbulent flow; and

text: stray current corrosion

text: , caused by poor electrical wiring technique, such as improper grounding and bonding.

text: Provenance (from the French provenir, "to come from"), is the place of origin or earliest known history of something. In geology (specifically, in sedimentary petrology), the term provenance deals with the question where sediments originate from. The purpose of sedimentary provenance studies is to reconstruct and to interpret the history of sediment from parent rocks at a source area to detritus at a burial place. The ultimate goal of provenance studies is to investigate the characteristics of a source area by analyzing the composition and texture of sediments. The studies of provenance involve the following aspects: "(1) the source(s) of the particles that make up the rocks, (2) the erosion and transport mechanisms that moved the particles from source areas to depositional sites, (3) the depositional setting and depositional processes responsible for sedimentation of the particles (the depositional environment), and (4) the physical and chemical conditions of the burial environment and diagenetic changes that occur in siliciclastic sediment during burial and uplift". Provenance studies are conducted to investigate many scientific questions, for example, the growth history of continental crust, collision time of Indian and Asian plates, Asian monsoon intensity, and Himalayan exhumation Meanwhile, the provenance methods are widely used in the oil and gas industry. "Relations between provenance and basin are important for hydrocarbon exploration because sand frameworks of contrasting detrital compositions respond differently to diagenesis, and thus display different trends of porosity reduction with depth of burial."

text: Provenance

text: detrital

text: compositions respond differently to

text: diagenesis

text: , and thus display different trends of

text: porosity

text: reduction with depth of burial."

text: Once initially established, continued lava flow creates a steeper upstream face as it battles the rising water, but with most lava flowing unimpeded downstream covering the now-dried river bed and its alluvial sediments, sometimes for miles. Thus emplaced, the shape of a lava dam resembles an elongated blob, wedged in the valley bottom. At the same time, the water continues to flow, the lake continues to rise and accumulate sediment, which previously had migrated unimpeded downstream.  Sediment filling, over-topping, downward erosion, waterfalls and under-cutting inevitably follow, unless an alternative outlet is established, for water and sediment elsewhere in the drainage.

text: Once initially established, continued lava flow creates a steeper upstream face as it battles the rising water, but with most lava flowing unimpeded downstream covering the now-dried river bed and its

text: alluvial

text: sediments, sometimes for miles. Thus emplaced, the shape of a lava dam resembles an elongated blob, wedged in the valley bottom. At the same time, the water continues to flow, the lake continues to rise and accumulate sediment, which previously had migrated unimpeded downstream.  Sediment filling, over-topping, downward erosion, waterfalls and under-cutting inevitably follow, unless an alternative outlet is established, for water and sediment elsewhere in the drainage.

text: Erosion corrosion, also known as impingement damage, is the combined effect of corrosion and erosion caused by rapid flowing turbulent water. It is probably the second most common cause of copper tube failures behind Type 1 pitting which is also known as Cold Water Pitting of Copper Tube.

text: Erosion corrosion, also known as impingement damage, is the combined effect of

text: corrosion

text: and

text: erosion

text: caused by rapid flowing turbulent

text: water

text: . It is probably the second most common cause of

text: copper tube

text: failures behind Type 1 pitting which is also known as

text: Cold Water Pitting of Copper Tube

text: To remove the small particles which are carried in the water, the flow must be slowed down in sedimentation tank so that the silt particles settle on the tank floor. The deposit formed should be periodically flushed away.

text: Flooding may occur as an overflow of water from water bodies, such as a river, lake, or ocean, in which the water overtops or breaks levees, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rainwater on saturated ground in an areal flood. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, these changes in size are unlikely to be considered significant unless they flood property or drown domestic animals.

text: Flooding may occur as an overflow of water from water bodies, such as a

text: river

text: lake

text: , or ocean, in which the water overtops or breaks

text: levee

text: s, resulting in some of that water escaping its usual boundaries, or it may occur due to an accumulation of rainwater on saturated ground in an areal flood. While the size of a lake or other body of water will vary with seasonal changes in

text: precipitation

text: and snow melt, these changes in size are unlikely to be considered significant unless they flood

text: property

text: or drown

text: domestic animals

text: Over thousands of years the waterfall has eroded its crest and slowly moved upstream. It currently appears to be two waterfalls most of the time but when the river is swollen due to summer rains can form one fall again.

text: A foiba (plural: foibas or foibe) is a type of deep natural sinkhole, doline, or sink, and is a collapsed portion of bedrock above a void. Sinks may be a sheer vertical opening into a cave, or a shallow depression of many hectares. They are common in the Kras (Carso) region, a karstic plateau region shared by Italy, Slovenia, and Croatia.

text: A foiba (plural: foibas or foibe) is a type of deep natural

text: sinkhole

text: , doline, or sink, and is a collapsed portion of bedrock above a void. Sinks may be a sheer vertical opening into a cave, or a shallow depression of many hectares. They are common in the

text: Kras

text: (Carso) region, a

text: karst

text: ic plateau region shared by

text: Italy

text: Slovenia

text: , and

text: Croatia

text: Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice, and/or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea be deposited by sedimentation and if buried this may eventually become sandstone and siltstone, ( sedimentary rocks).

text: Sediment is a naturally occurring material that is broken down by processes of

text: weathering

text: and

text: erosion

text: , and is subsequently

text: transported

text: by the action of wind, water, or ice, and/or by the force of

text: gravity

text: acting on the particles. For example,

text: sand

text: and

text: silt

text: can be carried in

text: suspension

text: in river water and on reaching the sea be deposited by

text: sedimentation

text: and if buried this may eventually become

text: sandstone

text: and

text: siltstone

text: sedimentary rock

text: s).

text: The largest and most abundant solutional caves are located in limestone. Limestone dissolves under the action of rainwater and groundwater charged with HCO (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. These include flowstones, stalactites, stalagmites, helictites, soda straws and columns. These secondary mineral deposits in caves are called speleothems.

text: The largest and most abundant solutional caves are located in limestone. Limestone dissolves under the action of rainwater and groundwater charged with HCO (

text: carbonic acid

text: ) and naturally occurring

text: organic acid

text: s. The dissolution process produces a distinctive landform known as

text: karst

text: , characterized by

text: sinkhole

text: s and underground drainage. Limestone caves are often adorned with

text: calcium carbonate

text: formations produced through slow precipitation. These include

text: flowstone

text: s,

text: stalactite

text: s,

text: stalagmite

text: s,

text: helictite

text: s,

text: soda straw

text: s and columns. These secondary mineral deposits in caves are called

text: speleothem

text: s.

text: St Cuthbert's Swallet is a classic example of a deep phreatic cave system at a depth of not less than  beneath the contemporary water table. It contains inclined bedding plane mazes at many levels, fault-guided rifts and some significant chambers. Nine successive phases of sediment deposition, stalagmite deposition and stream erosion have been recognised at the site, providing an exceptional record of environmental change through the warm and cold phases of the Ice Age.

text: St Cuthbert's Swallet is a classic example of a deep

text: phreatic

text: cave system at a depth of not less than  beneath the contemporary water table. It contains inclined bedding plane mazes at many levels, fault-guided rifts and some significant chambers. Nine successive phases of

text: sediment

text: deposition,

text: stalagmite

text: deposition and stream erosion have been recognised at the site, providing an exceptional record of environmental change through the warm and cold phases of the

text: Ice Age

text: The deposits from well recorded historical tsunamis can be compared with those from well recorded storm events. In both cases these overwash deposits are found in low-lying areas behind the coastline, such as lagoons. These depositional environments are generally characterised by slow lacustrine to swamp sedimentation, producing a sequence of fine-grained sediments. Both tsunami deposits and storm deposits may have strongly erosive bases and mainly consist of sand, often with shell fragments. The most reliable indicator of a tsunami origin appears to be the extent of the inundation, with tsunamis generally inundating further than storms on a particular coast. In some cases, tsunami deposits show clear separation into distinct sub-units deposited by successive tsunami waves, whereas storm waves normally show a higher number of sub-divisions. The presence of  material eroded from the shelf is considered more likely to suggest a tsunami rather than a storm event due to the much greater energy and erosive power associated with individual waves in the tsunami. The movement of large boulders has also been used to argue for a tsunami origin, but probably only the largest boulders represent good evidence of this as major storms, such as cyclones are known to be able to move large boulders. The amount of movement is also likely to be greater with tsunami waves  due to their much longer period.

text: The deposits from well recorded historical tsunamis can be compared with those from well recorded storm events. In both cases these

text: overwash

text: deposits are found in low-lying areas behind the coastline, such as lagoons. These depositional environments are generally characterised by slow lacustrine to swamp sedimentation, producing a sequence of fine-grained sediments. Both tsunami deposits and storm deposits may have strongly erosive bases and mainly consist of sand, often with shell fragments. The most reliable indicator of a tsunami origin appears to be the extent of the inundation, with tsunamis generally inundating further than storms on a particular coast. In some cases, tsunami deposits show clear separation into distinct sub-units deposited by successive tsunami waves, whereas storm waves normally show a higher number of sub-divisions. The presence of  material eroded from the shelf is considered more likely to suggest a tsunami rather than a storm event due to the much greater energy and erosive power associated with individual waves in the tsunami. The movement of large boulders has also been used to argue for a tsunami origin, but probably only the largest boulders represent good evidence of this as major storms, such as cyclones are known to be able to move large boulders. The amount of movement is also likely to be greater with tsunami waves  due to their much longer period.

text: During the summer when the current flows toward the northeast, Ekman transport (to the right of the flow in the Northern Hemisphere) is offshore, transporting warmer waters deeper into the Arabian sea, and permitting upwelling of cooler waters along the coast.  This sea surface temperature pattern (cooler waters west of warmer waters) reinforces the northward current through geostrophic flow.The Southwest Monsoon Current is eastward from April through November, and reaches a peak intensity of 30 cm s during the summer months. During a 1995 field campaign, the Somali current was measured to transport 37 +/- 5 Sv during mid-September.

text: It is estimated that the whirlpool formed approximately 4,200 years ago by the upstream erosion of the Niagara Escarpment by the Niagara River.  Niagara Falls is located along the boundary of the Niagara Escarpment and has been "retreating" upstream since its formation. During this normally slow process, the retreating falls intersected with an ancient pre-glacial river bed inside Saint David's Buried Gorge.  During the retreat of ice from the Wisconsinan glaciation of the last glacial period, the gorge was filled with loose sediment and rock.  When the falls intersected with this buried gorge, the river quickly washed away the filled-in silt and rocks. The ancient buried gorge was nearly perpendicular to the Niagara River.  This sharp and sudden change in direction of water flow, coupled with the rapid flow of water exiting the Niagara Gorge (speeds as high as 30 feet per second [9 m•s]), resulted in turbulent swirling of the river.  Further erosion of the harder rock has resulted in a rounded basin that extends just to the side of the actual river's course.

text: It is estimated that the whirlpool formed approximately 4,200 years ago by the upstream erosion of the

text: Niagara Escarpment

text: by the Niagara River.  Niagara Falls is located along the boundary of the Niagara Escarpment and has been "

text: retreating

text: " upstream since its formation. During this normally slow process, the retreating falls intersected with an ancient pre-glacial river bed inside

text: Saint David's Buried Gorge

text: .  During the retreat of ice from the

text: Wisconsinan glaciation

text: of the

text: last glacial period

text: , the gorge was filled with loose sediment and rock.  When the falls intersected with this buried gorge, the river quickly washed away the filled-in silt and rocks. The ancient buried gorge was nearly perpendicular to the Niagara River.  This sharp and sudden change in direction of water flow, coupled with the rapid flow of water exiting the Niagara Gorge (speeds as high as 30 feet per second [9 m•s]), resulted in turbulent swirling of the river.  Further erosion of the harder rock has resulted in a rounded basin that extends just to the side of the actual river's course.

text: Classic examples are found at the Banff townsite proper: Mount Rundle is a classic dip slope mountain. Just to the north of the Banff townsite, Castle Mountain is composed of numerous Cambrian age rock formations. The uppermost section of the peak consists of relatively harder dolomite from the Eldon Formation. Below that lies the less dense shales of the Stephen Formation and the lowest exposed cliffs are limestones of the Cathedral Formation. Dogtooth mountains, such as Mount Louis, exhibit sharp, jagged slopes. The Sawback Range, which consists of nearly vertical dipping sedimentary layers, has been eroded by cross gullies. The erosion of these almost vertical layers of rock strata in the Sawback Range has resulted in formations that appear like the teeth on a saw blade. Erosion and deposition of higher elevation rock layers has resulted in scree deposits at the lowest elevations of many of the mountains.

text: Classic examples are found at the Banff townsite proper:

text: Mount Rundle

text: is a classic dip slope mountain. Just to the north of the Banff townsite,

text: Castle Mountain

text: is composed of numerous

text: Cambrian

text: age rock formations. The uppermost section of the peak consists of relatively harder dolomite from the Eldon Formation. Below that lies the less dense shales of the

text: Stephen Formation

text: and the lowest exposed cliffs are limestones of the

text: Cathedral Formation

text: . Dogtooth mountains, such as

text: Mount Louis

text: , exhibit sharp, jagged slopes. The Sawback Range, which consists of nearly vertical dipping sedimentary layers, has been eroded by cross

text: gullies

text: . The erosion of these almost vertical layers of rock strata in the Sawback Range has resulted in formations that appear like the teeth on a saw blade. Erosion and deposition of higher elevation rock layers has resulted in

text: scree

text: deposits at the lowest elevations of many of the mountains.

text: Erosion can be the result of material movement by the wind. There are two main effects. First, wind causes small particles to be lifted and therefore moved to another region. This is called deflation. Second, these suspended particles may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation. An example is the formation of sand dunes, on a beach or in a desert. Loess is a homogeneous, typically nonstratified, porous, friable, slightly coherent, often calcareous, fine-grained, silty, pale yellow or buff, windblown (Aeolian) sediment. It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces. Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world. Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.

text: Erosion can be the result of material movement by the wind. There are two main effects. First, wind causes small particles to be lifted and therefore moved to another region. This is called deflation. Second, these suspended particles may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation. An example is the formation of sand

text: dunes

text: , on a beach or in a desert. Loess is a homogeneous, typically nonstratified, porous,

text: friable

text: , slightly coherent, often calcareous, fine-grained,

text: silt

text: y, pale yellow or buff, windblown (Aeolian)

text: sediment

text: . It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces. Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world. Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.

text: The western side of the park lies along Belize's border with Guatemala. The park lies west of the Maya Mountains. The park's landscape includes south Vaca Plateau and eastern slopes of the Maya Mountains. Doyle's Delight, the highest mountain in Belize, is located in the park. The park is located on a layer of limestone strata, the largest area of protected karst in Belize. The park incorporates portions of the Chiquibul Cave System, the longest known cave system in Central America. The cave system is made up of caves linked by water flows, including the Chiquibul River. The Chiquibul River flows through Belize, goes underground into the cave system, and resurfaces in Guatemala. The cave system includes the largest known underground passages and cave chamber discovered in the Western Hemisphere.

text: The western side of the park lies along Belize's border with

text: Guatemala

text: . The park lies west of the

text: Maya Mountains

text: . The park's landscape includes south

text: Vaca Plateau

text: and eastern slopes of the Maya Mountains.

text: Doyle's Delight

text: , the highest mountain in Belize, is located in the park. The park is located on a layer of

text: limestone

text: strata

text: , the largest area of protected

text: karst

text: in Belize. The park incorporates portions of the

text: Chiquibul Cave System

text: , the longest known cave system in

text: Central America

text: . The cave system is made up of caves linked by water flows, including the

text: Chiquibul River

text: . The Chiquibul River flows through Belize, goes underground into the cave system, and resurfaces in Guatemala. The cave system includes the largest known underground passages and cave chamber discovered in the

text: Western Hemisphere

text: There are cyclic variations in the thickness of the exposed sedimentary layers, possibly indicating cyclic variations in environmental conditions while the sediment was being laid down. Most of the layers are parallel to each other, suggesting they formed by vertical settling, but a few are cross-bedded, indicating that at the time that the layers were deposited the sediment was transported along the ground surface by wind or water. The sedimentary material appears to be easily eroded and active wind erosion may be continuing to the current day.

text: The Milbanke Sound Group in the Kitimat Ranges consists of young lava flows and monogenetic cinder cones that were probably formed in the last 10,000 years. Like Silverthrone and Franklin, little is known about the Milbanke Sound Group. As a result, its affinity also remains unclear. It may reflect a northern extension of the Garibaldi Volcanic Belt, but there is not enough data to support this hypothesis. Its formation might have also resulted from other tectonic processes that are currently not understood. Swindle Island contains a  high symmetrical cinder cone on its southern shoreline. This volcano, known as Kitasu Hill, comprises tephra and volcanic bombs. Its summit contains a volcanic crater that is breached to the east. Helmet Peak, a steep-sided cinder cone on Lake Island with an elevation of , consists of welded volcanic blocks and basaltic feeder dikes. During eruption, basaltic tuff breccia was deposited throughout Lake Island and nearby Lady Douglas Island. Lava flows on the shores of Price Island and Dufferin Island were erupted from forest-covered basalt cones, which have been reduced in size to small volcanic mounds. Basaltic lava flows on Finngal Island comprise well-developed columnar jointing. Like other volcanic deposits in the Milbanke Sound Group, very little is known about these lava flows. Although the Milbanke Sound Group was probably formed in the last 10,000 years, the exact age of the lava flows and cinder cones is unknown. It probably formed in the last 10,000 years because the volcanic formations have minimal erosion, indicative of post-glacial volcanism.

text: The

text: Milbanke Sound Group

text: in the Kitimat Ranges consists of young lava flows and monogenetic cinder cones that were probably formed in the last 10,000 years. Like Silverthrone and Franklin, little is known about the Milbanke Sound Group. As a result, its affinity also remains unclear. It may reflect a northern extension of the Garibaldi Volcanic Belt, but there is not enough data to support this hypothesis. Its formation might have also resulted from other tectonic processes that are currently not understood.

text: Swindle Island

text: contains a  high symmetrical cinder cone on its southern shoreline. This volcano, known as

text: Kitasu Hill

text: , comprises tephra and

text: volcanic bomb

text: s. Its summit contains a

text: volcanic crater

text: that is breached to the east.

text: Helmet Peak

text: , a steep-sided cinder cone on Lake Island with an elevation of , consists of welded

text: volcanic block

text: s and basaltic feeder dikes. During eruption, basaltic tuff breccia was deposited throughout

text: Lake Island

text: and nearby

text: Lady Douglas Island

text: . Lava flows on the shores of

text: Price Island

text: and

text: Dufferin Island

text: were erupted from forest-covered basalt cones, which have been reduced in size to small volcanic mounds. Basaltic lava flows on Finngal Island comprise well-developed columnar jointing. Like other volcanic deposits in the Milbanke Sound Group, very little is known about these lava flows. Although the Milbanke Sound Group was probably formed in the last 10,000 years, the exact age of the lava flows and cinder cones is unknown. It probably formed in the last 10,000 years because the volcanic formations have minimal erosion, indicative of

text: post-glacial

text: volcanism.

text: It is now believed that all three of these types of craters result from impacts into an icy layer.  Excess ejecta craters and perched craters, the larger ones, penetrated completely through the ice layer and also went into a rocky lower layer.  A portion of the rocky layer was deposited around the rim of the crater forming a rough ejecta deposit.  That ejecta protected the area beneath it from erosion.  Subsequent erosion left the craters sitting above the surrounding surface.  The smaller, "pedestal craters," developed a protective covering by a different process.  Simulations show that a large impact into ice would generate a great burst of heat that would be sufficient to melt some of the ice.  The resulting water could dissolve salts and minerals and produce a coating resistant to erosion.

text: River deltas form when a river carrying sediment reaches either (1) a body of water, such as a lake, ocean, or reservoir, (2) another river that cannot remove the sediment quickly enough to stop delta formation, or (3) an inland region where the water spreads out and deposits sediments. The tidal currents also cannot be too strong, as sediment would wash out into the water body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time. The river's velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta. When the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment. As a result, sediment drops out of the flow and deposits. Over time, this single channel builds a deltaic lobe (such as the bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the gradient of the river channel becomes lower because the river channel is longer but has the same change in elevation (see slope).

text: River deltas form when a river carrying sediment reaches either (1) a body of water, such as a lake, ocean, or

text: reservoir

text: , (2) another river that cannot remove the sediment quickly enough to stop delta formation, or (3) an inland region where the water spreads out and deposits sediments. The tidal currents also cannot be too strong, as sediment would wash out into the water body faster than the river deposits it. Of course, the river must carry enough sediment to layer into deltas over time. The river's velocity decreases rapidly, causing it to deposit the majority, if not all, of its load. This alluvium builds up to form the river delta. When the flow enters the standing water, it is no longer confined to its

text: channel

text: and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to

text: transport sediment

text: . As a result, sediment drops out of the flow and

text: deposits

text: . Over time, this single channel builds a deltaic lobe (such as the bird's-foot of the Mississippi or Ural river deltas), pushing its mouth into the standing water. As the deltaic lobe advances, the

text: gradient

text: of the river channel becomes lower because the river channel is longer but has the same change in elevation (see

text: slope

text: The bulk of the volcano was formed during the Pliocene and Pleistocene, one tephra deposit being carbon-14 dated to 27,20037,370 BP. In the early Holocene, andesite lava flows overran late moraines. Strong glacial and other erosion effects can be seen on Coropuna. Chlorine-36 exposure dating has found ages of 6,000 years ago for the western lava flow and 2,000 years ago and less for the eastern lava flows. These flows are tens of meters thick and  long and are only weakly eroded, conserving most of their breccia cover. Each of these lava emissions is associated with the formation of mudflows from lavaice interaction. The youngest date reported for one of these lava flows is 1,100 ± 100 years ago.

text: The bulk of the volcano was formed during the Pliocene and Pleistocene, one

text: tephra

text: deposit being

text: dated to 27,20037,370

text: BP

text: . In the early

text: Holocene

text: andesite

text: lava flow

text: s overran late

text: moraine

text: s. Strong glacial and other erosion effects can be seen on Coropuna.

text: exposure dating has found ages of 6,000 years ago for the western lava flow and 2,000 years ago and less for the eastern lava flows. These flows are tens of meters thick and  long and are only weakly eroded, conserving most of their

text: breccia

text: cover. Each of these lava emissions is associated with the formation of mudflows from lavaice interaction. The youngest date reported for one of these lava flows is 1,100 ± 100 years ago.

text: This technique is mostly used to produce coatings on structural materials. Such coatings provide protection against high temperatures (for example thermal barrier coatings for exhaust heat management), corrosion, erosion, wear; they can also change the appearance, electrical or tribological properties of the surface, replace worn material, etc. When sprayed on substrates of various shapes and removed, free-standing parts in the form of plates, tubes, shells, etc. can be produced. It can also be used for powder processing (spheroidization, homogenization, modification of chemistry, etc.). In this case, the substrate for deposition is absent and the particles solidify during flight or in a controlled environment (e.g., water). This technique with variation may also be used to create porous structures, suitable for bone ingrowth, as a coating for medical implants.A polymer dispersion aerosol can be injected into the plasma discharge in order to create a grafting of this polymer on to a substrate surface. This application is mainly used to modify the surface chemistry of polymers.

text: This technique is mostly used to produce coatings on structural materials. Such coatings provide protection against high temperatures (for example

text: thermal barrier coating

text: s for

text: exhaust heat management

text: corrosion

text: erosion

text: wear

text: ; they can also change the appearance, electrical or tribological properties of the surface, replace worn material, etc. When sprayed on substrates of various shapes and removed, free-standing parts in the form of plates, tubes, shells, etc. can be produced. It can also be used for powder processing (spheroidization, homogenization, modification of chemistry, etc.). In this case, the substrate for deposition is absent and the particles solidify during flight or in a controlled environment (e.g., water). This technique with variation may also be used to create porous structures, suitable for bone ingrowth, as a coating for medical implants.A polymer dispersion aerosol can be injected into the plasma discharge in order to create a grafting of this polymer on to a substrate surface. This application is mainly used to modify the surface chemistry of polymers.

text: Flood waters naturally spread out over the surface of this cone. Flows over 25,000 m³/s have been measured where the Kosi exits the Himalayan foothills, enough to create a flow of water 30 km wide. At this rate, in one week enough water would accumulate to cover the entire megafan to a depth of 1.5 meters.

text: Studies of the volcano's lava accumulation rate have put the volcano's age at somewhere near one million years. It is believed to have breached sea level more than 500,000 years ago. Beginning 300,000 years ago, the rate of eruption slowly decreased over a long period of time to a point where erosion wore the volcano down faster than Kohala rebuilt itself through volcanic activity. Decreasing eruptions combined with increasing erosion caused Kohala to slowly weather away and subside into the ocean. The oldest lava flows that are still exposed at the surface are just under 780,000 years old. It is difficult to determine the original size and shape of the volcano, as the southeast flank has been buried by volcanic lava flows from nearby Mauna Kea and Mauna Loa. However, based on a sharp increase of incline on the submarine slope of the volcano at a depth of , scientists estimate that in its prime the portion of Kohala that was above the water was more than  wide. Geologists estimate that the volcano was once about twice its current size.

text: Studies of the volcano's lava accumulation rate have put the volcano's age at somewhere near one million years. It is believed to have breached

text: sea level

text: more than 500,000 years ago. Beginning 300,000 years ago, the rate of eruption slowly decreased over a long period of time to a point where

text: erosion

text: wore the volcano down faster than Kohala rebuilt itself through volcanic activity. Decreasing eruptions combined with increasing erosion caused Kohala to slowly

text: weather

text: away and subside into the ocean. The oldest lava flows that are still exposed at the surface are just under 780,000 years old. It is difficult to determine the original size and shape of the volcano, as the southeast flank has been buried by volcanic

text: lava flow

text: s from nearby

text: Mauna Kea

text: and

text: Mauna Loa

text: . However, based on a sharp increase of incline on the submarine slope of the volcano at a depth of , scientists estimate that in its prime the portion of Kohala that was above the water was more than  wide. Geologists estimate that the volcano was once about twice its current size.

text: Beneath a waterfall in the Pemigewasset River is a granite pothole about  across known simply as "the Basin". It was scrubbed out by stones dragged (and eventually deposited) by the retreating North American ice sheet, and since made smooth by 15 millennia of rapidly whirling pebbles and grit. Below the Basin is "Old Man's Foot", a distinctively shaped rock formation, also the natural result of Pemigewasset's erosive energy.

text: Beneath a

text: waterfall

text: in the

text: Pemigewasset River

text: is a

text: granite

text: pothole

text: about  across known simply as "the Basin". It was scrubbed out by stones dragged (and eventually deposited) by the retreating

text: North American ice sheet

text: , and since made smooth by 15 millennia of rapidly whirling pebbles and grit. Below the Basin is "Old Man's Foot", a distinctively shaped

text: rock formation

text: , also the natural result of Pemigewasset's

text: erosive energy

text: The Facho-Pico Alto Volcanic Complex was constructed in three phases: the first related to stratovolcanic unit of Facho, and then, two lateral centres associated with Pico Alto. The volcanism that originated Facho was submarine in nature, with two visible centres positioned in the southern part of the island: Pico do Facho and a second pyroclastic cone situated  west of Rocha Alta (the remains of its chamber still visible along the coast). Both these emission centre were responsible for pyroclastic and submarine lava flows. In the northern coast, there was likely another eruptive centre associated within this volcanic unit, but erosion makes its localization difficult. Following a long period of volcanic activity, conditions changed, allowing the deposition of sediments and formation of beaches. These deposits were constructed of conglomerates of stone and marine fossils, such as in Pedraque-Pica.

text: Olsen is a small inline sinkhole approximately  from Peacock I down the Pothole tunnel.  There are two small entrances into the cave system at Olsen dropping into the same tunnel.  Being central to the cave system, Olsen was once a popular entrance for cave divers as it allowed easy access to much of the cave.  To prevent erosion, cave divers are no longer permitted to enter at Olsen sink as of 2002, although it remains a popular place to temporarily surface during a dive.

text: Entering Illinois, the river returns to its natural channel, winding its way to Momence, Illinois.  This is the last section of the Great Kankakee Swamp that has never been ditched.  It is at Momence that the river crosses a  limestone shelf, referred to as the Momence Dam.  This natural feature's resistance to erosion created a blockage in the flow of the Kankakee River, backing up water and thereby creating the Great Swamp that once covered .  The dam's removal is part of the story of the draining the marsh.

text: Entering Illinois, the river returns to its natural channel, winding its way to

text: Momence, Illinois

text: .  This is the last section of the Great Kankakee Swamp that has never been ditched.  It is at Momence that the river crosses a  limestone shelf, referred to as the Momence Dam.  This natural feature's resistance to erosion created a blockage in the flow of the Kankakee River, backing up water and thereby creating the Great Swamp that once covered .  The dam's removal is part of the story of the draining the marsh.

text: Both natural and man-made levees can fail in a number of ways. Factors that cause levee failure include overtopping, erosion, structural failures, and levee saturation. The most frequent (and dangerous) is a levee breach.  Here, a part of the levee actually breaks or is eroded away, leaving a large opening for water to flood land otherwise protected by the levee. A breach can be a sudden or gradual failure, caused either by surface erosion or by subsurface weakness in the levee. A breach can leave a fan-shaped deposit of sediment radiating away from the breach, described as a crevasse splay. In natural levees, once a breach has occurred, the gap in the levee will remain until it is again filled in by levee building processes. This increases the chances of future breaches occurring in the same location. Breaches can be the location of meander cutoffs if the river flow direction is permanently diverted through the gap.

text: Both natural and man-made levees can fail in a number of ways. Factors that cause levee failure include overtopping, erosion, structural failures, and levee saturation. The most frequent (and dangerous) is a

text: levee breach

text: .  Here, a part of the levee actually breaks or is eroded away, leaving a large opening for water to flood land otherwise protected by the levee. A breach can be a sudden or gradual failure, caused either by surface erosion or by subsurface weakness in the levee. A breach can leave a fan-shaped deposit of sediment radiating away from the breach, described as a

text: crevasse splay

text: . In natural levees, once a breach has occurred, the gap in the levee will remain until it is again filled in by levee building processes. This increases the chances of future breaches occurring in the same location. Breaches can be the location of

text: meander cutoff

text: s if the river flow direction is permanently diverted through the gap.

text: The upper curve shows the critical erosion velocity in cm/s as a function of particle size in mm, while the lower curve shows the deposition velocity as a function of particle size. Note that the axes are logarithmic.

text: The upper curve shows the critical erosion velocity in cm/s as a function of particle size in mm, while the lower curve shows the deposition velocity as a function of particle size. Note that the axes are

text: logarithmic

text: Visitors must be in good physical conditions in order to walk into "Cueva Clara" and reach "Sumidero y Cueva Espiral" to see the mouth of this cave.  They must go down to it through a scenic 205-step boardwalk. The challenge is getting the way back to the tram. Once walking down the 205 steps into the sinkhole, the cave itself is off limits to reach.  Only experienced spelunkers can penetrate the cave and the underground river with special permission from the National Parks Company of Puerto Rico. This sinkhole is believed to have once been an enormous cavern that collapsed thousands of years ago. At the opening of the cave there is an impressive sight.

text: Mackinac Falls is a submerged 100-foot (30 m)-high waterfall formation under the waters of the Straits of Mackinac.  The formation, which lies approximately 1 mile (1.5 km) east of Arch Rock on Mackinac Island, was the former outflow point for water flowing eastward from Lake Chippewa (proto-Lake Michigan) into Lake Stanley (proto-Lake Huron).  The formation was discovered on August 16, 2007.

text: Mackinac Falls is a submerged 100-foot (30 m)-high

text: waterfall

text: formation under the waters of the

text: Straits of Mackinac

text: .  The formation, which lies approximately 1 mile (1.5 km) east of

text: Arch Rock

text: on

text: Mackinac Island

text: , was the former outflow point for water flowing eastward from

text: Lake Chippewa

text: (proto-

text: Lake Michigan

text: ) into

text: Lake Stanley

text: (proto-

text: Lake Huron

text: ).  The formation was discovered on August 16, 2007.

text: The Dinosaur Park Formation is composed of sediments that were derived from the erosion of the mountains to the west. It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the Western Interior Seaway.  That sea gradually inundated the adjacent coastal plain, depositing the marine shales of the Bearpaw Formation on top of the Dinosaur Park Formation.

text: The Dinosaur Park Formation is composed of sediments that were derived from the erosion of the mountains to the west. It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the

text: Western Interior Seaway

text: .  That sea gradually inundated the adjacent coastal plain, depositing the marine

text: shale

text: s of the

text: Bearpaw Formation

text: on top of the Dinosaur Park Formation.

text: years. The maximum depth of the bay is about 4.75 m and its bottom is made of regional marine deposits. The bay waters draining south into the Champlain Lake and the Richelieu River. Until the late 2000s, the water of the bay was stagnant and the bay was dying. At the opening of the new bridge on the US side, on the old road embankment was partly demolished which brought a flow of fresh water from the Champlain.

text: years. The maximum depth of the bay is about 4.75 m and its bottom is made of regional marine deposits. The bay waters draining south into the

text: Champlain Lake

text: and the

text: Richelieu River

text: . Until the late 2000s, the water of the bay was stagnant and the bay was dying. At the opening of the new bridge on the US side, on the old road embankment was partly demolished which brought a flow of fresh water from the Champlain.

text: A flood is an overflow of water that 'submerges' land. The EU Floods Directive defines a flood as a temporary covering by water of land  which is usually not covered by water. In the sense of 'flowing water', the word may also be applied to the inflow of the tides. Flooding may result from the volume of water within a body of water, such as a river or lake, which overflows causing the result that some of the water escapes its usual boundaries. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless the water covers land used by man like a village, city or other inhabited area, roads, expanses of farmland, etc.

text: A

text: flood

text: is an overflow of water that 'submerges' land. The EU

text: Floods Directive

text: defines a flood as a temporary covering by water of land  which is usually not covered by water. In the sense of 'flowing water', the word may also be applied to the inflow of the

text: tides

text: . Flooding may result from the volume of water within a body of water, such as a

text: river

text: or

text: lake

text: , which overflows causing the result that some of the water escapes its usual boundaries. While the size of a lake or other body of water will vary with seasonal changes in precipitation and snow melt, it is not a significant flood unless the water covers land used by man like a village, city or other inhabited area, roads, expanses of farmland, etc.

text: Forests absorb and then gradually release water.The effect of upstream forest clearance and siltation has been to cause the river to flood over its banks onto fields and roads during the rainy seasons, and for insufficient water to flow during the dry seasons.In February 2010 plans were announced to expand the Gishwati National Conservation Park from , reforesting  of land in the Kinyenkanda area of Rutsiro District.About 150 families had moved into this area and cleared land on the steep slopes for small-scale farming.The result was rapid erosion, depositing silt into the Sebeya River. The families were relocated.

text: Forests absorb and then gradually release water.The effect of upstream forest clearance and siltation has been to cause the river to flood over its banks onto fields and roads during the rainy seasons, and for insufficient water to flow during the dry seasons.In February 2010 plans were announced to expand the

text: Gishwati National Conservation Park

text: from , reforesting  of land in the Kinyenkanda area of Rutsiro District.About 150 families had moved into this area and cleared land on the steep slopes for small-scale farming.The result was rapid erosion, depositing silt into the Sebeya River. The families were relocated.

text: The northwestern and northern portions of the Yucatán Peninsula experience lower rainfall than the rest of the peninsula; these regions feature highly porous limestone bedrock resulting in less surface water. This limestone geology results in most rainwater filtering directly through the bedrock to the phreatic zone, from whence it slowly flows to the coasts to form large submarine springs. Various freshwater springs rise along the coast to form watering holes. The filtering of rainwater through the limestone has caused the formation of extensive cave systems. These cave rooves are subject to collapse forming deep sinkholes; if the bottom of the cave is deeper than the groundwater level then a cenote is formed.

text: The northwestern and northern portions of the Yucatán Peninsula experience lower rainfall than the rest of the peninsula; these regions feature highly porous limestone bedrock resulting in less surface water. This limestone geology results in most rainwater filtering directly through the bedrock to the

text: phreatic zone

text: , from whence it slowly flows to the coasts to form large submarine springs. Various freshwater springs rise along the coast to form watering holes. The filtering of rainwater through the limestone has caused the formation of extensive cave systems. These cave rooves are subject to collapse forming deep

text: sinkhole

text: s; if the bottom of the cave is deeper than the

text: groundwater

text: level then a

text: cenote

text: is formed.

text: The abundance of water on earth's surface is a unique feature that distinguishes earth from other planets in the Solar System. Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of 10,911.4 m.

text: The abundance of water on earth's surface is a unique feature that distinguishes earth from other planets in the Solar System. Earth's

text: hydrosphere

text: consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is

text: Challenger Deep

text: of the Mariana Trench in the Pacific Ocean with a depth of 10,911.4 m.

text: The most common civil engineering use of gabions was refined and patented by Gaetano Maccaferri in the late 1800s in Sacerno, Emilia Romagna and used to stabilize shorelines, stream banks or slopes against erosion. Other uses include retaining walls, temporary flood walls, silt filtration from runoff, for small or temporary/permanent dams, river training, or channel lining. They may be used to direct the force of a flow of flood water around a vulnerable structure.

text: The most common civil engineering use of gabions was refined and

text: patent

text: ed by Gaetano

text: Maccaferri

text: in the late 1800s in Sacerno, Emilia Romagna and used to stabilize

text: shore

text: lines, stream banks or slopes against

text: erosion

text: . Other uses include retaining walls, temporary

text: flood wall

text: s,

text: silt

text: filtration from runoff, for small or temporary/permanent dams, river training, or channel lining. They may be used to direct the force of a flow of

text: flood

text: water

text: around a vulnerable structure.

text: Hydraulic toe erosion occurs when flow is in the direction of a bank at the bend of the river and the highest velocity is at the outer edge and in the center depth of the water. Centrifugal forces raise the water elevation so that it is highest on the outside bend, and as gravity pulls the water downward, a rolling, helical spiral happens, with downward velocities against the bank (erosive force). It will be highest in tight bends. The worst erosion will be immediately downstream from the point of maximum curvature. In cases with noncohesive layers, currents remove the material and create a cantilever overhang of cohesive material. Shear exceeds the critical shear at the toe of the bank, and particles are eroded. This then causes an overhand eventually resulting in bank retreat and failure.

text: Somali seasons include the Xagaa from July to September, the Dayr from October to December, the Jilal from December to March, and the Gu from late March to June. The Xagaa and Jilal seasons are notably dry, and can cause drought. Contrastingly, the Dayr and Gu seasons have the most rainfall, with the Gu being the heavier rain season of the two. The floods that shock the southeastern part of the nation are a result of the Gu rains that fall each year. The water from the rainfall flows to the lowlands near the Jubba River valley and the Shabelle River valley in the southwestern part of the nation. In addition, any excess water that runs down from the two rivers can also contribute to the water flow. The runoff then causes massive flooding for the communities in the area of the two river valleys. As the Gu rains fall every year, the Jubba River and Shabelle River Valleys are susceptible to flooding every year because of the terrain and climate of the area.

text: Somali seasons include the Xagaa from July to September, the Dayr from October to December, the Jilal from December to March, and the Gu from late March to June. The Xagaa and Jilal seasons are notably dry, and can cause drought. Contrastingly, the Dayr and Gu seasons have the most rainfall, with the Gu being the heavier rain season of the two. The floods that shock the southeastern part of the nation are a result of the Gu rains that fall each year. The water from the rainfall flows to the lowlands near the

text: Jubba River

text: valley and the

text: Shabelle River

text: valley in the southwestern part of the nation. In addition, any excess water that runs down from the two rivers can also contribute to the water flow. The runoff then causes massive flooding for the communities in the area of the two river valleys. As the Gu rains fall every year, the Jubba River and Shabelle River Valleys are susceptible to flooding every year because of the terrain and climate of the area.

text: The more easily accessible and more often visited of the two waterfalls is the "cascada chica," also called the Amphitheatre. This cliff rises over fifty metres above the valley floor, where there is a natural platform about sixty meters wide. This platform has four springs. The water from three of the four springs is captured by a number of small natural pools and two large artificial pools in which visitors can swim. The lower of the two pools is very close to the cliff edge and was built in 2007.   In these pools, the water appears a turquoise green due to the mineral concentration. The fourth spring is located closest to the edge and responsible for most of the waterfall rock formation. Two of the four springs on the Amphitheatre side rise from the level floor and appear to bubble up, which is the source of the name. The bubbling action of these and some other springs  is thought to occur due to construction of underground water currents. This bubbling action leads to the name of the area, Hierve el Agua (the water boils). Water constantly flows out of the springs and the process of depositing the calcium carbonate is ongoing, which can be seen on the walls of the artificial pools.

text: Before being deposited, sediments are formed by weathering of earlier rocks by erosion in a source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers (agents of denudation). Mud rocks comprise 65% (mudstone, shale and siltstone); sandstones 20 to 25% and carbonate rocks 10 to 15% (limestone and dolostone). About 7.9% of the crust by volume is composed of sedimentary rocks, with 82% of those being shales, while the remainder consist of limestone (6%), sandstone and arkoses (12%). Sedimentary rocks often contain fossils. Sedimentary rocks form under the influence of gravity and typically are deposited in horizontal or near horizontal layers or strata and may be referred to as stratified rocks. A small fraction of sedimentary rocks deposited on steep slopes will show cross bedding where one layer stops abruptly along an interface where another layer eroded the first as it was laid atop the first.

text: Before being deposited, sediments are formed by

text: weathering

text: of earlier rocks by

text: erosion

text: in a source area, and then transported to the place of deposition by

text: water

text: wind

text: ice

text: mass movement

text: or

text: glacier

text: s (agents of

text: denudation

text: ). Mud rocks comprise 65% (

text: mudstone

text: shale

text: and

text: siltstone

text: sandstone

text: s 20 to 25% and

text: carbonate rock

text: s 10 to 15% (

text: limestone

text: and

text: dolostone

text: ). About 7.9% of the crust by volume is composed of sedimentary rocks, with 82% of those being shales, while the remainder consist of limestone (6%), sandstone and

text: arkose

text: s (12%). Sedimentary rocks often contain

text: fossil

text: s. Sedimentary rocks form under the influence of gravity and typically are deposited in horizontal or near horizontal layers or

text: strata

text: and may be referred to as stratified rocks. A small fraction of sedimentary rocks deposited on steep slopes will show cross bedding where one layer stops abruptly along an interface where another layer eroded the first as it was laid atop the first.

text: She also holds the Italian women’s record for deepest dive in a sinkhole () and in a cave (), and leads the exploration team at the sinkhole Merro in Italy ().

text: She also holds the Italian women’s record for deepest dive in a

text: sinkhole

text: () and in a

text: cave

text: (), and leads the exploration team at the sinkhole Merro in

text: Italy

text: Before the works started in 1868, the Aare River did not flow into Lake Bienne, but divided into several branches after the city of Aarberg, to join the River Thielle, which flows into and out of Lake Bienne, near Büren an der Aare. Depending on weather and water conditions, the alluvial deposits and debris carried by the current would form banks damming the course of the Aare, resulting in rising waters upstream and unavoidable flooding, affecting the economic health of the whole area.

text: Before the works started in 1868, the Aare River did not flow into Lake Bienne, but divided into several branches after the city of

text: Aarberg

text: , to join the River

text: Thielle

text: , which flows into and out of Lake Bienne, near

text: Büren an der Aare

text: . Depending on weather and water conditions, the alluvial deposits and debris carried by the current would form banks damming the course of the Aare, resulting in rising waters upstream and unavoidable flooding, affecting the economic health of the whole area.

text: The images acquired by the Mariner 9 Mars orbiter, launched in 1971, revealed the first direct evidence of past water in the form of dry river beds, canyons (including the Valles Marineris, a system of canyons over about  long), evidence of water erosion and deposition, weather fronts, fogs, and more. The findings from the Mariner 9 missions underpinned the later Viking program. The enormous Valles Marineris canyon system is named after Mariner 9 in honor of its achievements.

text: The images acquired by the

text: Mariner 9

text: Mars orbiter, launched in 1971, revealed the first direct evidence of past water in the form of dry river beds,

text: canyon

text: s (including the

text: Valles Marineris

text: , a system of canyons over about  long), evidence of water

text: erosion

text: and deposition, weather fronts, fogs, and more. The findings from the Mariner 9 missions underpinned the later

text: Viking program

text: . The enormous

text: Valles Marineris

text: canyon system is named after Mariner 9 in honor of its achievements.

text: For each of the sources of water, different hydraulic intensities occur. Floods can occur because of a combination of sources of flooding, such as high groundwater and an inadequate surface water drainage system. The topography, hydrogeology and physical attributes of the existing or proposed development need to be considered. A flood risk assessment should be an evaluation of the flood risk and the consequences and impact and vulnerability.

text: A little more than 13,000 years ago, a sequence of nine tephra eruptions occurred within a period of less than a few hundred years. Associated with these eruptions were pyroclastic flows. Mixed with snow, ice and water, these formed lahars that raced into three nearby rivers, filling their valleys with deep deposits. Subsequently the mudflows drained into both the North Fork of the Stillaguamish River (at that time an outlet of the Sauk River) and Skagit Rivers. In Arlington,  downstream, lahars deposited seven feet of sediment. Subsequent erosion of lahar deposits near Darrington led to the current river system with the Stillaguamish River separated from the Sauk/Skagit Rivers. Lahar debris was deposited along both the Skagit and Stillaguamish Rivers all the way to Puget Sound. A small portion of the erupted tephra was deposited locally. However, most of the tephra reached higher levels of the atmosphere, and was transported by the wind hundreds of miles. Deposits from this congregation were as thick as  near Chelan and  near Missoula, Montana.

text: A little more than 13,000 years ago, a sequence of nine tephra eruptions occurred within a period of less than a few hundred years. Associated with these eruptions were pyroclastic flows. Mixed with snow, ice and water, these formed lahars that raced into three nearby rivers, filling their valleys with deep deposits. Subsequently the mudflows drained into both the North Fork of the

text: Stillaguamish River

text: (at that time an outlet of the

text: Sauk River

text: ) and

text: Skagit River

text: s. In

text: Arlington

text: ,  downstream, lahars deposited seven feet of sediment. Subsequent erosion of lahar deposits near

text: Darrington

text: led to the current river system with the Stillaguamish River separated from the Sauk/Skagit Rivers. Lahar debris was deposited along both the Skagit and Stillaguamish Rivers all the way to

text: Puget Sound

text: . A small portion of the erupted tephra was deposited locally. However, most of the tephra reached higher levels of the atmosphere, and was transported by the wind hundreds of miles. Deposits from this congregation were as thick as  near

text: Chelan

text: and  near

text: Missoula, Montana

text: It is formed where a small stream falls for approximately 305 feet to reach the slopes above Llyn Idwal. Depending on flow, it can be either an ice climbing route, a single drop waterfall, or a broken waterfall.

text: It is formed where a small stream falls for approximately 305 feet to reach the slopes above

text: Llyn Idwal

text: . Depending on flow, it can be either an ice climbing route, a single drop waterfall, or a broken waterfall.

text: Prismatically discretized models like SahysMod   have a grid over the land surface only. The 2-dimensional grid network consists of triangles, squares, rectangles or polygons (Fig. 7). Hence, the flow domain is subdivided into vertical blocks or prisms (Fig. 3). The prisms can be discretized into horizontal  layers with different characteristics that may also vary between the prisms. The groundwater flow between neighboring prisms is calculated using 2-dimensional horizontal groundwater flow equations. Vertical flows are found by applying one-dimensional flow equations in a vertical sense, or they can be derived from the water balance: excess of horizontal inflow over horizontal outflow (or vice versa) is translated into vertical flow, as demonstrated in the article Hydrology (agriculture).

text: Prismatically discretized models like

text: SahysMod

text: have a grid over the land surface only. The 2-dimensional grid network consists of triangles, squares, rectangles or

text: polygons

text: (Fig. 7). Hence, the flow domain is subdivided into vertical blocks or

text: prisms

text: (Fig. 3). The prisms can be discretized into horizontal  layers with different characteristics that may also vary between the prisms. The groundwater flow between neighboring prisms is calculated using 2-dimensional horizontal groundwater flow equations. Vertical flows are found by applying one-dimensional flow equations in a vertical sense, or they can be derived from the water balance: excess of horizontal inflow over horizontal outflow (or vice versa) is translated into vertical flow, as demonstrated in the article

text: Hydrology (agriculture)

text: The area was settled in the 1830s and named "Wilcockson". At that time the entrance to the as-yet-unnamed Mystic Caverns was a sinkhole which led to a  drop into the cave itself. It is likely that settlers became aware of the cave and visited it prior to the 1850s. However, the first known visitor to the cave carved his name and the date on one of the formations:

text: The area was settled in the 1830s and named "Wilcockson". At that time the entrance to the as-yet-unnamed Mystic Caverns was a

text: sinkhole

text: which led to a  drop into the cave itself. It is likely that settlers became aware of the cave and visited it prior to the 1850s. However, the first known visitor to the cave carved his name and the date on one of the formations:

text: The overall balance between sediment in transport and sediment being deposited on the bed is given by the Exner equation. This expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This equation is important in that changes in the power of the flow changes the ability of the flow to carry sediment, and this is reflected in patterns of erosion and deposition observed throughout a stream. This can be localized, and simply due to small obstacles: examples are scour holes behind boulders, where flow accelerates, and deposition on the inside of meander bends. Erosion and deposition can also be regional: erosion can occur due to dam removal and base level fall. Deposition can occur due to dam emplacement that causes the river to pool, and deposit its entire load or due to base level rise.

text: The overall balance between sediment in transport and sediment being deposited on the bed is given by the

text: Exner equation

text: . This expression states that the rate of increase in bed elevation due to deposition is proportional to the amount of sediment that falls out of the flow. This equation is important in that changes in the power of the flow changes the ability of the flow to carry sediment, and this is reflected in patterns of erosion and deposition observed throughout a stream. This can be localized, and simply due to small obstacles: examples are scour holes behind boulders, where flow accelerates, and deposition on the inside of

text: meander

text: bends. Erosion and deposition can also be regional: erosion can occur due to

text: dam removal

text: and

text: base level

text: fall. Deposition can occur due to dam emplacement that causes the river to pool, and deposit its entire load or due to base level rise.

text: Overtopping or overflow of an embankment dam beyond its spillway capacity will cause its eventual failure. The erosion of the dam's material by overtopping runoff will remove masses of material whose weight holds the dam in place and against the hydraulic forces acting to move the dam. Even a small sustained overtopping flow can remove thousands of tons of overburden soil from the mass of the dam within hours. The removal of this mass unbalances the forces that stabilize the dam against its reservoir as the mass of water still impounded behind the dam presses against the lightened mass of the embankment, made lighter by surface erosion. As the mass of the dam erodes, the force exerted by the reservoir begins to move the entire structure. The embankment, having almost no elastic strength, would begin to break into separate pieces, allowing the impounded reservoir  water to flow between them, eroding and removing even more material as it passes through. In the final stages of failure the remaining pieces of the embankment would offer almost no resistance to the flow of the water and continue to fracture into smaller and smaller sections of earth and/or rock until these would disintegrates into a thick mud soup of earth, rocks and water.

text: Overtopping or overflow of an embankment dam beyond its

text: spillway

text: capacity will cause its eventual

text: failure

text: . The erosion of the dam's material by overtopping runoff will remove masses of material whose weight holds the dam in place and against the hydraulic forces acting to move the dam. Even a small sustained overtopping flow can remove thousands of tons of overburden soil from the mass of the dam within hours. The removal of this mass unbalances the forces that stabilize the dam against its reservoir as the mass of water still impounded behind the dam presses against the lightened mass of the embankment, made lighter by surface erosion. As the mass of the dam erodes, the force exerted by the reservoir begins to move the entire structure. The embankment, having almost no elastic strength, would begin to break into separate pieces, allowing the impounded reservoir  water to flow between them, eroding and removing even more material as it passes through. In the final stages of failure the remaining pieces of the embankment would offer almost no resistance to the flow of the water and continue to fracture into smaller and smaller sections of earth and/or rock until these would disintegrates into a thick mud soup of earth, rocks and water.

text: The land is tilled after harvesting and has become sensitive to sheet erosion. The area suffers periodically from floods and droughts. Increased erosion since forest clearance has led to the increase of sediment load in rivers draining into the reservoir. As a result, sediment deposition in the dam gradually decreased the water storage capacity from 150 million m3 in 1970 to 121 and 108 million m3 in 1983 and 1991 respectivelyThe suspended sediments in the water bodies also affect water quality and cause pollution because of various agrochemicals adsorbed by the sediments into the catchments.

text: 33 sinkholes have been found in the main canal leading the water from Martebo mire to the cave. In the area west of the cliff there are five springs. After the draining of the mire the flow of water in the canal have decreased significantly, from  in 1948, to  in 1977. This has caused some of the sinkholes to disappear. During dry summers there is an impending danger that the cave is completely drained.

text: sinkhole

text: s have been found in the main canal leading the water from Martebo mire to the cave. In the area west of the cliff there are five springs. After the draining of the mire the flow of water in the canal have decreased significantly, from  in 1948, to  in 1977. This has caused some of the sinkholes to disappear. During dry summers there is an impending danger that the cave is completely drained.

text: These domed rock formations are composed of conglomerate, a sedimentary rock consisting of cobbles and boulders of varying rock types including granite and basalt, cemented by a matrix of sandstone. The crevasses are due to erosion, primarily by water.  Although it is a dry region, the large area of these domes collects a lot of rainwater, which runs off in steep waterfalls during rain.

text: These domed rock formations are composed of

text: conglomerate

text: , a

text: sedimentary

text: rock consisting of cobbles and boulders of varying rock types including

text: granite

text: and

text: basalt

text: , cemented by a matrix of

text: sandstone

text: . The crevasses are due to erosion, primarily by water.  Although it is a dry region, the large area of these domes collects a lot of rainwater, which runs off in steep waterfalls during rain.

text: The river is known as meandering and extremely slow, and it has a very small inclination in its basin - less than 10 m from Vinkovci until its mouth. Bosut is known for a phenomenon of being 'the river that flows backwards', because sometimes, with strong winds and being so slow, it appears as if the water is flowing backwards.

text: Meanders are sinuous bends in rivers or other channels, which form as a fluid, most often water, flows around bends. As soon as the path is slightly curved, the size and curvature of each loop increases as helical flow drags material like sand and gravel across the river to the inside of the bend. The outside of the loop is left clean and unprotected, so erosion accelerates, further increasing the meandering in a powerful positive feedback loop.

text: Meander

text: s are sinuous bends in rivers or other channels, which form as a fluid, most often water, flows around bends. As soon as the path is slightly curved, the size and curvature of each loop increases as

text: helical flow

text: drags material like sand and gravel across the river to the inside of the bend. The outside of the loop is left clean and unprotected, so

text: erosion

text: accelerates, further increasing the meandering in a powerful

text: positive feedback loop

text: Þjórsárdals's hot spring is west of the waterfall, east near Rauðukömbum. There is a hot spring bath, and an abundance of hot- and cold water that is freely flowing into the hot spring. Inside the valley is Háifoss, one of the highest waterfalls of Iceland. Skeiða- og Gnúpverjahreppur has provided a viewing platform west of Stangarfelli which is situated on the way from Hólaskógur.

text: Þjórsárdals's hot spring is west of the waterfall, east near Rauðukömbum. There is a hot spring bath, and an abundance of hot- and cold water that is freely flowing into the hot spring. Inside the valley is

text: Háifoss

text: , one of the highest waterfalls of Iceland.

text: Skeiða- og Gnúpverjahreppur

text: has provided a viewing platform west of Stangarfelli which is situated on the way from

text: Hólaskógur

text: Reduced crop productivity usually results from erosion, and these effects are studied in the field of soil conservation. The soil particles carried in runoff vary in size from about .001 millimeter to 1.0 millimeter in diameter. Larger particles settle over short transport distances, whereas small particles can be carried over long distances suspended in the water column. Erosion of silty soils that contain smaller particles generates turbidity and diminishes light transmission, which disrupts aquatic ecosystems.

text: Reduced crop productivity usually results from erosion, and these effects are studied in the field of

text: soil conservation

text: . The soil particles carried in runoff vary in size from about .001 millimeter to 1.0 millimeter in diameter. Larger particles

text: settle

text: over short transport distances, whereas small particles can be carried over long distances suspended in the

text: water column

text: . Erosion of silty soils that contain smaller particles generates

text: turbidity

text: and diminishes light transmission, which disrupts

text: aquatic ecosystem

text: s.

text: Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow, and so causes the stream channel to lengthen. It can also refer to widening of a canyon by erosion along its very top edge, when sheets of water first enter the canyon from a more roughly planar surface above it, such as at Canyonlands National Park in Utah. (See image at right.) When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression. This either causes the stream to grow longer at the very top of the stream, which moves its origin back, or causes the canyon formed by the stream to grow wider, by erosion along the length of its top side edge as sheets of water flow over the edge. Widening of the canyon by erosion inside the canyon, below the canyon side top edge, or origin or the stream, such as erosion caused by the streamflow inside it, is not called headwall erosion.

text: Headward erosion is

text: erosion

text: at the origin of a

text: stream channel

text: , which causes the origin to move back away from the direction of the stream flow, and so causes the stream channel to lengthen. It can also refer to widening of a

text: canyon

text: by erosion along its very top edge, when sheets of water first enter the canyon from a more roughly planar surface above it, such as at

text: Canyonlands National Park

text: in

text: Utah

text: . (See image at right.) When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression. This either causes the stream to grow longer at the very top of the stream, which moves its origin back, or causes the canyon formed by the stream to grow wider, by erosion along the length of its top side edge as sheets of water flow over the edge. Widening of the canyon by erosion inside the canyon, below the canyon side top edge, or origin or the stream, such as erosion caused by the streamflow inside it, is not called headwall erosion.

text: Flooding consists of multiple stages.  First, at the start of the flooding, nutrients rush in from the area where the flood begins.  During flood periods, the most important element is called the moving littoral.  As flooding begins and water levels increase nutrients that have been mineralized in the dry phase are suspended with sediments in the flood waters and main river.  The moving littoral consists of the water from the shoreline to a few meters deep in the river.  This pulse of water is the primary driver of high productivity and decomposition rates as it moves nutrients in and out of the system and is good breeding ground for many species of estuarial organisms. At this point in time production rates exceed decomposition rates.  As water levels stabilize, decomposition rates outpace production rates, frequently contributing to dissolved oxygen deficiency. When the water starts receding, the moving littoral reverses, concentrating nutrients and contributing to phytoplankton growth.

text: Flooding consists of multiple stages.  First, at the start of the flooding, nutrients rush in from the area where the flood begins.  During flood periods, the most important element is called the moving

text: littoral

text: .  As flooding begins and water levels increase nutrients that have been

text: mineralized

text: in the dry phase are suspended with sediments in the flood waters and main river.  The moving littoral consists of the water from the shoreline to a few meters deep in the river.  This pulse of water is the primary driver of high productivity and decomposition rates as it moves nutrients in and out of the system and is good breeding ground for many species of

text: estuarial

text: organisms. At this point in time production rates exceed decomposition rates.  As water levels stabilize, decomposition rates outpace production rates, frequently contributing to

text: dissolved oxygen

text: deficiency. When the water starts receding, the moving littoral reverses, concentrating nutrients and contributing to

text: phytoplankton

text: growth.

text: The Cambrian Tonto Group is the three-member sequence of geologic formations that represent the basal section of Paleozoic rocks in the Grand Canyon. The group is about  thick.  The base unit, the Cambrian Tapeats Sandstone was deposited upon the erosion surface of the Vishnu Basement Rocks, which is found in Granite Gorge (the Inner Gorge). The erosion resistant Tapeats Sandstone forms the platform, called Tonto Platform, that the two less erosion resistant upper layers, the Bright Angel Shale and Muav Limestone, rest on.

text: The

text: Cambrian

text: Tonto Group is the three-member sequence of

text: geologic formations

text: that represent the basal section of

text: Paleozoic

text: rocks in the

text: Grand Canyon

text: . The group is about  thick.  The base unit, the

text: Cambrian

text: Tapeats Sandstone

text: was deposited upon the

text: erosion surface

text: of the

text: Vishnu Basement Rocks

text: , which is found in Granite Gorge (the Inner Gorge). The erosion resistant Tapeats Sandstone forms the platform, called

text: Tonto Platform

text: , that the two less erosion resistant upper layers, the

text: Bright Angel Shale

text: and

text: Muav Limestone

text: , rest on.

text: The south two-fifths of the Bidahochi Formation is cut by the drainage of the southwest-flowing Puerco River out of New Mexico, but the river meets the Little Colorado at the central extent of the Bidahochi-(east to west), and the Little Colorado River then turns northwesterly, then more north-northwesterly to the Colorado River, at Grand Canyon. The entire region north and east of the Little Colorado River is the Painted Desert, composed of the bright, multi-colored, (non-consolidated), highly erodable Chinle Formation. From south of the Little Colorado-Puerco River, (towards the White Mountains), and extending north-northwest to the south of Black Mesa, the Bidahochi lies as a resistant layer, overlying the Chinle, and preventing its erosion in various exposures across the intervening washes, and mesas. In the centerpoint of the transect between the Puerco River, north-northwest to the southeast of Black Mesa is Bidahochi, Arizona. Due west, lies the Hopi Buttes volcanic field, where some of the up 200 vents are maars, erupted through the Bodahochi Formation; the thickest Bidahochi deposits lie due east of the Bidahochi townsite. The Bidahochi forms erosion-resistant, landslide slopes, at the base of specific individual Hopi volcanic buttes.

text: The south two-fifths of the Bidahochi Formation is cut by the drainage of the southwest-flowing

text: Puerco River

text: out of New Mexico, but the river meets the Little Colorado at the central extent of the Bidahochi-(east to west), and the Little Colorado River then turns northwesterly, then more north-northwesterly to the Colorado River, at Grand Canyon. The entire region north and east of the Little Colorado River is the

text: Painted Desert

text: , composed of the bright, multi-colored, (non-consolidated), highly erodable

text: Chinle Formation

text: . From south of the Little Colorado-Puerco River, (towards the White Mountains), and extending north-northwest to the south of Black Mesa, the Bidahochi lies as a resistant layer, overlying the Chinle, and preventing its erosion in various exposures across the intervening washes, and mesas. In the centerpoint of the transect between the Puerco River, north-northwest to the southeast of Black Mesa is

text: Bidahochi, Arizona

text: . Due west, lies the

text: Hopi Buttes volcanic field

text: , where some of the up 200 vents are

text: maar

text: s, erupted through the Bodahochi Formation; the thickest Bidahochi deposits lie due east of the Bidahochi townsite. The Bidahochi forms erosion-resistant, landslide slopes, at the base of specific individual Hopi volcanic buttes.

text: A river flowing in its channel is a source of energy which acts on the river channel to change its shape and form. In 1757, the German hydrologist Albert Brahms empirically observed that the submerged weight of objects that may be carried away by a river is proportional to the sixth power of the river flow speed. This formulation is also sometimes called Airy's law. Thus, if the speed of flow is doubled, the flow would dislodge objects with 64 times as much submerged weight. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks. In U-shaped glaciated valleys, the subsequent river valley can often easily be identified by the V-shaped channel that it has carved. In the middle reaches where a river flows over flatter land, meanders may form through erosion of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an oxbow lake or billabong. Rivers that carry large amounts of sediment may develop conspicuous deltas at their mouths. Rivers whose mouths are in saline tidal waters may form estuaries.

text: A river flowing in its channel is a source of energy which acts on the river channel to change its shape and form. In 1757, the German hydrologist

text: Albert Brahms

text: empirically observed that the submerged weight of objects that may be carried away by a river is proportional to the sixth power of the river flow speed. This formulation is also sometimes called Airy's law. Thus, if the speed of flow is doubled, the flow would dislodge objects with 64 times as much submerged weight. In mountainous torrential zones this can be seen as erosion channels through hard rocks and the creation of sands and gravels from the destruction of larger rocks. In U-shaped

text: glaciated

text: valleys, the subsequent river valley can often easily be identified by the V-shaped channel that it has carved. In the middle reaches where a river flows over flatter land,

text: meander

text: s may form through erosion of the river banks and deposition on the inside of bends. Sometimes the river will cut off a loop, shortening the channel and forming an

text: oxbow lake

text: or

text: billabong

text: . Rivers that carry large amounts of

text: sediment

text: may develop conspicuous

text: deltas

text: at their mouths. Rivers whose mouths are in saline

text: tidal

text: waters may form

text: estuaries

text: The sun, which drives the water cycle, heats water in oceans and seas. Water evaporates as water vapor into the air. Ice and snow can sublimate directly into water vapour. Evapotranspiration is water transpired from plants and evaporated from the soil. The water vapour molecule  has less density compared to the major components of the atmosphere, nitrogen and oxygen,  and . Due to the significant difference in molecular mass, water vapor in gas form gains height in open air as a result of buoyancy. However, as altitude increases, air pressure decreases and the temperature drops (see Gas laws). The lowered temperature causes water vapour to condense into a tiny liquid water droplet which is heavier than the air, such that it falls unless supported by an updraft. A huge concentration of these droplets over a large space up in the atmosphere become visible as cloud. Fog is formed if the water vapour condenses near ground level, as a result of moist air and cool air collision or an abrupt reduction in air pressure. Air currents move water vapour around the globe, cloud particles collide, grow, and fall out of the upper atmospheric layers as precipitation. Some precipitation falls as snow or hail, sleet, and can accumulate as ice caps and glaciers, which can store frozen water for thousands of years. Most water falls back into the oceans or onto land as rain, where the water flows over the ground as surface runoff. A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and water emerging from the ground (groundwater) may be stored as freshwater in lakes. Not all runoff flows into rivers, much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers, which can store freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge. Some groundwater finds openings in the land surface and comes out as freshwater springs. In river valleys and floodplains, there is often continuous water exchange between surface water and ground water in the hyporheic zone. Over time, the water returns to the ocean, to continue the water cycle.

text: The sun, which drives the water cycle, heats water in oceans and seas. Water evaporates as water vapor into the

text: air

text: . Ice and snow can

text: sublimate

text: directly into water vapour.

text: Evapotranspiration

text: is water

text: transpired

text: from plants and evaporated from the soil. The water vapour molecule  has less density compared to the major components of the atmosphere, nitrogen and oxygen,  and . Due to the significant difference in

text: molecular mass

text: , water vapor in gas form gains height in open air as a result of

text: buoyancy

text: . However, as altitude increases, air pressure decreases and the temperature drops (see

text: Gas laws

text: ). The lowered temperature causes water vapour to condense into a tiny liquid water droplet which is heavier than the air, such that it falls unless supported by an updraft. A huge concentration of these droplets over a large space up in the atmosphere become visible as cloud. Fog is formed if the water vapour condenses near ground level, as a result of moist air and cool air collision or an abrupt reduction in air pressure. Air currents move water vapour around the globe, cloud particles collide, grow, and fall out of the upper atmospheric layers as

text: precipitation

text: . Some precipitation falls as snow or hail, sleet, and can accumulate as ice caps and glaciers, which can store frozen water for thousands of years. Most water falls back into the oceans or onto land as rain, where the water flows over the ground as

text: surface runoff

text: . A portion of runoff enters rivers in valleys in the landscape, with streamflow moving water towards the oceans. Runoff and water emerging from the ground (

text: groundwater

text: ) may be stored as freshwater in lakes. Not all runoff flows into rivers, much of it soaks into the ground as

text: infiltration

text: . Some water infiltrates deep into the ground and replenishes

text: aquifer

text: s, which can store freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies (and the ocean) as groundwater discharge. Some groundwater finds openings in the land surface and comes out as freshwater springs. In river valleys and floodplains, there is often continuous water exchange between surface water and ground water in the

text: hyporheic zone

text: . Over time, the water returns to the ocean, to continue the water cycle.

text: Lake Mataro has been identified in the northern Altiplano, where deposits from this stage are found at an altitude of . For comparison, Lake Cabana deposits are found at altitudes of  and Lake Ballivian at an altitude of . Both Mataro and Cabana were named by Lavenu and others in 1984. The height of Lake Mataro was  above that of Lake Titicaca. It formed a single large lake over the central and northern Altiplano. Progressive erosion of the outlet of Lake Titicaca may be responsible for the observed reduction of the levels of the northern paleolakes during time, as it allowed water from the northern lakes to spill into the southern ones.

text: Landforms visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as outflow channels, cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples, Ma'adim Vallis is  long, much greater than the Grand Canyon, with a width of  and a depth of  in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels are thought to have formed as recently as only a few million years ago. Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic networks of valleys are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by runoff resulting from precipitation in early Mars history. Subsurface water flow and groundwater sapping may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.

text: Landforms

text: visible on Mars strongly suggest that liquid water has existed on the planet's surface. Huge linear swathes of scoured ground, known as

text: outflow channels

text: , cut across the surface in about 25 places. These are thought to be a record of erosion caused by the catastrophic release of water from subsurface aquifers, though some of these structures have been hypothesized to result from the action of glaciers or lava. One of the larger examples,

text: Ma'adim Vallis

text: is  long, much greater than the Grand Canyon, with a width of  and a depth of  in places. It is thought to have been carved by flowing water early in Mars's history. The youngest of these channels are thought to have formed as recently as only a few million years ago. Elsewhere, particularly on the oldest areas of the Martian surface, finer-scale, dendritic

text: networks of valleys

text: are spread across significant proportions of the landscape. Features of these valleys and their distribution strongly imply that they were carved by

text: runoff

text: resulting from precipitation in early Mars history. Subsurface water flow and

text: groundwater sapping

text: may play important subsidiary roles in some networks, but precipitation was probably the root cause of the incision in almost all cases.

text: A blackwater river is a river with a deep, slow-moving channel flowing through forested swamps or wetlands.

text: A

text: blackwater river

text: is a river with a deep, slow-moving channel flowing through forested swamps or wetlands.

text: At the mouth of a river, the change in flow condition can cause the river to drop any sediment it is carrying. This sediment deposition can generate a variety of landforms, such as deltas, sand bars, spits, and tie channels.

text: At the mouth of a river, the change in flow condition can cause the river to drop any sediment it is carrying. This

text: sediment

text: deposition can generate a variety of

text: landform

text: s, such as

text: deltas

text: sand bar

text: s,

text: spit

text: s, and tie channels.

text: It is composed primarily of settled silt and debris from the Fraser River and shaped by the erosive power of the river.  Geologically it was (10000 years ago) a peninsula on the shore of what is now Maple Ridge.  Erosion wore down the peninsula until it became an island, although one much larger than the current McMillan Island.  Once there was a channel worn between this large island and the mainland, the water flow slowed and silt and debris settled on the south side of the island, eventually connecting it to what is now Fort Langley.  The water eventually broke a small section of the original island off, resulting in the current McMillan Island.

text: It is composed primarily of settled

text: silt

text: and debris from the Fraser River and shaped by the erosive power of the river.  Geologically it was (10000 years ago) a

text: peninsula

text: on the shore of what is now Maple Ridge.

text: Erosion

text: wore down the peninsula until it became an island, although one much larger than the current McMillan Island.  Once there was a channel worn between this large island and the mainland, the water flow slowed and silt and debris settled on the south side of the island, eventually connecting it to what is now Fort Langley.  The water eventually broke a small section of the original island off, resulting in the current McMillan Island.

text: About 450 million years ago sedimentary rocks were deposited as the land was intermittently covered by shallow seas that transgressed and regressed. Over the eons the alternating deposits of mud and oceanic debris were compressed to form limestone, shale and sandstone layers. Today these layers are  above sea level. Within the last 500,000 to 1,000,000 years, flood waters dissolved along fractures in the limestone bedrock to create most of the cave. Acidic rainwater also sculpted the land above and around the cave, creating thousands of sinkholes and other karst features in the surrounding county.

text: About 450 million years ago sedimentary rocks were deposited as the land was intermittently covered by shallow seas that transgressed and regressed. Over the eons the alternating deposits of mud and oceanic debris were compressed to form

text: limestone

text: shale

text: and

text: sandstone

text: layers. Today these layers are  above sea level. Within the last 500,000 to 1,000,000 years, flood waters dissolved along fractures in the limestone bedrock to create most of the cave. Acidic rainwater also sculpted the land above and around the cave, creating thousands of

text: sinkholes

text: and other karst features in the surrounding county.

text: The park's waterfalls expose two distinct rock formations from the Devonian and Carboniferous periods. The higher and more recent of these is the Huntley Mountain Formation, from the late Devonian and early Mississippian. This is made of layers of olive green to gray sandstone and gray to red shale. The lower and older layer is the Catskill Formation, which is composed of red shale and siltstone up to 370 million years old. The harder Huntley Mountain Formation caps the Allegheny Front and has kept it from eroding as much as the softer Catskill Formation to the south. The portions of the Allegheny Front within the park are named North Mountain and Red Rock Mountain, with the latter name coming from an exposed band of Huntley Formation red shale and sandstone visible along Pennsylvania Route 487.

text: The park's waterfalls expose two distinct rock formations from the

text: Devonian

text: and

text: Carboniferous

text: periods. The higher and more recent of these is the

text: Huntley Mountain Formation

text: , from the late Devonian and early

text: Mississippian

text: . This is made of layers of olive green to gray sandstone and gray to red shale. The lower and older layer is the

text: Catskill Formation

text: , which is composed of red shale and siltstone up to 370 million years old. The harder Huntley Mountain Formation caps the Allegheny Front and has kept it from eroding as much as the softer Catskill Formation to the south. The portions of the Allegheny Front within the park are named North Mountain and Red Rock Mountain, with the latter name coming from an exposed band of Huntley Formation red shale and sandstone visible along

text: Pennsylvania Route 487

text: The Arbuckle Mountains of south central Oklahoma contain intensely folded and faulted carbonate beds that have produced some of the highest densities of karst features found in the United States. Due to the nature of the uplifted beds, the Arbuckle Mountains contains a sequence of limestone ridges and shale valleys. This causes waterfalls to develop where creeks descend over a limestone ridge into a shale valley. Because the waters are rich in calcium carbonate dissolved from the karst system, large deposits of travertine have accumulated on the waterfalls where turbulence causes mineral precipitation. The most notable of these waterfalls is Turner Falls near the city of Davis.

text: The

text: Arbuckle Mountains

text: of south central Oklahoma contain intensely folded and faulted carbonate beds that have produced some of the highest densities of karst features found in the United States. Due to the nature of the uplifted beds, the Arbuckle Mountains contains a sequence of limestone ridges and shale valleys. This causes waterfalls to develop where creeks descend over a limestone ridge into a shale valley. Because the waters are rich in calcium carbonate dissolved from the karst system, large deposits of

text: travertine

text: have accumulated on the waterfalls where turbulence causes mineral precipitation. The most notable of these waterfalls is

text: Turner Falls

text: near the city of Davis.

text: These landforms are created by earth flow ("solifluction"). They can also be former river terraces that are subsequently bisected by fluvial erosion. In cases where there is a deposit of younger sedimentary beds (loess, colluvium) the interfluves have a rounder and less rugged appearance. A consequence of interfluve formation is the so-called "interfluvial landscape."

text: These landforms are created by

text: earth flow

text: solifluction

text: "). They can also be former

text: river terrace

text: s that are subsequently bisected by

text: fluvial erosion

text: . In cases where there is a deposit of younger sedimentary beds (

text: loess

text: colluvium

text: ) the interfluves have a rounder and less rugged appearance. A consequence of interfluve formation is the so-called "interfluvial landscape."

text: Floods (in particular more frequent or smaller floods) can also bring many benefits, such as recharging ground water, making soil more fertile and increasing nutrients in some soils. Flood waters provide much needed water resources in arid and semi-arid regions where precipitation can be very unevenly distributed throughout the year and kills pests in the farming land. Freshwater floods particularly play an important role in maintaining ecosystems in river corridors and are a key factor in maintaining floodplain biodiversity. Flooding can spread nutrients to lakes and rivers, which can lead to increased biomass and improved fisheries for a few years.

text: Floods (in particular more frequent or smaller floods) can also bring many benefits, such as recharging

text: ground water

text: , making soil more

text: fertile

text: and increasing

text: nutrient

text: s in some soils. Flood waters provide much needed water resources in

text: arid

text: and

text: semi-arid

text: regions where precipitation can be very unevenly distributed throughout the year and kills pests in the farming land. Freshwater floods particularly play an important role in maintaining

text: ecosystem

text: s in river corridors and are a key factor in maintaining floodplain

text: biodiversity

text: . Flooding can spread nutrients to lakes and rivers, which can lead to increased

text: biomass

text: and improved

text: fisheries

text: for a few years.

text: Technically, a body of water can have a water level higher than full pond when the inflow of water into the body greatly exceeds the outflow (such as during a heavy rain event), even if the body of water is not at full flood level.  Most lakes and reservoirs have the ability to lower the level of the lake even when it is already significantly below full.  This is used for flood prevention during periods of high (or potentially high) inflow to prevent flooding and to prevent water from breaching containment when it is expected the body of water will soon exceed full pond status.

text: Technically, a body of water can have a water level higher than full pond when the inflow of water into the body greatly exceeds the outflow (such as during a heavy rain event), even if the body of water is not at full

text: flood level

text: .  Most lakes and reservoirs have the ability to lower the level of the lake even when it is already significantly below full.  This is used for

text: flood prevention

text: during periods of high (or potentially high) inflow to prevent flooding and to prevent water from breaching containment when it is expected the body of water will soon exceed full pond status.

text: The sedimentation of the area directly contributed to the formation of the rockshelter. The bedrock is composed of Denver and Dawson formations, deposited in the late Cretaceous to Paleogene, and overlaid with Castle Rock conglomerate. The Castle Rock conglomerate is harder than the relatively soft Denver and Dawson formations. Groundwater moving between these two major layers erodes the lower, softer formations and leaves the harder Castle Rock conglomerate behind. Where these layers form outcrops, the same groundwater erosion may produce natural caves as seen in the Cherry Creek rockshelter.

text: The sedimentation of the area directly contributed to the formation of the rockshelter. The bedrock is composed of Denver and Dawson formations, deposited in the late

text: Cretaceous

text: to

text: Paleogene

text: , and overlaid with Castle Rock conglomerate. The Castle Rock conglomerate is harder than the relatively soft Denver and Dawson formations. Groundwater moving between these two major layers erodes the lower, softer formations and leaves the harder Castle Rock conglomerate behind. Where these layers form outcrops, the same groundwater erosion may produce natural caves as seen in the Cherry Creek rockshelter.

text: Among various failure mechanisms that cause levee breaches, soil erosion is found to be one of the most important factors . Predicting soil erosion and scour generation when overtopping happens is important in order to design stable levee and floodwalls. There have been numerous studies to investigate the erodibility of soils. Briaud et al. (2008)  used Erosion Function Apparatus (EFA) test to measure the erodibility of the soils and afterwards by using Chen 3D software, numerical simulations were performed on the levee to find out the velocity vectors in the overtopping water and the generated scour when the overtopping water impinges the levee. By analyzing the results from EFA test, an erosion chart to categorize erodibility of the soils was developed.  Hughes and Nadal in 2009  studied the effect of combination of wave overtopping and storm surge overflow on the erosion and scour generation in levees. The study included hydraulic parameters and flow characteristics such as flow thickness, wave intervals, surge level above levee crown in analyzing scour development. According to the laboratory tests, empirical correlations related to average overtopping discharge were derived to analyze the resistance of levee against erosion. These equations could only fit to the situation similar to the experimental tests while they can give a reasonable estimation if applied to other conditions.Osouli et al. (2014) and Karimpour et al. (2015) conducted lab scale physical modeling of levees to evaluate score characterization of different levees due to floodwall overtopping.

text: Among various failure mechanisms that cause

text: levee breach

text: es,

text: soil erosion

text: is found to be one of the most important factors . Predicting soil erosion and scour generation when overtopping happens is important in order to design stable levee and

text: floodwalls

text: . There have been numerous studies to investigate the

text: erodibility

text: of soils. Briaud et al. (2008)  used

text: Erosion Function Apparatus

text: (EFA) test to measure the erodibility of the soils and afterwards by using Chen 3D software,

text: numerical simulations

text: were performed on the levee to find out the velocity vectors in the overtopping water and the generated scour when the overtopping water impinges the levee. By analyzing the results from EFA test, an

text: erosion

text: chart to categorize erodibility of the soils was developed.  Hughes and Nadal in 2009  studied the effect of combination of wave overtopping and storm surge overflow on the erosion and scour generation in levees. The study included hydraulic parameters and flow characteristics such as flow thickness, wave intervals, surge level above levee crown in analyzing scour development. According to the laboratory tests, empirical correlations related to average overtopping discharge were derived to analyze the resistance of levee against erosion. These equations could only fit to the situation similar to the experimental tests while they can give a reasonable estimation if applied to other conditions.Osouli et al. (2014) and Karimpour et al. (2015) conducted lab scale physical modeling of levees to evaluate

text: score characterization

text: of different levees due to

text: floodwall

text: overtopping.

text: 80% of the water India receives through its annual rains and surface water flow, happens over a 4-month period – June through September. This spatial and time variance in availability of natural water versus year round demand for irrigation, drinking and industrial water creates a demand-supply gap, that only worsens with India's rising population. Proponents claim the answers to India's water problem is to conserve the abundant monsoon water bounty, store it in reservoirs, and use this water in areas which have occasional inadequate rainfall, or are known to be drought-prone or in those times of the year when water supplies become scarce.

text: Water enters the alps as snow or rain. Bogs and frost hollows collect the water as snow melt and run off. A key element of these bogs is Sphagnum Moss, which acts as a sponge, absorbing up to twenty times its weight in water. These bogs then release the water over summer, ensuring creeks flow throughout most of the year maintaining the alps’ creeks and streams. The greatest risk to this system is damage to the Sphagnum bogs. Trampling by feral animals (pigs, cattle, horses, humans) reduces their ability to absorb and then release water; instead of a steady release, water flows increase significantly in spring, leading to erosion and scouring of river beds, and ceases over summer and autumn, leading to localised drought. Fire can remove riparian vegetation, also increasing run-off and erosion.

text: The upper lakes in terms of the shape and size are usually small, at the beginning with small depth 1–3 m, while in the eighth lake reaches up to 6.5 m. Waters of the lakes move from one lake to another through straits, thresholds and deepening that have created waterfalls of different heights. It is characteristic of the upper lakes, the trend of deepening due to the free fall of water and erosion that cause these drops of water. the width of the upper canyon is small from the first lake where the water begins to create waterfalls and lakes in 0.50–1 m river width which up to the last lake (the eighth) reaches maximum width of 3 m. Another interesting feature is the sound of waterfalls because this part of the canyon is very narrow.

text: As the slope of the river channel decreases, it becomes unstable for two reasons. First, gravity makes the water flow in the most direct course down slope. If the river breaches its natural levees (i.e., during a flood), it spills out onto a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope. Second, as its slope gets lower, the amount of shear stress on the bed decreases, which results in deposition of sediment within the channel and a rise in the channel bed relative to the floodplain. This makes it easier for the river to breach its levees and cut a new channel that enters the body of standing water at a steeper slope. Often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a distributary network.

text: As the slope of the river channel decreases, it becomes unstable for two reasons. First, gravity makes the water flow in the most direct course down slope. If the river breaches its natural levees (i.e., during a flood), it spills out onto a new course with a shorter route to the ocean, thereby obtaining a more stable steeper slope. Second, as its slope gets lower, the amount of shear stress on the bed decreases, which results in deposition of sediment within the channel and a rise in the channel bed relative to the floodplain. This makes it easier for the river to breach its levees and cut a new channel that enters the body of standing water at a steeper slope. Often when the channel does this, some of its flow remains in the abandoned channel. When these channel-switching events occur, a mature delta develops a

text: distributary

text: network.

text: The Mount Meager massif is the most voluminous composite volcano in the Garibaldi chain and British Columbia, as well as the most recent to erupt. It has a volume of  and consists of an eroded stratovolcano, ranging in composition from andesite to rhyodacite. Several dissected lava domes and volcanic plugs are present on its glaciated summit, as well as a clearly defined volcanic crater with a lava dome placed within it. At least eight volcanic vents compose the complex and have been the sources for volcanic activity throughout Meager's 2.2 million year history.  A well-documented history of volcanism is present at Meager, with its most recent eruption about 2,350 years ago that was similar in character to the 1980 eruption of Mount St. Helens and the continuous eruption of Soufrière Hills on the island of Montserrat. This is the largest recorded Holocene explosive eruption in Canada, originating from a volcanic vent on the northeastern flank of Plinth Peak. It was Plinian in nature, sending an eruption column at least  high into the stratosphere. As prevailing winds carried ash of the column eastwards, it deposited across British Columbia and Alberta. Subsequent pyroclastic flows were sent down Meager's flanks for  and were later succeeded by the eruption of a lava flow that demolished many times. This created thick agglutinated rubble that successfully blocked the adjacent Lillooet River to form a lake. Subsequently, the breccia dam collapsed to produce a catastrophic flood that deposited house-sized boulders more than  downstream. After the flood took place, a small dacite lava flow was erupted that later solidified to form a series of well-preserved columnar joints. This is the last phase of the 2350 BP eruption, and subsequent stream erosion has cut though this lava flow to form a waterfall.

text: The Mount Meager massif is the most voluminous

text: composite volcano

text: in the Garibaldi chain and British Columbia, as well as the most recent to erupt. It has a volume of  and consists of an eroded stratovolcano, ranging in composition from andesite to rhyodacite. Several dissected lava domes and volcanic plugs are present on its glaciated summit, as well as a clearly defined

text: volcanic crater

text: with a lava dome placed within it. At least eight volcanic vents compose the complex and have been the sources for volcanic activity throughout Meager's 2.2 million year history.  A well-documented history of volcanism is present at Meager, with its most recent eruption about 2,350 years ago that was similar in character to the

text: 1980 eruption of Mount St. Helens

text: and the continuous eruption of

text: Soufrière Hills

text: on the island of

text: Montserrat

text: . This is the largest recorded Holocene explosive eruption in Canada, originating from a volcanic vent on the northeastern flank of

text: Plinth Peak

text: . It was Plinian in nature, sending an eruption column at least  high into the

text: stratosphere

text: . As prevailing winds carried ash of the column eastwards, it deposited across British Columbia and

text: Alberta

text: . Subsequent pyroclastic flows were sent down Meager's flanks for  and were later succeeded by the eruption of a lava flow that demolished many times. This created thick agglutinated rubble that successfully blocked the adjacent Lillooet River to form a lake. Subsequently, the breccia dam collapsed to produce a catastrophic flood that deposited house-sized boulders more than  downstream. After the flood took place, a small dacite lava flow was erupted that later solidified to form a series of well-preserved columnar joints. This is the last phase of the 2350 BP eruption, and subsequent stream erosion has cut though this lava flow to form a waterfall.

text: Groundwater may exist in underground rivers (e.g., caves where water flows freely underground). This may occur in eroded limestone areas known as karst topography, which make up only a small percentage of Earth's area. More usual is that the pore spaces of rocks in the subsurface are simply saturated with water — like a kitchen sponge — which can be pumped out for agricultural, industrial, or municipal uses.

text: Groundwater may exist in underground rivers (e.g.,

text: cave

text: s where water flows freely underground). This may occur in

text: eroded

text: limestone

text: areas known as

text: karst topography

text: , which make up only a small percentage of Earth's area. More usual is that the pore spaces of rocks in the subsurface are simply saturated with water — like a kitchen sponge — which can be

text: pump

text: ed out for agricultural, industrial, or municipal uses.

text: The Tekenteri cave is located at  above sea level. Its only entrance—the hole of a large beech tree—has no bottom but the karst sinkhole  deep, with a lake of cold, clean water. A water stream stemming from it flows through a horizontal passage to form a waterfall, judging by noises from the depths. There are many metal buckets and pitchers floating in the lake, suggesting that cave water had been used by locals for many years.

text: The Tekenteri cave is located at  above

text: sea level

text: . Its only entrance—the hole of a large beech tree—has no bottom but the karst sinkhole  deep, with a lake of cold, clean water. A water stream stemming from it flows through a horizontal passage to form a waterfall, judging by noises from the depths. There are many metal buckets and pitchers floating in the lake, suggesting that cave water had been used by locals for many years.

text: The out-flowing undersea of cold and salty water makes the sea level of the Atlantic slightly lower than the Pacific and salinity or halinity of water at the Atlantic higher than the Pacific. This generates a large but slow flow of warmer and fresher upper ocean water from the tropical Pacific to the Indian Ocean through the Indonesian Archipelago to replace the cold and salty Antarctic Bottom Water. This is also known as 'haline forcing' (net high latitude freshwater gain and low latitude evaporation). This warmer, fresher water from the Pacific flows up through the South Atlantic to Greenland, where it cools off and undergoes evaporative cooling and sinks to the ocean floor, providing a continuous thermohaline circulation.

text: The out-flowing undersea of cold and salty water makes the sea level of the Atlantic slightly lower than the Pacific and salinity or halinity of water at the Atlantic higher than the Pacific. This generates a large but slow flow of warmer and fresher upper ocean water from the tropical Pacific to the

text: Indian Ocean

text: through the

text: Indonesian Archipelago

text: to replace the cold and salty

text: Antarctic Bottom Water

text: . This is also known as 'haline forcing' (net high latitude freshwater gain and low latitude evaporation). This warmer, fresher water from the Pacific flows up through the

text: South Atlantic

text: to

text: Greenland

text: , where it cools off and undergoes

text: evaporative cooling

text: and sinks to the ocean floor, providing a continuous thermohaline circulation.

text: Until water flows out to sea, it must go somewhere. This meant flooding on unprotected low-lying land. The amount of land inundated, and the height of peak flood waters was difficult to project for three reasons:

text: If it were true that, around a bend in a stream, the difference between the speed of the water near one bank and the other was sufficient to cause deposition of suspended solids on one bank but not the other, the deposition would occur near the concave bank rather than the convex bank because vortex flow is slowest where the radius of curvature is greatest.  Any fluid, including water in a stream, can only flow around a bend in vortex flow.

text: If it were true that, around a bend in a stream, the difference between the speed of the water near one bank and the other was sufficient to cause deposition of suspended solids on one bank but not the other, the deposition would occur near the concave bank rather than the convex bank because

text: vortex

text: flow is slowest where the radius of curvature is greatest.  Any fluid, including water in a stream, can only flow around a bend in vortex flow.

text: An irrigation scheme draws water from groundwater, rivers,  lakes or overland flow, and distributes it over an area. Hydrological, or direct, effects of doing this include reduction in downstream river flow, increased evaporation in the irrigated area, increased level in the water table as groundwater recharge in the area is increased and flow increased in the irrigated area. Likewise, irrigation has immediate effects on the provision of moisture to the atmosphere, inducing atmospheric instabilities and increasing downwind rainfall, or in other cases modifies the atmospheric circulation, delivering rain to different downwind areas. Increases or decreases in irrigation are a key area of concern in precipitationshed studies, that examine how significant modifications to the delivery of evaporation to the atmosphere can alter downwind rainfall.

text: An

text: irrigation scheme

text: draws water from groundwater,

text: river

text: s,

text: lake

text: s or

text: overland flow

text: , and distributes it over an area.

text: Hydrological

text: , or direct, effects of doing this include reduction in downstream river flow, increased

text: evaporation

text: in the irrigated area, increased level in the

text: water table

text: as

text: groundwater recharge

text: in the area is increased and flow increased in the irrigated area. Likewise, irrigation has immediate effects on the provision of moisture to the atmosphere, inducing atmospheric instabilities and increasing downwind rainfall, or in other cases modifies the atmospheric circulation, delivering rain to different downwind areas. Increases or decreases in irrigation are a key area of concern in

text: precipitationshed

text: studies, that examine how significant modifications to the delivery of evaporation to the atmosphere can alter downwind rainfall.

text: Due to the substantial amount of annual rainfall of the region and the action of the Cumberland River and surrounding tributaries the water acts to erode the softer Mississippian rock composed of limestone, shale, and calcareous sandstone from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone.   Flowing water hollows out the softer layers beneath and forms waterfalls and gorges.  Where there is hard capstone intact, arches can form creating natural bridges across streams or a dry ravines.  Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below.  As result, water eroded arches are formed in the Big South Fork.  Hoodoos are a rare but intriguing feature occurring in the Big South Fork.  These hoodoos form in a similar manner to those found in the western United States.  Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below.  The result is a naturally formed erect columnar rock where once was located a hill.

text: Due to the substantial amount of annual rainfall of the region and the action of the

text: Cumberland River

text: and surrounding tributaries the water acts to erode the softer Mississippian rock composed of

text: limestone

text: shale

text: , and calcareous

text: sandstone

text: from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone.   Flowing water hollows out the softer layers beneath and forms waterfalls and gorges.  Where there is hard capstone intact, arches can form creating natural bridges across streams or a dry ravines.  Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below.  As result, water eroded arches are formed in the Big South Fork.

text: Hoodoos

text: are a rare but intriguing feature occurring in the Big South Fork.  These hoodoos form in a similar manner to those found in the western United States.  Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below.  The result is a naturally formed erect columnar rock where once was located a hill.

text: Channelization of a stream may be undertaken for several reasons. One is to make a stream more suitable for navigation or for navigation by larger vessels with deep draughts. Another is to restrict water to a certain area of a stream's natural bottom lands so that the bulk of such lands can be made available for agriculture. A third reason is flood control, with the idea of giving a stream a sufficiently large and deep channel so that flooding beyond those limits will be minimal or nonexistent, at least on a routine basis. One major reason is to reduce natural erosion; as a natural waterway curves back and forth, it usually deposits sand and gravel on the inside of the corners where the water flows slowly, and cuts sand, gravel, subsoil, and precious topsoil from the outside corners where it flows rapidly due to a change in direction. Unlike sand and gravel, the topsoil that is eroded does not get deposited on the inside of the next corner of the river. It simply washes away.

text: Channelization of a stream may be undertaken for several reasons. One is to make a stream more suitable for navigation or for navigation by larger vessels with deep draughts. Another is to restrict water to a certain area of a stream's natural bottom lands so that the bulk of such lands can be made available for agriculture. A third reason is flood control, with the idea of giving a stream a sufficiently large and deep channel so that flooding beyond those limits will be minimal or nonexistent, at least on a routine basis. One major reason is to reduce natural

text: erosion

text: ; as a natural waterway curves back and forth, it usually deposits

text: sand

text: and

text: gravel

text: on the inside of the corners where the water flows slowly, and cuts sand, gravel,

text: subsoil

text: , and precious

text: topsoil

text: from the outside corners where it flows rapidly due to a change in direction. Unlike sand and gravel, the topsoil that is eroded does not get deposited on the inside of the next corner of the river. It simply washes away.

text: The additional water flowing down the capturing stream may accelerate erosion and encourage the development of a canyon (gorge).

text: The additional water flowing down the capturing stream may accelerate

text: erosion

text: and encourage the development of a

text: canyon

text: (gorge).

text: Thang Hen Mountain lake, in Trà Lĩnh district, consists of 36 small natural lakes located on the top of a hill at  elevation. The lakes have been created in limestone formations and some of them flow out as steams. An unusual feature of the lakes is that their water level fluctuates like the tides of the seas, which phenomenon is attributed to the springs of water emerging from artesian wells in lime stone formations. The lakes flow through the river, which eventually becomes the Ban Gioc waterfall.

text: The plot shows several key concepts about the relationships between erosion, transportation, and deposition. For particle sizes where friction is the dominating force preventing erosion, the curves follow each other closely and the required velocity increases with particle size. However, for cohesive sediment, mostly clay but also silt, the erosion velocity increases with decreasing grainsize, as the cohesive forces are relatively more important when the particles get smaller. The critical velocity for deposition, on the other hand, depends on the settling velocity, and that decreases with decreasing grainsize. The Hjulström curve shows that sand particles of a size around 0.1 mm require the lowest stream velocity to erode.

text: The plot shows several key concepts about the relationships between erosion, transportation, and deposition. For particle sizes where friction is the dominating force preventing erosion, the curves follow each other closely and the required velocity increases with particle size. However, for

text: cohesive

text: sediment, mostly

text: clay

text: but also

text: silt

text: , the erosion velocity increases with decreasing

text: grainsize

text: , as the cohesive forces are relatively more important when the particles get smaller. The critical velocity for deposition, on the other hand, depends on the

entity_section: Terminal velocity in the presence of buoyancy force

text: settling velocity

text: , and that decreases with decreasing grainsize. The Hjulström curve shows that sand particles of a size around 0.1 mm require the lowest stream velocity to erode.

text: German engineers have also devoted special attention to the measurement of the flow in rivers; the Beiträge zur Hydrographie des Königreiches Bohmen (Prague, 1872–1875) of AR Harlacher contained valuable measurements of this kind, together with a comparison of the experimental results with the formulae of flow that had been proposed up to the date of its publication, and important data were yielded by the gaugings of the Mississippi made for the United States government by AA Humphreys and HL Abbot, by Robert Gordon's gaugings of the Ayeyarwady River, and by Allen JC Cunningham's experiments on the Ganges canal. The friction of water, investigated for slow speeds by Coulomb, was measured for higher speeds by William Froude (1810–1879), whose work is of great value in the theory of ship resistance (Brit. Assoc. Report., 1869), and stream line motion was studied by Professor Osborne Reynolds and by Professor HS Hele-Shaw.

text: German engineers have also devoted special attention to the measurement of the flow in rivers; the Beiträge zur Hydrographie des Königreiches Bohmen (Prague, 1872–1875) of

text: AR Harlacher

text: contained valuable measurements of this kind, together with a comparison of the experimental results with the formulae of flow that had been proposed up to the date of its publication, and important data were yielded by the gaugings of the

text: Mississippi

text: made for the United States government by

text: AA Humphreys

text: and

text: HL Abbot

text: , by

text: Robert Gordon

text: 's gaugings of the

text: Ayeyarwady River

text: , and by Allen JC Cunningham's experiments on the

text: Ganges

text: canal. The friction of water, investigated for slow speeds by

text: Coulomb

text: , was measured for higher speeds by

text: William Froude

text: (1810–1879), whose work is of great value in the theory of ship resistance (Brit. Assoc. Report., 1869), and stream line motion was studied by

text: Professor Osborne Reynolds

text: and by

text: Professor HS Hele-Shaw

text: The action of the groundwater continually dissolves permeable bedrock such as limestone and dolomite, creating vast cave systems.

text: The action of the groundwater continually dissolves permeable bedrock such as

text: limestone

text: and

text: dolomite

text: , creating vast cave systems.

text: The massive amounts of sediment deposited by the Lake Bonneville Floods in the Snake River Plain also had a lasting effect on most of the middle Snake River. The high hydraulic conductivity of the mostly-basalt rocks in the plain led to the formation of the Snake River Aquifer, one of the most productive aquifers in North America. Many rivers and streams flowing from the north side of the plain sink into the aquifer instead of flowing into the Snake River, a group of watersheds called the lost streams of Idaho. The aquifer filled to hold nearly  of water, underlying about  in a plume  thick. In places, water exits from rivers at rates of nearly . Much of the water lost by the Snake River as it transects the plain issues back into the river at its western end, by way of many artesian springs.

text: The massive amounts of sediment deposited by the Lake Bonneville Floods in the Snake River Plain also had a lasting effect on most of the middle Snake River. The high

text: hydraulic conductivity

text: of the mostly-

text: basalt

text: rocks in the plain led to the formation of the

text: Snake River Aquifer

text: , one of the most productive aquifers in North America. Many rivers and streams flowing from the north side of the plain sink into the aquifer instead of flowing into the Snake River, a group of watersheds called the

text: lost streams of Idaho

text: . The aquifer filled to hold nearly  of water, underlying about  in a plume  thick. In places, water exits from rivers at rates of nearly . Much of the water lost by the Snake River as it transects the plain issues back into the river at its western end, by way of many

text: artesian

text: spring

text: s.

text: Only one size of particle is considered in this equation. However, river beds are often formed by a mixture of sediment of various sizes. In case of partial motion where only a part of the sediment mixture moves, the river bed becomes enriched in large gravel as the smaller sediments are washed away. The smaller sediments present under this layer of large gravel have a lower possibility of movement and total sediment transport decreases. This is called armouring effect. Other forms of armouring of sediment or decreasing rates of sediment erosion can be caused by carpets of microbial mats, under conditions of high organic loading.

text: Of particular note is the Moncodeno, an extensive natural amphitheater located on the north of the northern Grigna at an altitude of between  and , characterised by the presence of a large number of sinkholes (depressions in the ground) and almost 500 caves, formed by the combined action of the karst and erosion by ice that covered the area during the ice ages. In one of these caves, the Icebox of Moncodeno, are deposits of underground ice.

text: Of particular note is the Moncodeno, an extensive natural amphitheater located on the north of the northern Grigna at an altitude of between  and , characterised by the presence of a large number of

text: sinkhole

text: s (depressions in the ground) and almost 500 caves, formed by the combined action of the karst and erosion by ice that covered the area during the ice ages. In one of these caves, the Icebox of Moncodeno, are deposits of underground ice.

text: A foreset bed is one of the main parts of a river delta. It is the inclined part of a delta that is found at the end of the stream channel as the delta sediment is deposited along the arcuate delta front. As the sediments are deposited on a sloping surface the resulting bedding is not horizontal, but dips in the direction of current flow toward deeper water. A cross-section of a delta shows the cross bedding in the direction of stream flow into the still water.

text: A foreset bed is one of the main parts of a

text: river delta

text: . It is the inclined part of a delta that is found at the end of the stream channel as the delta

text: sediment

text: is deposited along the

text: arcuate delta

text: front. As the sediments are deposited on a sloping surface the resulting bedding is not horizontal, but

text: dips

text: in the direction of current flow toward deeper water. A cross-section of a delta shows the

text: cross bedding

text: in the direction of stream flow into the still water.

text: Major Rod-Kohi areas traversed by hill torrents constitute nearly 65 percent of the total area of Pakistan and encompass entire Balochistan i.e. (Makran coastal Basin and Kharan closed Desert Basin). The other major hill torrent areas include D.G.Khan and D.I.Khan, FATA and AJK. In Sindh province, the systems are spread in Dadu district (Kirthar range). There are around  as the potential area under hill torrent / Rod-Kohi / Sailaba fanning excluding riverine areas.Indigenous Spate Irrigation/ hill torrent-irrigation systems traditionally called Rod-Kohi. Rod means water channel and Kohi pertains to mountains. In these areas major constraint is the use of flood flow which is highly variable in quantity and distribution, both in time and space. Annual rainfall is low, uncertain and patchy. Flow is laden with high silt in each flood. It is unfortunate that in spite of scarcity of water, major part of flood flows is lost due to mismanagement. Spate irrigation often takes place in environments that are arid and remote. Poverty in these areas is a major issue. There are very few options for generating income and improvement of livelihood. Abject poverty in the areas affected by the Rod-Kohi water calls for a rational and scientific management of flood flows.

text: Becker concluded the sulfur of Sulphur Bank was deposited after the cinnabar had been deposited, because he could find no evidence of acid farther than  below the surface of the mine. He wrote the acid would have thrown the cinnabar down, instead of migrating up with the sulfur through the basalt rock which covered the mine site.But Becker was mystified when the water of the flooded shaft was tested and it contained no quicksilver: "The absence of mercury from these waters was not a little perplexing," he wrote.

text: Cliff Cave, also known as Indian Cave, is a natural cave that is considered the second longest cave in St. Louis County, with 4723 ft (1514 m) of cave passage surveyed. It is found at the head of a ravine, with a stream flowing from the entrance. It is developed in Mississippian Period St. Louis limestone. The cave maintains a temperature of  all year round. The cave was created from the karst plateau in the area forming many sinkholes, dissolving the dolomite/limestone bedrock over time. The cave is connected to a number of these sinkholes, causing the cave to be susceptible to flash flooding.

text: Cliff Cave, also known as Indian Cave, is a natural cave that is considered the second longest cave in St. Louis County, with 4723 ft (1514 m) of cave passage surveyed. It is found at the head of a

text: ravine

text: , with a stream flowing from the entrance. It is developed in

text: Mississippian Period

text: St. Louis limestone

text: . The cave maintains a temperature of  all year round. The cave was created from the

text: karst

text: plateau

text: in the area forming many

text: sinkhole

text: s, dissolving the

text: dolomite

text: /limestone

text: bedrock

text: over time. The cave is connected to a number of these sinkholes, causing the cave to be susceptible to

text: flash flood

text: ing.

text: The policy also deals with participation of farmers and voluntary agencies, water quality, water zoning, conservation of water, flood and drought management, erosion etc.

text: Floodgates, also called stop gates, are adjustable gates used to control water flow in flood barriers, reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and canals, or they may be designed to stop water flow entirely as part of a levee or storm surge system. Since most of these devices operate by controlling the water surface elevation being stored or routed, they are also known as crest gates. In the case of flood bypass systems, floodgates sometimes are also used to lower the water levels in a main river or canal channels by allowing more water to flow into a flood bypass or detention basin when the main river or canal is approaching a flood stage.

text: Floodgates, also called stop gates, are adjustable gates used to control water flow in

text: flood barrier

text: s,

text: reservoir

text: river

text: stream

text: , or

text: levee

text: systems. They may be designed to set

text: spillway

text: crest heights in

text: dam

text: s, to adjust flow rates in

text: sluice

text: s and

text: canals

text: , or they may be designed to stop water flow entirely as part of a levee or

text: storm surge

text: system. Since most of these devices operate by controlling the water surface elevation being stored or routed, they are also known as crest gates. In the case of flood bypass systems, floodgates sometimes are also used to lower the water levels in a main river or canal channels by allowing more water to flow into a flood bypass or

text: detention basin

text: when the main river or canal is approaching a flood stage.

text: Lake Manly left behind many deposits, indicating the range of its waters. Geologists have discovered 30 distinct deposits. The deposits range from strandlines to shoreline gravel to spit and bar complexes, among others. The numerous features span Death Valley from north to south, but are primarily located on the eastern side. Despite how far ranging the features are, the record of deposition is far more incomplete than other Pleistocene pluvial lakes such as Lake Bonneville or Lake Lahontan. Deposits from Lake Manly are often only partially intact because they have been affected by erosion or faulting. The depositional features provide insight into Lake Manly's history and expand the geologic understanding of the region.

text: Lake Manly left behind many deposits, indicating the range of its waters. Geologists have discovered 30 distinct deposits. The deposits range from strandlines to shoreline gravel to spit and bar complexes, among others. The numerous features span Death Valley from north to south, but are primarily located on the eastern side. Despite how far ranging the features are, the record of deposition is far more incomplete than other

text: Pleistocene

text: pluvial lakes such as

text: Lake Bonneville

text: or

text: Lake Lahontan

text: . Deposits from Lake Manly are often only partially intact because they have been affected by erosion or faulting. The depositional features provide insight into Lake Manly's history and expand the geologic understanding of the region.

text: Wetter and cooler conditions developed during the Pleistocene epoch and briefly returned via at least two neoglacial episodes (little ice ages) in the current epoch, the Holocene. The various rivers and streams in the area were engorged by increased precipitation and with melt-water from mountain glaciers on the Henry Mountains to the east and the Aquarius Plateau to the west of the park. Flash floods, mass wasting of hillsides, frost wedging, and landslides all contributed to a significantly faster rate of erosion. Glaciers plucked 20- to 30-million-year-old black basaltic boulders from atop Boulder and Thousand Lake Mountains that were subsequently deposited over the park area by meltwater streams from the glaciers, rockslides and floods.

text: Wetter and cooler conditions developed during the

text: Pleistocene

text: epoch and briefly returned via at least two neoglacial episodes (

text: little ice age

text: s) in the current epoch, the

text: Holocene

text: . The various rivers and streams in the area were engorged by increased precipitation and with melt-water from mountain

text: glacier

text: s on the

text: Henry Mountains

text: to the east and the

text: Aquarius Plateau

text: to the west of the park.

text: Flash flood

text: s,

text: mass wasting

text: of hillsides,

text: frost wedging

text: , and

text: landslide

text: s all contributed to a significantly faster rate of

text: erosion

text: . Glaciers plucked 20- to 30-million-year-old black basaltic boulders from atop

text: Boulder

text: and

text: Thousand Lake Mountain

text: s that were subsequently deposited over the park area by meltwater streams from the glaciers, rockslides and

text: flood

text: s.

text: Hydraulic action is erosion that occurs when the motion of water against a rock surface produces mechanical weathering. Most generally, it is the ability of moving water (flowing or waves) to dislodge and transport rock particles.  Within this rubric are a number of specific erosional processes, including abrasion, attrition, corrasion, saltation, and scouring (downcutting).  Hydraulic action is distinguished from other types of water facilitated erosion, such as static erosion where water leaches salts and floats off organic material from unconsolidated sediments, and from chemical erosion more often called chemical weathering.It is a mechanical process, in which the moving water current flows against the banks and bed of a river, thereby removing rock particles.

text: Hydraulic action is erosion that occurs when the motion of water against a rock surface produces mechanical weathering. Most generally, it is the ability of moving water (flowing or waves) to dislodge and transport rock particles.  Within this

text: rubric

text: are a number of specific erosional processes, including

text: abrasion

text: , attrition,

text: corrasion

text: , saltation, and scouring (

text: downcutting

text: ).  Hydraulic action is distinguished from other types of water facilitated erosion, such as static erosion where water leaches salts and floats off organic material from unconsolidated sediments, and from chemical erosion more often called

text: chemical weathering

text: .It is a mechanical process, in which the moving water current flows against the banks and bed of a river, thereby removing rock particles.

text: The year 1784 wrought catastrophe throughout Europe, and brought the river Moselle its greatest ever flood. On 9 February 1784, Pünderich’s lower village was particularly gravely stricken. After the frightful ice flows from 24 to 26 February, the Moselle’s waters rose until on 29 February, the flood reached the high water mark set in the 1740 flood, eventually exceeding it by three Schuh (roughly a metre). The flood also deposited sediments in many places, causing lasting problems.

text: The year 1784 wrought catastrophe throughout

text: Europe

text: , and brought the river Moselle its greatest ever flood. On 9 February 1784, Pünderich’s lower village was particularly gravely stricken. After the frightful ice flows from 24 to 26 February, the Moselle’s waters rose until on 29 February, the flood reached the high water mark set in the 1740 flood, eventually exceeding it by three Schuh (roughly a metre). The flood also deposited sediments in many places, causing lasting problems.

text: The Jing River flows for , with a basin area of . The river's flow varies greatly throughout the year, and soil erosion causes serious problems in its basin. Summer floods cause the Jing to be laden with sediment; in the dry season, the river flows with relatively clear water.

text: The Jing River flows for , with a basin area of . The river's flow varies greatly throughout the year, and

text: soil erosion

text: causes serious problems in its basin. Summer floods cause the Jing to be laden with sediment; in the dry season, the river flows with relatively clear water.

text: Karst topography is found throughout the Driftless area. This is characterized by caves and cave systems, disappearing streams, blind valleys, underground streams, sinkholes, springs, and cold streams. Disappearing streams occur where surface waters sinks down into the earth through fractured bedrock or a sinkhole, either joining an aquifer, or becoming an underground stream. Blind valleys are formed by disappearing streams and lack an outlet to any other stream. Sinkholes are the result of the collapse of the roof of a cave, and surface water can flow directly into them. Disappearing streams can re-emerge as large cold springs. Cold streams with cold springs as their sources are noted as superb trout habitat.

text: Karst topography

text: is found throughout the Driftless area. This is characterized by

text: cave

text: s and cave systems,

text: disappearing stream

text: s,

text: blind valley

text: s,

text: underground streams

text: sinkhole

text: s,

text: springs

text: , and cold streams. Disappearing streams occur where surface waters sinks down into the earth through fractured bedrock or a sinkhole, either joining an

text: aquifer

text: , or becoming an underground stream. Blind valleys are formed by disappearing streams and lack an outlet to any other stream. Sinkholes are the result of the collapse of the roof of a cave, and surface water can flow directly into them. Disappearing streams can re-emerge as large cold springs. Cold streams with cold springs as their sources are noted as superb

text: trout

text: habitat.

text: Urbanization increases surface runoff by creating more impervious surfaces such as pavement and buildings that do not allow percolation of the water down through the soil to the aquifer. It is instead forced directly into streams or storm water runoff drains, where erosion and siltation can be major problems, even when flooding is not. Increased runoff reduces groundwater recharge, thus lowering the water table and making droughts worse, especially for farmers and others who depend on the water wells.

text: Urbanization

text: increases surface runoff by creating more

text: impervious surface

text: s such as

text: pavement

text: and buildings that do not allow

text: percolation

text: of the water down through the soil to the

text: aquifer

text: . It is instead forced directly into streams or

text: storm water runoff drains

text: , where

text: erosion

text: and

text: siltation

text: can be major problems, even when flooding is not. Increased runoff reduces

text: groundwater

text: recharge, thus lowering the

text: water table

text: and making

text: drought

text: s worse, especially for farmers and others who depend on the

text: water well

text: s.

text: This erosion also deepened the channel draining one of the largest desert wetlands in the U.S. southwest as the water flowed down the channel rather than flooding the wetlands area.  This has had several consequences among them, increased flows of silt into Lake Mead, fewer migratory birds, reduced water polishing from the native plants, and infestation of invasive plant species such as African Tamarisk (Tamarix africana) and Sahara Mustard (Brassica tournefortii).

text: This erosion also deepened the channel draining one of the largest desert

text: wetland

text: s in the

text: U.S.

text: southwest

text: as the water flowed down the channel rather than flooding the wetlands area.  This has had several consequences among them, increased flows of silt into Lake Mead, fewer

text: migratory bird

text: s, reduced

text: water polishing

text: from the native plants, and infestation of invasive plant species such as African

text: Tamarisk

text: (Tamarix africana) and Sahara Mustard (

text: Brassica tournefortii

text: While the Horseshoe Falls absorbed the extra flow, the U.S. Army Corps of Engineers studied the riverbed and mechanically bolted and strengthened any faults they found; faults that would, if left untreated, have hastened the retreat of the American Falls. A plan to remove the huge mound of talus deposited in 1954 was abandoned owing to cost, and in November 1969, the temporary dam was dynamited, restoring flow to the American Falls. Even after these undertakings, Luna Island, the small piece of land between the main waterfall and the Bridal Veil, remained off limits to the public for years owing to fears that it was unstable and could collapse into the gorge.

text: While the Horseshoe Falls absorbed the extra flow, the

text: U.S. Army Corps of Engineers

text: studied the riverbed and mechanically bolted and strengthened any faults they found; faults that would, if left untreated, have hastened the retreat of the American Falls. A plan to remove the huge mound of

text: talus

text: deposited in 1954 was abandoned owing to cost, and in November 1969, the temporary dam was

text: dynamite

text: d, restoring flow to the American Falls. Even after these undertakings,

text: Luna Island

text: , the small piece of land between the main waterfall and the Bridal Veil, remained off limits to the public for years owing to fears that it was unstable and could collapse into the gorge.

text: The lakes are seasonally flooded with alkaline water in most years, drying out in the summer. Annual precipitation in the basin ranges from . The average annual runoff is , which occurs mainly between March and June as snowmelt. This is enough to flood the lake beds  deep; however, most of the water is either appropriated for irrigation, or evaporates in the desert heat. Formed by erosion during the Pleistocene, the alluvial deposits that make up the lake beds are up to  deep at Middle Alkali Lake and hold significant amounts of groundwater. The  Surprise Valley Groundwater Basin has an estimated volume of .

text: The lakes are seasonally flooded with alkaline water in most years, drying out in the summer. Annual precipitation in the basin ranges from . The average annual runoff is , which occurs mainly between March and June as snowmelt. This is enough to flood the lake beds  deep; however, most of the water is either appropriated for irrigation, or evaporates in the desert heat. Formed by erosion during the

text: Pleistocene

text: , the

text: alluvial

text: deposits that make up the lake beds are up to  deep at Middle Alkali Lake and hold significant amounts of

text: groundwater

text: . The  Surprise Valley Groundwater Basin has an estimated volume of .

text: The crater's rim is cut with gullies, and at the end of some gullies are fan-shaped deposits of material transported by water.   The crater is of great interest to scientists because it has some of the best-exposed lake deposits.  One of the layers has been found by the Mars Reconnaissance Orbiter to contain clays.Clays only form in the presence of water. There are two unit of sediments in the crater.  The lower unit formed in a large lake.  It is believed the lake waters originated from the crater walls/or groundwater.  Water from the crater walls may have come from precipitation when the Martian climate was different.  The upper unit formed when water that was ponded to the south in Uzboi Vallis broke through Holden's rim.   It is believed that great amount of water went through the rim; one flow was caused by  a body of water larger than Earth's Lake Huron.  Some of the evidence for such a large flow of water is the presence of boulders tens of meters in size sticking above the surface.  To transport such huge rocks takes a great deal of water.

text: The crater's rim is cut with

text: gullies

text: , and at the end of some gullies are fan-shaped deposits of material transported by water.   The crater is of great interest to scientists because it has some of the best-exposed lake deposits.  One of the layers has been found by the

text: Mars Reconnaissance Orbiter

text: to contain

text: clay

text: s.Clays only form in the presence of water. There are two unit of sediments in the crater.  The lower unit formed in a large lake.  It is believed the lake waters originated from the crater walls/or groundwater.  Water from the crater walls may have come from precipitation when the Martian climate was different.  The upper unit formed when water that was ponded to the south in

text: Uzboi Vallis

text: broke through Holden's rim.   It is believed that great amount of water went through the rim; one flow was caused by  a body of water larger than Earth's

text: Lake Huron

text: .  Some of the evidence for such a large flow of water is the presence of boulders tens of meters in size sticking above the surface.  To transport such huge rocks takes a great deal of water.

text: Songdalselva (also known as Sogna / Sogne / Sygna / Søgneelva) is a river that originates in Finsland in Songdalen municipality, Vest-Agder, Norway. The catchment area is located between Otra's and Mandalselva's watersheds. The highest hills in the catchment area goes up to   above sea level. Water flows are normally at its lowest in summer and highest in autumn and spring. There are only a few and small lakes in the river system. The steep slopes down from the moors can create short and intense flood rapids. The river flows through the valley Stallemodalen in Vennesla, and falls into Songdalen through a gorge at Underåsen. Here it receives more water from the right from the Gumpedalselva tributary. The river drops no more than about  over the last  to the river mouth, and has on this stretch a very meandering run. By Søgne Landbruksskole is a few meters high waterfall, Søgne waterfall. From the waterfall to the sea the river is called the Søgneelva.  Songdalselva flows into the sea between Høllen and Åros in Høllefjorden in Søgne municipality.

text: Songdalselva (also known as Sogna / Sogne / Sygna / Søgneelva) is a

text: river

text: that originates in

text: Finsland

text: in

text: Songdalen

text: municipality,

text: Vest-Agder

text: Norway

text: . The catchment area is located between

text: Otra

text: 's and

text: Mandalselva

text: 's watersheds. The highest hills in the catchment area goes up to   above sea level. Water flows are normally at its lowest in summer and highest in autumn and spring. There are only a few and small lakes in the river system. The steep slopes down from the moors can create short and intense flood rapids. The river flows through the valley Stallemodalen in

text: Vennesla

text: , and falls into Songdalen through a

text: gorge

text: at Underåsen. Here it receives more water from the right from the Gumpedalselva

text: tributary

text: . The river drops no more than about  over the last  to the river mouth, and has on this stretch a very

text: meander

text: ing run. By Søgne Landbruksskole is a few meters high waterfall, Søgne waterfall. From the waterfall to the sea the river is called the Søgneelva.  Songdalselva flows into the sea between

text: Høllen

text: and

text: Åros

text: in Høllefjorden in

text: Søgne

text: municipality.

text: Water near the surface of the hillside can cause the erosion of surface material due to water runoff. This process tends to weaken the slope by removing material and triggering excess pore pressures due to the water flow.

text: The decision to employ the Schwimmtor depended on the level of the water at the Ferdinandsbrücke (today the Schwedenbrücke). When the Danube flooded, ballast was loaded onto the barrier to make it sit deeper in the water, although it was essential that it never completely blocked the flow of the canal. The amount of ballast on board therefore had to be constantly adjusted as the level of the water in the Danube rose and fell.

text: The decision to employ the Schwimmtor depended on the level of the water at the Ferdinandsbrücke (today the

text: Schwedenbrücke

text: ). When the Danube flooded, ballast was loaded onto the barrier to make it sit deeper in the water, although it was essential that it never completely blocked the flow of the canal. The amount of ballast on board therefore had to be constantly adjusted as the level of the water in the Danube rose and fell.

text: Sedimentation began in the Caradoc (upper Ordovician, ).  During the Llandovery, the Stockdale Supergroup is marked by a number of oxic-anoxic transitions, with black shales corresponding to transgressions - these may have helped to mitigate a runaway greenhouse effect.The rate of sediment accumulation accelerated with time; it held fairly steady at a low ~50 metres per million years (m/Ma) until the Wenlock (mid Silurian, ), when it increased greatly, eventually reaching over 1000 m/Ma when the record is terminated by erosion in the Pridoli (terminal Silurian, ).  This sudden upturn in deposition rate is a result of the increasing proximity of the Avalon mountain belt, which started to depress the plate from the Ordovician, but was not close enough to increase the sedimentary input until the Silurian.  The latest phase of sedimentation reflected a change in the basin's state.  Instead of being underfilled, and trapping all sediment that flowed into it, it became overfilled. This was reflected by a shallowing of water depth, as the basin silted up. This culminated with a transition to terrestrial conditions in the Přídolí.

text: Sedimentation began in the Caradoc (upper Ordovician, ).  During the Llandovery, the Stockdale Supergroup is marked by a number of oxic-

text: anoxic

text: transitions, with black shales corresponding to transgressions - these may have helped to mitigate a

text: runaway greenhouse effect

text: .The rate of sediment accumulation accelerated with time; it held fairly steady at a low ~50 metres per million years (m/Ma) until the Wenlock (mid Silurian, ), when it increased greatly, eventually reaching over 1000 m/Ma when the record is terminated by erosion in the Pridoli (terminal Silurian, ).  This sudden upturn in deposition rate is a result of the increasing proximity of the Avalon mountain belt, which started to depress the plate from the Ordovician, but was not close enough to increase the sedimentary input until the Silurian.  The latest phase of sedimentation reflected a change in the basin's state.  Instead of being underfilled, and trapping all sediment that flowed into it, it became overfilled. This was reflected by a shallowing of water depth, as the basin silted up. This culminated with a transition to terrestrial conditions in the Přídolí.

text: Sediments are moved by moving water and wind according to their particle size and state of compaction. Particles tend to settle and compact in still water.  Once compacted, they are more resistant to erosion.  Established vegetation (especially species with complex network root systems) will resist erosion by slowing the fluid flow at the surface layer.

text: Rivers are parts of integrated systems that include floodplains and riparian corridors.  Collectively these systems provide a large suite of benefits.  However, the world's rivers are increasingly being altered through the construction of dams, diversions, and levees. More than half of the world's large rivers are dammed, a figure that continues to increase.  Almost 1,000 dams are planned or under construction in South America and 50 new dams are planned on China's Yangtze River alone.  Dams and other river structures change the downstream flow patterns and consequently affect water quality, temperature, sediment movement and deposition, fish and wildlife, and the livelihoods of people who depend on healthy river ecosystems. Environmental flows seek to maintain these river functions while at the same time providing for traditional offstream benefits.

text: Rivers are parts of integrated systems that include

text: floodplains

text: and

text: riparian corridor

text: s.  Collectively these systems provide a large suite of benefits.  However, the world's rivers are increasingly being altered through the construction of dams, diversions, and

text: levee

text: s. More than half of the world's large rivers are dammed, a figure that continues to increase.  Almost 1,000 dams are planned or under construction in South America and 50 new dams are planned on China's Yangtze River alone.  Dams and other river structures change the downstream flow patterns and consequently affect water quality, temperature, sediment movement and deposition, fish and wildlife, and the livelihoods of people who depend on healthy river ecosystems. Environmental flows seek to maintain these river functions while at the same time providing for traditional offstream benefits.

text: Heavy rains fell in December 1999 along the north-central coast of Venezuela, culminating in a period of extreme intensity from 14 to 16 December. Starting around 8 PM local time (AST) on 15 December, runoff entered channels and rushed towards the sea, picking up and depositing sediments on its way. Generally after this first wave of flooding, from the coast to just past the crest of the Sierra de Avila, these rains triggered thousands of shallow landslides that stripped soil and rock off of the landscape and sent them slipping down the mountainside. Additional water liquefied these landslides into debris flows, which are granular flows in which water mixes with high concentrations of rock and mud. The first eyewitness accounts of debris flows were from 8:30 PM on the 15th, and the final debris flows were reported between 8 and 9 AM on 16 December. Many catchments released multiple debris flows, some of which carried large boulders and tree trunks onto the alluvial fan deltas. Starting between 7 and 9 AM on the 16th and continuing until late that afternoon, a new wave of floods occurred. These floodwaters were less concentrated in sediment and were therefore able to entrain new material and incise new channels into the flood and debris flow deposits from the previous days.

text: Heavy rains fell in December 1999 along the north-central coast of Venezuela, culminating in a period of extreme intensity from 14 to 16 December. Starting around 8 PM local time (

text: AST

text: ) on 15 December, runoff entered channels and rushed towards the sea, picking up and depositing sediments on its way. Generally after this first wave of flooding, from the coast to just past the crest of the Sierra de Avila, these rains triggered thousands of shallow landslides that stripped soil and rock off of the landscape and sent them slipping down the mountainside. Additional water liquefied these landslides into

text: debris flows

text: , which are

text: granular flow

text: s in which water mixes with high concentrations of rock and mud. The first eyewitness accounts of debris flows were from 8:30 PM on the 15th, and the final debris flows were reported between 8 and 9 AM on 16 December. Many catchments released multiple debris flows, some of which carried large boulders and tree trunks onto the alluvial fan deltas. Starting between 7 and 9 AM on the 16th and continuing until late that afternoon, a new wave of floods occurred. These floodwaters were less concentrated in sediment and were therefore able to entrain new material and incise new channels into the flood and debris flow deposits from the previous days.

text: The coastal land masses are formed or modified both by action of the sea currents and tides, and by the rainwater flow through the estuaries, from the rivers and backwater systems, supplying sediments. Deposition or erosion of coastal areas are common and dynamic. Sea erosion claims land in some areas with the eroded soil being deposited in other areas. Severe floods and tidal changes have caused more abrupt and drastic transformations at times. The Cochin estuary itself is said to have resulted from the floods of 1341, which caused the silting up of the ancient harbor of Muziris and the opening of the channel at Cochin Azhi.

text: The coastal land masses are formed or modified both by action of the sea currents and tides, and by the rainwater flow through the estuaries, from the rivers and backwater systems, supplying sediments. Deposition or erosion of coastal areas are common and dynamic. Sea erosion claims land in some areas with the eroded soil being deposited in other areas. Severe floods and tidal changes have caused more abrupt and drastic transformations at times. The Cochin estuary itself is said to have resulted from the floods of 1341, which caused the silting up of the ancient harbor of

text: Muziris

text: and the opening of the channel at Cochin Azhi.

text: The strong discharge of groundwater from the spring has created an area of peatland or karst fen. The vast majority of peat is located in the high-rainfall regions of the northern hemisphere and its occurrence in South Africa is rare. The spring is fed by water issuing from a system of interlinked dolomitic aquifers or compartments. Four of the nine compartments which feed the Wonderfonteinspruit are affected by deep level gold mining. Large-scale pumping of water has led to a lowering of the groundwater table by up to 1000 metres, the trapping of uranium-bearing tailings in caves and sinkholes, the discharge of pollutants into the Wonderfonteinspruit, and seepage from tailings into the aquifer beneath.

text: Unconformities mark both the base and, possibly, the top of the Nankoweap Formation. The red beds of the Nankoweap Formation unconformably overlie the Cardenas Lavas of the Unkar Group. At most places, the upper member of the Nankoweap Formation directly overlies the Cardenas Basalt. In Basalt Canyon, an angular discordance in this lower contact reflects the erosion of 60 m of Cardenas Basalt has been recognized. West of Tanner Canyon, erosion has locally removed as much as 300 m of Cardenas Basalt before the deposition of the Nankoweap Formation. As demonstrated by a 10 m thick ferruginous weathered zone (paleosol), deep chemical weathering of the exposed lava flows of the Cardenas Basalt occurred before deposition of the Nankoweap Formation west of Tanner Canyon. The deeply weathered lavas retain their original textures but have been pervasively stained and altered to earthy hematite and siderite.

text: Unconformities mark both the base and, possibly, the top of the Nankoweap Formation. The red beds of the Nankoweap Formation unconformably overlie the Cardenas Lavas of the Unkar Group. At most places, the upper member of the Nankoweap Formation directly overlies the Cardenas Basalt. In Basalt Canyon, an angular discordance in this lower contact reflects the erosion of 60 m of Cardenas Basalt has been recognized. West of Tanner Canyon, erosion has locally removed as much as 300 m of Cardenas Basalt before the deposition of the Nankoweap Formation. As demonstrated by a 10 m thick ferruginous weathered zone (paleosol), deep chemical weathering of the exposed lava flows of the Cardenas Basalt occurred before deposition of the Nankoweap Formation west of Tanner Canyon. The deeply weathered lavas retain their original textures but have been pervasively stained and altered to earthy hematite and

text: siderite

text: Since pre-Inca times, salt has been obtained in Maras by evaporating salty water from a local subterranean stream. The highly salty water emerges at a spring, a natural outlet of the underground stream. The flow is directed into an intricate system of tiny channels constructed so that the water runs gradually down onto the several hundred ancient terraced ponds. Almost all the ponds are less than four meters square in area, and none exceeds thirty centimeters in depth. All are necessarily shaped into polygons with the flow of water carefully controlled and monitored by the workers. The altitude of the ponds slowly decreases, so that the water may flow through the myriad branches of the water-supply channels and be introduced slowly through a notch in one sidewall of each pond. The proper maintenance of the adjacent feeder channel, the side walls and the water-entry notch, the pond's bottom surface, the quantity of water, and the removal of accumulated salt deposits requires close cooperation among the community of users. It is agreed among local residents and pond workers that the cooperative system was established during the time of the Incas, if not earlier. As water evaporates from the sun-warmed ponds, the water becomes supersaturated and salt precipitates as various size crystals onto the inner surfaces of a pond's earthen walls and on the pond's earthen floor. The pond's keeper then closes the water-feeder notch and allows the pond to go dry. Within a few days the keeper carefully scrapes the dry salt from the sides and bottom, puts it into a suitable vessel, reopens the water-supply notch, and carries away the salt. Color of the salt varies from white to a light reddish or brownish tan, depending on the skill of an individual worker. Some salt is sold at a gift store nearby.

text: Since pre-Inca times,

text: salt

text: has been obtained in Maras by evaporating salty water from a local subterranean stream. The highly salty water emerges at a spring, a natural outlet of the underground stream. The flow is directed into an intricate system of tiny channels constructed so that the water runs gradually down onto the several hundred ancient terraced ponds. Almost all the ponds are less than four meters square in area, and none exceeds thirty centimeters in depth. All are necessarily shaped into polygons with the flow of water carefully controlled and monitored by the workers. The altitude of the ponds slowly decreases, so that the water may flow through the myriad branches of the water-supply channels and be introduced slowly through a notch in one sidewall of each pond. The proper maintenance of the adjacent feeder channel, the side walls and the water-entry notch, the pond's bottom surface, the quantity of water, and the removal of accumulated salt deposits requires close cooperation among the community of users. It is agreed among local residents and pond workers that the cooperative system was established during the time of the Incas, if not earlier. As water evaporates from the sun-warmed ponds, the water becomes

text: supersaturate

text: d and salt precipitates as various size crystals onto the inner surfaces of a pond's earthen walls and on the pond's earthen floor. The pond's keeper then closes the water-feeder notch and allows the pond to go dry. Within a few days the keeper carefully scrapes the dry salt from the sides and bottom, puts it into a suitable vessel, reopens the water-supply notch, and carries away the salt. Color of the salt varies from white to a light reddish or brownish tan, depending on the skill of an individual worker. Some salt is sold at a gift store nearby.

text: The canyon was created by progressive erosion by flowing water from glaciers through the rocks and palagonite over millennia.

text: The canyon was created by progressive

text: erosion

text: by flowing water from glaciers through the rocks and

text: palagonite

text: over millennia.

text: The three headwaters of the Jordan River – the Hasbani River (annual stable flow of 250 Mm^3), the Banias River (annual stable flow of 125 Mm^3), and the Dan River (annual stable flow of 250 Mm^3) originate in Lebanon, Syria, and Israel, respectively. They merge in Lake Huleh and then flow south as the Jordan River. Just south of Tiberias, the Yarmuk River joins the Jordan River. In total, the Jordan River flows for roughly 350 km, starting in the foothills of Mount Hermon in the north and ending in the Dead Sea to the south. The River has an estimated flow of 1880 MCM/Y, 73 percent of which originates in Arab countries and 27 percent of which originates in Israel. According to a September 2000 USAF study, over 90% of Syria’s water is shared with neighboring Iraq, Turkey, Israel, Lebanon, and Jordan. Approximately 36 percent of Jordan’s water sources are shared with Syria, the West Bank, and Israel, and more than half of Israel’s waters is shared with Syria, Lebanon, Jordan, and the West Bank.

text: The three headwaters of the Jordan River – the

text: Hasbani River

text: (annual stable flow of 250 Mm^3), the

text: Banias River

text: (annual stable flow of 125 Mm^3), and the

text: Dan River

text: (annual stable flow of 250 Mm^3) originate in

text: Lebanon

text: Syria

text: , and

text: Israel

text: , respectively. They merge in

text: Lake Huleh

text: and then flow south as the Jordan River. Just south of

text: Tiberias

text: , the

text: Yarmuk River

text: joins the Jordan River. In total, the Jordan River flows for roughly 350 km, starting in the foothills of

text: Mount Hermon

text: in the north and ending in the

text: Dead Sea

text: to the south. The River has an estimated flow of 1880 MCM/Y, 73 percent of which originates in Arab countries and 27 percent of which originates in Israel. According to a September 2000 USAF study, over 90% of Syria’s water is shared with neighboring

text: Iraq

text: Turkey

text: , Israel, Lebanon, and

text: Jordan

text: . Approximately 36 percent of Jordan’s water sources are shared with Syria, the

text: West Bank

text: , and Israel, and more than half of Israel’s waters is shared with Syria, Lebanon, Jordan, and the West Bank.

text: Streams become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the kinetic energy of the water hitting the bottom. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by earthquakes or landslides or volcanoes can cause a differential in land heights which interfere with the natural course of a water flow, and result in waterfalls.

text: Streams become wider and shallower just above waterfalls due to flowing over the rock shelf, and there is usually a deep area just below the waterfall because of the

text: kinetic energy

text: of the water hitting the bottom. Waterfalls normally form in a rocky area due to erosion. After a long period of being fully formed, the water falling off the ledge will retreat, causing a horizontal pit parallel to the waterfall wall. Eventually, as the pit grows deeper, the waterfall collapses to be replaced by a steeply sloping stretch of river bed. In addition to gradual processes such as erosion, earth movement caused by

text: earthquakes

text: or

text: landslides

text: or

text: volcano

text: es can cause a differential in land heights which interfere with the natural course of a water flow, and result in waterfalls.

text: An infiltration basin (also known as a recharge basin or in some areas, a sump), is a type of best management practice (BMP) that is used to manage stormwater runoff, prevent flooding and downstream erosion, and improve water quality in an adjacent river, stream, lake or bay. It is essentially a shallow artificial pond that is designed to infiltrate stormwater though permeable soils into the groundwater aquifer.  Infiltration basins do not release water except by infiltration, evaporation or emergency overflow during flood conditions.

text: An infiltration basin (also known as a recharge basin or in some areas, a

text: sump

text: ), is a type of

entity_name: Best management practice for water pollution

text: best management practice

text: (BMP) that is used to manage

text: stormwater

text: runoff

text: , prevent

text: flood

text: ing and downstream

text: erosion

text: , and improve

text: water quality

text: in an adjacent

text: river

text: stream

text: lake

text: or

text: bay

text: . It is essentially a shallow artificial pond that is designed to

text: infiltrate

text: stormwater though permeable soils into the

text: groundwater

text: aquifer

text: .  Infiltration basins do not release water except by infiltration, evaporation or emergency overflow during flood conditions.

text: Tributaries flowing into the Minnesota River had to drop down into the deep glacial valley, creating numerous waterfalls.  The waterfall on Minneopa Creek was likely once near its mouth on the river.  Over the millennia downcutting of the creek has carved a gorge through the soft Jordan Sandstone, causing the waterfall to "migrate" upstream.  The double waterfall in Minneopa is the result of there being three layers of differing hardness in the sandstone.  The upper and lower layers are softer than the middle, which creates a short stretch of erosion-resistant creekbed between two waterfalls.  The gorge is littered with blocks of the middle sandstone that broke off as the supporting layer below wore away.  Weathering from the constant spray of the falls helps keep the gorge walls nearly vertical.

text: Tributaries flowing into the Minnesota River had to drop down into the deep glacial valley, creating numerous waterfalls.  The waterfall on Minneopa Creek was likely once near its mouth on the river.  Over the millennia

text: downcutting

text: of the creek has carved a gorge through the soft Jordan Sandstone, causing the waterfall to "migrate" upstream.  The double waterfall in Minneopa is the result of there being three layers of differing hardness in the sandstone.  The upper and lower layers are softer than the middle, which creates a short stretch of erosion-resistant creekbed between two waterfalls.  The gorge is littered with blocks of the middle sandstone that broke off as the supporting layer below wore away.  Weathering from the constant spray of the falls helps keep the gorge walls nearly vertical.

text: Streambed topography is the primary factor in creating rapids, and is generally consistent over time.  Increased flow, as during a flood or high rainfall season can make permanent changes to the streambed by displacing rocks and boulders, by deposition of alluvium or by creating new channels for flowing water.

text: Streambed topography is the primary factor in creating rapids, and is generally consistent over time.  Increased flow, as during a flood or high rainfall season can make permanent changes to the streambed by displacing rocks and boulders, by deposition of

text: alluvium

text: or by creating new channels for flowing water.

text: Slowing stream bed erosion by taking advantage of a thalweg helps stabilize running water sources. Placing boulders along the thalweg in a running water source helps to protect the channel's sedimentary erosion and deposit balance. In concurrence with the placement of boulders along a thalweg, the placement of boulders along an instream to form man-made sills also helps to slow the sedimentary erosion and deposit of running water sources, while keeping the esteem (fishing, local wildlife, and recreation) and natural resources of the running water source intact. The placement of boulders along a thalweg and the creation of instream sills help to aid the flow of water during late summer months when the flow rate drops, and helps to slow sedimentary erosion and deposit in the spring and fall months when the flow rates are high. This process of utilizing a thalweg to slow stream bed erosion was used in Meacham Creek in Umatilla, Oregon.

text: Slowing stream bed erosion by taking advantage of a thalweg helps stabilize running water sources. Placing boulders along the thalweg in a running water source helps to protect the channel's sedimentary erosion and deposit balance. In concurrence with the placement of boulders along a thalweg, the placement of boulders along an

text: instream

text: to form man-made sills also helps to slow the sedimentary erosion and deposit of running water sources, while keeping the esteem (fishing, local wildlife, and recreation) and natural resources of the running water source intact. The placement of boulders along a thalweg and the creation of instream sills help to aid the flow of water during late summer months when the flow rate drops, and helps to slow sedimentary erosion and deposit in the spring and fall months when the flow rates are high. This process of utilizing a thalweg to slow stream bed erosion was used in Meacham Creek in

text: Umatilla, Oregon

text: In some places molten rock intruded into depositional sand but it failed to erupt through the surface, so erosion took place to expose the igneous formations. In other places molten rock erupted explosively, producing clouds of solidified lava that later fell back to earth as ash, forming a cone around the vent. In some cases, it erupted several times as a succession of lava flows from a single vent forming widespread basalt layers taking on the form of a shield. At times, molten rock came into contact with water-saturated sand and it produced superheated and highly pressurized water vapor that exploded though the earth’s surface with a devastating force creating large craters known as maars or lakes.

text: In some places molten rock intruded into depositional sand but it failed to erupt through the surface, so erosion took place to expose the igneous formations. In other places molten rock erupted explosively, producing clouds of solidified lava that later fell back to earth as ash, forming a cone around the vent. In some cases, it erupted several times as a succession of lava flows from a single vent forming widespread basalt layers taking on the form of a shield. At times, molten rock came into contact with water-saturated sand and it produced superheated and highly pressurized water vapor that exploded though the earth’s surface with a devastating force creating large

text: craters

text: known as maars or lakes.

text: Groundwater may have played an important part in forming layers in many locations.  Calculations and simulations show that groundwater carrying dissolved minerals would surface in the same locations that have abundant rock layers.   According to these ideas, deep canyons and large craters would receive water coming from the ground.  Many craters in the Arabia area of Mars contain groups of layers.  Some of these layers may have resulted from climate changes.  The tilt of the rotational axis of Mars has repeatedly changed in the past.  Some changes are large.  Because of these variations of climate, at times the atmosphere of Mars will be much thicker and contain more moisture.  The amount of atmospheric dust also has increased and decreased. It is believed that these frequent changes helped to deposit material in craters and other low places. The rising of mineral-rich ground water cemented these materials. The model also predicts that after a crater is full of layered rocks; additional layers will be laid down in the area around the crater. So, the model predicts that layers may also have formed in intercrater regions, and layers in these regions have been observed.Layers can be hardened by the action of groundwater.  Martian ground water probably moved hundreds of kilometers, and in the process it dissolved many minerals from the rock it passed through.  When ground water surfaces in low areas containing sediments, water evaporates in the thin atmosphere and leaves behind minerals as deposits and/or cementing agents. Consequently, layers of dust could not later easily erode away since they were cemented together. On Earth, mineral-rich waters often evaporate forming large deposits of various types of salts and other minerals. Sometimes water flows through Earth's aquifers, and then evaporates at the surface just as is hypothesed for Mars.  One location this occurs on Earth is the Great Artesian Basin of Australia.  On Earth the hardness of many sedimentary rocks, like sandstone, is largely due to the cement that was put in place as water passed through.

text: salts

text: and other

text: mineral

text: s. Sometimes water flows through Earth's aquifers, and then evaporates at the surface just as is hypothesed for Mars.  One location this occurs on Earth is the

text: Great Artesian Basin

text: of

text: Australia

text: .  On Earth the hardness of many

text: sedimentary rock

text: s, like

text: sandstone

text: , is largely due to the cement that was put in place as water passed through.

text: Floods also frequently damage power transmission and sometimes power generation, which then has knock-on effects caused by the loss of power. This includes loss of drinking water treatment and water supply, which may result in loss of drinking water or severe water contamination. It may also cause the loss of sewage disposal facilities. Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases, which can include typhoid, giardia, cryptosporidium, cholera and many other diseases depending upon the location of the flood.

text: Floods also frequently damage

text: power transmission

text: and sometimes

text: power generation

text: , which then has

text: knock-on effect

text: s caused by the loss of power. This includes loss of drinking

text: water treatment

text: and water supply, which may result in loss of drinking water or severe water contamination. It may also cause the loss of sewage disposal facilities. Lack of clean water combined with

text: human sewage

text: in the flood waters raises the risk of

text: waterborne diseases

text: , which can include

text: typhoid

text: giardia

text: cryptosporidium

text: cholera

text: and many other diseases depending upon the location of the flood.

text: Groundwater (or ground water) is the water present beneath Earth's surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock become completely saturated with water is called the water table. Groundwater is recharged from, and eventually flows to, the surface naturally; natural discharge often occurs at springs and seeps, and can form oases or wetlands. Groundwater is also often withdrawn for agricultural, municipal, and industrial use by constructing and operating extraction wells. The study of the distribution and movement of groundwater is hydrogeology, also called groundwater hydrology.

text: Groundwater (or ground water) is the

text: water

text: present beneath

text: Earth

text: 's surface in

text: soil pore spaces

text: and in the

text: fracture

text: s of

text: rock formations

text: . A unit of rock or an unconsolidated deposit is called an

text: aquifer

text: when it can yield a usable quantity of water. The depth at which

text: soil

text: pore spaces or fractures and voids in rock become completely saturated with water is called the

text: water table

text: Groundwater is recharged

text: from, and eventually flows to, the surface naturally; natural discharge often occurs at

text: springs

text: and

text: seeps

text: , and can form

text: oases

text: or

text: wetland

text: s. Groundwater is also often withdrawn for

text: agricultural

text: municipal

text: , and

text: industrial

text: use by constructing and operating extraction

text: wells

text: . The study of the distribution and movement of groundwater is

text: hydrogeology

text: , also called groundwater

text: hydrology

text: Positive-displacement (PD) meters can measure both liquids and gases. Like turbine meters, PD flow meters work best with clean, non-corrosive, and non-erosive liquids and gases, although some models will tolerate some impurities. Because of their high accuracy, PD meters are widely used at residences to measure the amount of gas or water used. Other applications include:  chemical injection, fuel measurement, precision test stands, high pressure, hydraulic testing, and similar precision applications.

text: A water bar or interceptor dyke is a road construction feature that is used to prevent erosion on sloping roads, cleared paths through woodland (for utility companies such as electricity pylons), or other accessways by reducing flow length.  It is a diagonal channel across the road that diverts surface water (that would otherwise flow down the whole length of the road) off the road and into a stable drain way.  By constructing a series of water bars at intervals along a road, the volume of water flowing down the road is reduced. Without water bars, flooding, washouts, and accelerated road degradation can occur.

text: A water bar or interceptor dyke is a road construction feature that is used to prevent

text: erosion

text: on sloping roads, cleared paths through woodland (for utility companies such as electricity pylons), or other accessways by reducing flow length.  It is a diagonal channel across the road that diverts surface water (that would otherwise flow down the whole length of the road) off the road and into a stable drain way.  By constructing a series of water bars at intervals along a road, the volume of water flowing down the road is reduced. Without water bars,

text: flood

text: ing,

text: washouts

text: , and accelerated road degradation can occur.

text: After 349 days in orbit, Mariner 9 had transmitted 7,329 images, covering 85% of Mars' surface, whereas previous flyby missions had returned less than one thousand images covering only a small portion of the planetary surface. The images revealed river beds, craters, massive extinct volcanoes (such as Olympus Mons, the largest known volcano in the Solar System; Mariner 9 led directly to its reclassification from Nix Olympica), canyons (including the Valles Marineris, a system of canyons over about  long), evidence of wind and water erosion and deposition, weather fronts, fogs, and more. Mars' small moons, Phobos and Deimos, were also photographed.

text: After 349 days in orbit, Mariner 9 had transmitted 7,329 images, covering 85% of Mars' surface, whereas previous flyby missions had returned less than one thousand images covering only a small portion of the planetary surface. The images revealed

text: river

text: beds,

text: crater

text: s, massive extinct

text: volcano

text: es (such as

text: Olympus Mons

text: , the largest known volcano in the

text: Solar System

text: ; Mariner 9 led directly to its reclassification from Nix Olympica),

text: canyon

text: s (including the

text: Valles Marineris

text: , a system of canyons over about  long), evidence of wind and water

text: erosion

text: and deposition, weather fronts,

text: fog

text: s, and more. Mars' small

text: moon

text: s,

text: Phobos

text: and

text: Deimos

text: , were also photographed.

text: The canyon formation is along the banks of the fast flowing Charyn River in a northern flow stretch of about  ( is also stated) which is a tributary of the Ile River; the river has a total length of . The river rises from the Tian Shan Mountains (meaning: "Heavenly Mountains",) that is spread over the arid semi-desert to the east of Almaty. In parts, it attains a depth of . The geological formation of the canyon is of sedimentary red sandstone  which have been subject to the "atmogenic process" (defined in Websters dictionary as "atmospheric origin by condensation, wind action, or deposition from volcanic vapors") of water and wind erosion resulting in "weird and colourful formations" in the form of sculptures.

text: The canyon formation is along the banks of the fast flowing Charyn River in a northern flow stretch of about  ( is also stated) which is a tributary of the

text: Ile River

text: ; the river has a total length of . The river rises from the

text: Tian Shan Mountains

text: (meaning: "Heavenly Mountains",) that is spread over the arid semi-desert to the east of Almaty. In parts, it attains a depth of . The geological formation of the canyon is of sedimentary red sandstone  which have been subject to the "atmogenic process" (defined in Websters dictionary as "atmospheric origin by condensation, wind action, or deposition from volcanic vapors") of water and wind erosion resulting in "weird and colourful formations" in the form of sculptures.

text: The River Enrick passes Corrimony, before flowing down Glenurquhart to Loch Ness. The river flows over Corrimony Falls, a waterfall to the south of the settlement.

text: The River Enrick passes Corrimony, before flowing down Glenurquhart to

text: Loch Ness

text: . The river flows over

text: Corrimony Falls

text: , a waterfall to the south of the settlement.

text: Used in hydrogeology, the groundwater flow equation is the mathematical relationship which is used to describe the flow of groundwater through an aquifer. The transient flow of groundwater is described by a form of the diffusion equation, similar to that used in heat transfer to describe the flow of heat in a solid (heat conduction). The steady-state flow of groundwater is described by a form of the Laplace equation, which is a form of potential flow and has analogs in numerous fields.

text: Used in

text: hydrogeology

text: , the groundwater flow equation is the

text: mathematical

text: relationship which is used to describe the flow of

text: groundwater

text: through an

text: aquifer

text: . The

text: transient

text: flow of groundwater is described by a form of the

text: diffusion equation

text: , similar to that used in

text: heat transfer

text: to describe the flow of heat in a solid (

text: heat conduction

text: ). The steady-state flow of groundwater is described by a form of the

text: Laplace equation

text: , which is a form of

text: potential flow

text: and has analogs in numerous fields.

text: The above reaction is very important to the formation of stalactites, stalagmites, columns, and other speleothems within caves, and for that matter, in the formation of the caves themselves.  As water containing carbon dioxide (including extra CO acquired from soil organisms) passes through limestone or other calcium carbonate-containing minerals, it dissolves part of the calcium carbonate,  hence becomes richer in bicarbonate.  As the groundwater enters the cave, the excess carbon dioxide is released from the solution of the bicarbonate, causing the much less soluble calcium carbonate to be deposited.

text: The above reaction is very important to the formation of

text: stalactites

text: stalagmite

text: s, columns, and other

text: speleothems

text: within

text: caves

text: , and for that matter, in the formation of the caves themselves.  As water containing carbon dioxide (including extra CO acquired from soil organisms) passes through limestone or other calcium carbonate-containing minerals, it dissolves part of the calcium carbonate,  hence becomes richer in bicarbonate.  As the groundwater enters the cave, the excess carbon dioxide is released from the solution of the bicarbonate, causing the much less soluble calcium carbonate to be deposited.

text: There have been many different theories about the formation of Valles Marineris that have changed over the years.  Ideas in the 1970s were erosion by water or thermokarst activity, which is the melting of permafrost in glacial climes. Thermokarst activity may contribute, but erosion by water is a problematic mechanism because liquid water cannot exist in most current Martian surface conditions, which typically experience about 1% of Earth’s atmospheric pressure and a temperature range of  to . Many scientists agree that there was liquid water flowing on the Martian surface in the past. Valles Marineris may have been enlarged by flowing water at this time. Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma. Around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, later made bigger by erosion and collapsing of the rift walls. It has also been proposed that Valles Marineris was formed by flowing lava.

text: There have been many different theories about the formation of Valles Marineris that have changed over the years.  Ideas in the 1970s were erosion by

text: water

text: or

text: thermokarst

text: activity, which is the melting of

text: permafrost

text: in glacial climes. Thermokarst activity may contribute, but erosion by water is a problematic mechanism because liquid water cannot exist in most current Martian surface conditions, which typically experience about 1% of Earth’s atmospheric pressure and a temperature range of  to . Many scientists agree that there was

text: liquid water

text: flowing on the Martian surface in the past. Valles Marineris may have been enlarged by flowing water at this time. Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma. Around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. The most agreed upon theory today is that Valles Marineris was formed by rift faults like the

text: East African Rift

text: , later made bigger by erosion and collapsing of the rift walls. It has also been proposed that Valles Marineris was formed by flowing lava.

text: A losing stream, disappearing stream or influent stream, is a stream or river that loses water  as it flows downstream. The water infiltrates into the ground recharging the local groundwater, because the water table is below the bottom of the stream channel. This is the opposite of a more common gaining  stream (or effluent stream) which increases in water volume farther down stream as it gains water from the local aquifer.

text: A losing stream, disappearing stream or influent stream, is a

text: stream

text: or

text: river

text: that loses water  as it flows downstream. The water

text: infiltrates

text: into the ground recharging the local

text: groundwater

text: , because the

text: water table

text: is below the bottom of the stream channel. This is the opposite of a more common gaining  stream (or effluent stream) which increases in water volume farther down stream as it gains water from the local

text: aquifer

text: The Palo Alto Flood Basin was constructed in 1956 in order to prevent a repeat of the floods of 1955, when a high tide prevented the escape of heavy runoff from Matadero, Adobe, and Barron Creeks into the San Francisco Bay. The trapped runoff waters overflowed upstream creek banks and caused severe flooding in Palo Alto. In order to control the flow of water into the flood basin, a tidegate was placed at the confluence of Adobe Creek, Matadero Creek, and the San Francisco Bay, so that the flood basin could be maintained at approximately 2 feet below sea level, creating room to absorb floodwaters. The tidegate consists of several weirs and one operator-controlled sluice gate that enables tidal flows into the basin in order to improve water quality and for mosquito control. Three agencies oversee the tidegates: Santa Clara Valley Water District, City of Palo Alto, and Santa Clara County Vector Control. Because the trash grate and weirs separate the mouth of the flood basin from the San Francisco Bay estuary, large fish cannot swim freely between the Bay and the basin, unless the sluice gate is open. In addition, the tidegates are set to reduce tidal inflows into the basin, so that the basin is mostly freshwater. After a rainstorm the tidegate is kept closed, however this is precisely when steelhead trout in-migrations should occur. In 2002 a small opening was cut in the trash grate on the tidal gate to permit fish passage but local fisherman in the Flood Basin no longer report catching steelhead trout in recent years.

text: The Palo Alto Flood Basin was constructed in 1956 in order to prevent a repeat of the floods of 1955, when a high tide prevented the escape of heavy runoff from Matadero, Adobe, and Barron Creeks into the San Francisco Bay. The trapped runoff waters overflowed upstream creek banks and caused severe flooding in Palo Alto. In order to control the flow of water into the flood basin, a tidegate was placed at the confluence of Adobe Creek, Matadero Creek, and the San Francisco Bay, so that the flood basin could be maintained at approximately 2 feet below sea level, creating room to absorb floodwaters. The tidegate consists of several

text: weir

text: s and one operator-controlled

text: sluice

text: gate that enables tidal flows into the basin in order to improve water quality and for mosquito control. Three agencies oversee the tidegates:

text: Santa Clara Valley Water District

text: City of Palo Alto

text: , and Santa Clara County Vector Control. Because the trash grate and weirs separate the mouth of the flood basin from the San Francisco Bay estuary, large fish cannot swim freely between the Bay and the basin, unless the sluice gate is open. In addition, the tidegates are set to reduce tidal inflows into the basin, so that the basin is mostly freshwater. After a rainstorm the tidegate is kept closed, however this is precisely when steelhead trout in-migrations should occur. In 2002 a small opening was cut in the trash grate on the tidal gate to permit fish passage but local fisherman in the Flood Basin no longer report catching steelhead trout in recent years.

text: Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways.  Volcanoes, wind, or water can produce layers.  Layers may be formed by groundwater rising up depositing minerals and cementing sediments.  The hardned layers are consequently more protected from erosion.  This process may occur instead of layers forming under lakes.

text: Flowing water appears to have been common on the surface of Mars at various points in its history, and especially on ancient Mars. Many of these flows carved the surface, forming valley networks and producing sediment. This sediment has been redeposited in a wide variety of wet environments, including in alluvial fans, meandering channels, deltas, lakes, and perhaps even oceans. The processes of deposition and transportation are associated with gravity. Due to gravity, related differences in water fluxes and flow speeds, inferred from grain size distributions, Martian landscapes were created by different environmental conditions. Nevertheless, there are other ways of estimating the amount of water on ancient Mars (see: Water on Mars). Groundwater has been implicated in the cementation of aeolian sediments and the formation and transport of a wide variety of sedimentary minerals including clays, sulphates and hematite.

text: Flowing water appears to have been common on the surface of Mars at various points in its history, and especially on ancient Mars. Many of these flows carved the surface, forming

text: valley networks

text: and producing sediment. This sediment has been redeposited in a wide variety of wet environments, including in

text: alluvial fans

text: , meandering channels,

text: deltas

text: lake

text: s, and perhaps even oceans. The processes of deposition and transportation are associated with gravity. Due to gravity, related differences in water fluxes and flow speeds, inferred from grain size distributions, Martian landscapes were created by different environmental conditions. Nevertheless, there are other ways of estimating the amount of water on ancient Mars (see:

text: Water on Mars

text: ). Groundwater has been implicated in the cementation of

text: aeolian

text: sediments and the formation and transport of a wide variety of sedimentary minerals including clays, sulphates and

text: hematite

text: The location and altitude of ice-rafted boulders relative to the modern landscape has been used to identify the highest level of water in proglacial lakes (e.g., Lake Musselshell in central Montana) and temporary lakes (e.g., Lake Lewis in Washington state. Ice-rafted debris is deposited when the iceberg strands on the shore and subsequently melts, or drops out of the ice floe as it melts. Hence all erratic deposits are deposited below the actual high water level of the lake; however the measured altitude of ice-rafted debris can be used to estimate the lake surface elevation.

text: The location and altitude of ice-rafted boulders relative to the modern landscape has been used to identify the highest level of water in proglacial lakes (e.g.,

text: Lake Musselshell

text: in central

text: Montana

text: ) and temporary lakes (e.g.,

text: Lake Lewis

text: in

text: Washington

text: state. Ice-rafted debris is deposited when the iceberg strands on the shore and subsequently melts, or drops out of the ice floe as it melts. Hence all erratic deposits are deposited below the actual high water level of the lake; however the measured altitude of ice-rafted debris can be used to estimate the lake surface elevation.

text: Dynamic steady states of sediment erosion and deposition work to sustain alluvial channel morphology, as river reaches import and export fine and coarse sediments at approximately equal rates. At the apex of meander curves, high velocity flows scour out sediment and form pools. The mobilized sediment is then deposited at the point bar directly across the channel or downstream. Flows of high magnitude and duration can be seen as important thresholds that drive channelbed mobility. Channel aggradation or degradation indicate sediment budget imbalances.

text: Dynamic steady states of sediment erosion and deposition work to sustain alluvial channel morphology, as river reaches import and export fine and coarse sediments at approximately equal rates. At the apex of meander curves, high velocity flows scour out sediment and form pools. The mobilized sediment is then deposited at the point bar directly across the channel or downstream. Flows of high magnitude and duration can be seen as important thresholds that drive channelbed mobility. Channel

text: aggradation

text: or

text: degradation

text: indicate sediment budget imbalances.

text: There are at least 120 named waterfalls in Montana.A waterfall is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff. Waterfalls are most commonly formed when a river is young.

text: There are at least 120 named waterfalls in

text: Montana

text: .A

text: waterfall

text: is a place where flowing water rapidly drops in elevation as it flows over a steep region or a cliff. Waterfalls are most commonly formed when a river is young.

text: Some areas of Mars show inverted relief, where features that were once depressions, like streams, are now instead above the surface.  These may have been formed when materials, like large rocks, were deposited in low-lying areas, then left behind after erosion (perhaps wind which can not move large rocks) removed much of the surface layers.  Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.  On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces.  Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.  There are many examples of inverted channels near Juventae Chasma; some are shown in the image of Juventae Chasma below.

text: Some areas of Mars show

text: inverted relief

text: , where features that were once depressions, like streams, are now instead above the surface.  These may have been formed when materials, like large rocks, were deposited in low-lying areas, then left behind after erosion (perhaps wind which can not move large rocks) removed much of the surface layers.  Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water.  On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces.  Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times.  There are many examples of inverted channels near Juventae Chasma; some are shown in the image of Juventae Chasma below.

text: There is a correlation between the size and density of a particle and the rate that the particle separates from a heterogeneous mixture, when the only force applied is that of gravity. The larger the size and the larger the density of the particles, the faster they separate from the mixture. By applying a larger effective gravitational force to the mixture, like a centrifuge does, the separation of the particles is accelerated. This is ideal in industrial and lab settings because particles that would naturally separate over a long period of time can be separated in much less time.

text: There is a correlation between the size and

text: density

text: of a particle and the rate that the particle separates from a heterogeneous mixture, when the only force applied is that of gravity. The larger the size and the larger the density of the particles, the faster they separate from the mixture. By applying a larger effective gravitational force to the mixture, like a centrifuge does, the separation of the particles is accelerated. This is ideal in industrial and lab settings because particles that would naturally separate over a long period of time can be separated in much less time.

text: The volcanic activity took place in several phases. In the first phase, uplift and extension of the Precambrian basement occurred in the central area. The first structure to be formed was probably Tarso Abeki, followed by Tarso Tamertiou, Tarso Tieroko, Tarso Yega, Tarso Toon, and Ehi Yéy. The product of this early volcanic activity has been completely obscured by later eruptions. In the second phase, the volcanic activity moved north and east, forming Tarso Ourari and the ignimbrite bases of the vast tarsos, as well as Emi Koussi to the southeast. Thereafter, during the third phase, the outpouring of lava and ejecta deposits increased from Tarso Yega, Tarso Toon, Tarso Tieroko and Ehi Yéy; the collapse of these structures formed the first calderas. This phase also saw the formation of the Bounaï lava dome and Tarson Voon. To the east, the lava flows formed the large plateaus of Tarso Emi Chi, Tarso Ahon and Tarso Toon. Emi Koussi increased in height. The fourth phase saw the formation of Tarso Toussidé and the lava flows of Tarso Tôh in the west, the collapse of the caldera on the summit of Tarso Voon and associated ejecta deposits in the center, and the decline in lava production in the east, with the exception of Emi Koussi, which continued to rise. The end of this phase coincided with the beginning of the Holocene. The Yirrigué volcano emitted pyroclastic ignimbrite up to  in all directions, filling in valleys. In the fifth phase, volcanic activity became much more localized and lava production continued to wane. Calderas form on top of Tarso Toussidé and Emi Koussi, and the lava domes Ehi Sosso and Ehi Mousgou appeared. Finally, in the sixth phase, Pic Toussidé formed on the western rim of several pre-Trou au Natron calderas, along with new lava flows, including Timi on the northern slope of Tarso Toussidé. With scarce time for erosion, these lava flows have a dark, youthful appearance. The Trou au Natron and Doon Kidimi craters have formed even more recently, with the former dissecting the earlier Toussidé calderas. Lava flows, minor pyroclastic deposits, and the appearance of small cinder cones, and the formation of the Era Kohor crater are the most recent volcanic activities on Emi Koussi. Presently, there are reports of volcanic activity in various parts of the massif, including hot springs at the Soborom geothermal field and fumaroles on Tarso Voon, Yi Yerra near Emi Koussi and Pic Toussidé. Deposits of sodium carbonate in the Trou au Natron and Era Kohor craters reflect recent events, as does the formation of volcanic centers on the floor of Trou au Natron.

text: The volcanic activity took place in several phases. In the first phase, uplift and extension of the Precambrian

text: basement

text: occurred in the central area. The first structure to be formed was probably Tarso Abeki, followed by Tarso Tamertiou, Tarso Tieroko, Tarso Yega, Tarso Toon, and Ehi Yéy. The product of this early volcanic activity has been completely obscured by later eruptions. In the second phase, the volcanic activity moved north and east, forming Tarso Ourari and the ignimbrite bases of the vast tarsos, as well as Emi Koussi to the southeast. Thereafter, during the third phase, the outpouring of lava and ejecta deposits increased from Tarso Yega, Tarso Toon, Tarso Tieroko and Ehi Yéy; the collapse of these structures formed the first calderas. This phase also saw the formation of the Bounaï

text: lava dome

text: and Tarson Voon. To the east, the lava flows formed the large plateaus of Tarso Emi Chi, Tarso Ahon and Tarso Toon. Emi Koussi increased in height. The fourth phase saw the formation of Tarso Toussidé and the lava flows of Tarso Tôh in the west, the collapse of the caldera on the summit of Tarso Voon and associated ejecta deposits in the center, and the decline in lava production in the east, with the exception of Emi Koussi, which continued to rise. The end of this phase coincided with the beginning of the Holocene. The Yirrigué volcano emitted

text: pyroclastic

text: ignimbrite up to  in all directions, filling in valleys. In the fifth phase, volcanic activity became much more localized and lava production continued to wane. Calderas form on top of Tarso Toussidé and Emi Koussi, and the lava domes Ehi Sosso and Ehi Mousgou appeared. Finally, in the sixth phase, Pic Toussidé formed on the western rim of several pre-Trou au Natron calderas, along with new lava flows, including Timi on the northern slope of Tarso Toussidé. With scarce time for erosion, these lava flows have a dark, youthful appearance. The Trou au Natron and Doon Kidimi craters have formed even more recently, with the former dissecting the earlier Toussidé calderas. Lava flows, minor pyroclastic deposits, and the appearance of small

text: cinder cone

text: s, and the formation of the Era Kohor crater are the most recent volcanic activities on Emi Koussi. Presently, there are reports of volcanic activity in various parts of the massif, including hot springs at the Soborom geothermal field and fumaroles on Tarso Voon, Yi Yerra near Emi Koussi and Pic Toussidé. Deposits of

text: sodium carbonate

text: in the Trou au Natron and Era Kohor craters reflect recent events, as does the formation of volcanic centers on the floor of Trou au Natron.

text: This experiment contained two sealed pressure zones, extending along the interior walls of the satellite, which were designed to record the impact of micrometeorites large enough to pierce the satellite shell. These pressure zones were partial vacuums, each at a different pressure, and were protected by 0.66 mm magnesium walls that presented an exposed surface area of 0.162 m², which was 20% of the area of the shell. A puncture in the walls of either zone was detected by a differential pressure gauge mounted between them, and telemetered as a change in the length of one of the telemetry channels. Erosion of the satellite shell through bombardment by space dust, micrometeorites, and other particles was recorded by three chromium-strip erosion gauges mounted on the satellite surface, and by a photosensitive detector. Electrical resistances of the gauges changed as their surfaces were changed by erosion. The photosensitive detector, a cadmium sulfide cell protected by an opaque covering of aluminized PET film, also showed a resistance change as the covering was eroded or penetrated. Erosion measurements also were telemetered as channel lengths, which permitted estimates of the erosion rates. Four barium titanate-type microphones recorded micrometeorite impacts on the satellite's surface. The microphone output was amplified, shaped, and fed into a magnetic counter unit, which provided continuously, in three-decimal digits, the cumulative count of impacts. The unit counted up to 1000 and then reset to zero. The satellite recorded 6600 micrometeorite impacts during 66 days of operation, of which 2800 occurred during a 70-h interval from November 16 to 18, 1959. No penetrations or fractures were recorded in the sensors of the surface penetration experiment. Because the erosion sensors were not disrupted, no definite results could be drawn from that experiment.

text: This experiment contained two sealed pressure zones, extending along the interior walls of the satellite, which were designed to record the impact of

text: micrometeorite

text: s large enough to pierce the satellite shell. These pressure zones were partial vacuums, each at a different pressure, and were protected by 0.66 mm

text: magnesium

text: walls that presented an exposed surface area of 0.162 m², which was 20% of the area of the shell. A puncture in the walls of either zone was detected by a differential pressure gauge mounted between them, and telemetered as a change in the length of one of the telemetry channels. Erosion of the satellite shell through bombardment by

text: space dust

text: , micrometeorites, and other particles was recorded by three

text: chromium

text: -strip erosion gauges mounted on the satellite surface, and by a photosensitive detector. Electrical resistances of the gauges changed as their surfaces were changed by erosion. The photosensitive detector, a

text: cadmium sulfide

text: cell protected by an opaque covering of

text: aluminized PET film

text: , also showed a resistance change as the covering was eroded or penetrated. Erosion measurements also were telemetered as channel lengths, which permitted estimates of the erosion rates. Four

text: barium titanate

text: -type

text: microphone

text: s recorded micrometeorite impacts on the satellite's surface. The microphone output was amplified, shaped, and fed into a magnetic counter unit, which provided continuously, in three-decimal digits, the cumulative count of impacts. The unit counted up to 1000 and then reset to zero. The satellite recorded 6600 micrometeorite impacts during 66 days of operation, of which 2800 occurred during a 70-h interval from November 16 to 18, 1959. No penetrations or fractures were recorded in the sensors of the surface penetration experiment. Because the erosion sensors were not disrupted, no definite results could be drawn from that experiment.

text: Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks.  The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain. A single grain can be composed of several crystals. Granular material can range from very small colloidal particles, through clay, silt, sand, gravel, and cobbles, to boulders.

text: Particle size, also called grain size, refers to the

text: diameter

text: of individual grains of

text: sediment

text: , or the

text: lithified

text: particles in

text: clastic rock

text: s.  The term may also be applied to other

text: granular material

text: s. This is different from the

text: crystallite

text: size, which refers to the size of a single

text: crystal

text: inside a particle or grain. A single grain can be composed of several

text: crystal

text: s.

text: Granular material

text: can range from very small

text: colloidal particles

text: , through

text: clay

text: silt

text: sand

text: gravel

text: , and

text: cobbles

text: , to

text: boulder

text: s.

text: The particle size distribution of a soil sample may indicate the conditions under which the strata or sediment were deposited. Particle sizes are generally separated by means of dry or wet sieving (coarse samples such as till, gravel and sands, sometimes coarser silts) or by measuring the changes of the density of a dispersed solution (in sodiumpyrophosphate, for example))of the sample (finer silts, clays). A rotating clock-glass with a very fine-grained dispersed sample under a heat lamp is useful in separating particles.

text: The particle size distribution of a soil sample may indicate the conditions under which the

text: strata

text: or

text: sediment

text: were deposited. Particle sizes are generally separated by means of dry or wet sieving (coarse samples such as

text: till

text: gravel

text: and

text: sand

text: s, sometimes coarser

text: silt

text: s) or by measuring the changes of the density of a dispersed solution (in sodiumpyrophosphate, for example))of the sample (finer silts,

text: clay

text: s). A rotating clock-glass with a very fine-grained dispersed sample under a heat lamp is useful in separating particles.

text: Most of the gully alcove heads occur at the same level, just as one would expect if water came out of an aquifer. Various measurements and calculations show that liquid water could exist in aquifers at the usual depths where gullies begin. One variation of this model is that rising hot magma could have melted ice in the ground and caused water to flow in aquifers. Aquifers are layers that allow water to flow. They may consist of porous sandstone. The aquifer layer would be perched on top of another layer that prevents water from going down (in geological terms it would be called impermeable). Because water in an aquifer is prevented from going down, the only direction the trapped water can flow is horizontally. Eventually, water could flow out onto the surface when the aquifer reaches a break—like a crater wall. The resulting flow of water could erode the wall to create gullies. Aquifers are quite common on Earth. A good example is "Weeping Rock" in Zion National Park Utah. However, the idea that aquifers formed the gullies does not explain the ones found on isolated peaks, like knobs and the central peaks of craters. Also, a type of gully seems to be present on sand dunes. Aquifers need a wide collecting area which is not present on sand dunes or on isolated slopes. Even though most of the original gullies that were seen seemed to come from the same layer in the slope, some exceptions to this pattern have been found. Examples of gullies coming from different levels is shown below in the image of Lohse Crater and the image of gullies in Ross Crater.

text: Most of the gully alcove heads occur at the same level, just as one would expect if water came out of an

text: aquifer

text: . Various measurements and calculations show that liquid water could exist in aquifers at the usual depths where gullies begin. One variation of this model is that rising hot

text: magma

text: could have melted ice in the ground and caused water to flow in aquifers. Aquifers are layers that allow water to flow. They may consist of porous sandstone. The aquifer layer would be perched on top of another layer that prevents water from going down (in geological terms it would be called impermeable). Because water in an aquifer is prevented from going down, the only direction the trapped water can flow is horizontally. Eventually, water could flow out onto the surface when the aquifer reaches a break—like a crater wall. The resulting flow of water could erode the wall to create gullies. Aquifers are quite common on Earth. A good example is "Weeping Rock" in

text: Zion National Park

text: Utah

text: . However, the idea that aquifers formed the gullies does not explain the ones found on isolated peaks, like knobs and the central peaks of craters. Also, a type of gully seems to be present on sand dunes. Aquifers need a wide collecting area which is not present on sand dunes or on isolated slopes. Even though most of the original gullies that were seen seemed to come from the same layer in the slope, some exceptions to this pattern have been found. Examples of gullies coming from different levels is shown below in the image of Lohse Crater and the image of gullies in Ross Crater.

text: In areas of heavy water flow along a trail, a ditch is often dug on the uphill side of the trail with drainage points across the trail. The cross-drainage is also accomplished by means of culverts, which are cleared on a semi-annual basis, or by means of cross-channels, often created by placing logs or timbers across the trail in a downhill direction, called "thank-you-marms", "deadmen", or waterbars.  Timbers or rocks are also used for this purpose to creates erosion barriers. Rock paving in the bottom of these channels and in the trailside ditches are also sometimes used o maintain stability. The creation of water bars, with or without ditching, at major points of water flow on or along the trail, and in conjunction with existing drainage channels below the trail is also a technique that is applied Another important technique that is adopted is the construction coweeta dips, or drain dips, points on the trail where it falls briefly (for a meter or so) and then rises again. These provide positive drainage points that are almost never clogged by debris.

text: In areas of heavy water flow along a trail, a ditch is often dug on the uphill side of the trail with drainage points across the trail. The cross-drainage is also accomplished by means of

text: culvert

text: s, which are cleared on a semi-annual basis, or by means of cross-channels, often created by placing logs or timbers across the trail in a downhill direction, called "thank-you-marms", "deadmen", or

text: waterbar

text: s.  Timbers or rocks are also used for this purpose to creates

text: erosion

text: barriers. Rock paving in the bottom of these channels and in the trailside ditches are also sometimes used o maintain stability. The creation of water bars, with or without ditching, at major points of water flow on or along the trail, and in conjunction with existing drainage channels below the trail is also a technique that is applied Another important technique that is adopted is the construction coweeta dips, or drain dips, points on the trail where it falls briefly (for a meter or so) and then rises again. These provide positive drainage points that are almost never clogged by debris.

text: Hundested is situated at the tip of the Halsnæs peninsula which projects west from the northwestern corner of North Zealand, forming the west side of the entrance to Issefjord. The south coast of the peninsula is fronted by two cliffs which at Store Karlsminde Klint rises to 33 metres. It is located opposite the northern tip of Horns Herred, defining Kulhuse Rende, the one kilometer long entrance to Roskilde Fjord. To the west of Store Karlsminde Klint is the lower Skuldslev Klint which continues for about 1 kilometer to Kynæs Harbour. in the southern part of Hundested. The cliffs have formerly been subject to continuous erosion but is now sheltered by the harbor. The erosion has resulted in a shallow-watered area with water depths of only about one metre. To the east of Store Karlsminde Klint is a low area with coastal meadows, Sølager, which further inland gives way to forested slopes.

text: Hundested is situated at the tip of the Halsnæs peninsula which projects west from the northwestern corner of

text: North Zealand

text: , forming the west side of the entrance to

text: Issefjord

text: . The south coast of the peninsula is fronted by two cliffs which at Store Karlsminde Klint rises to 33 metres. It is located opposite the northern tip of

text: Horns Herred

text: , defining Kulhuse Rende, the one kilometer long entrance to

text: Roskilde Fjord

text: . To the west of Store Karlsminde Klint is the lower Skuldslev Klint which continues for about 1 kilometer to Kynæs Harbour. in the southern part of Hundested. The cliffs have formerly been subject to continuous erosion but is now sheltered by the harbor. The erosion has resulted in a shallow-watered area with water depths of only about one metre. To the east of Store Karlsminde Klint is a low area with coastal meadows, Sølager, which further inland gives way to forested slopes.

text: A post-earthquake survey of the land was undertaken by seismologists N. N. Ambraseys and C. P. Melville, but it was not completed until the mid 1970s. At that time,  of surface breaks with right-lateral offsets between  were located between the villages of Shurgil and Kuhneh Shahr. Substantial vertical movement of the west-northwest trending fault was also seen, with even greater maximum displacements of , but the average vertical slip was about  throughout the extent of the observed surface faulting. They estimated that about  of visible fault breaks were present immediately following the shocks, but by the time they had completed their survey 45 years later about half of the surface features had succumbed to erosion. Other effects included disturbed stream and spring flow, water table fluctuations, and landslides.

text: A post-earthquake survey of the land was undertaken by seismologists

text: N. N. Ambraseys

text: and C. P. Melville, but it was not completed until the mid 1970s. At that time,  of surface breaks with right-lateral offsets between  were located between the villages of Shurgil and Kuhneh Shahr. Substantial vertical movement of the west-northwest trending fault was also seen, with even greater maximum displacements of , but the average vertical slip was about  throughout the extent of the observed surface faulting. They estimated that about  of visible fault breaks were present immediately following the shocks, but by the time they had completed their survey 45 years later about half of the surface features had succumbed to

text: erosion

text: . Other effects included disturbed stream and

text: spring

text: flow,

text: water table

text: fluctuations, and landslides.

text: Klevevž is known for the ruins of Klevevž Castle with the remains of the castle park, the hypothermal spring Klevevž Spa (''Klevevške toplice''), also suitable for bathing, and two caves, Upper Klevevž Cave (''Zgornja Klevevška jama'') and Lower Klevevž (or Heathen) Cave (''Spodnja Kleveška jama'' or ''Ajdovska jama''). The first one is an over -long dry cave, with some dripstones at its end. Some prehistoric ceramics has been found there. The latter is a water cave inside of which there is the only known thermal spring in a cave in Slovenia. It is a home to a rich animal life, including bat colonies. The hypothermal spring flows to the Radulja, which flows through a gorge formed in the Triassic limestone and forms a cascade in this part.

text: Klevevž is known for the ruins of Klevevž Castle with the remains of the castle park, the

text: hypothermal

text: spring Klevevž Spa (''Klevevške toplice''), also suitable for bathing, and two caves, Upper Klevevž Cave (''Zgornja Klevevška jama'') and Lower Klevevž (or Heathen) Cave (''Spodnja Kleveška jama'' or ''Ajdovska jama''). The first one is an over -long dry cave, with some

text: dripstones

text: at its end. Some prehistoric

text: ceramics

text: has been found there. The latter is a water cave inside of which there is the only known thermal spring in a cave in Slovenia. It is a home to a rich animal life, including bat colonies. The hypothermal spring flows to the

text: Radulja

text: , which flows through a

text: gorge

text: formed in the

text: Triassic

text: limestone

text: and forms a

text: cascade

text: in this part.

text: Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their erosive potential on banks and river bottoms.  Very often these devices look like small waterfalls or cascades, where water flows vertically or over riprap to lose some of its kinetic energy.

text: Dissipation is the process of converting mechanical energy of downward-flowing water into thermal and acoustical energy. Various devices are designed in stream beds to reduce the kinetic energy of flowing waters to reduce their

text: erosive potential

text: on banks and

text: river bottoms

text: .  Very often these devices look like small

text: waterfall

text: s or

text: cascades

text: , where water flows vertically or over

text: riprap

text: to lose some of its

text: kinetic energy

text: In hydrology and geography, armor is the association of surface pebbles, rocks or boulders with stream beds or beaches. Most commonly hydrological armor occurs naturally; however, a man-made form is usually called riprap, when shorelines or stream banks are fortified for erosion protection with large boulders or sizable manufactured concrete objects.  When armor is associated with beaches in the form of pebbles to medium-sized stones grading from two to 200 millimeters across, the resulting landform is often termed a shingle beach.  Hydrological modeling indicates that stream armor typically persists in a flood stage environment. Bed Armor is most often transported through entrainment, and more specifically suspension and saltation. Both of these processes involve moving the sediment both near and around the bed of a river. When a sediment is entrained it is being moved downstream through the forces between the layers of water around it, and once it settles it begins to create a layer on the bed of the river. This layer of sediment changes the hydrology of the river around it, as once this layer on the bottom is formed it affects the hydraulics of the river. This layer of sediments on the bed of the river can act as barrier to the incoming flow, and depending on the size and distribution of the grains, can change the river. Understanding the Hjulstroms Diagram is important, as it represents at what grain size and flow speed a particle is transported. The slope present at the top left of the graph is due to clay and silt cohesion.

text: In

text: hydrology

text: and

text: geography

text: , armor is the association of surface

text: pebble

text: s, rocks or

text: boulder

text: s with

text: stream bed

text: s or

text: beach

text: es. Most commonly hydrological armor occurs naturally; however, a man-made form is usually called

text: riprap

text: , when

text: shoreline

text: s or stream banks are fortified for

text: erosion

text: protection with large boulders or sizable manufactured concrete objects.  When armor is associated with

text: beach

text: es in the form of pebbles to medium-sized stones grading from two to 200 millimeters across, the resulting

text: landform

text: is often termed a

text: shingle beach

text: .  Hydrological modeling indicates that stream armor typically persists in a

text: flood stage

text: environment. Bed Armor is most often transported through entrainment, and more specifically suspension and saltation. Both of these processes involve moving the sediment both near and around the bed of a river. When a sediment is entrained it is being moved downstream through the forces between the layers of water around it, and once it settles it begins to create a layer on the bed of the river. This layer of sediment changes the hydrology of the river around it, as once this layer on the bottom is formed it affects the hydraulics of the river. This layer of sediments on the bed of the river can act as barrier to the incoming flow, and depending on the size and distribution of the grains, can change the river. Understanding the

text: Hjulstroms Diagram

text: is important, as it represents at what grain size and flow speed a particle is transported. The slope present at the top left of the graph is due to clay and silt

text: cohesion

text: The female T. annulata is thought to deposit her eggs by flying over the surface and dipping the tip of her abdomen in the water. The larvae develop in water where they are aggressive predators. The adults are also predators, using their excellent eyesight to detect prey and their legs to hold and carry their victims.

text: The female T. annulata is thought to deposit her eggs by flying over the surface and dipping the tip of her abdomen in the water. The larvae develop in water where they are aggressive

text: predators

text: . The adults are also predators, using their excellent eyesight to detect prey and their legs to hold and carry their victims.

text: The National Conservation Strategy Report has three explicit objectives: conservation of natural resources, promotion of sustainable development, and improvement of efficiency in the use and management of resources. It sees itself as a "call for action" addressed to central and provincial governments, businesses, non-governmental organizations (NGOs), local communities, and individuals. The primary agricultural nonpoint source pollutants are nutrients (particularly nitrogen and phosphorus), sediment, animal wastes, pesticides, and salts. Agricultural nonpoint sources enter surface water through direct surface runoff or through seepage to ground water that discharges to a surface water outlet. Various farming activities result in the erosion of soil particles. The sediment produced by erosion can damage fish habitat and wetlands and, in addition, often transports excess agricultural chemicals resulting in contaminated runoff. This runoff in turn affects changes to aquatic habitat such as temperature increases and decreased oxygen. The most common sources of excess nutrients in surface water from non point sources are chemical fertilizers and manure from animal facilities. Such nutrients cause eutrophication in surface water. Pesticides used for pest control in agricultural operations can also contaminate surface as well as ground-water resources. Return flows, runoff, and leach ate from irrigated lands may transport sediment, nutrients, salts, and other materials. Finally, improper grazing practices in riparian, as well as upland areas, can also cause water quality degradation able development of Pakistan is viewed as a multigenerational enterprise. In seeking to transform attitudes and practices, the National Conservation Strategy recognizes that two key changes in values are needed: the restoration of the conservation ethic derived from Islam ix moral values, called Qantas, and the revival of community spirit and responsibility, Aquila-UL-bad.

text: The National Conservation Strategy Report has three explicit objectives: conservation of natural resources, promotion of sustainable development, and improvement of efficiency in the use and management of resources. It sees itself as a "call for action" addressed to central and provincial governments, businesses, non-governmental organizations (NGOs), local communities, and individuals. The primary agricultural nonpoint source pollutants are nutrients (particularly nitrogen and phosphorus), sediment, animal wastes, pesticides, and salts. Agricultural nonpoint sources enter surface water through direct

text: surface runoff

text: or through seepage to ground water that discharges to a surface water outlet. Various farming activities result in the erosion of soil particles. The sediment produced by erosion can damage fish habitat and wetlands and, in addition, often transports excess agricultural chemicals resulting in contaminated runoff. This runoff in turn affects changes to aquatic habitat such as temperature increases and decreased oxygen. The most common sources of excess nutrients in surface water from non point sources are chemical fertilizers and manure from animal facilities. Such nutrients cause eutrophication in surface water. Pesticides used for pest control in agricultural operations can also contaminate surface as well as ground-water resources. Return flows, runoff, and

text: leach ate

text: from irrigated lands may transport sediment, nutrients, salts, and other materials. Finally, improper grazing practices in riparian, as well as upland areas, can also cause water quality degradation able development of Pakistan is viewed as a multigenerational enterprise. In seeking to transform attitudes and practices, the National Conservation Strategy recognizes that two key changes in values are needed: the restoration of the conservation ethic derived from

text: Islam

text: ix moral values, called Qantas, and the revival of community spirit and responsibility, Aquila-UL-bad.

text: Water vapor generated through surface evaporation is transported by circulatory patterns in the atmosphere. When atmospheric conditions permit an uplift of warm, humid air, this water condenses and falls to the surface as precipitation. Most of the water is then transported to lower elevations by river systems and usually returned to the oceans or deposited into lakes. This water cycle is a vital mechanism for supporting life on land and is a primary factor in the erosion of surface features over geological periods. Precipitation patterns vary widely, ranging from several meters of water per year to less than a millimeter. Atmospheric circulation, topographic features, and temperature differences determine the average precipitation that falls in each region.

text: Water vapor generated through surface evaporation is transported by circulatory patterns in the atmosphere. When atmospheric conditions permit an uplift of warm, humid air, this water condenses and falls to the surface as precipitation. Most of the water is then transported to lower elevations by river systems and usually returned to the oceans or deposited into lakes. This

text: water cycle

text: is a vital mechanism for supporting life on land and is a primary factor in the erosion of surface features over geological periods. Precipitation patterns vary widely, ranging from several meters of water per year to less than a millimeter. Atmospheric circulation, topographic features, and temperature differences determine the average precipitation that falls in each region.

text: The formation of the cinder cone is currently a point of contention, with some arguing that lava flowing into the sea was suddenly cooled, forming an edifice on the coastline (a literal cone) and others noting that the cone was most likely too far away from the ocean at the time of formation to make such an event possible. Regardless of how it was formed according to the United States Geological Survey, the last lava flow in the area ended over 10,000 years ago, making the area one of the more stable features in the geologically turbulent Kaū region. As such, the geologic history of the site can be seen in the rock surrounding the beach and bay, which are not subject to erosion and thus display geologic layers formed by previous eruptions, lava flows, and other volcanic events. In addition, the current patterns of erosion can be seen first-hand, as only the portions at the bottom of the cinder cone collapse have been subject to the waves and turned into green sand; the remaining portions appear gray.

text: The formation of the cinder cone is currently a point of contention, with some arguing that lava flowing into the sea was suddenly cooled, forming an edifice on the coastline (a literal cone) and others noting that the cone was most likely too far away from the ocean at the time of formation to make such an event possible. Regardless of how it was formed according to the

text: United States Geological Survey

text: , the last lava flow in the area ended over 10,000 years ago, making the area one of the more stable features in the geologically turbulent Kaū region. As such, the geologic history of the site can be seen in the rock surrounding the beach and bay, which are not subject to erosion and thus display geologic layers formed by previous eruptions, lava flows, and other volcanic events. In addition, the current patterns of erosion can be seen first-hand, as only the portions at the bottom of the cinder cone collapse have been subject to the waves and turned into green sand; the remaining portions appear gray.

text: Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles (detritus) to settle in place. The particles that form a sedimentary rock by accumulating are called sediment. Before being deposited, the sediment was formed by weathering and erosion from the source area, and then transported to the place of deposition by water, wind, ice, mass movement or glaciers, which are called agents of denudation. Sedimentation may also occur as minerals precipitate from water solution or shells of aquatic creatures settle out of suspension.

text: Sedimentary rocks are types of

text: rock

text: that are formed by the

text: deposition

text: and subsequent cementation of that material at the

text: Earth's surface

text: and within bodies of water.

text: Sedimentation

text: is the collective name for processes that cause

text: mineral

text: and/or

text: organic

text: particles (

text: detritus

text: ) to settle in place. The particles that form a sedimentary rock by accumulating are called

text: sediment

text: . Before being deposited, the sediment was formed by

text: weathering

text: and

text: erosion

text: from the source area, and then transported to the place of deposition by

text: water

text: wind

text: ice

text: mass movement

text: or

text: glacier

text: s, which are called agents of

text: denudation

text: . Sedimentation may also occur as minerals precipitate from water solution or shells of aquatic creatures settle out of suspension.

text: Grant (1946) – the elevation of the beach watertable had an important bearing on deposition and erosion across the foreshore. A high watertable coincided with periods of accelerated beach erosion, and conversely, a low watertable coincided with pronounced aggradation of the foreshoreA lower watertable (unsaturated beach face) facilitates deposition by reducing flow velocities during backwash and prolonging laminar flow. In contrast, a high watertable results in condition favoring beach erosion. With the beach in a saturated state, Grant proposed that backwash velocity is accelerated by the addition of groundwater seepage out of the beach within the effluent zone.

text: During first half of 2004 various sinkholes appeared, as a result of too much groundwater being pumped out by vegetable farmers in the area.

text: A groyne's length and elevation, and the spacing between groynes is determined according to local wave energy and beach slope. Groynes that are too long or too high tend to accelerate downdrift erosion, and are ineffective because they trap too much sediment. Groynes that are too short, too low, or too permeable are ineffective because they trap too little sediment. If a groyne does not extend far enough landward, water (for example at a high tide combined with a storm surge) may flow past the landward end and erode a channel bypassing the groyne, a process known as  flanking.

text: A groyne's length and elevation, and the spacing between groynes is determined according to local wave energy and beach slope. Groynes that are too long or too high tend to accelerate downdrift erosion, and are ineffective because they trap too much sediment. Groynes that are too short, too low, or too

text: permeable

text: are ineffective because they trap too little sediment. If a groyne does not extend far enough landward, water (for example at a high tide combined with a storm surge) may flow past the landward end and erode a channel bypassing the groyne, a process known as  flanking.

text: Water can increase or decrease the stability of a slope depending on the amount present.  Small amounts of water can strengthen soils because the surface tension of water increases soil cohesion.  This allows the soil to resist erosion better than if it were dry.  If too much water is present the water may act to increase the pore pressure, reducing friction, and accelerating the erosion process and resulting in different types of mass wasting (i.e. mudflows, landslides, etc.).  A good example of this is to think of a sand castle.  Water must be mixed with sand in order for the castle to keep its shape.  If too much water is added the sand washes away, if not enough water is added the sand falls and cannot keep its shape. Water also increases the mass of the soil, this is important because an increase in mass means that there will be an increase in velocity if mass wasting is triggered.

text: Water can increase or decrease the stability of a slope depending on the amount present.  Small amounts of water can strengthen soils because the surface tension of water increases soil cohesion.  This allows the soil to resist erosion better than if it were dry.  If too much water is present the water may act to increase the pore pressure, reducing friction, and accelerating the erosion process and resulting in different types of mass wasting (i.e. mudflows, landslides, etc.).  A good example of this is to think of a

text: sand castle

text: .  Water must be mixed with sand in order for the castle to keep its shape.  If too much water is added the sand washes away, if not enough water is added the sand falls and cannot keep its shape. Water also increases the mass of the soil, this is important because an increase in mass means that there will be an increase in velocity if mass wasting is triggered.

text: Much of Florida consists of karst limestone veined with water-filled caves and sinkholes, which provide homes to many species of aquatic life, some unique to particular Florida locations. As urban and suburban development have increased over the last decades, demand for groundwater has also risen, resulting in damage and drying out of portions of the cave system. This has led to ground subsidence as dry caves collapse, threatening property as well as ecosystems.

text: Much of Florida consists of

text: karst

text: limestone

text: veined with water-filled

text: cave

text: s and

text: sinkhole

text: s, which provide homes to many species of aquatic life, some unique to particular Florida locations. As urban and suburban development have increased over the last decades, demand for groundwater has also risen, resulting in damage and drying out of portions of the cave system. This has led to ground subsidence as dry caves collapse, threatening property as well as ecosystems.

text: The effect of increased human and animal population, as well as land use in the Himalayan Mountains have caused soil erosion, which could have resulted in the extra deposition of sediments in the Bangladesh watersheds. This may have effects on the soil composition near the watershed and the propensity of the area to flood. While Eckholm and Myers have proposed a now popular theory that there is a direct causal relationship between deforestation in Nepal and higher flooding in the Bangladesh watersheds, there is not enough evidence to determine whether or not this is true. Improper watershed management does lead to sedimentation in reservoirs and changing patterns of stream flow. Sedimentation in reservoirs effects the turbidity of the reservoir, and erosion patters along the river. It also presents a cost to the government who has to dredge the rivers of its sediments. In Bangladesh, the government has to remove 0.8 million cubic meters of maintenance dredging and 2 million cubic meters of capital dredging per year. Since scientists do not unanimously agree the degree to which watershed management affects patterns of stream flow and flooding, it is difficult determine the extent of this effect.

text: Eventually, the face of a waterfall will become undermined by the plunge-pool, and will cave into the pool, filling it with debris.  Subsequently, the debris is removed by additional heavy rainfalls, leaving a new plunge-pool relatively free of debris.  The waterfall, however, has moved up-slope by a few feet.  Over time, the waterfalls slowly recede upslope.  If a waterfall hits a stronger region that resists erosion, lower level waterfalls can 'catch-up' and two waterfalls merge into one deeper waterfall.  This process is causing the Umauma Falls to slowly move upslope over geologic time, though we can see the plunge-pools at the bases of the three Umauma Falls (Note:  there are many other waterfalls on the Umauma River, also slowly moving upslope over geologic time).  We can see what Umauma Falls might look like in the far distant future by visiting the neighboring river (KoleKole) just to the south of the Umauma River, which has a very large single waterfall, known as Akaka Falls, formed in just such a manner in the distant geologic past.  It is further upslope than the Umauma Falls, and it is in a much heavier rainfall region.

text: Eventually, the face of a waterfall will become undermined by the plunge-pool, and will cave into the pool, filling it with debris.  Subsequently, the debris is removed by additional heavy rainfalls, leaving a new plunge-pool relatively free of debris.  The waterfall, however, has moved up-slope by a few feet.  Over time, the waterfalls slowly recede upslope.  If a waterfall hits a stronger region that resists erosion, lower level waterfalls can 'catch-up' and two waterfalls merge into one deeper waterfall.  This process is causing the Umauma Falls to slowly move upslope over geologic time, though we can see the plunge-pools at the bases of the three Umauma Falls (Note:  there are many other waterfalls on the Umauma River, also slowly moving upslope over geologic time).  We can see what Umauma Falls might look like in the far distant future by visiting the neighboring river (KoleKole) just to the south of the Umauma River, which has a very large single waterfall, known as

text: Akaka Falls

text: , formed in just such a manner in the distant geologic past.  It is further upslope than the Umauma Falls, and it is in a much heavier rainfall region.

text: River flow is intermittent and when it flows, its water flows very slowly owing to a gradient of only 0.76 m/km. Floods are rare because the vast sandveld areas of the Kalahari Desert on the Namibian side of its basin absorb all water from the seasonal rains. In case of exceptionally heavy and continuous precipitation the flow discharges into the Orange River, which it meets downstream of Augrabies Falls National Park at . It is believed that this last occurred more than 100 years ago.

text: River flow is intermittent and when it flows, its water flows very slowly owing to a gradient of only 0.76 m/km. Floods are rare because the vast

text: sandveld

text: areas of the

text: Kalahari Desert

text: on the Namibian side of its basin absorb all water from the seasonal rains. In case of exceptionally heavy and continuous precipitation the flow discharges into the

text: Orange River

text: , which it meets downstream of

text: Augrabies Falls National Park

text: at . It is believed that this last occurred more than 100 years ago.

text: Langavatnet is a lake in the municipality of Odda in Hordaland county, Norway.  The  lake lies about  straight east of the town of Odda.  The lake has a dam at the north end to regulate the water level for the purposes of hydroelectric power generation.  The water of the lake previously flowed north to create the large Ringedalsfossen waterfall which now only flows when the lake gets too full.  The water flows over the falls into the lake Ringedalsvatnet (which has a dam at its western end) before flowing through the short river Tysso which empties into the Sørfjorden.

text: Langavatnet is a

text: lake

text: in the municipality of

text: Odda

text: in

text: Hordaland

text: county,

text: Norway

text: .  The  lake lies about  straight east of the town of

text: Odda

text: .  The lake has a

text: dam

text: at the north end to regulate the water level for the purposes of

text: hydroelectric power

text: generation.  The water of the lake previously flowed north to create the large Ringedalsfossen

text: waterfall

text: which now only flows when the lake gets too full.  The water flows over the falls into the lake

text: Ringedalsvatnet

text: (which has a dam at its western end) before flowing through the short river Tysso which empties into the

text: Sørfjorden

text: Erosion, Flooding and  Surface Water

text: Erosion, Flooding and  Surface Water

text: The waterfall is made by two streams, Arroyo del Durazno and Arroyo de Basaseachic, which merge in the high mountains and then fall down the canyon wall. Past the falls, the stream is called Río Candameña (Candamena River), which is the namesake of the canyon it flows through, Candamena Canyon (Cañon Candameña). Candamena River contributes to the formation of Río Mayo (Mayo River).

text: The waterfall is made by two streams, Arroyo del Durazno and Arroyo de Basaseachic, which merge in the high mountains and then fall down the canyon wall. Past the falls, the stream is called

text: Río Candameña

text: (Candamena River), which is the namesake of the canyon it flows through, Candamena Canyon (Cañon Candameña). Candamena River contributes to the formation of

text: Río Mayo

text: (Mayo River).

text: Flows in the river are swelled by discharges from several sewage treatment works. The three largest are at Princes Marsh, Petersfield and Ambersham, all of which have outflows between  per day, with another three discharging between  per day at Rogate, Coultershaw and Fittleworth. The entire river, including parts of some of its tributaries, is designated as a Site of Nature Conservation Importance by the local authorities through which it flows, in recognition of its value for wildlife. The upper reaches of the Rother are important for their fish populations of brown trout, grayling, juvenile sea trout, and the spawning and early development of salmonids. There are also populations of bullhead, eel, lamprey, minnow and stone loach. There has been some concern about declining fish stocks, thought to be partly caused by soil erosion, leading to silt and sediments being deposited on the river bed, which has been exacerbated by low flows in the river. Parts of the lower river support the same types of fish, but there are areas, particularly immediately upstream of weirs, where the major species are bream, pike and roach, with chubb, dace and perch on the lowest reaches. In order to assist the movement of fish along the river, particularly those that migrate to the headwaters to spawn, fish passes have been constructed around the gauging stations. The only known population of native white clawed crayfish in Sussex is located in the upper reaches of the Rother.

text: Flows in the river are swelled by discharges from several sewage treatment works. The three largest are at Princes Marsh, Petersfield and Ambersham, all of which have outflows between  per day, with another three discharging between  per day at Rogate, Coultershaw and Fittleworth. The entire river, including parts of some of its tributaries, is designated as a

text: Site of Nature Conservation Importance

text: by the local authorities through which it flows, in recognition of its value for wildlife. The upper reaches of the Rother are important for their fish populations of

text: brown trout

text: grayling

text: , juvenile sea trout, and the spawning and early development of

text: salmonids

text: . There are also populations of

text: bullhead

text: eel

text: lamprey

text: minnow

text: and

text: stone loach

text: . There has been some concern about declining fish stocks, thought to be partly caused by soil erosion, leading to silt and sediments being deposited on the river bed, which has been exacerbated by low flows in the river. Parts of the lower river support the same types of fish, but there are areas, particularly immediately upstream of weirs, where the major species are

text: bream

text: pike

text: and

text: roach

text: , with

text: chubb

text: dace

text: and

text: perch

text: on the lowest reaches. In order to assist the movement of fish along the river, particularly those that migrate to the headwaters to spawn,

text: fish pass

text: es have been constructed around the gauging stations. The only known population of native

text: white clawed crayfish

text: in Sussex is located in the upper reaches of the Rother.

text: The caves are naturally formed by water erosion through the limestone rock. The calcium-rich water that runs through the caves have formed the unusual stalactites and stalagmites formations. Travel through the caves is by tram, at certain points during the tour visitors are allowed to alight from the tram and get close up to the formations. One main area of the caves is a huge cavern, termed "The Great Hall", measuring over 50 feet in height. After the Great Hall the tram stops at "The Village". At The Village some of the formations have joined together to form columns after thousands of years. Other areas the tram stops along the tour is "The Chapel," "The Rotundra," and the "The Altar." Visitors travel through the Boyce Tunnel via tram to all depths of the cave. Harrison's Cave is in the central uplands of Barbados. It is situated at 700 ft above sea level. The three (3) characteristics of the central uplands are gullies, sinkholes and caverns. It is also an entrance for another place of insterest Welchman Hall Gully which is shut off for a purpose.

text: The caves are naturally formed by water

text: erosion

text: through the

text: limestone

text: rock. The

text: calcium

text: -rich water that runs through the caves have formed the unusual

text: stalactite

text: s and

text: stalagmite

text: s formations. Travel through the caves is by

text: tram

text: , at certain points during the tour visitors are allowed to alight from the tram and get close up to the formations. One main area of the caves is a huge cavern, termed "The Great Hall", measuring over 50 feet in height. After the Great Hall the tram stops at "The Village". At The Village some of the formations have joined together to form columns after thousands of years. Other areas the tram stops along the tour is "The Chapel," "The Rotundra," and the "The Altar." Visitors travel through the Boyce Tunnel via tram to all depths of the cave. Harrison's Cave is in the central uplands of Barbados. It is situated at 700 ft above sea level. The three (3) characteristics of the central uplands are gullies, sinkholes and caverns. It is also an entrance for another place of insterest Welchman Hall Gully which is shut off for a purpose.

text: Dolines (or sinkholes) are mostly found in its suffusion form. Suffusion dolines are depressions formed above caves and smaller cavities in unconsolidated sediments. Many dolines in the Eramosa Karst are formed by a combination of soil piping and erosion of the glacially deposited sediments, overlying the bedrock.

text: Dolines (or

text: sinkhole

text: s) are mostly found in its suffusion form. Suffusion dolines are depressions formed above caves and smaller cavities in unconsolidated sediments. Many dolines in the Eramosa Karst are formed by a combination of soil piping and erosion of the glacially deposited sediments, overlying the bedrock.

text: Like most of the rivers that rise in the heights of Limousin, the Auvézère is a water-rich river. Its flow has been observed during the period of 27 years (between 1982 and 2008) at Le Change, just upstream of its confluence with the Isle. The mean annual flow at this station was 8.52 m³/s. The Auvézère is a seasonal river with the highest flows during winter and early spring. The median flows between December and April lie between 12.2 and 16.8 m³/s. In spring the flow rapidly decreases to 4.62 m³/s in June. The lowest flow is observed in August: 1.87 m³/s. The lowest three-day aaverage flow is only 0.22 m³/s. The highest calculated flow is 250 m³/s, and the highest observed flow at Le Change was 182 m³/s on January 7, 1982.

text: Like most of the rivers that rise in the heights of Limousin, the Auvézère is a water-rich river. Its flow has been observed during the period of 27 years (between 1982 and 2008) at

text: Le Change

text: , just upstream of its confluence with the Isle. The mean annual flow at this station was 8.52 m³/s. The Auvézère is a seasonal river with the highest flows during winter and early spring. The median flows between December and April lie between 12.2 and 16.8 m³/s. In spring the flow rapidly decreases to 4.62 m³/s in June. The lowest flow is observed in August: 1.87 m³/s. The lowest three-day aaverage flow is only 0.22 m³/s. The highest calculated flow is 250 m³/s, and the highest observed flow at Le Change was 182 m³/s on January 7, 1982.

text: The waterfalls are located in an area of mature karst formations where the original limestone bedrock layers are being eroded. Numerous streams spring from underground fissures along the lower levels of the area. The waterfalls have multiple drops, from bedrock layer to layer, which shows the multiple depositions of sediments of different hardness which formed the terrain over millions of years.

text: The waterfalls are located in an area of mature

text: karst

text: formations where the original limestone bedrock layers are being eroded. Numerous streams spring from underground fissures along the lower levels of the area. The waterfalls have multiple drops, from bedrock layer to layer, which shows the multiple depositions of sediments of different hardness which formed the terrain over millions of years.

text: Human activity can directly trigger exacerbating factors such as over farming, excessive irrigation, deforestation, and erosion adversely impact the ability of the land to capture and hold water.  In arid climates, the main source of erosion is wind.  Erosion can be the result of material movement by the wind.  The wind can cause small particles to be lifted and therefore moved to another region (deflation).  Suspended particles within the wind may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation.

text: Human activity can directly trigger exacerbating factors such as over farming, excessive irrigation,

text: deforestation

text: , and

text: erosion

text: adversely impact the ability of the land to capture and hold water.  In arid climates, the main source of erosion is wind.  Erosion can be the result of material movement by the wind.  The wind can cause small particles to be lifted and therefore moved to another region (deflation).  Suspended particles within the wind may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation.

text: Head cut in stream geomorphology is an erosional feature of some intermittent and perennial streams where an abrupt vertical drop, also known as a knickpoint in the stream bed occurs. The knickpoint, where a head cut begins, can be as small as an overly-steep riffle zone or as a large as a waterfall. When not flowing, the head cut will resemble a very short cliff or bluff.  A small plunge pool may be present at the base of the head cut due to the high energy of falling water. As erosion of the knickpoint and the streambed continues, the head cut will migrate upstream.

text: Head cut in

text: stream

text: geomorphology

text: is an

text: erosion

text: al feature of some

text: intermittent

text: and

text: perennial

text: stream

text: s where an abrupt vertical drop, also known as a

text: knickpoint

text: in the stream bed occurs. The knickpoint, where a head cut begins, can be as small as an overly-steep

text: riffle

text: zone or as a large as a

text: waterfall

text: . When not flowing, the head cut will resemble a very short

text: cliff

text: or

text: bluff

text: .  A small

text: plunge pool

text: may be present at the base of the head cut due to the high energy of falling water. As erosion of the knickpoint and the streambed continues, the head cut will migrate upstream.

text: Urbanization and clearing of vegetation increase runoff water, which in turn increases water volume, especially during rainy seasons. Therefore, the increased level of vertical erosion of the river increases the power of the water, leading to erosion of the river. A study of San Pedro River and another river in the southwest have indicated that floods were the main cause of river entrenchment in the 18th century. The study shows that increased population and human activities in these places increased floods and, consequently, the volume of runoff water (Hereford 43).

text: Urbanization

text: and clearing of

text: vegetation

text: increase runoff water, which in turn increases water

text: volume

text: , especially during rainy seasons. Therefore, the increased level of vertical

text: erosion

text: of the river increases the power of the water, leading to

text: erosion

text: of the river. A study of

text: San Pedro River

text: and another river in the southwest have indicated that floods were the main cause of river entrenchment in the 18th century. The study shows that increased population and human activities in these places increased

text: floods

text: and, consequently, the

text: volume

text: of runoff water (Hereford 43).

text: Trails lead from the cascada chica to the cascada grande, the valley floor and other areas in the vicinity.  The cascada grande is just to the south of the cascada chica and easily visible from it. This waterfall rock formation is more vertical than the cascada chica. Similarly, it is a rock shelf from which flows mineral laden water over the side. This shelf is ninety metres above the valley floor, eighty metres wide with the waterfall extending down for about thirty metres. This shelf does not have artificial pools.

text: Formations in Petty John's Cave include: Stalagmites that are a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate.  Stalactites are also found in the cave. These formations hang from the ceiling or wall of the cave. There are also pillars, soda straws, cave pearls, flowstones, and cave popcorn are other formations in the cave. In addition, waterfalls can be found in the stream passage section.

text: Formations in Petty John's Cave include:

text: Stalagmite

text: s that are a type of

text: speleothem

text: that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate.

text: Stalactite

text: s are also found in the cave. These formations hang from the ceiling or wall of the cave. There are also pillars,

text: soda straw

text: s,

text: cave pearl

text: s,

text: flowstone

text: s, and

text: cave popcorn

text: are other formations in the cave. In addition, waterfalls can be found in the stream passage section.

text: Hamilton Pool Preserve is a natural pool that was created when the dome of an underground river collapsed due to massive erosion thousands of years ago.  The pool is located about 23 miles (37 km) west of Austin, Texas off Highway 71.  Since the 1960s, Hamilton Pool has been a popular summer swimming spot for Austin visitors and residents.  Hamilton Pool Preserve consists of  of protected natural habitat featuring a jade green pool into which a  waterfall flows.

text: Hamilton Pool Preserve is a natural pool that was created when the dome of an underground

text: river

text: collapsed due to massive

text: erosion

text: thousands of years ago.  The pool is located about 23 miles (37 km) west of

text: Austin

text: Texas

text: off

text: Highway 71

text: .  Since the 1960s, Hamilton Pool has been a popular summer swimming spot for Austin visitors and residents.  Hamilton Pool Preserve consists of  of protected natural habitat featuring a jade green pool into which a  waterfall flows.

text: In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth's crust, then transport it away to another location. The particulate breakdown of rock or soil into clastic sediment is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by its dissolving into a solvent (typically water), followed by the flow away of that solution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.

text: In

text: earth science

text: , erosion is the action of surface processes (such as

text: water flow

text: or

text: wind

text: ) that remove

text: soil

text: rock

text: , or dissolved material from one location on the

text: Earth's crust

text: , then

text: transport

text: it away to another location. The particulate breakdown of rock or soil into

text: clastic

text: sediment

text: is referred to as physical or mechanical erosion; this contrasts with chemical erosion, where soil or rock material is removed from an area by its dissolving into a solvent (typically water), followed by the flow away of that solution. Eroded

text: sediment

text: or solutes may be transported just a few millimetres, or for thousands of kilometres.

text: The density of vegetation in mangrove forests, seagrass meadows, and tidal marshes is an important factor in carbon burial rates.The density of the vegetation must be sufficient to change water flows enough to reduce erosion and increase sediment deposition.

text: Some of Queensland's towns are located on relatively flat land on the banks of rivers. During severe floods, such as the 2010 Queensland floods, numerous towns are inundated as flood waters rise. Levees have alleviated some minor flooding but after prolonged periods of heavy rainfall the sheer volume of flood waters cannot be held back. Disruptions from flooding have become accepted in inland towns like Charleville and to a lesser degree in coastal towns such as Gympie.

text: Some of Queensland's towns are located on relatively flat land on the banks of rivers. During severe floods, such as the

text: 2010 Queensland floods

text: , numerous towns are inundated as flood waters rise.

text: Levee

text: s have alleviated some minor flooding but after prolonged periods of heavy rainfall the sheer volume of flood waters cannot be held back. Disruptions from flooding have become accepted in inland towns like

text: Charleville

text: and to a lesser degree in coastal towns such as

text: Gympie

text: The waterfalls are on the section of Kitchen Creek that flows down the Allegheny Front, a steep escarpment between the Allegheny Plateau to the north and the Ridge-and-Valley Appalachians to the south. The glens are made of sedimentary rocks from the Huntley Mountain and Catskill Formations that formed up to 370 million years ago in the Devonian and Carboniferous periods. The waterfalls are the result of increased flow in Kitchen Creek from glaciers enlarging its drainage basin during the last Ice Age.

text: The waterfalls are on the section of Kitchen Creek that flows down the

text: Allegheny Front

text: , a steep

text: escarpment

text: between the

text: Allegheny Plateau

text: to the north and the

text: Ridge-and-Valley Appalachians

text: to the south. The glens are made of sedimentary rocks from the

text: Huntley Mountain

text: and

text: Catskill Formation

text: s that formed up to 370 million years ago in the

text: Devonian

text: and

text: Carboniferous

text: periods. The waterfalls are the result of increased flow in Kitchen Creek from glaciers enlarging its

text: drainage basin

text: during the

text: last Ice Age

text: It had been known since before the 20th century that the Black Sea and the Sea of Marmara flow into each other in a geographic example of "density flow", and in August 2010, a continuous 'underwater channel' of suspension composition was discovered to flow along the floor of the Bosphorus, which would be the sixth largest river on Earth if it were to be on land.  The study of the water and wind erosion of the straits relates to that of its formation.   Sections of the shore have been reinforced with concrete or rubble and sections of the strait prone to deposition are periodically dredged.

text: It had been known since before the 20th century that the Black Sea and the Sea of Marmara flow into each other in a geographic example of "density flow", and in August 2010, a continuous 'underwater channel' of

text: suspension

text: composition was discovered to flow along the floor of the Bosphorus, which would be the sixth largest river on Earth if it were to be on land.  The study of the

text: water

text: and

text: wind erosion

text: of the straits relates to that of its formation.   Sections of the shore have been reinforced with concrete or rubble and sections of the strait prone to

text: deposition

text: are periodically dredged.

text: When sufficient data have been assembled, it is possible to determine some of missing information by calibration. This implies that one assumes a range of values for the unknown or doubtful value of a certain parameter and one runs the model repeatedly while comparing results with known corresponding data. For example, if salinity figures of the groundwater are available and the value of hydraulic conductivity is uncertain, one assumes a range of conductivities and the selects that value of conductivity as "true" that yields salinity results close to the observed values, meaning that the groundwater flow as governed by the hydraulic conductivity is in agreemnent with the salinity conditions. This procedure is similar to the measurement of the flow in a river or canal by letting very saline water of a known salt concentration drip into the channel and measuring the resulting salt concentration downstream.

text: When sufficient data have been assembled, it is possible to determine some of missing information by calibration. This implies that one assumes a range of values for the unknown or doubtful value of a certain parameter and one runs the model repeatedly while comparing results with known corresponding data. For example, if

text: salinity

text: figures of the groundwater are available and the value of

text: hydraulic conductivity

text: is uncertain, one assumes a range of conductivities and the selects that value of conductivity as "true" that yields salinity results close to the observed values, meaning that the groundwater flow as governed by the hydraulic conductivity is in agreemnent with the salinity conditions. This procedure is similar to the measurement of the flow in a river or canal by letting very saline water of a known salt concentration drip into the channel and measuring the resulting salt concentration downstream.

text: The New Zealand Resource Management Act 1991  dictates that as part of mitigation for the loss of recreational amenities on the Tongariro River, Genesis Energy must divert water into natural riverbed for 3 weekends per year. This is purely for recreational enjoyment and separate from any maintenance or flushing flows that are otherwise necessary. The dates for these releases are set in conjunction with the national body WhitewaterNZ and generally are structured such that Access 10 releases are on a Saturday and Access 14/13 are on the Sunday of the same weekend. Flows of  are released from Rangipo Dam for a duration of 8 hours.  Flows of 30 cumecs are released from the Poutu Intake for 6 hours. The Access 14/13 sections are not able to be paddled without a release from Genesis Energy, due to the fact that the minimum required flow from below Rangipo Dam is negligible in terms of whitewater and the intake structure at Rangipo is able to take huge amounts of water; so if there is extra storm flow in these sections the flow is generally dangerously high. Access 10 is able to be paddled year-round as the minimum flow of  below Poutu Intake is paddleable - albeit scratchy, and the amount of extra water able to be taken during storm events at Poutu Intake is relatively small so water is often spilled into the river.

text: The New Zealand Resource Management Act 1991  dictates that as part of mitigation for the loss of recreational amenities on the Tongariro River,

text: Genesis Energy

text: must divert water into natural riverbed for 3 weekends per year. This is purely for recreational enjoyment and separate from any maintenance or flushing flows that are otherwise necessary. The dates for these releases are set in conjunction with the national body WhitewaterNZ and generally are structured such that Access 10 releases are on a Saturday and Access 14/13 are on the Sunday of the same weekend. Flows of  are released from Rangipo Dam for a duration of 8 hours.  Flows of 30 cumecs are released from the Poutu Intake for 6 hours. The Access 14/13 sections are not able to be paddled without a release from

text: Genesis Energy

text: , due to the fact that the minimum required flow from below Rangipo Dam is negligible in terms of whitewater and the intake structure at Rangipo is able to take huge amounts of water; so if there is extra storm flow in these sections the flow is generally dangerously high. Access 10 is able to be paddled year-round as the minimum flow of  below Poutu Intake is paddleable - albeit scratchy, and the amount of extra water able to be taken during storm events at Poutu Intake is relatively small so water is often spilled into the river.

text: Hjulström is most known for creating the Hjulström curve, which describes the thresholds for erosion and deposition of particles in running water.

text: Hjulström is most known for creating the

text: Hjulström curve

text: , which describes the thresholds for

text: erosion

text: and

text: deposition

text: of particles in running water.

text: Pandavleni, also known as Panch Pandav, is ancient rock-cut sculptures complex located at  in Gomai River around 6 kilometer north of Shahada, Maharashtra. The Pandavleni complex is in the bed of Gomai river carved in one solid rock. The Pandavleni is around 10 metres below the rest of terrain. There are rather identical two structures around 15 metres apart in east-west line. Sculptures in rock are carved in such a way that water in river flows over the rock, water falls in sculpture complex but force of water do not impact sculptures. It is like sculpture carved on the wall of well. During flood well will be filled with water and water will flow over well without causing any damage to sculpture on the wall of the well.

text: Pandavleni, also known as Panch Pandav, is ancient rock-cut sculptures complex located at  in

text: Gomai River

text: around 6 kilometer north of

text: Shahada

text: Maharashtra

text: . The Pandavleni complex is in the bed of Gomai river carved in one solid rock. The Pandavleni is around 10 metres below the rest of terrain. There are rather identical two structures around 15 metres apart in east-west line. Sculptures in rock are carved in such a way that water in river flows over the rock, water falls in sculpture complex but force of water do not impact sculptures. It is like sculpture carved on the wall of well. During flood well will be filled with water and water will flow over well without causing any damage to sculpture on the wall of the well.

text: Water supplies from wells in karst topography may be unsafe, as the water may have run unimpeded from a sinkhole in a cattle pasture, through a cave and to the well, bypassing the normal filtering that occurs in a porous aquifer. Karst formations are cavernous and therefore have high rates of permeability, resulting in reduced opportunity for contaminants to be filtered.Groundwater in karst areas is just as easily polluted as surface streams. Sinkholes have often been used as farmstead or community trash dumps.  Overloaded or malfunctioning septic tanks in karst landscapes may dump raw sewage directly into underground channels.

text: Water supplies from

text: wells

text: in karst topography may be unsafe, as the water may have run unimpeded from a sinkhole in a cattle pasture, through a cave and to the well, bypassing the normal filtering that occurs in a porous aquifer. Karst formations are cavernous and therefore have high rates of permeability, resulting in reduced opportunity for contaminants to be filtered.

text: Groundwater

text: in karst areas is just as easily

text: polluted

text: as surface streams. Sinkholes have often been used as farmstead or community

text: trash dumps

text: .  Overloaded or malfunctioning

text: septic tank

text: s in karst landscapes may dump raw sewage directly into underground channels.

text: Nanded is the second largest city in Marathawada after Aurangabad with an area of 63.22 km. Also it is 8th largest city/urban agglomeration in Maharshatra after Mumbai, Pune, Nagpur, Nasik, Aurangabad, Solapur and Amravati. Nanded district borders Latur district and Parbhani district to the west and Yavatmal district to the north, the district is bounded by Nizamabad, Medak and Adilabad districts of Telangana on the east. Nanded City is divided in two parts: Old Nanded (20.62 km) on the north bank of Godavari River, and New Nanded (31.14 km), comprising Waghala and six other newly merged villages which are situated on south of the Godavari river.22. The entire area is covered by the Deccan Traps lava flows of Upper Cretaceous to Lower Eocene age. The lava flows are overlain by thin alluvial deposits along the Kham and Sukhana river. The basaltic lava flows belonging to the Deccan Trap is the only major geological formation occurring in Aurangabad. The lava flows are horizontal and each flow has two distinct units.  The highly weathered vesicular trap and underlying weathered jointed and fractured massive trap constitutes the main water-yielding zones. The soil is mostly formed from igneous rocks and are black, medium black, shallow and calcareous types having different depths and profiles

text: Nanded is the second largest city in Marathawada after

text: Aurangabad

text: with an area of 63.22 km. Also it is 8th largest city/urban agglomeration in Maharshatra after Mumbai, Pune, Nagpur, Nasik, Aurangabad, Solapur and Amravati. Nanded district borders

text: Latur district

text: and

text: Parbhani district

text: to the west and

text: Yavatmal district

text: to the north, the district is bounded by

text: Nizamabad

text: , Medak and Adilabad districts of Telangana on the east. Nanded City is divided in two parts: Old Nanded (20.62 km) on the north bank of

text: Godavari

text: River, and New Nanded (31.14 km), comprising Waghala and six other newly merged villages which are situated on south of the

text: Godavari

text: river.22. The entire area is covered by the Deccan Traps lava flows of Upper Cretaceous to Lower Eocene age. The lava flows are overlain by thin alluvial deposits along the Kham and Sukhana river. The basaltic lava flows belonging to the Deccan Trap is the only major geological formation occurring in Aurangabad. The lava flows are horizontal and each flow has two distinct units.  The highly weathered vesicular trap and underlying weathered jointed and fractured massive trap constitutes the main water-yielding zones. The soil is mostly formed from igneous rocks and are black, medium black, shallow and calcareous types having different depths and profiles

text: The Sumidero Canyon was formed by cracks in the earth’s crust along with erosion by the Grijalva River, which still flows through it. The process of its formation began about 35 million years ago, making the Sumidero contemporary with the Grand Canyon on the Colorado River . The Grijalva is the main water system in the area, beginning in the Cuchumatanes in Guatemala. The river then flows through Chiapas, including the thirteen km length of the canyon from south to north then onto Tabasco before it empties into the Usumacinta River. This river basin is one of the two most important in Chiapas, and one of the most important in Mexico with a total river length of 766 km, draining an area of 7,940km2, with an average flow of about forty million cubic meters.

text: The Sumidero Canyon was formed by cracks in the earth’s crust along with erosion by the

text: Grijalva River

text: , which still flows through it. The process of its formation began about 35 million years ago, making the Sumidero contemporary with the

text: Grand Canyon

text: on the

text: Colorado River

text: . The Grijalva is the main water system in the area, beginning in the

text: Cuchumatanes

text: in Guatemala. The river then flows through Chiapas, including the thirteen km length of the canyon from south to north then onto

text: Tabasco

text: before it empties into the

text: Usumacinta River

text: . This river basin is one of the two most important in Chiapas, and one of the most important in Mexico with a total river length of 766 km, draining an area of 7,940km2, with an average flow of about forty million cubic meters.

text: The rocks in the Nahe region are predominantly of Cisuralian (early Permian) age and part of the Rotliegendes. At that time, an impetuous volcanism appeared in the region. Huge deposits of the reddish volcanic rock Rhyolite and of the more alkaline volcanic rock Andesite were left. The valleys of the Nahe and its tributaries have been being formed since 2.6 million years ago during the Quaternary, the geologically latest period, as a result of ground heaving of the surrounding mountains of Hunsrück and North Palatine Uplands. This led to a steep decline of all waters and hence to strong erosion activities. Particularly strong erosion occurred in warmer melting periods during the ice ages, when tundra climate reigned and the soil was not protected by a dense cover of vegetation. Depending on the underground, narrow gorges with cliffy precipices arose in areas with hard volcanic rocks or wide gentle valleys with flood plains in areas with soft sedimentary deposits. The frequent change between both forms is charming along the Nahe.

text: The rocks in the Nahe region are predominantly of

text: Cisuralian

text: (early

text: Permian

text: ) age and part of the

text: Rotliegendes

text: . At that time, an impetuous volcanism appeared in the region. Huge deposits of the reddish volcanic rock

text: Rhyolite

text: and of the more alkaline volcanic rock

text: Andesite

text: were left. The valleys of the Nahe and its tributaries have been being formed since 2.6 million years ago during the

text: Quaternary

text: , the geologically latest period, as a result of ground heaving of the surrounding mountains of Hunsrück and North Palatine Uplands. This led to a steep decline of all waters and hence to strong erosion activities. Particularly strong erosion occurred in warmer melting periods during the ice ages, when tundra climate reigned and the soil was not protected by a dense cover of vegetation. Depending on the underground, narrow gorges with cliffy precipices arose in areas with hard volcanic rocks or wide gentle valleys with flood plains in areas with soft sedimentary deposits. The frequent change between both forms is charming along the Nahe.

text: Streamlined shapes are formed from erosion by flowing water.

text: The eruption of 1257 occurred probably around September. Based on the deposits of the eruption, it commenced with a first phreatic stage that deposited  of ash over  of northwest Lombok. In the subsequent first magmatic stage, a lithic rich pumice ash fell, reaching a thickness of  both upwind on East Lombok and on Bali. Subsequently, various phases of lapilli and ash falls occurred, as well as pyroclastic flows that were partially confined within the valleys on Samalas's western flank. Some ash deposits were eroded by the pyroclastic flows, generating furrow structures. Pyroclastic flows even crossed the Bali Sea, reaching the Gili Islands. This eruption phase was probably phreatomagmatic, as the deposits show evidence of interaction with water. Three pumice fallouts subsequently fell, reaching the widest extend of all deposits formed by the eruption. These pumices fell as far as Sumbawa in the east, where they were up to  thick. The formation of these pumices was followed by another stage of pyroclastic flow activity, probably caused by the collapse of the eruption column and the beginning of the formation of the caldera, where the conditions changed from column-generating to fountain-generating. These pyroclastic flows were deflected by older volcanic edifices and incinerated the vegetation. Interaction between these flows and the air triggered the formation of additional eruption clouds and secondary pyroclastic flows. Where the flows entered the sea north and east of Lombok, steam explosions generated pumice cones on the beach and additional secondary pyroclastic flows. These pyroclastic flows had an on-land volume of , and reached thicknesses of  as far as  away from Samalas. These phases are also known as P1 (phreatic and first magmatic phase), P2 (phreatomagmatic with pyroclastic flows), P3 (plinian) and P4 (pyroclastic flows). The whole eruption lasted between 12 and 15 hours, not accounting for the first emission of pyroclastic flows (P2).

text: The eruption of 1257 occurred probably around September. Based on the deposits of the eruption, it commenced with a first

text: phreatic

text: stage that deposited  of ash over  of northwest Lombok. In the subsequent first magmatic stage, a

text: lithic

text: rich

text: pumice

text: ash fell, reaching a thickness of  both upwind on East Lombok and on Bali. Subsequently, various phases of

text: lapilli

text: and ash falls occurred, as well as pyroclastic flows that were partially confined within the valleys on Samalas's western flank. Some ash deposits were eroded by the pyroclastic flows, generating furrow structures. Pyroclastic flows even crossed the

text: Bali Sea

text: , reaching the

text: Gili Islands

text: . This eruption phase was probably

text: phreatomagmatic

text: , as the deposits show evidence of interaction with water. Three pumice fallouts subsequently fell, reaching the widest extend of all deposits formed by the eruption. These pumices fell as far as

text: Sumbawa

text: in the east, where they were up to  thick. The formation of these pumices was followed by another stage of pyroclastic flow activity, probably caused by the collapse of the eruption column and the beginning of the formation of the caldera, where the conditions changed from column-generating to fountain-generating. These pyroclastic flows were deflected by older volcanic edifices and incinerated the vegetation. Interaction between these flows and the air triggered the formation of additional eruption clouds and secondary pyroclastic flows. Where the flows entered the sea north and east of Lombok, steam explosions generated pumice cones on the beach and additional secondary pyroclastic flows. These pyroclastic flows had an on-land volume of , and reached thicknesses of  as far as  away from Samalas. These phases are also known as P1 (phreatic and first magmatic phase), P2 (phreatomagmatic with pyroclastic flows), P3 (plinian) and P4 (pyroclastic flows). The whole eruption lasted between 12 and 15 hours, not accounting for the first emission of pyroclastic flows (P2).

text: The river is just about 100 meters in width and is slow-flowing. It is an olive shade of green during the dry months and a bluish-brown in the monsoon months attributed to much algae and aquatic plant life.The impounded water of the Koyna Dam though has submerged a significant amount of Rain forest of the Western Ghats, it has helped a lot to the surrounding forest by supplying water all round the year. Hence a wide biodiversity of plants and animals is observed in the evergreen forest surrounding the river.

text: The river is just about 100 meters in width and is slow-flowing. It is an olive shade of green during the dry months and a bluish-brown in the

text: monsoon

text: months attributed to much

text: algae

text: and aquatic plant life.The impounded water of the Koyna Dam though has submerged a significant amount of

text: Rain forest

text: of the

text: Western Ghats

text: , it has helped a lot to the surrounding forest by supplying water all round the year. Hence a wide biodiversity of plants and animals is observed in the evergreen forest surrounding the river.

text: For two weeks water flowed through the spillway to a maximum depth of .  The continuous rush of water removed tons of soil, numerous trees, and a portion of the 244 Spur Highway.  Pooling waters from the spillway flow also threatened to damage U.S. Highway 77.  To protect the U.S. highway, a culvert was intentionally breached on State Highway 57 to allow the pooling floodwaters to drain back into the Republican River channel.  Throughout the entire flood, the dam performed as designed and held floodwaters back, lessening the downstream flood damage.  During the highest release of water through the dam,  which lasted for approximately 10 hours, the riverbank channel immediately below the dam suffered some erosion damage.  In the winter of 1996/7, repairs were made to the damaged channel below the dam.  To prevent future damage during extremely high releases, the river channel was dropped  in elevation by excavation.  The removed rock was used to create a berm across the south bank washout.  The channel banks were re-graded, re-rocked, and re-grouted.

text: For two weeks water flowed through the spillway to a maximum depth of .  The continuous rush of water removed tons of soil, numerous trees, and a portion of the

text: 244 Spur Highway

text: .  Pooling waters from the spillway flow also threatened to damage

text: U.S. Highway 77

text: .  To protect the U.S. highway, a

text: culvert

text: was intentionally breached on State Highway 57 to allow the pooling floodwaters to drain back into the Republican River channel.  Throughout the entire flood, the dam performed as designed and held floodwaters back, lessening the downstream flood damage.  During the highest release of water through the dam,  which lasted for approximately 10 hours, the riverbank channel immediately below the dam suffered some

text: erosion

text: damage.  In the winter of 1996/7, repairs were made to the damaged channel below the dam.  To prevent future damage during extremely high releases, the river channel was dropped  in elevation by excavation.  The removed rock was used to create a

text: berm

text: across the south bank washout.  The channel banks were re-graded, re-rocked, and re-grouted.

text: Glacial lake volumes vary, but may hold millions to hundreds of millions of cubic metres of water.  Catastrophic failure of the containing ice or glacial sediment can release this water over periods of minutes to days.  Peak flows as high as 15,000 cubic metres per second have been recorded in such events, suggesting that the v-shaped canyon of a normally small mountain stream could suddenly develop an extremely turbulent and fast-moving torrent some  deep. Glacial Lake Outburst Floods are often compounded by a massive river bed erosion in the steep moraine valleys, as a result, the flood peaks increase as they flow downstream until the river reaches, where the sediment deposits. On a downstream floodplain, it suggests a somewhat slower inundation spreading as much as  wide.  Both scenarios are significant threats to life, property and infrastructure.

text: One generally accepted view for the formation of large outflow channels is that they were formed by catastrophic floods of water released from giant groundwater reservoirs. Perhaps, the water started to come out of the ground due to faulting or volcanic activity. Sometimes hot magma just travels under the surface. If that is the case, the ground will be heated, but there may be no evidence of lava at the surface. After water escapes, the surface collapses. Moving across the surface, the water would have simultaneously frozen and evaporated. Chunks of ice that would have rapidly formed may have enhanced the erosive power of the flood. Furthermore, the water may have frozen over at the surface, but continuing to flow underneath, eroding the ground as it moved along. Rivers in cold climates on the Earth often become ice-covered, yet continue to flow.

text: One generally accepted view for the formation of large outflow channels is that they were formed by catastrophic floods of water released from giant groundwater reservoirs. Perhaps, the water started to come out of the ground due to faulting or volcanic activity. Sometimes hot

text: magma

text: just travels under the surface. If that is the case, the ground will be heated, but there may be no evidence of

text: lava

text: at the surface. After water escapes, the surface collapses. Moving across the surface, the water would have simultaneously frozen and evaporated. Chunks of ice that would have rapidly formed may have enhanced the erosive power of the flood. Furthermore, the water may have frozen over at the surface, but continuing to flow underneath, eroding the ground as it moved along. Rivers in cold climates on the Earth often become ice-covered, yet continue to flow.

text: Mariner 9 imaging revealed the first direct evidence of water in the form of river beds, canyons (including the Valles Marineris, a system of canyons over about  long), evidence of water erosion and deposition, weather fronts, fogs, and more. The findings from the Mariner 9 missions underpinned the later Viking program. The enormous Valles Marineris canyon system is named after Mariner 9 in honor of its achievements.

text: Mariner 9

text: imaging revealed the first direct evidence of water in the form of river beds,

text: canyon

text: s (including the

text: Valles Marineris

text: erosion

text: and deposition, weather fronts,

text: fog

text: s, and more. The findings from the Mariner 9 missions underpinned the later

text: Viking program

text: . The enormous

text: Valles Marineris

text: The ascent to Orcombe Point shows the successive layers of different sedimentary rocks, which were deposited under varying geological conditions. At the base are cross-bedded sandstones. Towards the top, the rock types are those deposited by quieter, slower-flowing waters (i.e. siltstones and mudstones). The sediments are markedly red and this indicates that they were formed in a desert. These formations belong to the "Aylesbeare Mudstone Group" and date from the Triassic period 250 million years ago.

text: The ascent to Orcombe Point shows the successive layers of different

text: sedimentary rock

text: s, which were deposited under varying

text: geological

text: conditions. At the base are

text: cross-bedded

text: sandstone

text: s. Towards the top, the rock types are those deposited by quieter, slower-flowing waters (i.e.

text: siltstone

text: s and

text: mudstone

text: s). The sediments are markedly red and this indicates that they were formed in a desert. These formations belong to the "Aylesbeare Mudstone Group" and date from the Triassic period 250 million years ago.

text: The monophyly of Centrolenidae is supported by morphological and behavioral characters, including:1) presence of a dilated process on the medial side of the third metacarpal (an apparently unique synapomorphy); 2) ventral origin of the musculus flexor teres digiti III relative to the musculus transversi metacarpi I; 3) terminal phalanges T-shaped; 4) exotroph, lotic, burrower/fossorial tadpoles with a vermiform body and dorsal C-shaped eyes, that live buried within leaf packs in still or flowing water systems; and 5) eggs clutches deposited outside of water on vegetation or rocks above still or flowing water systems. Several molecular synapomorphies also support the monophyly of the clade.

text: The

text: monophyly

text: of Centrolenidae is supported by morphological and behavioral characters, including:1) presence of a dilated process on the medial side of the third

text: metacarpal

text: (an apparently unique

text: synapomorphy

text: ); 2) ventral origin of the musculus flexor teres digiti III relative to the musculus transversi metacarpi I; 3) terminal phalanges T-shaped; 4)

text: exotroph

text: lotic

text: , burrower/fossorial tadpoles with a

text: vermiform

text: body and dorsal C-shaped eyes, that live buried within leaf packs in still or flowing water systems; and 5) eggs clutches deposited outside of water on vegetation or rocks above still or flowing water systems. Several molecular

text: synapomorphies

text: also support the monophyly of the clade.

text: Sinkholes have been used for centuries as disposal sites for various forms of waste. A consequence of this is the pollution of groundwater resources, with serious health implications in such areas. The Maya civilization sometimes used sinkholes in the Yucatán Peninsula (known as cenotes) as places to deposit precious items and human sacrifices.

text: Sinkholes have been used for centuries as disposal sites for various forms of

text: waste

text: . A consequence of this is the

text: pollution of groundwater

text: resources, with serious health implications in such areas. The

text: Maya civilization

text: sometimes used sinkholes in the

text: Yucatán Peninsula

text: (known as

text: cenotes

text: ) as places to deposit precious items and human sacrifices.

text: When dealing with tons of water, it has to be distributed evenly and slowly. Occasionally main channels will need maintenance, or may be damaged due to external reasons. In order to even assess the problem, tons of water need to be removed from the main channel. The best way to do this is to slow the overall flow from the main dam and redirect all water flowing originally through the damaged channel to backup channels. Radial gates serve this purpose, they regulate the flow of water. It is imperative to keep water flowing. Lack of the flow will not only compromise all irrigation linked to that channel but also all cities linked will experience a power outage.

text: Most meanders occur in the region of a river channel with shallow gradients, a well-developed floodplain, and cohesive floodplain material. Deposition of sediment occurs on the inner edge, because the secondary flow of the river sweeps and rolls sand, rocks and other submerged objects across the bed of the river towards the inside radius of the river bend, creating a point bar below the slip-off slope. Meandering morphology is dependent upon similar bank erosion and bar growth rates. Erosion is greater on the outside of the bend where the soil is not protected by deposits of sand and rocks. The current on the outside bend is more effective in eroding the unprotected soil, and the inside bend receives steadily increasing deposits of sand and rocks, and the meander tends to grow in the direction of the outside bend, forming a small cliff called a cut bank. This can be seen in areas where willows grow on the banks of rivers; on the inside of meanders, willows are often far from the bank, whilst on the outside of the bend, the roots of the willows are often exposed and undercut, eventually leading the trees to fall into the river. This demonstrates the river's movement. Slumping usually occurs on the concave sides of the banks resulting in mass movements such as slides.

text: Most meanders occur in the region of a river channel with shallow

text: gradient

text: s, a well-developed

text: floodplain

text: , and cohesive floodplain material.

text: Deposition

text: of

text: sediment

text: occurs on the inner edge, because the

text: secondary flow

text: of the river sweeps and rolls sand, rocks and other submerged objects across the bed of the river towards the inside radius of the river bend, creating a

text: point bar

text: below the slip-off slope. Meandering morphology is dependent upon similar bank erosion and bar growth rates. Erosion is greater on the outside of the bend where the soil is not protected by deposits of sand and rocks. The current on the outside bend is more effective in eroding the unprotected soil, and the inside bend receives steadily increasing deposits of sand and rocks, and the meander tends to grow in the direction of the outside bend, forming a small cliff called a

text: cut bank

text: . This can be seen in areas where

text: willows

text: grow on the banks of rivers; on the inside of meanders, willows are often far from the bank, whilst on the outside of the bend, the roots of the willows are often exposed and undercut, eventually leading the trees to fall into the river. This demonstrates the river's movement. Slumping usually occurs on the concave sides of the banks resulting in mass movements such as slides.

text: Loess is a homogeneous, typically nonstratified, porous, friable, slightly coherent, often calcareous, fine-grained, silty, pale yellow or buff, windblown (Aeolian) sediment. It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces. Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world. Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.  Wind erosion is much more severe in arid areas and during times of drought. For example, in the Great Plains, it is estimated that soil loss due to wind erosion can be as much as 6100 times greater in drought years than in wet years.

text: Loess is a homogeneous, typically nonstratified, porous,

text: friable

text: silt

text: y, pale yellow or buff, windblown (

text: Aeolian

text: sediment

text: . It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces. Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world. Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, windbreaks (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.  Wind erosion is much more severe in arid areas and during times of drought. For example, in the

text: Great Plains

text: , it is estimated that soil loss due to wind erosion can be as much as 6100 times greater in drought years than in wet years.

text: Water has a high surface tension of  71.99 mN/m at 25 °C, caused by the strong cohesion between water molecules, the highest of the common non-ionic, non-metallic liquids. This can be seen when small quantities of water are placed onto a sorption-free (non-adsorbent and non-absorbent) surface, such as polyethylene or Teflon, and the water stays together as drops. Just as significantly, air trapped in surface disturbances forms bubbles, which sometimes last long enough to transfer gas molecules to the water.

text: Water has a high

text: surface tension

text: of  71.99 mN/m at 25 °C, caused by the strong cohesion between water molecules, the highest of the common non-ionic, non-metallic liquids. This can be seen when small quantities of water are placed onto a

text: sorption

text: -free (non-adsorbent and non-absorbent) surface, such as

text: polyethylene

text: or

text: Teflon

text: , and the water stays together as drops. Just as significantly, air trapped in surface disturbances forms bubbles, which sometimes last long enough to transfer gas molecules to the water.

text: The hype about septic systems being the major culprit for the spread of green algae in the embayments, the killing of eelgrass and the cause of hypoxia in Cape Cod waterways is egregiously overdone.  Nitrogen emanating from Septic Systems is likely a very small fraction unless the leaching fields or devices are plugged or have otherwise failed to deliver orderly flow into the subterranean.  A properly functioning Septic System that has an adequate surface area of biological mat interface will deliver partially treated effluent without overflowing to the surface and short circuiting effluent into surface waters.    There are estimates that 80% of nitrogen in waters surrounding the Cape is from onsite Septic Systems.  This is totally flawed as there are many other sources of nitrogen, both anthropogenic and natural.  There are huge quantities of nitrogen released from vegetation, animals and bacteria that occur in natural systems and from atmospheric deposition.  In addition the Boston Deer Island Wastewater Treatment Facility releases vast amounts of Nitrogen into Massachusetts Bay Waters.  Further, there are many other nutrients and detrimental compounds from sources other than Septic Systems which affect water quality in Cape Cod water bodies.

text: When precipitation flows down South Mountain, a large amount of groundwater is produced. Much of the water, which has an acidic pH, is able to erode the valley's limestone bedrock and continue flowing at about  below the soil. However, some of the water is trapped by the impermeable diabase dikes, which act as a hydrologic barrier. The water becomes progressively confined by the dikes as it nears the tip of the "V". Due to the positive pressure created by this confinement, water is pushed up to the surface and out of the artesian aquifer, giving the impression of "boiling" springs. The springs have a median flow of  per minute.

text: When precipitation flows down

entity_name: South Mountain (Maryland and Pennsylvania)

text: South Mountain

text: , a large amount of

text: groundwater

text: is produced. Much of the water, which has an acidic

text: pH

text: , is able to erode the valley's limestone bedrock and continue flowing at about  below the soil. However, some of the water is trapped by the impermeable diabase dikes, which act as a hydrologic barrier. The water becomes progressively confined by the dikes as it nears the tip of the "V". Due to the

text: positive pressure

text: created by this confinement, water is pushed up to the surface and out of the

text: artesian aquifer

text: , giving the impression of "boiling" springs. The springs have a median flow of  per minute.

text: Originally open at both ends, collapsing ground closed one of the caves when the underground water flow sharply diminished. This cave now ends with basins at ground level formed by limestone deposits left by the water.

text: Flood stage is the level at which a body of water's surface has risen to a sufficient level to cause sufficient inundation of areas that are not normally covered by water, causing an inconvenience or a threat to life and/or property. When a body of water rises to this level, it is considered a flood event. Flood stage does not apply to areal flooding. Because areal flooding occurs, by definition, over areas not normally covered by water, any water at all creates a flood. Usually, Moderate and Major stages are not defined for areal floodplains.

text: Flood stage is the level at which a body of water's surface has risen to a sufficient level to cause sufficient inundation of areas that are not normally covered by water, causing an inconvenience or a threat to life and/or property. When a body of water rises to this level, it is considered a

text: flood

text: event. Flood stage does not apply to

text: areal flooding

text: . Because areal flooding occurs, by definition, over areas not normally covered by water, any water at all creates a flood. Usually, Moderate and Major stages are not defined for areal

text: floodplain

text: s.

text: In physical geography, entrainment is the process by which surface sediment is incorporated into a fluid flow (such as air, water or even ice ) as part of the operation of erosion.

text: In

text: physical geography

text: , entrainment is the process by which surface

text: sediment

text: is incorporated into a

text: fluid flow

text: (such as

text: air

text: water

text: or even

text: ice

text: ) as part of the operation of

text: erosion

text: The Wallula Gap was widened about the 14th millennium BC, by the historic flow of the Salmon, Snake, and Columbia rivers combined with the glacial waters that poured across the Channeled Scablands during the Missoula Floods. The Wallula Gap constrained the flow such that less than 1/5 of the 800 km³ (192 mi³) of water per day entering could be discharged as it passed into Lake Condon downstream. As a result, the floods filled the Pasco Basin and formed, for a short period, Lake Lewis. The large volumes of flood water passing through the gap contributed substantially to the erosion of the gap, as is evidenced by the shear walls and by scab-features such as "Twin Sisters".

text: The Wallula Gap was widened about the 14th millennium BC, by the historic flow of the

text: Salmon

text: Snake

text: , and Columbia rivers combined with the glacial waters that poured across the

text: Channeled Scablands

text: during the

text: Missoula Floods

text: . The Wallula Gap constrained the flow such that less than 1/5 of the 800 km³ (192 mi³) of water per day entering could be discharged as it passed into

text: Lake Condon

text: downstream. As a result, the floods filled the

text: Pasco Basin

text: and formed, for a short period,

text: Lake Lewis

text: . The large volumes of flood water passing through the gap contributed substantially to the erosion of the gap, as is evidenced by the shear walls and by scab-features such as "Twin Sisters".

text: Within an aquifer, the water table is rarely horizontal, but reflects the surface relief due to the capillary effect in soils, sediments and other porous media. In the aquifer, groundwater flows from points of higher pressure to points of lower pressure, and the direction of groundwater flow typically has both a horizontal and a vertical component. The slope of the water table is known as the hydraulic gradient, which depends on the rate at which water is added to and removed from the aquifer and the permeability of the material. The water table does not always mimic the topography due to variations in the underlying geological structure (e.g., folded, faulted, fractured bedrock)

text: Within an aquifer, the water table is rarely horizontal, but reflects the surface relief due to the capillary effect in

text: soil

text: s,

text: sediment

text: s and other

text: porous media

text: . In the aquifer, groundwater flows from points of higher pressure to points of lower pressure, and the direction of groundwater flow typically has both a horizontal and a vertical component. The slope of the water table is known as the hydraulic gradient, which depends on the rate at which water is added to and removed from the aquifer and the permeability of the material. The water table does not always mimic the topography due to variations in the underlying geological structure (e.g., folded, faulted, fractured bedrock)

text: Spring Creek Reservoir is the artificial lake formed behind the dam. The reservoir is used mostly for flood control storage, and is rarely filled to its  capacity. During the dry season, water from Spring Creek pools in a small, stagnant pond retained behind the dam, depositing contaminated sediment and acidic mine waste in the reservoir space. When flows from the Shasta Dam, upstream on the Sacramento River, are sufficient to flush contaminated water away, water held in the reservoir is released through the outlet works into the Keswick Reservoir and the Sacramento River. Despite this operation strategy, the reservoir was eventually deemed inadequate for the watershed, and can be filled to capacity by a single heavy storm event. Uncontrollable spills frequently poured into the Sacramento River during floods, through the crest spillway of the dam, which lacks gates. As a result, numerous fish kills have occurred during these sudden releases of contaminants, a major one of which was in 1969. Due to this consistent acid pollution from the reservoir, most large fish spawn downstream of Red Bluff Diversion Dam, a dam also on the Sacramento River near Red Bluff, California.

text: Spring Creek Reservoir

text: is the

text: artificial lake

text: formed behind the dam. The reservoir is used mostly for flood control storage, and is rarely filled to its  capacity. During the dry season, water from Spring Creek pools in a small,

text: stagnant

text: pond retained behind the dam, depositing contaminated sediment and acidic mine waste in the reservoir space. When flows from the

text: Shasta Dam

text: , upstream on the

text: Sacramento River

text: , are sufficient to flush contaminated water away, water held in the reservoir is released through the outlet works into the

text: Keswick Reservoir

text: and the Sacramento River. Despite this operation strategy, the reservoir was eventually deemed inadequate for the watershed, and can be filled to capacity by a single heavy storm event. Uncontrollable spills frequently poured into the Sacramento River during floods, through the crest spillway of the dam, which lacks gates. As a result, numerous

text: fish kill

text: s have occurred during these sudden releases of contaminants, a major one of which was in 1969. Due to this consistent acid pollution from the reservoir, most large fish spawn downstream of

text: Red Bluff Diversion Dam

text: , a dam also on the Sacramento River near

text: Red Bluff, California

text: A pediment is a very gently sloping (.5°-7°) inclined bedrock surface. It typically slopes down from the base of a steeper retreating desert cliff, or escarpment, but may continue to exist after the mountain has eroded away. It is caused by erosion. It develops when sheets of running water (laminar sheet flows) wash over it in intense rainfall events. It may be thinly covered with fluvial gravel that has washed over it from the foot of mountains produced by cliff retreat erosion. It is typically a concave surface gently sloping away from mountainous desert areas.

text: A pediment is a very gently sloping (.5°-7°) inclined

text: bedrock

text: surface. It typically slopes down from the base of a steeper

text: retreating desert cliff

text: , or

text: escarpment

text: , but may continue to exist after the mountain has eroded away. It is caused by

text: erosion

text: . It develops when sheets of running water (

text: laminar sheet flows

text: ) wash over it in intense rainfall events. It may be thinly covered with

text: fluvial

text: gravel that has washed over it from the foot of mountains produced by

text: cliff retreat

text: erosion. It is typically a concave surface gently sloping away from mountainous desert areas.

text: The following is a list of sinkholes, blue holes, dolines, cenotes, and pit caves. A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. Some are caused by karst processes—for example, the chemical dissolution of carbonate rocks<ref>{{cite journal|author = Lard, L., Paull, C., & Hobson, B. |year = 1995|title = Genesis of a submarine sinkhole without subaerial exposure|journal = Geology|volume = 23|issue = 10|pages = 949–951|doi = 10.1130/0091-7613(1995)023

text: The following is a list of

text: sinkhole

text: s,

text: blue hole

text: s,

text: dolines

text: cenote

text: s, and

text: pit cave

text: s. A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. Some are caused by

text: karst processes

text: —for example, the chemical dissolution of

text: carbonate rocks

text: <ref>{{cite journal|author = Lard, L., Paull, C., & Hobson, B. |year = 1995|title = Genesis of a submarine sinkhole without subaerial exposure|journal = Geology|volume = 23|issue = 10|pages = 949–951|doi = 10.1130/0091-7613(1995)023

text: The water enters from the top and down the inner tube. At this point the water starts to bleed out the bleed hole which goes into the grey water system, a garden watering system, or drain. As the flow from the roof exceeds the bleed amount, the tube fills up, depositing any heavy material in the lower part of the tube, most of which flushes out the bleed hole. Some debris floats, (such as seeds, leaves, insect bodies) and remains floating between the inner and outer pipe, it is prevented from entering the collection pipe due to the entry of the collection pipe being submerged under water.

text: A corduroy or beach ladder (or board and chain) is an array of planks (usually hardwood or treated timber) laid close together and perpendicular to the direction of traffic flow, and secured at each end by a chain or cable to form a pathway or ramp over the sand dune.  Corduroys are cheap and easy to construct and quick to deploy or relocate.  They are commonly used for pedestrian access paths and light duty vehicular access ways.  They naturally conform to the shape of the underlying beach or dune profile, and adjust well to moderate erosion, especially longshore drift.  However, they can cease to be an effective access surface if they become buried or undermined by erosion by surface runoff coming from the beach head.  If the corduroy is not wide enough for vehicles using it, the sediment on either side may be displaced creating a spoon drain that accelerates surface run off and can quickly lead to serious  erosion.  Significant erosion of the sediment beside and under the corduroy can render it completely ineffective and make it dangerous to pedestrian users who may fall between the planks.

text: Borrow pits containing suitable material are accessible at an elevation such that the earth can be sluiced to the fill after being washed from the bank by high-pressure nozzles. Hydraulic fill is likely to be the most economic method of construction. Even when the source material lacks sufficient elevation, it can be elevated to the sluice by a dredge pump. In the construction of a hydraulic fill dam, the edges of the dam are defined by low embankments or dykes which are built upward as the fill progresses. The sluices are carried parallel to, and just inside of, these dykes. The sluices discharge their water-earth mixture at intervals, the water fanning out and flowing towards the central pool which is maintained at the desired level by discharge control. While flowing from the sluices, coarse material is deposited first and then finer material is deposited (fine material has a slower terminal velocity thus takes longer to settle, see Stoke's Law) as the flow velocity is reduced towards the center of the dam. This fine material forms an impervious core to the dam. The water flow must be well controlled at all times, otherwise the central section may be bridged by tongues of coarse material which would facilitate seepage through the dam later.

text: Borrow pit

text: s containing suitable material are accessible at an elevation such that the earth can be

text: sluice

text: d to the fill after being washed from the bank by high-pressure nozzles. Hydraulic fill is likely to be the most economic method of construction. Even when the source material lacks sufficient elevation, it can be elevated to the sluice by a dredge pump. In the construction of a hydraulic fill

text: dam

text: , the edges of the dam are defined by low embankments or

text: dykes

text: which are built upward as the fill progresses. The sluices are carried parallel to, and just inside of, these dykes. The sluices discharge their water-earth mixture at intervals, the water fanning out and flowing towards the central pool which is maintained at the desired level by discharge control. While flowing from the sluices, coarse material is deposited first and then finer material is deposited (fine material has a slower terminal velocity thus takes longer to settle, see

text: Stoke's Law

text: ) as the flow velocity is reduced towards the center of the dam. This fine material forms an impervious core to the dam. The water flow must be well controlled at all times, otherwise the central section may be bridged by tongues of coarse material which would facilitate seepage through the dam later.

text: Because of erosions, numerous cracks, caves and sinkholes which prevail in the limestone, two of the three lakes have no surface drainage: the water of the Fälensees flows by the mountain ridge southwest into the Rhine.

text: Because of erosions, numerous cracks, caves and sinkholes which prevail in the limestone, two of the three lakes have no surface drainage: the water of the Fälensees flows by the mountain ridge southwest into the

text: Rhine

text: The Devil's Sinkhole is a vertical natural bat habitat.  The  opening drops down to reveal a cavern some  below. The cavern was first discovered by local residents in 1876.  H. S. Barber carved his name inside the cave in 1889. The area was transferred to the state of Texas in 1985, and open to the public in 1992.  Carved by water erosion, the cavern is home to several million Mexican free-tailed bats who emerge at sunset during April through October.

text: The Devil's Sinkhole is a vertical natural bat habitat.  The  opening drops down to reveal a cavern some  below. The cavern was first discovered by local residents in 1876.  H. S. Barber carved his name inside the cave in 1889. The area was transferred to the state of Texas in 1985, and open to the public in 1992.  Carved by water erosion, the cavern is home to several million

text: Mexican free-tailed bat

text: s who emerge at sunset during April through October.

text: Imagery of the surrounding massive sulfate deposits sent back by the NASA Opportunity Rover in Meridiani Planum, has indicated the existence of pervasive needle-shaped void spaces throughout the deposit. The now empty angular holes are interpreted as being cavities once filled by a highly soluble mineral species, most likely a magnesium sulfate. These cavities are observed to closely match the crystal habit of Meridianiite, and have been proposed as sites where crystals of Meridianiite were located, having subsequently dissolved when environmental conditions rendered the crystal unstable. Due to the decomposition of Meridianiite to 70% epsomite and 30% water, it has been proposed that meridianiite may represent a periodic reservoir of water near the Martian surface. During warmer periods in Mars’ history it is possible that triggered melting of this mineral may help explain the occurrence of some of the chaotic, and short lived, surface-water episodes throughout Martian history.

text: Imagery of the surrounding massive sulfate deposits sent back by the

text: NASA

text: Opportunity Rover

text: in

text: Meridiani Planum

text: , has indicated the existence of pervasive needle-shaped void spaces throughout the deposit. The now empty angular holes are interpreted as being cavities once filled by a highly soluble mineral species, most likely a

text: magnesium sulfate

text: . These cavities are observed to closely match the crystal habit of Meridianiite, and have been proposed as sites where crystals of Meridianiite were located, having subsequently dissolved when environmental conditions rendered the crystal unstable. Due to the decomposition of Meridianiite to 70%

text: epsomite

text: and 30%

text: water

text: , it has been proposed that meridianiite may represent a periodic reservoir of water near the Martian surface. During warmer periods in Mars’ history it is possible that triggered melting of this mineral may help explain the occurrence of some of the chaotic, and short lived, surface-water episodes throughout Martian history.

text: Jotabeche is a  high volcano with a caldera. A rhyolitic dome formed inside of the caldera. The Jotabeche complex reaches a thickness of  when including ignimbrite, lava domes and lavas. The  high and  wide Jotabeche Norte stratovolcano is found northeast of Jotabeche and is surrounded by pyroclastic flows. The Santa Cecilia lava domes () have diametres of  and sit along a  long fault. The Miocene volcanic complex branches out in four chains stretching in east-west direction, the Cadillal, Aguas Blancas, Jotabeche Norte and Cordon de Yeguas Heladas. N-S to NE-SW trending faults border the volcanic complex and have allowed the intrusion of diorite porphyries. The resulting hydrothermally altered rocks are the sites of mineral deposits and prospects. These faults include the Yeguas Heladas, Rio La Gallina and Rio Astaburuaga and form a hexagonal structure which partly forms the margin of the caldera. Otherwise, only little erosion has taken place at Jotabeche; stronger erosion though has exposed a > thick hydrothermally altered complex at Aldebaran-Cerro Casale. Other hydrothermally altered areas are found within depressions. The crust beneath Jotabeche reaches a thickness of .

text: Jotabeche is a  high volcano with a caldera. A

text: rhyolitic

text: dome formed inside of the caldera. The Jotabeche complex reaches a thickness of  when including ignimbrite, lava domes and lavas. The  high and  wide Jotabeche Norte

text: stratovolcano

text: is found northeast of Jotabeche and is surrounded by

text: pyroclastic flow

text: s. The Santa Cecilia lava domes () have diametres of  and sit along a  long

text: fault

text: . The Miocene volcanic complex branches out in four chains stretching in east-west direction, the Cadillal, Aguas Blancas, Jotabeche Norte and Cordon de Yeguas Heladas. N-S to NE-SW trending faults border the volcanic complex and have allowed the intrusion of

text: diorite

text: porphyries

text: . The resulting hydrothermally altered rocks are the sites of mineral deposits and

text: prospects

text: . These faults include the Yeguas Heladas, Rio La Gallina and Rio Astaburuaga and form a hexagonal structure which partly forms the margin of the caldera. Otherwise, only little erosion has taken place at Jotabeche; stronger erosion though has exposed a > thick hydrothermally altered complex at Aldebaran-Cerro Casale. Other hydrothermally altered areas are found within depressions. The crust beneath Jotabeche reaches a thickness of .

text: Erosion along the tributaries and upper reaches coupled with rain-on-snow events contribute to sediment transport and floods along Ashland Creek. About  of sediment per year accumulates in Reeder Reservoir, but a flood in 1974 deposited  quickly, forcing the city to temporarily shut down the municipal water supply. In addition to moving sediment, heavy flows block the creek with woody debris, creating dams that, upon breaking, cause flood surges. Five significant floods, the last in 1997, damaged property in Ashland during the second half of the 20th century. The 1997 rain-on-snow event caused many streams in the Bear Creek watershed to reach 100-year flood levels, resulting in $4.5 million in damages.

text: Erosion along the tributaries and upper reaches coupled with rain-on-snow events contribute to sediment transport and floods along Ashland Creek. About  of sediment per year accumulates in Reeder Reservoir, but a flood in 1974 deposited  quickly, forcing the city to temporarily shut down the municipal water supply. In addition to moving sediment, heavy flows block the creek with woody debris, creating dams that, upon breaking, cause flood surges. Five significant floods, the last in 1997, damaged property in Ashland during the second half of the 20th century. The 1997 rain-on-snow event caused many streams in the Bear Creek watershed to reach

text: 100-year flood

text: levels, resulting in $4.5 million in damages.

text: Tree, shrubs and ground-cover are effective perimeter treatment for soil erosion prevention, by impeding surface flows. A special form of this perimeter or inter-row treatment is the use of a “grass way” that both channels and dissipates runoff through surface friction, impeding surface runoff and encouraging infiltration of the slowed surface water.

text: Tree,

text: shrub

text: s and

text: ground-cover

text: are effective perimeter treatment for

text: soil erosion

text: prevention, by impeding surface flows. A special form of this perimeter or inter-row treatment is the use of a “grass way” that both

text: channel

text: s and dissipates runoff through surface friction, impeding

text: surface runoff

text: and encouraging infiltration of the slowed surface water.

text: Erosion by moving water can happen in two ways. Firstly, the movement of water across the bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. However, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed (abrasion). At the same time the fragments themselves are ground down, becoming smaller and more rounded (attrition).

text: Erosion by moving water can happen in two ways. Firstly, the movement of water across the

text: bed

text: exerts a

text: shear stress

text: directly onto the bed. If the

text: cohesive

text: strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. However, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed (

text: abrasion

text: ). At the same time the fragments themselves are ground down, becoming smaller and more rounded (attrition).

text: Depression storage capacity, in soil science, is the ability of a particular area of land to retain water in its pits and depressions, thus preventing it from flowing. Depression storage capacity, along with infiltration capacity, is one of the main factors involved in Horton overland flow, whereby water volume surpasses both infiltration and depression storage capacity and begins to flow horizontally across land, possibly leading to flooding and soil erosion. The study of land's depression storage capacity is important in the fields of geology, ecology, and especially hydrology.

text: Depression storage capacity, in

text: soil science

text: , is the ability of a particular area of land to retain water in its pits and depressions, thus preventing it from flowing. Depression storage capacity, along with

text: infiltration capacity

text: , is one of the main factors involved in

text: Horton overland flow

text: , whereby water volume surpasses both infiltration and depression storage capacity and begins to flow horizontally across land, possibly leading to

text: flood

text: ing and

text: soil erosion

text: . The study of land's depression storage capacity is important in the fields of

text: geology

text: ecology

text: , and especially

text: hydrology

text: The Pyrddin is best known for two spectacular waterfalls, Sgwd Gwladus and Sgwd Einion Gam, meaning the 'lady's fall' and the 'fall of crooked Einion' respectively.  Sgwd Gwladus is formed where a band of erosion-resistant gritstone known as the 'Twelve Foot Sandstone' creates a lip over which the river plunges.  It is easily accessible by footpath from Pontneddfechan. A notable feature beside the fall is the erratic block of gritstone which was balanced so that it rocked - at least until Victorian times when it was displaced.  The ruins of a small building close to the falls are thought to be those of a corn-mill.

text: The Pyrddin is best known for two

text: spectacular waterfalls

text: Sgwd Gwladus

text: and

text: Sgwd Einion Gam

text: , meaning the 'lady's fall' and the 'fall of crooked Einion' respectively.  Sgwd Gwladus is formed where a band of erosion-resistant gritstone known as the 'Twelve Foot Sandstone' creates a lip over which the river plunges.  It is easily accessible by footpath from

text: Pontneddfechan

text: . A notable feature beside the fall is the erratic block of gritstone which was balanced so that it rocked - at least until Victorian times when it was displaced.  The ruins of a small building close to the falls are thought to be those of a corn-mill.

text: Flood waters that occur during monsoon seasons can often host numerous protozoa, bacterial, and viral microorganisms. Mosquitoes and flies will lay their eggs within the contaminated bodies of water. These disease agents may cause infections of foodborne and waterborne diseases. Diseases associated with exposure to flood waters include malaria, cholera, typhoid, hepatitis A, and the common cold. Possible trenchfoot infections may also occur when personnel are exposed for extended periods of time within flooded areas.

text: Flood waters that occur during monsoon seasons can often host numerous

text: protozoa

text: bacteria

text: l, and

text: viral

text: microorganisms. Mosquitoes and flies will lay their eggs within the contaminated bodies of water. These disease agents may cause infections of foodborne and waterborne diseases. Diseases associated with exposure to flood waters include

text: malaria

text: cholera

text: typhoid

text: hepatitis A

text: , and the

text: common cold

text: . Possible

text: trenchfoot

text: infections may also occur when personnel are exposed for extended periods of time within flooded areas.

text: Drainage tile sometimes decreases soil erosion and runoff of some nutrients, including phosphorus. Phosphorus is an important nutrient to control because it is the limiting nutrient in most aquatic ecosystems. Thus phosphorus is the main culprit in eutrophication of surface water; however, the other limiting nutrient, nitrogen, causes substantial damage to waters. For example, nitrogen has been implicated in the gulf hypoxia. Drainage tile sometimes increases water quality because the water flows into the ground then the tile, instead of running off the field into a ditch, carrying soil and nutrients with it. The soil has a chance to filter the water before it enters the streams and rivers. However, by bypassing surface improvements like conservation tillage or riparian buffers, tile drainage can also create problems with water quality  and outflow from tile drainage tends to be extremely high in nitrogen. Furthermore, some tile drainage sometime contains very high levels of other chemicals. Since surface forms of conservation agriculture are less effective in tile-drained systems, other practices such as controlled drainage or constructed wetlands may be more effective. In very flat areas, where the natural topography does not provide the gradient necessary for water flow, "agricultural wells" can be dug to provide tile lines sufficient outlet. In these cases, it is the groundwater that stands to be polluted by unfiltered tile output.

text: Floods create a scenario in which stream flow and velocity are unusually high due to the drastic addition of water to a stream.  These heightened characteristics increase both the potential of stream erosion and heavier stream load (Knighton, 1998).  Flooded streams are often responsible for heavy sediment transportation and deposition downstream.  Stream capacity is greatly increased during a flood (Knighton, 1998).  During a flood, increased suspended load may be visible, giving the stream a muddy color. Floods can also cause extreme damage to homes by lifting them up and forcing them into the ocean, where they then are subducted at mid-ocean ridges.

text: Floods

text: create a scenario in which stream flow and velocity are unusually high due to the drastic addition of water to a stream.  These heightened characteristics increase both the potential of stream erosion and heavier stream load (Knighton, 1998).  Flooded streams are often responsible for heavy sediment transportation and deposition downstream.  Stream capacity is greatly increased during a flood (Knighton, 1998).  During a flood, increased suspended load may be visible, giving the stream a muddy color. Floods can also cause extreme damage to homes by lifting them up and forcing them into the ocean, where they then are subducted at mid-ocean ridges.

text: In the 2002 flood, the peak flow was about 70,000 cubic feet per second (2,000 m³/s).  The amount of water that flowed over the spillway was about 3½ times the amount of water that the reservoir holds. Erosion over the course of three days tore away soil to reveal what is now the Canyon Lake Gorge.

text: In the 2002 flood, the peak flow was about 70,000 cubic feet per second (2,000 m³/s).  The amount of water that flowed over the spillway was about 3½ times the amount of water that the reservoir holds. Erosion over the course of three days tore away soil to reveal what is now the

text: Canyon Lake Gorge

text: Rivers within the basin have a low gradient, slow flow rate and a naturally turbid water quality. Several of the major Lake Eyre Basin river systems are well-known. Because the Lake Eyre Basin is almost flat, rivers flow slowly and frequently split up into floodplains or multiple braided channels. Water is lost to evaporation, to seepage, and in the many ephemeral wetland systems, with the result that downstream flows are typically smaller than upstream flows. Only in exceptional years is there sufficient upstream rain to provide a flow into Lake Eyre itself.

text: Rivers within the basin have a low gradient, slow

text: flow rate

text: and a naturally

text: turbid

text: water quality. Several of the major Lake Eyre Basin river systems are well-known. Because the Lake Eyre Basin is almost flat, rivers flow slowly and frequently split up into

text: floodplain

text: s or multiple braided channels. Water is lost to evaporation, to

text: seepage

text: , and in the many ephemeral

text: wetland

text: systems, with the result that downstream flows are typically smaller than upstream flows. Only in exceptional years is there sufficient upstream rain to provide a flow into Lake Eyre itself.

text: Geologically the landscape demonstrates the contrast between the retention of the top of the Greensand Ridge from coastal deposition (geology) followed by avoiding sea rise changes and the formation of the lower Weald because of water erosion on the three-county-sized calciferous and sandy beds south of this ridge.  The Ridge forms the highest hills in the south east, excluding the southwest Berkshire Downs.

text: Geologically the landscape demonstrates the contrast between the retention of the top of the

text: Greensand Ridge

text: from coastal

text: deposition (geology)

text: followed by avoiding sea rise changes and the formation of the lower

text: Weald

text: because of water erosion on the three-county-sized calciferous and sandy beds south of this ridge.  The Ridge forms the highest hills in the south east, excluding the southwest

text: Berkshire Downs

text: Two to four and a half barrels of water are required to produce a barrel of oil from the tar sands. Water is used to create the slurry of bitumen and oil that is heated and processed.  Water is also disposed of through Steam Assisted Gravity Drainage method of extraction where steam is pumped into the ground to cause bitumen to flow into a lower pipe for removal. For every barrel of oil produced approximately one barrel of water is contaminated in the process and deposited into a tailings pond.

text: Erosion, and subsequent sea water inundation poses a serious threat along the length of the Canterbury Bight. To date, erosion has led to the loss of agricultural land, threatened valuable infrastructure and some holiday settlements, and reduced coastal lagoons and wetlands (Ecan, 2005). One of the main areas of concern is the Washdyke barrier. The shoreline at Washdyke was naturally eroding before construction of the Timaru harbour commenced in 1879. The harbour has prevented sediment being transported from the south meaning that no coarse sediment is able to nourish the Washdyke beach/barrier. The material that is currently on the beach is undergoing abrasion (discussed above), which has reduced grain sizes and lowered the berm heights increasing the amount of washover, which further increases erosion (Kirk, 1992).

text: Although cultivation has added markedly to the sediment in the river as it flows through the valley, the water was turbid even before the widespread introduction of agriculture, according to early European travellers. Erosion and deposition are believed to be in equilibrium in the trench. Siltation now provides a major challenge for the impounded sections of the river in the valley.

text: Although

text: cultivation

text: has added markedly to the sediment in the river as it flows through the valley, the water was turbid even before the widespread introduction of

text: agriculture

text: , according to early

text: Europe

text: an travellers.

text: Erosion

text: and

text: deposition

text: are believed to be in equilibrium in the trench.

text: Silt

text: ation now provides a major challenge for the impounded sections of the river in the valley.

text: The main deposit settled  from the face of Dzhimarai-Khokh. A  thick chunk of the Kolka Glacier travelled  down the Karmadon Gorge and Koban Valley at over . The outflow of mud and debris measured  wide and  thick. Two villages along the gorge were under surveillance as flood waters backed up along the choked rivers. It finally came to rest in the village of Nijni Karmadon, burying most of the village in ice, snow, and debris. On September 25, a first round of explosives intended to break up the avalanche flow was unsuccessful in reducing flood waters lapping through the village of Gornaya Saniba.  The avalanche had two distinct flows.

text: The main deposit settled  from the face of Dzhimarai-Khokh. A  thick chunk of the Kolka Glacier travelled  down the

text: Karmadon Gorge

text: and Koban Valley at over . The outflow of mud and debris measured  wide and  thick. Two villages along the gorge were under surveillance as flood waters backed up along the choked rivers. It finally came to rest in the village of Nijni Karmadon, burying most of the village in ice, snow, and debris. On September 25, a first round of explosives intended to break up the avalanche flow was unsuccessful in reducing flood waters lapping through the village of Gornaya Saniba.  The avalanche had two distinct flows.

text: It is suspected that the disappearance of mimic shiners in some areas may be due to a change in hydraulic regimes due to fragmentation of landscapes along with urbanization and development. Due to fragmentation of the landscape near or around riverine ecosystems, there is less available vegetation along these areas. With less vegetation, a faster flow of water pours into streams and rivers and possibly causes erosion to its banks. This influx of water and higher velocity of flow could have negative impacts on this species that lives in areas that has a relatively slow to moderate current.

text: Water runoff often collects over watersheds flowing into rivers. A mathematical model used to simulate river or stream flow and calculate water quality parameters is a hydrological transport model. Some water is diverted to irrigation for agriculture. Rivers and seas offer opportunity for travel and commerce. Through erosion, runoff shapes the environment creating river valleys and deltas which provide rich soil and level ground for the establishment of population centers. A flood occurs when an area of land, usually low-lying, is covered with water. It is when a river overflows its banks or flood comes from the sea. A drought is an extended period of months or years when a region notes a deficiency in its water supply. This occurs when a region receives consistently below average precipitation.

text: Water runoff often collects over

text: watersheds

text: flowing into rivers. A mathematical model used to simulate river or stream flow and calculate water quality parameters is a

text: hydrological transport model

text: . Some water is diverted to

text: irrigation

text: for agriculture. Rivers and seas offer opportunity for

text: travel

text: and

text: commerce

text: . Through

text: erosion

text: , runoff shapes the environment creating river

text: valley

text: s and

text: deltas

text: which provide rich soil and level ground for the establishment of population centers. A

text: flood

text: occurs when an area of land, usually low-lying, is covered with water. It is when a river overflows its banks or flood comes from the sea. A

text: drought

text: is an extended period of months or years when a region notes a deficiency in its water supply. This occurs when a region receives consistently below average precipitation.

text: Surface erosion of the surface of a levee is usually caused by the action of wind and water (waves but also normal flow). Erosion can be worsened by pre-existing or new damage to a levee. Areas with no surface protection are more prone to erosion. A levee grazed by certain types of animals, like sheep, can show trails used by the animals where grass does not grow.

text: Surface erosion of the surface of a levee is usually caused by the action of wind and water (waves but also normal flow). Erosion can be worsened by pre-existing or new damage to a levee. Areas with no surface protection are more prone to erosion. A levee grazed by certain types of animals, like

text: sheep

text: , can show trails used by the animals where grass does not grow.

text: The formation was formed by the erosion of the Ancestral Rocky Mountains, and deposition by fluvial processes as alluvial fans.

text: The formation was formed by the erosion of the

text: Ancestral Rocky Mountains

text: , and deposition by fluvial processes as

text: alluvial fan

text: s.

text: A lazy river is a water ride found in water parks, hotels, resorts, and recreation centers, which usually consists of a shallow (2½ ft. to 3½ ft.) pool that flows similarly to a river.There is generally a slow current, usually just enough to allow guests to gently ride along lying on rafts.  There may also be scenic elements added, such as small waterfalls on the edge of the river. Some lead into wave pools, while some just go around in circles.

text: A lazy river is a

text: water ride

text: found in

text: water park

text: s, hotels, resorts, and recreation centers, which usually consists of a shallow (2½ ft. to 3½ ft.) pool that flows similarly to a river.There is generally a slow current, usually just enough to allow guests to gently ride along lying on rafts.  There may also be scenic elements added, such as small waterfalls on the edge of the river. Some lead into

text: wave pool

text: s, while some just go around in circles.

text: Following the Deepwater Horizon oil spill (called the "Gulf oil spill"), the entrance to Perdido Pass was closed, with a barrier system in June 2010, to control tidal flow of oil entering from the Gulf of Mexico. The daily high tide was causing oil-contaminated water to enter Perdido Bay. The barrier system is designed to allow boats to travel through Perdido Pass, during the outflowing tide, but to close during the incoming tide and collect oil deposits in a retention area on the eastern edge of the pass.

text: Following the

text: Deepwater Horizon oil spill

text: (called the "Gulf oil spill"), the entrance to

text: Perdido Pass

text: was closed, with a barrier system in June 2010, to control tidal flow of oil entering from the Gulf of Mexico. The daily

text: high tide

text: was causing oil-contaminated water to enter Perdido Bay. The barrier system is designed to allow boats to travel through Perdido Pass, during the outflowing tide, but to close during the incoming tide and collect oil deposits in a retention area on the eastern edge of the pass.

text: Riparian zones dissipate stream energy. The meandering curves of a river, combined with vegetation and root systems, slow the flow of water, which reduces soil erosion and flood damage. Sediment is trapped, reducing suspended solids to create less turbid water, replenish soils, and build stream banks. Pollutants are filtered from surface runoff, enhancing water quality via biofiltration.

text: Riparian zones dissipate stream energy. The

text: meander

text: ing curves of a river, combined with vegetation and root systems, slow the flow of water, which reduces soil erosion and flood damage. Sediment is trapped, reducing suspended solids to create less

text: turbid

text: water, replenish soils, and build stream banks. Pollutants are filtered from surface runoff, enhancing water quality via biofiltration.

text: Agate Falls is a 39-foot-high (12 m) waterfall of the Middle Branch of the Ontonagon River. Dropping down from the highlands of the western Upper Peninsula, this river drops  from the Bond Falls Flowage to Lake Superior, and Agate Falls is part of this change in elevation. The water flows over a shelf of erosion-resistant sandstone.

text: Agate Falls is a 39-foot-high (12 m) waterfall of the Middle Branch of the Ontonagon River. Dropping down from the highlands of the western

text: Upper Peninsula

text: , this river drops  from the

text: Bond Falls Flowage

text: to

text: Lake Superior

text: , and Agate Falls is part of this change in elevation. The water flows over a shelf of erosion-resistant

text: sandstone

text: Madhav Kunda Falls is a must-see tourist  It is Bangladesh's largest waterfall boasting a height of 200 ft (61m) and is set in a lush green Eco-park setting makes for a spectacular viewing. Madhabkunda is surrounded by beautiful tea estates and is full of water lilies. Every year thousands of tourists are drawn to Madhabkunda because of its natural beauty, especially in winter. It is about 5 km from Barlekha railway station, and 350 km from the city of Dhaka. Geologically, this waterfall is in the Patharia Structure and is composed of the rocks of the Bhuban Formation. Local Hindus believe the circular pool where the water falls is a magical place, and many worshippers go there every year. Although the water in the pool is not very deep, several tourists have lost their lives in Madhabkunda by the force of the water.

text: Madhav Kunda

text: Falls is a must-see tourist  It is Bangladesh's largest waterfall boasting a height of 200 ft (61m) and is set in a lush green Eco-park setting makes for a spectacular viewing. Madhabkunda is surrounded by beautiful tea estates and is full of water lilies. Every year thousands of tourists are drawn to Madhabkunda because of its natural beauty, especially in winter. It is about 5 km from Barlekha railway station, and 350 km from the city of Dhaka. Geologically, this waterfall is in the Patharia Structure and is composed of the rocks of the Bhuban Formation. Local Hindus believe the circular pool where the water falls is a magical place, and many worshippers go there every year. Although the water in the pool is not very deep, several tourists have lost their lives in Madhabkunda by the force of the water.

text: Analyses by Piotrowski demonstrate that the annual production of water from one typical catchment of  would normally drain through its associated tunnel valley in less than 48 hours. The debris found in tunnels and at the mouth of tunnels tends to be coarse rocks and boulders – this is indicative of high flow velocities and an extremely erosive environment. This erosive environment is consistent with creation of tunnels over  deep and  wide, as have been observed in the Antarctic. Piotrowski’s model predicts a cycle as follows:

text: Residents and legislators met in October 1993 to discuss possible solutions to the recurring sinkhole problems.  The installation of a storm sewer system was widely supported, but the estimated $10 million cost was a major hurdle.  Since the meeting, several projects have been introduced to correct some of the water flow problems of the borough.

text: A river sometimes flows over a large step in the rocks that may have been formed by a fault line. Waterfalls can occur along the edge of a glacial trough, where a stream or river flowing into a glacier continues to flow into a valley after the glacier has receded or melted. The large waterfalls in Yosemite Valley are examples of this phenomenon, which is referred to as a hanging valley. Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other.Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall (which depends on both the waterfall's average flow and its height) using a logarithmic scale. Class 10 waterfalls include Niagara Falls, Paulo Afonso Falls and Khone Falls.

text: A river sometimes flows over a large step in the rocks that may have been formed by a

text: fault line

text: . Waterfalls can occur along the edge of a

text: glacial trough

text: , where a stream or river flowing into a

text: glacier

text: continues to flow into a valley after the glacier has receded or melted. The large waterfalls in

text: Yosemite Valley

text: are examples of this phenomenon, which is referred to as a

text: hanging valley

text: . Another reason hanging valleys may form is where two rivers join and one is flowing faster than the other.Waterfalls can be grouped into ten broad classes based on the average volume of water present on the fall (which depends on both the waterfall's average flow and its height) using a

text: logarithmic scale

text: . Class 10 waterfalls include

text: Niagara Falls

text: Paulo Afonso Falls

text: and

text: Khone Falls

text: The water discharge varies between  with the average of . The flow is relatively strong – about 10 times that of such rivers as Volga and Kama; it is about  on average and may reach  in some places. Chusovaya usually freezes in late October through early December and thaws in April. Ice jams are common for the lower reaches with the increase in the water level of up to . The river is fed by snow (55%). precipitation (29%) and underground waters (18%). The floods typically occur between mid-April and mid-June. During the early summer, there are 6–7 rain floods with water levels rising up to . In July through August, the river depth decreases to  in some places.

text: The water discharge varies between  with the average of . The flow is relatively strong – about 10 times that of such rivers as Volga and Kama; it is about  on average and may reach  in some places. Chusovaya usually freezes in late October through early December and thaws in April.

text: Ice jam

text: s are common for the lower reaches with the increase in the water level of up to . The river is fed by snow (55%). precipitation (29%) and underground waters (18%). The floods typically occur between mid-April and mid-June. During the early summer, there are 6–7 rain floods with water levels rising up to . In July through August, the river depth decreases to  in some places.

text: This species’ typical habitat has been described as relatively shallow, fast flowing water with fine to intermediate gravel substratum. However, broad-scale habitat use appears to vary for this mussel; and live specimens have been collected from both sand-gravel bars and bedrock fissures. For example, habitat use by this mussel in the Spring River and Shoal Creek differs considerably from habitat use in other Kansas rivers. In the Spring River where water currents are faster than in many other Kansas waters, the Neosho mucket occurs in high densities in the fast flow, and dominates over other freshwater mussel species; whereas in Shoal Creek and also the Oklahoma portion of the Illinois River, it has been often found in backwater areas out of the strongest currents where it is less dominant than most heterospecifics. However, the gravel beds of Shoal Creek and the Spring River are less compacted than in other Kansas streams and the availability of loose substratum to bury in may therefore be important for this mussel even where water currents are slow such as in Shoal Creek. Overall, its optimal habitat conditions appear to comprise fast water currents and plentiful loose gravel substratum; whereas low water currents with compact substratum are probably least optimal. The Neosho mucket also appears more adapted to unstable habitats than most other local unionids.

text: This species’ typical habitat has been described as relatively shallow, fast flowing water with fine to intermediate gravel

text: substratum

text: . However, broad-scale habitat use appears to vary for this mussel; and live specimens have been collected from both sand-gravel bars and bedrock fissures. For example, habitat use by this mussel in the Spring River and Shoal Creek differs considerably from habitat use in other Kansas rivers. In the Spring River where water currents are faster than in many other Kansas waters, the Neosho mucket occurs in high densities in the fast flow, and dominates over other freshwater mussel species; whereas in Shoal Creek and also the Oklahoma portion of the Illinois River, it has been often found in backwater areas out of the strongest currents where it is less dominant than most heterospecifics. However, the gravel beds of Shoal Creek and the Spring River are less compacted than in other Kansas streams and the availability of loose substratum to bury in may therefore be important for this mussel even where water currents are slow such as in Shoal Creek. Overall, its optimal habitat conditions appear to comprise fast water currents and plentiful loose gravel substratum; whereas low water currents with compact substratum are probably least optimal. The Neosho mucket also appears more adapted to unstable habitats than most other local unionids.

text: The mouth of Popes Creek is plugged by a flood-tide delta making it an efficient trap for sediment and enriched run-off from three primary sources: farmed watersheds consisting of broad terraces and open upland slopes, erosion of the bluffs and beaches of the Potomac, and the creek bluff erosion itself. Agriculturally derived fill deposited in adjacent ravines to a depth of 2 meters is found covering stumps from the 17th century. Beaver dams and ponds dot the flood plains as well as several old mill ponds which interrupt the flow. Historically, the navigation of the creek has been limited to shallow-draft vessels with present depth up to one meter augmented by 0.3 to 0.4 meter tide. The tributary continues to shoal as the sea level rises driving Potomac silt more than a kilometer inland. Core drilling in the delta has indicated 15 meters of mollusk-bearing sediment, over peat and sand deposits dating back over 6000 years. The taking of oysters is abundantly evident. Aboriginal shell middens were found during archeological excavations, post structure and land preparation for the Visitors’ Center at the site of George Washington’s birthplace. The 18th century refuse pit at the birthplace containing food garbage yielded shucked oyster shells as well. Fishing at the creek mouth is highlighted by the white perch run. In Captain John Smith’s explorations the fish were so thick their heads stuck out of water, prompting his men to attempt to catch them in a frying pan. The entrance to the smaller estuaries would be clogged during spring migrations including shad runs. Later colonial inventories of the Popes Creek plantation list seine corks, lead, seine rope, a knot of perch lines, yielding to the more than adequate kitchen utensil, or fish kettle, serving up the local delicacy.

text: The mouth of Popes Creek is plugged by a flood-tide delta making it an efficient trap for sediment and enriched run-off from three primary sources: farmed watersheds consisting of broad terraces and open upland slopes, erosion of the bluffs and beaches of the Potomac, and the creek bluff erosion itself. Agriculturally derived fill deposited in adjacent ravines to a depth of 2 meters is found covering stumps from the 17th century. Beaver dams and ponds dot the flood plains as well as several old mill ponds which interrupt the flow. Historically, the navigation of the creek has been limited to shallow-draft vessels with present depth up to one meter augmented by 0.3 to 0.4 meter tide. The tributary continues to shoal as the

text: sea level rise

text: s driving Potomac silt more than a kilometer inland. Core drilling in the delta has indicated 15 meters of mollusk-bearing sediment, over peat and sand deposits dating back over 6000 years. The taking of

text: oyster

text: s is abundantly evident. Aboriginal shell

text: midden

text: s were found during archeological excavations, post structure and land preparation for the Visitors’ Center at the site of George Washington’s birthplace. The 18th century refuse pit at the birthplace containing food garbage yielded shucked oyster shells as well. Fishing at the creek mouth is highlighted by the

text: white perch

text: run. In

text: Captain John Smith

text: ’s explorations the fish were so thick their heads stuck out of water, prompting his men to attempt to catch them in a frying pan. The entrance to the smaller estuaries would be clogged during spring migrations including

text: shad

text: runs. Later colonial inventories of the Popes Creek plantation list seine corks, lead, seine rope, a knot of perch lines, yielding to the more than adequate kitchen utensil, or fish kettle, serving up the local delicacy.

text: The water velocity of the Aller is very slow in places. In its upper reaches, at the height of the Drömling, the water compares to a sluggish canal and, in some sections, it is almost like a stretch of still water. Its sluggishness is due to the very gradual slope of the channel, which in Lower Saxony averages a mere 10–20 cm per kilometre. Even in the upper course of the river, the flow across the whole of the stream bed is uniformly slow, due to the river having been widened and straightened. Here, the bed is covered by a mixture of sand and mud.

text: The water velocity of the Aller is very slow in places. In its upper reaches, at the height of the

text: Drömling

text: , the water compares to a sluggish canal and, in some sections, it is almost like a stretch of still water. Its sluggishness is due to the very gradual slope of the channel, which in Lower Saxony averages a mere 10–20 cm per kilometre. Even in the upper course of the river, the flow across the whole of the stream bed is uniformly slow, due to the river having been widened and straightened. Here, the bed is covered by a mixture of sand and mud.

text: Experiments and mathematical models show that more of a given volume can be filled with hard spheres if it is first filled with large spheres, then the spaces between (interstices) are filled with smaller spheres, and the new interstices filled with still smaller spheres as many times as possible. For this reason, control of particle size distribution can be quite important in the choice of aggregate; appropriate simulations or experiments are necessary to determine the optimal proportions of different-sized particles.

text: Experiments and mathematical models show that more of a given volume can be filled with hard spheres if it is first filled with large spheres, then the spaces between (

text: interstices

text: ) are filled with smaller spheres, and the new interstices filled with still smaller spheres as many times as possible. For this reason, control of particle size distribution can be quite important in the choice of aggregate; appropriate simulations or experiments are necessary to determine the optimal proportions of different-sized particles.

text: Nidhan Kund: Almost 1/2 km from the Bhainsaghat Rest House towards the Bhainsa village (5 km from Singrampur), a road goes to this waterfall. One kilometer from the main road a stream between the high black rocks flows down from more than 100 ft (30 m) height. This is called Nidan Kund. During the months of July and August there is much water in the stream so the sight of this fall from the front is impressive. It becomes a picnic spot in September and October as water in the stream is reduced. There are step-like formations on the black rocks against the flow of the stream which create a spectacle when the water flow is high.

text: If the soil is saturated, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs. If the runoff has sufficient flow energy, it will transport loosened soil particles (sediment) down the slope. Sheet erosion is the transport of loosened soil particles by overland flow.

text: If

text: the soil is saturated

text: , or if the rainfall rate is

text: greater than the rate at which water can infiltrate

text: into the soil, surface runoff occurs. If the runoff has sufficient

text: flow energy

text: , it will

text: transport

text: loosened soil particles (

text: sediment

text: ) down the slope. Sheet erosion is the transport of loosened soil particles by overland flow.

text: In June 2000, possible evidence for current liquid water flowing at the surface of Mars was discovered in the form of flood-like gullies.  Additional similar images were published in 2006, taken by the Mars Global Surveyor, that suggested that water occasionally flows on the surface of Mars. The images did not actually show flowing water. Rather, they showed changes in steep crater walls and sediment deposits, providing the strongest evidence yet that water coursed through them as recently as several years ago.

text: In June 2000, possible evidence for current liquid water flowing at the surface of Mars was discovered in the form of flood-like gullies.  Additional similar images were published in 2006, taken by the

text: Mars Global Surveyor

text: , that suggested that water occasionally flows on the surface of Mars. The images did not actually show flowing water. Rather, they showed changes in steep crater walls and sediment deposits, providing the strongest evidence yet that water coursed through them as recently as several years ago.

text: The cave is located in the Driftless Area of Iowa and Minnesota, a region characterized by karst topography, which involves disappearing streams, blind valleys, sinkholes, caves, cold springs, and cold streams, all of which are present here.

text: The cave is located in the

text: Driftless Area

text: of Iowa and Minnesota, a region characterized by

text: karst topography

text: , which involves

text: disappearing streams

text: blind valleys

text: sinkhole

text: s,

text: cave

text: s, cold springs, and cold streams, all of which are present here.

text: The mining activity has caused severe environmental impact in Brazil area. Among the different types of environmental degradation, mining activities has caused landscape degradation, erosion, soil contamination, groundwater and surface water pollution.

text: The mining activity has caused severe

text: environmental impact

text: in Brazil area. Among the different types of

text: environmental degradation

text: , mining activities has caused landscape degradation,

text: erosion

text: soil contamination

text: groundwater

text: and

text: surface

text: water pollution

text: The most effective known method for erosion prevention is to increase vegetative cover on the land, which helps prevent both wind and water erosion. Terracing is an extremely effective means of erosion control, which has been practiced for thousands of years by people all over the world. Windbreaks (also called shelterbelts) are rows of trees and shrubs that are planted along the edges of agricultural fields, to shield the fields against winds. In addition to significantly reducing wind erosion, windbreaks provide many other benefits such as improved microclimates for crops (which are sheltered from the dehydrating and otherwise damaging effects of wind), habitat for beneficial bird species, carbon sequestration, and aesthetic improvements to the agricultural landscape. Traditional planting methods, such as mixed-cropping (instead of monocropping) and crop rotation have also been shown to significantly reduce erosion rates. Crop residues play a role in the mitigation of erosion, because they reduce the impact of raindrops breaking up the soil particles. There is a higher potential for erosion when producing potatoes than when growing cereals, or oilseed crops.  Forages have a fibrous root system, which helps combat erosion by anchoring the plants to the top layer of the soil, and covering the entirety of the field, as it is a non-row crop. In tropical coastal systems, properties of mangroves have been examined as a potential means to reduce soil erosion. Their complex root structures are known to help reduce wave damage from storms and flood impacts while binding and building soils. These roots can slow down water flow, leading to the deposition of sediments and reduced erosion rates. However, in order to maintain sediment balance, adequate mangrove forest width needs to be present.

text: The most effective known method for erosion prevention is to increase vegetative cover on the land, which helps prevent both wind and water erosion.

text: Terracing

text: is an extremely effective means of erosion control, which has been practiced for thousands of years by people all over the world.

text: Windbreaks

text: (also called shelterbelts) are rows of trees and shrubs that are planted along the edges of agricultural fields, to shield the fields against winds. In addition to significantly reducing wind erosion, windbreaks provide many other benefits such as improved

text: microclimate

text: s for crops (which are sheltered from the dehydrating and otherwise damaging effects of wind), habitat for beneficial bird species,

text: carbon sequestration

text: , and aesthetic improvements to the agricultural landscape. Traditional planting methods, such as mixed-cropping (instead of

text: monocropping

text: ) and

text: crop rotation

text: have also been shown to significantly reduce erosion rates. Crop residues play a role in the mitigation of erosion, because they reduce the impact of raindrops breaking up the soil particles. There is a higher potential for erosion when producing potatoes than when growing cereals, or oilseed crops.  Forages have a fibrous root system, which helps combat erosion by anchoring the plants to the top layer of the soil, and covering the entirety of the field, as it is a non-row crop. In tropical coastal systems, properties of mangroves have been examined as a potential means to reduce soil erosion. Their complex root structures are known to help reduce wave damage from storms and flood impacts while binding and building soils. These roots can slow down water flow, leading to the deposition of sediments and reduced erosion rates. However, in order to maintain sediment balance, adequate mangrove forest width needs to be present.

text: Overland flow can erode soil particles and transport them downslope. The erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions.

text: Overland flow

text: can erode soil particles and transport them downslope. The erosion associated with overland flow may occur through different methods depending on meteorological and flow conditions.

text: Uplifting of the north of the Kaapvaal Craton, in addition to orogenesis (mountain formation), towards the end of the deposition of the “West Rand Group” of sediments caused the Witwatersrand sea to retreat. The area of the craton on top of which Johannesburg is now situated, became a vast riverine plain, which extended along the entire northern and western shoreline of the shrunken sea, in an arc extending from Evander in the east, through Johannesburg, Carletonville and then southwards to Klerksdorp and Welkom in the south-west. The rivers formed braided deltas with many interlacing, slow flowing channels where all the heavy materials brought down from the mountains were deposited: large pebbles, and heavy minerals, such as gold, iron pyrite, and uraninite. The gold was in its free elemental form. Cyanobacteria grew in relative abundance in these mineral rich waters. The kerogen, or bitumen, that is found in association with the gold deposits almost certainly represents what remains of these Archean photosynthesizing micro-organisms.

text: Uplifting of the north of the Kaapvaal Craton, in addition to

text: orogenesis

text: (mountain formation), towards the end of the deposition of the “West Rand Group” of sediments caused the Witwatersrand sea to retreat. The area of the craton on top of which Johannesburg is now situated, became a vast riverine plain, which extended along the entire northern and western shoreline of the shrunken sea, in an arc extending from Evander in the east, through Johannesburg, Carletonville and then southwards to Klerksdorp and Welkom in the south-west. The rivers formed

text: braided deltas

text: with many interlacing, slow flowing channels where all the heavy materials brought down from the mountains were deposited: large pebbles, and heavy minerals, such as

text: gold

text: iron pyrite

text: , and

text: uraninite

text: . The gold was in its free elemental form. Cyanobacteria grew in relative abundance in these mineral rich waters. The

text: kerogen

text: , or

text: bitumen

text: , that is found in association with the gold deposits almost certainly represents what remains of these Archean photosynthesizing micro-organisms.

text: A flood is an overflow of water that submerges land which is usually dry. The European Union (EU) Floods Directive defines a flood as a  covering by water of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the tide.

text: A flood is an overflow of water that submerges land which is usually dry. The

text: European Union

text: (EU)

text: Floods Directive

text: defines a flood as a  covering by

text: water

text: of land not normally covered by water. In the sense of "flowing water", the word may also be applied to the inflow of the

text: tide

text: Another major determinant is the soil particle size. Clay particles are some of the smallest particles commonly found in soils. Due to their structure the spaces between individual clay particles is small and already restricts the passage of water, reducing infiltration and hence drainage. Soils with a high clay content are also easily compacted and affected by man-made discharges. Clay particles have a strong negative electrostatic charge and will readily bond to positively charged ions dissolved in the soil-water matrix. Common salts such as sodium ions contained in wastewater can fulfil this role and lead to a localized hardpan in some soil types. This is a common cause of septic system failure due to the prevention of proper drainage in field.

text: Another major determinant is the soil particle size.

text: Clay

text: particles are some of the smallest particles commonly found in soils. Due to their structure the spaces between individual clay particles is small and already restricts the passage of water, reducing infiltration and hence drainage. Soils with a high clay content are also easily compacted and affected by man-made discharges. Clay particles have a strong negative electrostatic charge and will readily bond to positively charged ions dissolved in the soil-water matrix. Common salts such as

text: sodium

text: ions contained in wastewater can fulfil this role and lead to a localized hardpan in some soil types. This is a common cause of

text: septic system

text: failure due to the prevention of proper drainage in field.

text: When ponds were the vogue, they served not only as water reservoirs but also as drains during the rainy season. Consequently, the streets became dry as all the water flowed into the ponds through channels made for that purpose.Fruit trees like the cherry (udala enwe, udala omumu), mango, pepper fruit (mmimi) berry (anene) ugili, agbono, plantain (ogede ji-oko), banana (ogede ntiti) and bread fruit (ukwa) were usually planted around the homes and provided nutritious fruit, shades and necessary checks against erosion.

text: In the water cycle, when precipitation falls on the earth's land, some of the water flows on the surface forming streams and rivers. The remaining water, through infiltration, penetrates the soil traveling underground, hydrating the vadose zone soil, recharging aquifers, with the excess flowing in subsurface runoff. In hydrogeology it is measured by the Groundwater flow equation.

text: In the water cycle, when

text: precipitation

text: falls on the earth's land, some of the water flows on the surface forming

text: stream

text: s and

text: river

text: s. The remaining water, through

text: infiltration

text: , penetrates the soil traveling underground, hydrating the

text: vadose zone

text: soil,

text: recharging

text: aquifer

text: s, with the excess flowing in subsurface runoff. In

text: hydrogeology

text: it is measured by the

text: Groundwater flow equation

text: Surface runoff is water that flows when heavy rains do not infiltrate soil; excess water from rain, meltwater, or other sources flowing over the land.  This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source. When runoff flows along the ground, it can pick up soil contaminants including, but not limited to petroleum, pesticides, or fertilizers that become discharge or nonpoint source pollution.

text: Surface runoff is water that flows when heavy rains do not infiltrate soil; excess water from rain, meltwater, or other sources flowing over the land.  This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a

text: channel

text: is also called a

text: nonpoint source

text: . When runoff flows along the ground, it can pick up

text: soil contaminants

text: including, but not limited to petroleum, pesticides, or fertilizers that become

text: discharge

text: or nonpoint source pollution.

text: For a surface water system to operate without filtration it has to fulfill certain criteria set by the EPA under its Surface Water Treatment Rule, including the implementation of a watershed control program. The water system of New York City has repeatedly fulfilled these criteria.

text: The geologic history from Tertiary and Quaternary periods includes 1) deposition and folding of the Potoco Formation, 2) erosion of this formation, 3) deposition of the Quehua Formation, 4) intrusion of the andesite porphyry stocks, 5) hydrothermal circulation altering rocks and depositing oxide-siderite-barite veins containing silver, 6) intrusion of dacite porphyry stocks, uplift of the Potoco and Quehua Formations, and deposition of dacite porphyry lava flows, 7) intrusion of breccia pipes and faulting, 8) deposition of dacite tuff, 9) hydrothermal circulation altering rocks and depositing galena, sphalerite, pyrite, native silver and barite, 10) erosion.

text: The geologic history from

text: Tertiary

text: and

text: Quaternary

text: periods includes 1)

text: deposition

text: and

text: folding

text: of the Potoco

text: Formation

text: , 2)

text: erosion

text: of this formation, 3) deposition of the Quehua Formation, 4)

text: intrusion

text: of the

text: andesite

text: porphyry

text: stock

text: s, 5)

text: hydrothermal circulation

text: altering rocks and depositing oxide-

text: siderite

text: barite

text: vein

text: s containing silver, 6) intrusion of

text: dacite

text: porphyry stocks, uplift of the Potoco and Quehua Formations, and deposition of dacite porphyry

text: lava

text: flows, 7) intrusion of

text: breccia pipe

text: s and

text: faulting

text: , 8) deposition of dacite

text: tuff

text: , 9) hydrothermal circulation altering rocks and depositing

text: galena

text: sphalerite

text: pyrite

text: , native silver and barite, 10) erosion.

text: –	Quantification of water (Water level, Floods, Minimum Flow, Availability of Water, Water use)

text: A flood is an overflow of any amount of water that reaches land. Floods occur usually when the volume of water within a body of water, such as a river or lake, exceeds the total capacity of the formation, and as a result some of the water flows or sits outside of the normal perimeter of the body. However, floods may be secondary effects of earthquakes, if dams are damaged. Earthquakes may cause landslips to dam rivers, which collapse and cause floods.

text: or suffosion processes.  Sinkholes vary in size from  both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.

text: or

text: suffosion

text: processes.  Sinkholes vary in size from  both in diameter and depth, and vary in form from soil-lined bowls to bedrock-edged chasms. Sinkholes may form gradually or suddenly, and are found worldwide.

text: The Mekong, which is 4,220 kilometers long, is one of the 12 great rivers of the world. From its source in the Tibetan Plateau, it flows through the Tibetan and Yunnan regions of China, forms the boundary between Laos and Myanmar as well as between Laos and Thailand.  At Phnom Penh it merges with the Tonlé Sap and divides into two branches - the Sông Hậu Giang (Hậu Giang river) (known as the Bassac River on the Cambodian side) and the Sông Tiền Giang (Tiền Giang river) - and continues through Cambodia and the Mekong basin before draining into the South China Sea through nine mouths known as the Cửu Long (nine dragons). The river is heavily silted and is navigable by seagoing craft of shallow draft as far as Kompong Cham in Cambodia. A tributary entering the river at Phnom Penh drains the Tonlé Sap, a shallow freshwater lake that acts as a natural reservoir to stabilize the flow of water through the lower Mekong. When the river is in flood stage, its silted delta outlets are unable to carry off the high volume of water. Floodwaters back up into the Tonlé Sap, causing the lake to inundate as much as 10,000 square kilometers. As the flood subsides, the flow of water reverses and proceeds from the lake to the sea. The effect is to reduce significantly the danger of devastating floods in the Mekong delta, where the river floods the surrounding fields each year to a level of one to two meters.

text: The Mekong, which is 4,220 kilometers long, is one of the 12 great rivers of the world. From its source in the

text: Tibetan Plateau

text: , it flows through the Tibetan and Yunnan regions of China, forms the boundary between Laos and

text: Myanmar

text: as well as between Laos and Thailand.  At

text: Phnom Penh

text: it merges with the

text: Tonlé Sap

text: and divides into two branches - the Sông Hậu Giang (Hậu Giang river) (known as the

text: Bassac River

text: on the Cambodian side) and the Sông Tiền Giang (Tiền Giang river) - and continues through Cambodia and the Mekong basin before draining into the

text: South China Sea

text: through nine mouths known as the Cửu Long (nine dragons). The river is heavily silted and is navigable by seagoing craft of shallow draft as far as

text: Kompong Cham

text: in Cambodia. A tributary entering the river at Phnom Penh drains the

text: Tonlé Sap

text: , a shallow

text: freshwater

text: lake that acts as a natural reservoir to stabilize the flow of water through the lower Mekong. When the river is in flood stage, its

text: silt

text: ed delta outlets are unable to carry off the high volume of water. Floodwaters back up into the Tonlé Sap, causing the lake to inundate as much as 10,000 square kilometers. As the flood subsides, the flow of water reverses and proceeds from the lake to the sea. The effect is to reduce significantly the danger of devastating floods in the Mekong delta, where the river floods the surrounding fields each year to a level of one to two meters.

text: Deposits reduce the heat transfer in the boiler, reduce the flow rate and eventually block boiler tubes. Any non-volatile salts and minerals that will remain when the feedwater is evaporated must be removed, because they will become concentrated in the liquid phase and require excessive  "blow-down" (draining) to prevent the formation of solid precipitates. Even worse are minerals that form scale. Therefore, the make-up water added to replace any losses of feedwater must be demineralized/deionized water, unless a purge valve is used to remove dissolved minerals.

text: Deposits reduce the heat transfer in the boiler, reduce the flow rate and eventually block boiler tubes. Any non-

text: volatile

text: salts and minerals that will remain when the feedwater is

text: evaporate

text: d must be removed, because they will become concentrated in the liquid phase and require excessive

text: "blow-down"

text: (draining) to prevent the formation of solid precipitates. Even worse are minerals that form

text: scale

text: . Therefore, the

text: make-up water

text: added to replace any losses of feedwater must be

text: demineralized

text: deionized water

text: , unless a purge valve is used to remove dissolved minerals.

text: Sinkholes can be classified on the basis of the processes by which they are formed: dissolution, cover-subsidence, and cover-collapse. Formation of sinkholes can be accelerated by intense withdrawals of groundwater over short periods of time, such as those caused by pumping for frost-protection of winter crops in west-central Florida. Sinkholes that developed beneath gypsum stacks in 1994 and 2016 caused a loss of millions of gallons mineralized water containing phosphogypsum and phosphoric acid,  by-products of the production of fertilizer from phosphate rock. These sinkholes were likely formed from the collapse of preexisting dissolution cavities in the limestone beneath the stacks. Lake Jackson near Tallahassee, FL occasionally drains into a sinkhole in the bottom of the lake bed when water levels in the aquifer drop. Dover Sinkhole, located along the Peace River near Bartow, FL, was witnessed draining about 10 Mgal/d of water from the Peace River during June 2006.

text: Sinkholes can be classified on the basis of the processes by which they are formed: dissolution, cover-subsidence, and cover-collapse. Formation of sinkholes can be accelerated by intense withdrawals of groundwater over short periods of time, such as those caused by pumping for frost-protection of winter crops in west-central Florida. Sinkholes that developed beneath gypsum stacks in 1994 and 2016 caused a loss of millions of gallons mineralized water containing

text: phosphogypsum

text: and

text: phosphoric acid

text: ,  by-products of the production of

text: fertilizer

text: from

text: phosphate rock

text: . These sinkholes were likely formed from the collapse of preexisting dissolution cavities in the limestone beneath the stacks.

text: Lake Jackson

text: near

text: Tallahassee, FL

text: occasionally drains into a sinkhole in the bottom of the lake bed when water levels in the aquifer drop. Dover Sinkhole, located along the

text: Peace River

text: near

text: Bartow, FL

text: , was witnessed draining about 10 Mgal/d of water from the Peace River during June 2006.

text: The main branch of the Knife River flows  from source to mouth, flowing parallel to the shoreline from the direction of Two Harbors. It has four or five major tributaries. Its watershed is , and contains  of streams. Since data began being collected in 1974, its mean annual daily discharge of water has been calculated as . There is concern over the river's water quality due to suspended sediment, and it was placed on the state's impaired waters list in 1998. A 2008 study found that about sixty percent of the sediment was coming from erosion of the streambanks, and about thirty from erosion of the river's bluffs.

text: The fourth incarnation of Lord Vishnu, Lord Narasimha, is half human and half lion. Legend says that Narasimha after killing Hiranyakashipu, slew another giant named Jharasura (Jalasura) who was a staunch devotee of Lord Shiva. While breathing his last, Jharasura beseeched Vishnu (or rather, his incarnation) to reside in the cave in which he was living and to grant boons to devotees. Granting last wish of his, Narasimha came to live in the cave. There is a roughly carved image of Narasimha on a stone wall at the end of the cave. After being killed, the demon turned into water and started flowing down the feet of the Lord Narasimha. The flow of water in the cave tunnel is continuous since then. The spring has never dried out.

text: The fourth incarnation of Lord Vishnu, Lord Narasimha, is half human and half lion. Legend says that Narasimha after killing Hiranyakashipu, slew another giant named Jharasura (Jalasura) who was a staunch devotee of Lord

text: Shiva

text: . While breathing his last, Jharasura beseeched Vishnu (or rather, his incarnation) to reside in the cave in which he was living and to grant boons to devotees. Granting last wish of his,

text: Narasimha

text: came to live in the cave. There is a roughly carved image of Narasimha on a stone wall at the end of the cave. After being killed, the demon turned into water and started flowing down the feet of the Lord Narasimha. The flow of water in the cave tunnel is continuous since then. The spring has never dried out.

text: Where the Floridan aquifer system is at or near land surface (areas shaded brown in image above), clays are thin or absent and dissolution of the limestone is intensified and many springs and sinkholes are apparent. Transmissivity of the aquifer in karstified areas such as these is much higher owing to the development of large, well-connected conduits within the rock (see image at right). Springs form where the water pressure is great enough for the groundwater to flow out on the land surface. More than 700 springs have been mapped in Florida. Wakulla Springs in Wakulla County is one of a number of major outflows of the aquifer with a flow rate of 200–300 million US gallons (757,082 - 1,135,623 cubic meters) of water per day. A record peak flow from the spring on April 11, 1973, was measured at  per second - equal to 1.2 billion gallons (4,542,494 cubic meters) per day.

text: Where the Floridan aquifer system is at or near land surface (areas shaded brown in image above), clays are thin or absent and dissolution of the limestone is intensified and many springs and sinkholes are apparent.

text: Transmissivity

text: of the aquifer in

text: karst

text: ified areas such as these is much higher owing to the development of large, well-connected conduits within the rock (see image at right). Springs form where the water pressure is great enough for the groundwater to flow out on the land surface. More than 700 springs have been mapped in Florida.

text: Wakulla Springs

text: in

text: Wakulla County

text: is one of a number of major outflows of the aquifer with a flow rate of 200–300 million US gallons (757,082 - 1,135,623 cubic meters) of water per day. A record peak flow from the spring on April 11, 1973, was measured at  per second - equal to 1.2 billion gallons (4,542,494 cubic meters) per day.

text: Any obstruction within flowing water will produce changes in velocity within the water column. The flow changes that occur in the vicinity of the substrate may cause differential movement in the bed materials near the obstruction. The magnitude of these changes varies with stream velocity, feature shape and substrate character. Generally the stream bed is deepened at the upstream end of the obstruction, and the material removed from the substrate is usually deposited in the sheltered areas behind or adjacent to the obstruction where the local velocity is sufficiently reduced. In conditions of high stream velocities, mobile bed materials, and poorly streamlined structures scour depths can be quite deep.

text: There has been considerable debate over the years as to the depth of the Yogo dike and how many ounces of rough sapphires per ton it contains. In the late 1970s and early 1980s, Delmer L. Brown, a geological engineer and gemologist, conducted the most thorough scientific exploration up to that time, concluding that the dike was at least  deep and that the concentration of rough sapphires was not constant throughout the deposit. Brown found that the dike had intruded into a pre-existing fault that had been a conduit for groundwater circulation. The overlying shale, the Kibbey Formation, was deposited on an unconformity, an ancient Mississippian-age karst erosion surface, and was not intruded by the dike. This groundwater action produced collapsed zones which were intruded by the dike to form breccia zones. Recent erosion in the area removed the overlying shales and again exposed the limestone to groundwater action which produced collapse breccias which include fragments of the dike rock. He determined that the erosion of the dike in the current erosion cycle was minimal.

text: There has been considerable debate over the years as to the depth of the Yogo dike and how many ounces of rough sapphires per ton it contains. In the late 1970s and early 1980s, Delmer L. Brown, a

text: geological engineer

text: and gemologist, conducted the most thorough scientific exploration up to that time, concluding that the dike was at least  deep and that the concentration of rough sapphires was not constant throughout the deposit. Brown found that the dike had intruded into a pre-existing

text: fault

text: that had been a conduit for groundwater circulation. The overlying shale, the

text: Kibbey Formation

text: , was deposited on an

text: unconformity

text: , an ancient Mississippian-age

text: karst

text: erosion surface

text: , and was not intruded by the dike. This groundwater action produced collapsed zones which were intruded by the dike to form breccia zones. Recent erosion in the area removed the overlying shales and again exposed the limestone to groundwater action which produced collapse breccias which include fragments of the dike rock. He determined that the erosion of the dike in the current erosion cycle was minimal.

text: Melaleuca viminalis provides food for nectivores. Its adaptations to survive strong currents during flood events allow it to slow the flow of floodwater and reduce erosion, thereby improving the water quality in streams and rivers. The matted roots of this species also strengthen the soil of riverbanks, further reducing the potential for erosion.

text: Melaleuca viminalis provides food for

text: nectivore

text: s. Its adaptations to survive strong currents during flood events allow it to slow the flow of floodwater and reduce erosion, thereby improving the water quality in streams and rivers. The matted roots of this species also strengthen the soil of riverbanks, further reducing the potential for erosion.

text: Braided rivers, as distinct from meandering rivers, occur when a threshold level of sediment load or slope is reached whilst a steep gradient is also maintained.  Geologically speaking, an increase in sediment load will over time increase in the slope of the river, so these two conditions can be considered synonymous; and, consequently, a variation of slope can model a variation in sediment load.  A threshold slope was experimentally determined to be 0.016 (ft/ft) for a  stream with poorly sorted coarse sand.  Any slope over this threshold created a braided stream, while any slope under the threshold created a meandering stream or— for very low slopes—a straight channel. So the main controlling factor on river development is the amount of sediment that the river carries; once a given system crosses a threshold value for sediment load, it will convert from a meandering system to a braided system.  Also important to channel development is the proportion of suspended load sediment to bed load.  An increase in suspended sediment allowed for the deposition of fine erosion-resistant material on the inside of a curve, which accentuated the curve and in some instances caused a river to shift from a braided to a meandering profile.The channels and braid bars are usually highly mobile, with the river layout often changing significantly during flood events. Channels move sideways via differential velocity: On the outside of a curve, deeper, swift water picks up sediment (usually gravel or larger stones), which is re-deposited in slow-moving water on the inside of a bend.

text: Braided rivers, as distinct from

text: meander

text: ing rivers, occur when a threshold level of

text: sediment

text: load or slope is reached whilst a steep gradient is also maintained.  Geologically speaking, an increase in sediment load will over time increase in the slope of the river, so these two conditions can be considered synonymous; and, consequently, a variation of slope can model a variation in sediment load.  A threshold slope was experimentally determined to be 0.016 (ft/ft) for a  stream with poorly sorted coarse sand.  Any slope over this threshold created a braided stream, while any slope under the threshold created a

text: meander

text: ing stream or— for very low slopes—a straight channel. So the main controlling factor on river development is the amount of sediment that the river carries; once a given system crosses a threshold value for sediment load, it will convert from a

text: meander

text: ing system to a braided system.  Also important to channel development is the proportion of

text: suspended load

text: sediment to

text: bed load

text: .  An increase in suspended sediment allowed for the deposition of fine

text: erosion

text: -resistant material on the inside of a curve, which accentuated the curve and in some instances caused a river to shift from a braided to a

text: meander

text: ing profile.The channels and braid bars are usually highly mobile, with the river layout often changing significantly during

text: flood

text: events. Channels move sideways via differential velocity: On the outside of a curve, deeper, swift water picks up sediment (usually

text: gravel

text: or larger stones), which is re-deposited in slow-moving water on the inside of a bend.

text: The roots of trees growing by a stream are undercut by such erosion.  As the roots bind the soil tightly, they form abutments which jut out over the water.  These have a significant effect upon the rate and progress of the erosion.

text: The

text: root

text: s of

text: tree

text: s growing by a stream are undercut by such erosion.  As the roots bind the soil tightly, they form abutments which jut out over the water.  These have a significant effect upon the rate and progress of the erosion.

text: In summer, the cooler talus-covered slopes power an air exchange with sinkholes atop the ridge, with warm air entering the sinkhole to an ice cave. The air is cooled and vented on the algific slope. In winter, the airflow is reversed. Cool or cold air is drawn through the algific talus into the ice cave, with flowing water or atmospheric humidity being turned to ice. The air temperature on these slopes ranges from "30 degrees F to 55 degrees F spring to fall".

text: After this period of filling in, came a period of isostatic deepening. The weight of the recent deposits bore down on the sediments below, at the same time as erosion decreased and the mountains began to grow. At the same time, the drainage basin that had basically been an inland sea began to pour out its waters through the River Genil and the Infiernos de Loja. The river and its tributaries were carved out, and after the Quaternary climate crisis, river terraces formed. The River Genil has two well-defined terraces. The deepening of the Depression of Granada at the foot of the Sierra Nevada led to the formation of a flooded area between Santa Fe and Granada. The Quaternary also produced a diapiric uprising of a mass of gypsum clay to the height of the town of Láchar, which made area from Láchar to Granada more easily flooded, and broke the original depression into two units the Depression of Granada and the Pasillo or Depression of Loja.

text: After this period of filling in, came a period of

text: isostatic

text: deepening. The weight of the recent deposits bore down on the sediments below, at the same time as erosion decreased and the mountains began to grow. At the same time, the drainage basin that had basically been an

text: inland sea

text: began to pour out its waters through the River Genil and the Infiernos de Loja. The river and its tributaries were carved out, and after the

text: Quaternary

text: climate crisis, river terraces formed. The River Genil has two well-defined terraces. The deepening of the Depression of Granada at the foot of the Sierra Nevada led to the formation of a flooded area between

text: Santa Fe

text: and

text: Granada

text: . The Quaternary also produced a

text: diapir

text: ic uprising of a mass of

text: gypsum

text: clay

text: to the height of the town of

text: Láchar

text: , which made area from Láchar to Granada more easily flooded, and broke the original depression into two units the Depression of Granada and the Pasillo or

text: Depression of Loja

text: Immediately southeast of Mount Cayley lies Mount Fee, an extensively eroded volcano containing a north-south trending ridge. It is one of the older volcanic features in the central Garibaldi chain. Its volcanics are undated, but its large amount of dissection and evidence of glacai ice overriding the volcano indicates that it formed more than 75,000 years ago before the Wisconsinan Glaciation. Therefore, volcanism at Mount Fee does not display evidence of interaction with glacial ice. The remaining product from Fee's earliest volcanic activity is a minor portion of pyroclastic rock. This is evidence of explosive volcanism from Fee's eruptive history, as well as its first volcanic event. The second volcanic event produced a sequence of lavas and breccias on the eastern flank of the main ridge. These volcanics were likely placed when a sequence of lava flows and broken lava fragments erupted from a volcanic vent and moved down the flanks during the construction of a large volcano. Following extensive dissection, renewed volcanism produced a viscous series of lava flows forming its narrow, flat-topped, steep-sided northern limit and the northern end of the main ridge. The conduit for which these lava flows originated from was likely vertical in structure and intruded through older volcanics deposited during Fee's earlier volcanic events. This volcanic event was also followed by a period of erosion, and likely one or more glacial periods. Extensive erosion following the last volcanic event at Mount Fee has created the rugged north-south trending ridge that currently forms a prominent landmark.

text: Immediately southeast of Mount Cayley lies

text: Mount Fee

text: , an extensively eroded volcano containing a north-south trending ridge. It is one of the older volcanic features in the central Garibaldi chain. Its volcanics are undated, but its large amount of dissection and evidence of glacai ice overriding the volcano indicates that it formed more than 75,000 years ago before the

text: Wisconsinan Glaciation

text: . Therefore, volcanism at Mount Fee does not display evidence of interaction with glacial ice. The remaining product from Fee's earliest volcanic activity is a minor portion of

text: pyroclastic rock

text: . This is evidence of explosive volcanism from Fee's eruptive history, as well as its first volcanic event. The second volcanic event produced a sequence of lavas and breccias on the eastern flank of the main ridge. These volcanics were likely placed when a sequence of lava flows and broken lava fragments erupted from a volcanic vent and moved down the flanks during the construction of a large volcano. Following extensive dissection, renewed volcanism produced a viscous series of lava flows forming its narrow, flat-topped, steep-sided northern limit and the northern end of the main ridge. The conduit for which these lava flows originated from was likely vertical in structure and intruded through older volcanics deposited during Fee's earlier volcanic events. This volcanic event was also followed by a period of erosion, and likely one or more glacial periods. Extensive erosion following the last volcanic event at Mount Fee has created the rugged north-south trending ridge that currently forms a prominent landmark.

text: The Reid Glacier was named by the members of the Harriman Alaska Expedition for Harry Fielding Reid (1859–1944), professor of geology at Johns Hopkins University, who was well known for his studies of glacier flow and stratification in Alaska and the Alps. The glacier has its origin in Brady Icefield and has a flow rate of  per day. At the water edge, its width is , rises to a height of  and stretches to a length of  and flows into Bigourdan Fjord. In view of fast rate of retreat, this glacier has turned from tide water to terrestrial glacier, particularly on its eastern and western one third widths. Sediment deposits from the glacier have gradually filled the eastern and western margins at its inlet, as seen during low tides. The central one third of the glacier, however, touches water edge with a recorded depth of  of water, during high tide. The walls of the fjord of the glacier, however, also show marks of lateral deposits of the glaciers right up to rock faces.

text: The Reid Glacier was named by the members of the

text: Harriman Alaska Expedition

text: for

text: Harry Fielding Reid

text: (1859–1944), professor of geology at

text: Johns Hopkins University

text: , who was well known for his studies of glacier flow and stratification in Alaska and the

text: Alps

text: . The glacier has its origin in

text: Brady Icefield

text: and has a flow rate of  per day. At the water edge, its width is , rises to a height of  and stretches to a length of  and flows into

text: Bigourdan Fjord

text: . In view of fast rate of retreat, this glacier has turned from tide water to terrestrial glacier, particularly on its eastern and western one third widths. Sediment deposits from the glacier have gradually filled the eastern and western margins at its inlet, as seen during low tides. The central one third of the glacier, however, touches water edge with a recorded depth of  of water, during high tide. The walls of the fjord of the glacier, however, also show marks of lateral deposits of the glaciers right up to rock faces.

text: Although 70.8% of all Earth's surface is covered in water, water accounts for just some 0.05% of Earth’s mass. There are worlds where more than 10% of the mass may be water. This may be the case, for example, for all the six innermost planets orbiting the star Kepler-11. These planets may have oceans hundreds of kilometres deep.Their abyssal depths would be so deep and dense that even at high temperatures the pressure would turn the water into ice. The immense pressures in the lower regions of these oceans could lead to the formation of a mantle of exotic forms of ice. This ice would not necessarily be as cold as conventional ice. If the planet is close enough to its star that the water reaches its boiling point, the water will become supercritical and lack a well-defined surface. Even on cooler water-dominated planets, the atmosphere can be much thicker than that of Earth, and composed largely of water vapor, producing a very strong greenhouse effect. Such planets would have to be small enough not to be able to retain a thick envelope of hydrogen and helium, otherwise they would form a warmer version of an ice giant instead, like Uranus and Neptune.

text: Although 70.8% of all

text: Earth

text: 's surface is covered in water, water accounts for just some 0.05% of Earth’s mass. There are worlds where more than 10% of the mass may be water. This may be the case, for example, for all the six innermost planets orbiting the star

text: . These planets may have oceans hundreds of kilometres deep.Their abyssal depths would be so deep and dense that even at high temperatures the pressure would turn the water into ice. The immense pressures in the lower regions of these oceans could lead to the formation of a mantle of exotic forms of

text: ice

text: . This ice would not necessarily be as cold as conventional ice. If the planet is close enough to its star that the water reaches its boiling point, the water will become

text: supercritical

text: and lack a well-defined surface. Even on cooler water-dominated planets, the atmosphere can be much thicker than that of Earth, and composed largely of water vapor, producing a very strong

text: greenhouse effect

text: . Such planets would have to be small enough not to be able to retain a thick envelope of hydrogen and helium, otherwise they would form a

text: warmer version

text: of an

text: ice giant

text: instead, like

text: Uranus

text: and

text: Neptune

text: Some crater floors in the Syrtis Major area show elongated ridges in a lattice-like pattern.  Such patterns are typical of faults and breccia dikes formed as a result of an impact.  Some have suggested that these ridges are dikes made up of molten rock, but others have advanced the idea that other fluids, like water were involved.  The ridges are found where there has been enhanced erosion.   Pictures below show examples of these dikes.  Water may flow along faults.  The water often carries minerals that serve to cement rock materials thus making them harder.  Later when the whole area undergoes erosion the dikes will remain as ridges because they are more resistant to erosion.  This discovery may be of great importance for future colonization of Mars because these types of faults and breccia dikes on earth are associated with key mineral resources.  It has been estimated that 25% of the Earth's impacts are connected to mineral production.  The largest gold deposit on Earth is the Vredefort 300 km diameter impact structure in South Africa. Perhaps, when people live on Mars these kinds of areas will be mined as they are on earth.

text: Some crater floors in the Syrtis Major area show elongated ridges in a lattice-like pattern.  Such patterns are typical of

text: faults

text: and breccia

text: dikes

text: formed as a result of an impact.  Some have suggested that these ridges are dikes made up of molten rock, but others have advanced the idea that other fluids, like water were involved.  The ridges are found where there has been enhanced

text: erosion

text: .   Pictures below show examples of these dikes.  Water may flow along faults.  The water often carries minerals that serve to cement rock materials thus making them harder.  Later when the whole area undergoes erosion the dikes will remain as ridges because they are more resistant to erosion.  This discovery may be of great importance for future colonization of Mars because these types of faults and breccia dikes on earth are associated with key mineral resources.  It has been estimated that 25% of the Earth's impacts are connected to mineral production.  The largest

text: gold

text: deposit on Earth is the

text: Vredefort

text: 300 km diameter impact structure in

text: South Africa

text: . Perhaps, when people live on Mars these kinds of areas will be mined as they are on earth.

text: The sediment taken from the bank during the process of bank erosion is deposited on the opposing side of the channel fueling the process called point bar deposition. The helicoidal flow also plays a role in this process by acting as a cross channel component that moves the sediment to the other side. The processes of point bar deposition and bank erosion are intertwined and in most cases the erosion rate of cut banks is equal to the deposition rate of point bars. In addition, point bars act as topographic obstructions once formed that further drive flow into the opposite bank, creating a positive feedback loop. This leads to the meanders of an alluvial river becoming more well defined over time.

text: The sediment taken from the bank during the process of

text: bank erosion

text: is deposited on the opposing side of the channel fueling the process called point bar deposition. The

text: helicoidal flow

text: also plays a role in this process by acting as a cross channel component that moves the sediment to the other side. The processes of point bar deposition and bank erosion are intertwined and in most cases the erosion rate of cut banks is equal to the deposition rate of point bars. In addition, point bars act as topographic obstructions once formed that further drive flow into the opposite bank, creating a

text: positive feedback loop

text: . This leads to the meanders of an alluvial river becoming more well defined over time.

text: The effects of wind and water were able to chemically and mechanically erode and destroy the Hercynic mountain ranges. In the Permian, the main deposits in Europe were sandstone and conglomerate, products of erosion in the Hercynic mountain range.  At the same time, crustal extension took place because the mountain range was isostatically unstable (this is called orogenic collapse). Due to extension, basins formed along the axis of the mountain range and felsic volcanism occurred. This was the first phase of rifting between Europe and Africa. Due to the rising sealevel in the Triassic period, the eastern margin of Pangaea was flooded. Shallow shelf seas and epicontinental seas existed in which evaporites and limestones were deposited.

text: The effects of

text: wind

text: and water were able to chemically and mechanically

text: erode

text: and destroy the Hercynic mountain ranges. In the

text: Permian

text: , the main deposits in Europe were

text: sandstone

text: and

text: conglomerate

text: , products of erosion in the Hercynic mountain range.  At the same time, crustal extension took place because the mountain range was

text: isostatically

text: unstable (this is called

text: orogenic collapse

text: ). Due to extension, basins formed along the axis of the mountain range and

text: felsic

text: volcanism

text: occurred. This was the first phase of

text: rifting

text: between Europe and Africa. Due to the

text: rising sealevel

text: in the

text: Triassic

text: period, the eastern margin of Pangaea was flooded. Shallow

text: shelf sea

text: s and

text: epicontinental sea

text: s existed in which

text: evaporite

text: s and

text: limestone

text: s were deposited.

text: Academician Ridge represents a unique sedimentary environment within Lake Baikal. The depths of the two basins it separates, about 900 m in the North Basin and about 1600 m deep in the Central basin, isolate the ridge from mass-flows and turbidites. Therefore, sedimentation on Academician Ridge is restricted to fine, continuous hemipelagic sedimentation with dispersed coarse-grained sediment deposited by ice rafting (Kuzmin et al., 2000). The stratigraphy observed in boreholes drilled into Academician Ridge shows that the upper sequence of continuous hemipelagic deposits, which are consistent with a bathymetric high in a deep lacustrine environment, is underlain by a lower sequence that is consistent with prograding, deltaic deposits in a shallow-water environment (Mats et al., 2000). This change from a shallow-water environment to a deep-water environment represents two things: one, that Academician Ridge experienced gradual flooding and, two, that the presence of a lake in the North Basin occurred long after the  presence of a lake in the Central and South basins first occurred (Mats et al., 2000).

text: Academician Ridge represents a unique

text: sedimentary environment

text: within Lake Baikal. The depths of the two basins it separates, about 900 m in the North Basin and about 1600 m deep in the Central basin, isolate the ridge from mass-flows and

text: turbidites

text: . Therefore, sedimentation on Academician Ridge is restricted to fine, continuous

text: hemipelagic

text: sedimentation with dispersed coarse-grained sediment deposited by

text: ice rafting

text: (Kuzmin et al., 2000). The stratigraphy observed in boreholes drilled into Academician Ridge shows that the upper sequence of continuous hemipelagic deposits, which are consistent with a bathymetric high in a deep

text: lacustrine

text: environment, is underlain by a lower sequence that is consistent with prograding, deltaic deposits in a shallow-water environment (Mats et al., 2000). This change from a shallow-water environment to a deep-water environment represents two things: one, that Academician Ridge experienced gradual flooding and, two, that the presence of a lake in the North Basin occurred long after the  presence of a lake in the Central and South basins first occurred (Mats et al., 2000).

text: The composition, moisture, and compaction of soil are all major factors in determining the erosivity of rainfall. Sediments containing more clay tend to be more resistant to erosion than those with sand or silt, because the clay helps bind soil particles together. Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure. The amount of water present in the soil before the precipitation also plays an important role, because it sets limits on the amount of water that can be absorbed by the soil (and hence prevented from flowing on the surface as erosive runoff). Wet, saturated soils will not be able to absorb as much rain water, leading to higher levels of surface runoff and thus higher erosivity for a given volume of rainfall. Soil compaction also affects the permeability of the soil to water, and hence the amount of water that flows away as runoff. More compacted soils will have a larger amount of surface runoff than less compacted soils.

text: The composition, moisture, and compaction of soil are all major factors in determining the erosivity of rainfall. Sediments containing more

text: clay

text: tend to be more resistant to erosion than those with sand or silt, because the clay helps bind soil particles together. Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure. The amount of water present in the soil before the precipitation also plays an important role, because it sets limits on the amount of water that can be absorbed by the soil (and hence prevented from flowing on the surface as erosive runoff). Wet, saturated soils will not be able to absorb as much rain water, leading to higher levels of surface runoff and thus higher erosivity for a given volume of rainfall.

text: Soil compaction

text: also affects the permeability of the soil to water, and hence the amount of water that flows away as runoff. More compacted soils will have a larger amount of surface runoff than less compacted soils.

text: Dredging was feared to increase water flow velocity and erosion in upper streams and flooding in their lower reaches. A collapsed bridge in eastern Korea has been blamed on dredging.

text: A sinkhole, also known as a cenote, sink, sink-hole, shakehole, swallet, swallow hole, or doline (the different terms for sinkholes are often used interchangeably), is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by karst processes—for example, the chemical dissolution of carbonate rocks

text: A sinkhole, also known as a cenote, sink, sink-hole, shakehole, swallet, swallow hole, or doline (the different terms for sinkholes are often used interchangeably), is a depression or hole in the ground caused by some form of collapse of the surface layer. Most are caused by

text: karst processes

text: carbonate rocks

text: Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension. This sediment is often formed when weathering and erosion break down a rock into loose material in a source area. The material is then transported from the source area to the deposition area. The type of sediment transported depends on the geology of the hinterland (the source area of the sediment). However, some sedimentary rocks, such as evaporites, are composed of material that form at the place of deposition. The nature of a sedimentary rock, therefore, not only depends on the sediment supply, but also on the sedimentary depositional environment in which it formed.

text: Sedimentary

text: rock

text: s are formed when

text: sediment

text: is

text: deposited

text: out of air, ice, wind, gravity, or water flows carrying the particles in

text: suspension

text: . This sediment is often formed when

text: weathering

text: and

text: erosion

text: break down a rock into loose material in a source area. The material is then

text: transported

text: from the source area to the deposition area. The type of sediment transported depends on the geology of the

text: hinterland

text: (the source area of the sediment). However, some sedimentary rocks, such as

text: evaporite

text: s, are composed of material that form at the place of deposition. The nature of a sedimentary rock, therefore, not only depends on the sediment supply, but also on the

text: sedimentary depositional environment

text: in which it formed.

text: The abundance of water on Earth's surface is a unique feature that distinguishes the "Blue Planet" from other planets in the Solar System. Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of 10,911.4 m.

text: The abundance of water on Earth's surface is a unique feature that distinguishes the "Blue Planet" from other planets in the Solar System. Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m. The deepest underwater location is

text: Challenger Deep

text: The garden presents Mughal architecture as used in different Mughal gardens. The artistically build garden has Iranian influence in its art and architecture and the design is based on the Persian gardens. It is built around a fresh water spring, discovered by Rupa Bhawani, which flows through its centre in terraces. The topography and the steepness of the land has led the formation of the garden. The main focus of the garden is the spring which flows down in terraces and is divided into three sections: an aqueduct, waterfall, and fountains. A two-storey Kashmiri hut stands at the first terrace which is the origin of the spring. The water then flows down through a water ramp (chadar) into the second terrace. The second terrace serves as a water pool and a large fountain stands at its centre. The water again flows down through a water ramp into the third terrace, which is a square five-fountain pool. It is the lowest pool at the entrance of the garden. The visitors are received through a flight of stairs on both sides of the terraces which leads up to the origin of the spring. The English writer and traveler Amit Kumar wrote about the garden that "the little Chashma Shahi is architecturally the most charming of the gardens near Srinagar". The water of the spring is believed to have some medicinal properties. The former Premier of India, Pandit Jawahar Lal Nehru, used to get the water of the spring to Delhi. 2

text: The garden presents Mughal architecture as used in different Mughal gardens. The artistically build garden has Iranian influence in its art and architecture and the design is based on the

text: Persian gardens

text: . It is built around a fresh water spring, discovered by Rupa Bhawani, which flows through its centre in terraces. The topography and the steepness of the land has led the formation of the garden. The main focus of the garden is the spring which flows down in terraces and is divided into three sections: an aqueduct, waterfall, and fountains. A two-storey Kashmiri hut stands at the first terrace which is the origin of the spring. The water then flows down through a water ramp (chadar) into the second terrace. The second terrace serves as a water pool and a large fountain stands at its centre. The water again flows down through a water ramp into the third terrace, which is a square five-fountain pool. It is the lowest pool at the entrance of the garden. The visitors are received through a flight of stairs on both sides of the terraces which leads up to the origin of the spring. The English writer and traveler

text: Amit Kumar

text: wrote about the garden that "the little Chashma Shahi is architecturally the most charming of the gardens near Srinagar". The water of the spring is believed to have some medicinal properties. The former Premier of India,

text: Pandit Jawahar Lal Nehru

text: , used to get the water of the spring to Delhi. 2

text: This scenario seeks to describe the formation of the valley networks without appeal to conditions or processes different from those already known to exist on Mars today. Modeling indicates that seeps of groundwater could occur on the surface even under modern conditions, but will freeze very quickly. However, under this suggestion ice cover could insulate the water flowing beneath it well enough to allow long distance transport (and associated erosion), much like a lava tube insulates the molten lava inside it.

text: This scenario seeks to describe the formation of the valley networks without appeal to conditions or processes different from those already known to exist on Mars today. Modeling indicates that seeps of groundwater could occur on the surface even under modern conditions, but will freeze very quickly. However, under this suggestion ice cover could insulate the water flowing beneath it well enough to allow long distance transport (and associated erosion), much like a

text: lava tube

text: insulates the molten lava inside it.

text: The verdant green colour of the water flowing over the Niagara Falls is a byproduct of the estimated 60 tonnes/minute of dissolved salts and "rock flour" (very finely ground rock) generated by the erosive force of the Niagara River itself. The current rate of erosion is approximately  per year, down from a historical average of  per year. It is estimated that 50,000 years from now, even at this reduced rate of erosion, the remaining  to Lake Erie will have been undermined and the falls will cease to exist.

text: Roxar Flow Measurement develops real-time flow measurement and instrumentation of wells and data acquisition systems. From high temperature reservoir monitoring to multiphase flow metering, sand erosion sensors, oil in water monitoring, and corrosion detection, the technology helps operators make reservoir management and flow assurance decisions.

text: Roxar Flow Measurement develops real-time

text: flow measurement

text: and instrumentation of

text: wells

text: and

text: data acquisition

text: systems. From high temperature

text: reservoir

text: monitoring to

text: multiphase flow

text: metering, sand

text: erosion

text: sensors,

text: oil

text: in water monitoring, and

text: corrosion

text: detection, the technology helps operators make reservoir management and

text: flow assurance

text: decisions.

text: The waters of the Tigris and Euphrates are essential to the life of the country, but they sometimes threaten it. The rivers are at their lowest level in September and October and at flood in March, April, and May when they may carry forty times as much water as at low mark. Moreover, one season's flood may be ten or more times as great as that in another year. In 1954, for example, Baghdad was seriously threatened, and dikes protecting it were nearly topped by the flooding Tigris. Since Syria built a dam on the Euphrates, the flow of water has been considerably diminished and flooding was no longer a problem in the mid-1980s. In 1988 Turkey was also constructing a dam on the Euphrates that would further restrict the water flow.

text: The waters of the Tigris and Euphrates are essential to the life of the country, but they sometimes threaten it. The rivers are at their lowest level in September and October and at flood in March, April, and May when they may carry forty times as much water as at low mark. Moreover, one season's flood may be ten or more times as great as that in another year. In 1954, for example, Baghdad was seriously threatened, and

text: dikes

text: protecting it were nearly topped by the flooding Tigris. Since Syria built a dam on the Euphrates, the flow of water has been considerably diminished and flooding was no longer a problem in the mid-1980s. In 1988 Turkey was also constructing a dam on the Euphrates that would further restrict the water flow.

text: The Tibesti Mountains are a mountain range in the central Sahara, primarily located in the extreme north of Chad, with a small extension into southern Libya. The highest peak in the range, Emi Koussi, lies to the south at a height of  and is the highest point in both Chad and the Sahara. Bikku Bitti, the highest peak in Libya, is located in the north of the range. The central third of the Tibesti is of volcanic origin and consists of five shield volcanoes topped by large craters: Emi Koussi, Tarso Toon, Tarso Voon, Tarso Yega, and Toussidé. Major lava flows have formed vast plateaus that overlie Paleozoic sandstone. The volcanic activity was the result of a continental hotspot that arose during the Oligocene and continued in some places until the Holocene, creating fumaroles, hot springs, mud pools, and deposits of natron and sulfur. Erosion has shaped volcanic spires and carved an extensive network of canyons through which run rivers subject to highly irregular flows that are rapidly lost to the desert sands.

text: The Tibesti Mountains are a

text: mountain range

text: in the central

text: Sahara

text: , primarily located in the extreme north of

text: Chad

text: , with a small extension into southern

text: Libya

text: . The highest peak in the range,

text: Emi Koussi

text: , lies to the south at a height of  and is the highest point in both Chad and the Sahara.

text: Bikku Bitti

text: , the highest peak in Libya, is located in the north of the range. The central third of the Tibesti is of volcanic origin and consists of five

text: shield volcano

text: es topped by large

text: crater

text: s: Emi Koussi, Tarso Toon,

text: Tarso Voon

text: , Tarso Yega, and

text: Toussidé

text: . Major

text: lava flow

text: s have formed vast plateaus that overlie

text: Paleozoic

text: sandstone. The volcanic activity was the result of a continental

text: hotspot

text: that arose during the

text: Oligocene

text: and continued in some places until the

text: Holocene

text: , creating

text: fumaroles

text: hot spring

text: s,

text: mud pool

text: s, and deposits of

text: natron

text: and

text: sulfur

text: Erosion

text: has shaped volcanic spires and carved an extensive network of canyons through which run rivers subject to highly irregular flows that are rapidly lost to the desert sands.

text: The rock formations are often described as "cascadas de sal" (salt waterfalls), "cascadas petrificadas" (petrified waterfalls)  and "cascadas pétreas" (rock waterfalls) . The falls are formed by relatively small amounts of water which is oversaturated with calcium carbonate and comes to the surface through cracks or figures on the mountainside. The water has a temperature of 22 to 27C. As the water runs down the rock face, it forms large stalactites similar to those found in caves. The flow of water from the spring varies significantly between the dry and rainy seasons. 95% of the surface rock formations are of calcium carbonate; however, lower layers of both rock and water currents are little known as they are sealed by the above layers. The calcium carbonate gives the formations a white or near white appearance, but other minerals that can be present in the water, such as silver, barium and iron can also be found and determines the color of a particular stalactite. The calcium carbonate in the water is due to rainwater which passes underground. First it absorbs carbon dioxide, and forms molecules of carbonic acid. This acid comes into contact with underground marble and partially dissolves creating calcium bicarbonate. When the water runs above ground, the excess minerals fall out.

text: The rock formations are often described as "cascadas de sal" (salt waterfalls), "cascadas petrificadas" (petrified waterfalls)  and "cascadas pétreas" (rock waterfalls) . The falls are formed by relatively small amounts of water which is oversaturated with calcium carbonate and comes to the surface through cracks or figures on the mountainside. The water has a temperature of 22 to 27C. As the water runs down the rock face, it forms large stalactites similar to those found in caves. The flow of water from the spring varies significantly between the dry and rainy seasons. 95% of the surface rock formations are of calcium carbonate; however, lower layers of both rock and water currents are little known as they are sealed by the above layers. The calcium carbonate gives the formations a white or near white appearance, but other minerals that can be present in the water, such as silver,

text: barium

text: and iron can also be found and determines the color of a particular stalactite. The calcium carbonate in the water is due to rainwater which passes underground. First it absorbs carbon dioxide, and forms molecules of carbonic acid. This acid comes into contact with underground marble and partially dissolves creating calcium bicarbonate. When the water runs above ground, the excess minerals fall out.

text: The formation of slopes of different gradients depends on the one hand on the type of underlying rock of the mountain or hill - and this may result in slopes varying from those on the other side of a mountain, hill or valley – and on the other hand on its local hardness, and circumstances of its deposition (sedimentation, stratigraphy, bedding or jointing), on its resistance to erosion and not least on the water flow and local climatic conditions.

text: The formation of slopes of different gradients depends on the one hand on the type of underlying

text: rock

text: of the mountain or hill - and this may result in slopes varying from those on the other side of a mountain, hill or valley – and on the other hand on its local hardness, and circumstances of its deposition (

text: sedimentation

text: , stratigraphy,

text: bedding

text: or

text: jointing

text: ), on its resistance to

text: erosion

text: and not least on the water flow and local

text: climatic conditions

text: Downcutting, also called erosional downcutting, downward erosion or vertical erosion is a geological process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream's bed or the valley's floor. The speed of downcutting depends on the stream's base level, the lowest point to which the stream can erode. Sea level is the ultimate base level, but many streams have a higher "temporary" base level because they empty into another body of water that is above sea level or encounter bedrock that resists erosion. A concurrent process called lateral erosion refers to the widening of a stream channel or valley. When a stream is high above its base level, downcutting will take place faster than lateral erosion; but as the level of the stream approaches its base level, the rate of lateral erosion increases. This is why streams in  mountainous areas tend to be narrow and swift, forming V-shaped valleys, while streams in lowland areas tend to be wide and slow-moving, with valleys that are correspondingly wide and flat-bottomed. The term gradient refers to the elevation of a stream relative to its base level. The steeper the gradient, the faster the stream flows. Sometimes geological uplift will increase the gradient of a stream even while the stream downcuts toward its base level, a process called "rejuvenation." This happened in the case of the Colorado River in the western United States, resulting in the process that created the Grand Canyon.

text: Downcutting, also called erosional downcutting, downward erosion or vertical erosion is a

text: geological

text: process by

text: hydraulic action

text: that deepens the

text: channel

text: of a

text: stream

text: or

text: valley

text: by removing material from the stream's bed or the valley's floor. The speed of downcutting depends on the stream's

text: base level

text: , the lowest point to which the stream can

text: erode

text: Sea level

text: is the ultimate base level, but many streams have a higher "temporary" base level because they empty into another body of water that is above sea level or encounter

text: bedrock

text: that resists erosion. A concurrent process called

text: lateral erosion

text: refers to the widening of a stream channel or valley. When a stream is high above its base level, downcutting will take place faster than lateral erosion; but as the level of the stream approaches its base level, the rate of lateral erosion increases. This is why streams in

text: mountain

text: ous areas tend to be narrow and swift, forming

text: V-shaped valley

text: s, while streams in

text: lowland

text: areas tend to be wide and slow-moving, with valleys that are correspondingly wide and flat-bottomed. The term

text: gradient

text: refers to the elevation of a stream relative to its base level. The steeper the gradient, the faster the stream flows. Sometimes geological

text: uplift

text: will increase the gradient of a stream even while the stream downcuts toward its base level, a process called "

text: rejuvenation

text: ." This happened in the case of the

text: Colorado River

text: in the western

text: United States

text: , resulting in the process that created the

text: Grand Canyon

text: The animals apparently fell to their deaths tens of metres below, through narrow openings in the roof of the caves known as sinkholes. The caves and sinkholes were formed by groundwater slowly dissolving and eroding the limestone forming the bed of the plain (once a shallow sea).

text: The animals apparently fell to their deaths tens of metres below, through narrow openings in the roof of the caves known as

text: sinkhole

text: s. The caves and sinkholes were formed by groundwater slowly dissolving and eroding the limestone forming the bed of the plain (once a shallow sea).

text: Directly to the left of this waterfall, another stream drops over the cliff, which is undercut to an extent that its lip has over  of empty space between it and the canyon floor, of approximately the same height in two channels, and slams onto a ledge before emptying into the same pool as the Bras de Caverne waterfall. This waterfall is not as high, and has a smaller water flow. It is fed by several other falls streaming off the cliffs above it. Further to the left, at about twice the distance from the first falls to the second, another large stream plunges into the canyon. In total, there are at least six waterfalls feeding the canyon. At the base of the canyon, a separate slot canyon, or "The Narrows", begins. The water from the Bras de Caverne waterfall and the waterfall to its left drain into the slot canyon at a 90-degree angle, through a waterfall known informally as the "Washing Machine". The name stems from the mist it generates, which drenches people who stand near the base of the falls.

text: Directly to the left of this waterfall, another stream drops over the cliff, which is undercut to an extent that its lip has over  of empty space between it and the canyon floor, of approximately the same height in two channels, and slams onto a ledge before emptying into the same pool as the Bras de Caverne waterfall. This waterfall is not as high, and has a smaller water flow. It is fed by several other falls streaming off the cliffs above it. Further to the left, at about twice the distance from the first falls to the second, another large stream plunges into the canyon. In total, there are at least six waterfalls feeding the canyon. At the base of the canyon, a separate

text: slot canyon

text: , or "The Narrows", begins. The water from the Bras de Caverne waterfall and the waterfall to its left drain into the slot canyon at a 90-degree angle, through a waterfall known informally as the "Washing Machine". The name stems from the mist it generates, which drenches people who stand near the base of the falls.

text: Alluvium on gravel (with London Clay outcrops, such as Harrow on the Hill, Hampstead Heath and the Hertfordshire border hills) is the soil profile of the north bank, west of the City of London as far as the Chiltern Hills.  As to topsoil the river marks a divide between permeable shallow gravelly topsoil for many miles to the north and almost impermeable alluvium to the south.  A very thin, agriculturally prosperous alluvial belt by the River Thames  to  away was caused by deposition from seasonal floods. This prevents for 6 miles the rivers joining despite their proximity.  As the gravel former terraces of the Thames slope from north to south lowering the water table as far as the more clay-rich parts of the north, the Ash collects almost all its water from the Colne having no springs of its own, and having a bed largely divorcing it from the rise and fall of the Thames Basin's water table.  Water quality is good despite the effluent treatment works along the Colne and for a slow-flowing river eutrophication and depostion is moderate to low.

text: Alluvium on gravel (with

text: London Clay

text: outcrops, such as

text: Harrow on the Hill

text: Hampstead Heath

text: and the Hertfordshire border hills) is the soil profile of the north bank, west of the

text: City of London

text: as far as the

text: Chiltern Hills

text: .  As to topsoil the river marks a divide between permeable shallow gravelly topsoil for many miles to the north and almost impermeable

text: alluvium

text: to the south.  A very thin, agriculturally prosperous alluvial belt by the

text: River Thames

text: to  away was caused by deposition from seasonal floods. This prevents for 6 miles the rivers joining despite their proximity.  As the gravel former terraces of the Thames slope from north to south lowering the water table as far as the more clay-rich parts of the north, the Ash collects almost all its water from the Colne having no

text: springs

text: of its own, and having a bed largely divorcing it from the rise and fall of the

text: Thames Basin

text: 's

text: water table

text: .  Water quality is good despite the effluent treatment works along the Colne and for a slow-flowing river

text: eutrophication

text: and

text: depostion

text: is moderate to low.

text: When the Cleurie river valley was blocked by Würmian moraine in a double vallum  thick, the waters of the Hohneck massif stopped flowing towards le Tholy and accumulated upstream of the deposit, forming the lac de Gérardmer. With no outlet to the west, the waters left the lake in the opposite direction to their historic one, via the Jamagne, which flows into the Vologne downstream of the hamlet of Kichompré.

text: When the

text: Cleurie

text: river valley was blocked by

text: Würmian

text: moraine

text: in a double

text: vallum

text: thick, the waters of the Hohneck massif stopped flowing towards

text: le Tholy

text: and accumulated upstream of the deposit, forming the

text: lac de Gérardmer

text: . With no outlet to the west, the waters left the lake in the opposite direction to their historic one, via the Jamagne, which flows into the Vologne downstream of the

text: hamlet

text: of Kichompré.

text: A company known as Tomlin Infrastructure Group is partnered with the Angelina & Neches River Authority for a water supply operation based on surface water. This is highly unusual, as surface water supply operations are typically done by the private sector.

text: A company known as

text: Tomlin Infrastructure Group

text: is partnered with the Angelina & Neches River Authority for a

text: water supply

text: operation based on

text: surface water

text: . This is highly unusual, as surface water supply operations are typically done by the private sector.

text: Initially, the extraction of ore or coal took place near the surface at outcrops of the main deposits. Excavations of seam-like deposits were carried out by digging out bowl-shaped depressions, the so-called Pütts, that miners hewed out along the course of the seam with picks and shovels. Once digging reached the water table, groundwater ran into the hole. If the quantity of water was so great that it entered the pit faster than it could be drained, the holes filled up with groundwater. To make matters worse, the ingress of water and the consequent softening of the soil reduced the stability of the side walls. For this reason, the pit was simply abandoned in such cases and a new one dug some distance away. Over the years, these hollows became Pingen. In the southern Ruhr, there are numerous such Pingen caused by surface mining. Subsequent erosion and collapse has produced funnel-shaped hollows, the Pingen. Where Pingen have resulted from surface mining, small ring-shaped tips were often made by dumping the waste rock.

text: Initially, the

text: extraction

text: of

text: ore

text: or

text: coal

text: took place near the surface at

text: outcrop

text: s of the main deposits. Excavations of seam-like deposits were carried out by digging out bowl-shaped depressions, the so-called

text: Pütt

text: s, that

text: miner

text: s hewed out along the course of the seam with picks and shovels. Once digging reached the

text: water table

text: groundwater

text: ran into the hole. If the quantity of water was so great that it entered the pit faster than it could be drained, the holes filled up with groundwater. To make matters worse, the ingress of water and the consequent softening of the soil reduced the stability of the side walls. For this reason, the pit was simply abandoned in such cases and a new one dug some distance away. Over the years, these hollows became Pingen. In the southern

text: Ruhr

text: , there are numerous such Pingen caused by surface mining. Subsequent erosion and collapse has produced funnel-shaped hollows, the Pingen. Where Pingen have resulted from surface mining, small ring-shaped tips were often made by dumping the waste rock.

text: Although the cave has been open to the environment for many tens of thousands of years, as evidenced by numerous prehistoric animal finds discovered there, known human contact with the cave began only in the early 20th century, when a small farm animal became trapped in the small external opening of the cave, known as a sinkhole.  The cave went largely unnoticed again until the 1920s during the era of Prohibition when a small moonshine distillery was installed in the uppermost cavern.  It again fell into obscurity until three local farm children rediscovered the sinkhole in 1935. These children are believed to be the first who actually entered the main chambers of the cave.

text: Although the cave has been open to the environment for many tens of thousands of years, as evidenced by numerous

text: prehistoric

text: animal finds discovered there, known human contact with the cave began only in the early 20th century, when a small farm animal became trapped in the small external opening of the cave, known as a

text: sinkhole

text: .  The cave went largely unnoticed again until the 1920s during the era of

text: Prohibition

text: when a small moonshine distillery was installed in the uppermost cavern.  It again fell into obscurity until three local farm children rediscovered the sinkhole in 1935. These children are believed to be the first who actually entered the main chambers of the cave.

text: Peat "hags" are a form of erosion that occurs at the sides of gullies that cut into the peat or, sometimes, in isolation. Hags may result when flowing water cuts downwards into the peat or when fire or overgrazing exposes the peat surface. Once the peat is exposed in these ways, it is prone to further erosion by wind, water and livestock. The result is overhanging vegetation and peat. Hags are too steep and unstable for vegetation to establish and so they continue to erode unless restoration action is taken.

text: It is located on the southern edge of an area of basalt which runs across Syria and eastern Jordan and is an attempt to harness the major water resources of Wadi Rajil: a dry river bed which floods irregularly during the winter months. Wadi Rajil has a catchment area of 300 km reaching 35 km north into Jebel Druze. The basalt allows very little water to soak into the ground. Any rainfall in the mountains results in violent short lived flash floods. The total annual flow down the wadi at Jawa is estimated to be 2,000,000 m per year arriving in a few dramatic winter floods with flows of 80–110 m/s. Research suggests that the community at Jawa could survive on 3% of that total flow: if they could store it in sufficient quantities to last through the four dry summer months. It would have to support their population of 2,000 to 5,000 as well as their large herds of sheep, goats and some cattle. Estimates based on bone counts indicate there may have been as many as 10,000 sheep and goats as well as 800 cattle. There were also 200 equids and 160 dogs. From seed remains it is apparent that some of the water was also used for irrigation agriculture. The inhabitants ate barley, wheat, chickpeas, lentils and grapes.

text: It is located on the southern edge of an area of

text: basalt

text: which runs across

text: Syria

text: and

text: eastern Jordan

text: and is an attempt to harness the major water resources of Wadi Rajil: a dry river bed which floods irregularly during the winter months. Wadi Rajil has a catchment area of 300 km reaching 35 km north into

text: Jebel Druze

text: . The basalt allows very little water to soak into the ground. Any rainfall in the mountains results in violent short lived flash floods. The total annual flow down the wadi at Jawa is estimated to be 2,000,000 m per year arriving in a few dramatic winter floods with flows of 80–110 m/s. Research suggests that the community at Jawa could survive on 3% of that total flow: if they could store it in sufficient quantities to last through the four dry summer months. It would have to support their population of 2,000 to 5,000 as well as their large herds of sheep, goats and some cattle. Estimates based on bone counts indicate there may have been as many as 10,000 sheep and goats as well as 800 cattle. There were also 200

text: equids

text: and 160 dogs. From seed remains it is apparent that some of the water was also used for irrigation agriculture. The inhabitants ate barley, wheat, chickpeas, lentils and grapes.

text: Surface runoff (also known as overland flow) is the flow of water that occurs when excess stormwater, meltwater, or other sources flows over the Earth's surface. This might occur because soil is saturated to full capacity, because rain arrives more quickly than soil can absorb it, or because impervious areas (roofs and pavement) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the water cycle. It is the primary agent in soil erosion by water.

text: Surface runoff (also known as overland flow) is the flow of

text: water

text: that occurs when excess

text: stormwater

text: meltwater

text: , or other sources flows over the

text: Earth's surface

text: . This might occur because

text: soil

text: is

text: saturated

text: to full capacity, because rain arrives

text: more quickly than soil can absorb

text: it, or because

text: impervious

text: areas (

text: roof

text: s and

text: pavement

text: ) send their runoff to surrounding soil that cannot absorb all of it. Surface runoff is a major component of the

text: water cycle

text: . It is the primary agent in

text: soil erosion by water

text: Liquid water is known to be present on Earth, covering 71% of its surface. Scientists believe liquid water is present in the Saturnian moons of Enceladus, as a 10-kilometre thick ocean approximately 30–40 kilometres below Enceladus' south polar surface, and Titan, as a subsurface layer, possibly mixed with ammonia. Jupiter's moon Europa has surface characteristics which suggest a subsurface liquid water ocean. Liquid water may also exist on Jupiter's moon Ganymede as a layer sandwiched between high pressure ice and rock.

text: Liquid water is known to be present on Earth, covering 71% of its surface. Scientists believe liquid water is present in the Saturnian moons of

text: Enceladus

text: , as a 10-kilometre thick ocean approximately 30–40 kilometres below Enceladus' south polar surface, and

text: Titan

text: , as a subsurface layer, possibly mixed with

text: ammonia

text: . Jupiter's moon

text: Europa

text: has surface characteristics which suggest a subsurface liquid water ocean. Liquid water may also exist on Jupiter's moon

text: Ganymede

text: as a layer sandwiched between high pressure ice and rock.

text: Whereas a sinkhole is a depression (doline) of surface topography with a pit or cavity directly underneath, a ponor is kind of a portal where a surface stream or lake flows either partially or completely underground into a karst groundwater system. Steady water erosion may have formed or enlarged the portal in (mainly limestone) rock, in a conglomerate, or in looser materials.

text: Whereas a

text: sinkhole

text: is a depression (

text: doline

text: ) of surface topography with a pit or cavity directly underneath, a ponor is kind of a portal where a surface stream or lake flows either partially or completely underground into a karst

text: groundwater

text: system. Steady water erosion may have formed or enlarged the portal in (mainly

text: limestone

text: ) rock, in a

text: conglomerate

text: , or in looser materials.

text: Riffles are instrumental in the formation of meanders, with deeper pools forming alternately.  Although simple fluid flow suggests slower flow in deeper water and faster flow over riffles, the true flow pattern pool and riffle waters is often helicoidal flow or turbulent, which permits more rapid erosion of the wetted perimeter.  Nevertheless, the coarse-grained bedding of riffles suggests erosion of smaller particles, according to the Hjulström curve.Riffles are typically found in the middle course of rivers, and are theoretically found at intervals around 6 times the width of the river, although local conditions cause this to vary.

text: Riffles are instrumental in the formation of

text: meander

text: s, with deeper pools forming alternately.  Although simple fluid flow suggests slower flow in deeper water and faster flow over riffles, the true flow pattern pool and riffle waters is often

text: helicoidal flow

text: or

text: turbulent

text: , which permits more rapid

text: erosion

text: of the

text: wetted perimeter

text: .  Nevertheless, the coarse-grained bedding of riffles suggests erosion of smaller particles, according to the

text: Hjulström curve

text: .Riffles are typically found in the middle course of rivers, and are theoretically found at intervals around 6 times the width of the river, although local conditions cause this to vary.

text: Biofilm and previously deposited solids may be scoured and re-entrained during peak flow turbulence. The high pollution load in wastewater at the beginning of a runoff event occurs when increased flow rate erodes accumulated sewer sediment. Erosion of sediments in sewers can release pollutants in concentrations exceeding levels found in contributing sources. The initial highly polluting foul flush is released at the start of wet weather flow during speedy erosion of a weak layer of highly concentrated surficial sediment bed-load. When conditions favor dry-weather solids deposition, the first foul flush may contain as much as 30 percent of the annual total suspended solids discharged to a combined sewer system.  Combined sewer suspended solids concentrations of several thousand milligrams per liter (mg/L) may be observed during the first foul flush.

text: The phlogiston is essentially a big ocean of a unique element that is neither air, fire, water, or earth. The phlogiston (also known as "the Flow") is a bright, extremely combustible gas-like medium that exists between the Crystal Spheres.  A signature property of the substance is that it does not exist within the boundaries of a crystal sphere, to the degree that it cannot be brought into a crystal sphere by any known means up to and including the direct will of deities. Every crystal sphere floats in the phlogiston, very slowly bobbing up and down over time.  Travel between Crystal Spheres is facilitated by the formation of "Flow rivers" — sections of the phlogiston which have a current and greatly reduce travel time.  Travel through the "slow flow" (i.e. off the Flow rivers) is possible, but very dangerous.

text: The

text: phlogiston

text: is essentially a big ocean of a unique element that is neither air, fire, water, or earth. The phlogiston (also known as "the Flow") is a bright, extremely combustible gas-like medium that exists between the Crystal Spheres.  A signature property of the substance is that it does not exist within the boundaries of a crystal sphere, to the degree that it cannot be brought into a crystal sphere by any known means up to and including the direct will of deities. Every crystal sphere floats in the phlogiston, very slowly bobbing up and down over time.  Travel between Crystal Spheres is facilitated by the formation of "Flow rivers" — sections of the phlogiston which have a

text: current

text: and greatly reduce travel time.  Travel through the "slow flow" (i.e. off the Flow rivers) is possible, but very dangerous.

text: The Guatemala City holes are instead an example of "piping pseudokarst", created by the collapse of large cavities that had developed in the weak, crumbly Quaternary volcanic deposits underlying the city. Although weak and crumbly, these volcanic deposits have enough cohesion to allow them to stand in vertical faces and to develop large subterranean voids within them. A process called "soil piping" first created large underground voids, as water from leaking water mains flowed through these volcanic deposits and mechanically washed fine volcanic materials out of them, then progressively eroded and removed coarser materials. Eventually, these underground voids became large enough that their roofs collapsed to create large holes.

text: The Guatemala City holes are instead an example of "piping pseudokarst", created by the collapse of large cavities that had developed in the weak, crumbly

text: Quaternary

text: volcanic deposits underlying the city. Although weak and crumbly, these volcanic deposits have enough cohesion to allow them to stand in vertical faces and to develop large subterranean voids within them. A process called "

text: soil piping

text: " first created large underground voids, as water from leaking

text: water main

text: s flowed through these volcanic deposits and mechanically washed fine volcanic materials out of them, then progressively eroded and removed coarser materials. Eventually, these underground voids became large enough that their roofs collapsed to create large holes.

text: Yazoo NWR's primary feature is a 4,000+ acre (16 km) oxbow lake named Swan Lake which formed thousands of years ago when the Mississippi River abandoned a segment of riverbed. In years past, Silver Lake Bayou flowed into the oxbow lake, accelerating the deposit of silt and sediment on the lake bottom, making the lake more shallow. Recently, the Corps of Engineers constructed a new channel to divert silt-laden waters around Swan Lake. Weirs and water control structures maintain water levels in the oxbow lake while the new channel diverts silt-laden flows around the north side of Swan Lake and into Steele Bayou. The Corps project successfully prevents the accelerated build-up of sediment that has reduced water depths in Swan Lake.

text: Yazoo NWR's primary feature is a 4,000+ acre (16 km)

text: oxbow lake

text: named Swan Lake which formed thousands of years ago when the Mississippi River abandoned a segment of riverbed. In years past, Silver Lake Bayou flowed into the oxbow lake, accelerating the deposit of

text: silt

text: and sediment on the lake bottom, making the lake more shallow. Recently, the

text: Corps of Engineers

text: constructed a new

text: channel

text: to divert silt-laden waters around Swan Lake. Weirs and water control structures maintain water levels in the oxbow lake while the new channel diverts silt-laden flows around the north side of Swan Lake and into Steele Bayou. The Corps project successfully prevents the accelerated build-up of sediment that has reduced water depths in Swan Lake.

text: A blue hole is a water-filled sinkhole with the entrance below the water level. They can be formed in different karst processes, for example, by rainwater soaking through fractures of limestone bedrock onto the watertable. Sea level here has changed: for example, during the glacial age during the Pleistocene epoch (ice age), some 15,000 years ago, sea level was considerably lower.

text: A

text: blue hole

text: is a water-filled

text: sinkhole

text: with the entrance below the water level. They can be formed in different

text: karst

text: processes, for example, by rainwater soaking through fractures of limestone bedrock onto the watertable. Sea level here has changed: for example, during the glacial age during the

text: Pleistocene

text: epoch (

text: ice age

text: ), some 15,000 years ago, sea level was considerably lower.

text: Concrete exposed to seawater is susceptible to its corrosive effects. The effects are more pronounced above the tidal zone than where the concrete is permanently submerged. In the submerged zone, magnesium and hydrogen carbonate ions precipitate a layer of brucite, about 30 micrometers thick, on which a slower deposition of calcium carbonate as aragonite occurs. These layers somewhat protect the concrete from other processes, which include attack by magnesium, chloride and sulfate ions and carbonatation. Above the water surface, mechanical damage may occur by erosion by waves themselves or sand and gravel they carry, and by crystallization of salts from water soaking into the concrete pores and then drying up. Pozzolanic cements and cements using more than 60% of slag as aggregate are more resistant to sea water than pure Portland cement. Sea water corrosion contains elements of both chloride and sulfate corrosion.

text: Concrete exposed to

text: seawater

text: is susceptible to its corrosive effects. The effects are more pronounced above the tidal zone than where the concrete is permanently submerged. In the submerged zone, magnesium and

text: hydrogen carbonate

text: ions precipitate a layer of

text: brucite

text: , about 30 micrometers thick, on which a slower deposition of calcium carbonate as

text: aragonite

text: occurs. These layers somewhat protect the concrete from other processes, which include attack by magnesium, chloride and sulfate ions and carbonatation. Above the water surface, mechanical damage may occur by

text: erosion

text: by waves themselves or sand and gravel they carry, and by crystallization of salts from water soaking into the concrete pores and then drying up.

text: Pozzolan

text: ic cements and cements using more than 60% of slag as aggregate are more resistant to sea water than pure Portland cement. Sea water corrosion contains elements of both chloride and sulfate corrosion.

text: Particle size is a notion introduced for comparing dimensions of solid particles (flecks), liquid particles (droplets), or gaseous particles (bubbles). The notion of particle size applies tocolloidal particles, particles in ecology, particles present in granular material (whether airborne or not), and particles that form a granular material (see also grain size).

text: Particle size is a

text: notion

text: introduced for comparing

text: dimension

text: s of

text: solid

text: particles (flecks),

text: liquid

text: particles (droplets), or

text: gas

text: eous particles (bubbles). The notion of particle size applies to

text: colloidal particle

text: s,

text: particles

text: in ecology, particles present in

text: granular material

text: (whether

text: airborne

text: or not), and particles that form a

text: granular material

text: (see also

text: grain size

text: The female spawns clear marble-like eggs on the surface of the water, which is deposited as a mosaic structure. The egg mass is round or squarish, with 10 to 150 eggs deposited as clusters in each mass. The female deposits over 800 tiny eggs that hatch within 1.5 to 3.0 days.

text: The required space for hotels, flats and secondary residences has increased the amount of space occupied by roads and buildings. While a large amount of people requires special water, sewage and electricity systems, a great deal of construction work is needed. Access roads and the treatment of salt are responsible for high amounts of erosion at ski resorts. In some cases natural lakes must be tapped or reservoirs built to cater for the population demand.  The urbanization of mountainous areas have increased the space of impervious surface, and prevents the natural flow of water into the ground. Resulting in a disturbed water table and potential cause of erosion in undesired places. Lastly, when building ski lifts, its line of operation must be shaped and drained, and large concrete blocks must be set down for pylons. If the pylons are not carefully placed, it could cause damage to surface vegetation.

text: The required space for hotels, flats and secondary residences has increased the amount of space occupied by roads and buildings. While a large amount of people requires special water, sewage and electricity systems, a great deal of construction work is needed. Access roads and the treatment of salt are responsible for high amounts of

text: erosion

text: at ski resorts. In some cases natural lakes must be tapped or reservoirs built to cater for the population demand.  The

text: urbanization

text: of mountainous areas have increased the space of

text: impervious surface

text: , and prevents the natural flow of water into the ground. Resulting in a disturbed

text: water table

text: and potential cause of erosion in undesired places. Lastly, when building

text: ski lifts

text: , its line of operation must be shaped and drained, and large concrete blocks must be set down for pylons. If the

text: pylons

text: are not carefully placed, it could cause damage to surface vegetation.

text: St Dunstan's Well Catchment is an important and well-known cave system which includes a series of spectacularly-decorated caves which in total extend to about  of mapped passage. The caves at Fairy Cave Quarry were formed mainly by the erosive action ofwater flowing beneath the water-table at considerable pressure (so called 'phreatic' development), but as the water table has fallen many of the caves now lie well above it and the system now contains a variety of cave formations (stalagmites, stalactites and calcite curtains) which in their extent and preservation are amongst the best in Britain. Shatter Cave and Withyhill Cave are generally considered to be amongst the finest decorated caves in Britain in terms of their sheer abundance of pure white and translucent calcite deposits.

text: St Dunstan's Well Catchment is an important and well-known cave system which includes a series of spectacularly-decorated caves which in total extend to about  of mapped passage. The caves at

text: Fairy Cave Quarry

text: were formed mainly by the erosive action ofwater flowing beneath the water-table at considerable pressure (so called '

text: phreatic

text: ' development), but as the water table has fallen many of the caves now lie well above it and the system now contains a variety of cave formations (

text: stalagmite

text: s,

text: stalactites

text: and

text: calcite

text: curtains) which in their extent and preservation are amongst the best in Britain.

text: Shatter Cave

text: and

text: Withyhill Cave

text: are generally considered to be amongst the finest decorated caves in Britain in terms of their sheer abundance of pure white and translucent calcite deposits.

text: Deposition consists of transport to the surface and subsequent attachment. Deposit removal is either through deposit dissolution, particle re-entrainment, or deposit spalling, erosive wear, or exfoliation. Fouling results from foulant generation, foulant deposition, deposit removal, and deposit consolidation.

text: Deposition

text: consists of transport to the surface and subsequent attachment. Deposit removal is either through deposit dissolution, particle re-entrainment, or deposit spalling, erosive wear, or exfoliation. Fouling results from foulant generation, foulant deposition, deposit removal, and deposit consolidation.

text: Carlsbad Caverns National Park is situated in a bed of limestone above groundwater level. During cavern development, it was within the groundwater zone.   Deep below the limestones are petroleum reserves (part of the Mid-Continent Oil Field). At a time near the end of the Cenozoic, hydrogen sulfide (HS) began to seep upwards from the petroleum into the groundwater. The combination of hydrogen sulfide and oxygen from the water formed sulfuric acid: HS + 2O → HSO. The sulfuric acid then continued upward, aggressively dissolving the limestone deposits to form caverns. The presence of gypsum within the cave is a confirmation of the occurrence of this process, as it is a byproduct of the reaction between sulfuric acid and limestone.

text: Carlsbad Caverns National Park is situated in a bed of

text: limestone

text: above groundwater level. During cavern development, it was within the groundwater zone.   Deep below the limestones are

text: petroleum

text: reserves (part of the

text: Mid-Continent Oil Field

text: ). At a time near the end of the Cenozoic,

text: hydrogen sulfide

text: (HS) began to seep upwards from the petroleum into the groundwater. The combination of hydrogen sulfide and oxygen from the water formed

text: sulfuric acid

text: : HS + 2O → HSO. The sulfuric acid then continued upward, aggressively dissolving the limestone deposits to form caverns. The presence of

text: gypsum

text: within the cave is a confirmation of the occurrence of this process, as it is a byproduct of the reaction between sulfuric acid and limestone.

text: The Africa Resources Working Group (ARWG), a collaborative of eight consultants from around the world, conducted an independent environmental impact statement of their own for the Gibe III dam. The alternative impact statement was performed because of the alleged corruption and inaccuracy of the official impact assessment. The ARWG criticizes many of the statements made in the official Gibe III ESIA. Regarding the flow of water into Lake Turkana, they state that the Gibe III dam will result in a 57-60% decrease of river flow volume. The ARWG also notes that it is not necessarily the volume of water that is important to the Omo River and Turkana ecosystems, but that the seasonality and timing of the water flow is crucial, because certain biota are adapted to feeding, reproducing, growing, etc. in response to seasonal changes in water flow. Artificially releasing water from the Gibe III dam into the Omo River will not be sufficient to meet the needs of these biota. Additionally, the ARWG states that there is "no precedent of successful and sustained implementation" of an artificial flood simulation program in sub-Saharan Africa, so it is not guaranteed that such a program will be maintained at the Gibe III dam.

text: There also appears to be discrete time periods in which porphyry deposit formation appears to be concentrated or preferred. For copper-molybdenum porphyry deposits, formation is broadly concentrated in three time periods: Palaeocene-Eocene, Eocene-Oligocene, and middle Miocene-Pliocene. For both porphyry and epithermal gold deposits, they are generally from the time period ranging from the middle Miocene to the Recent period., however notable exceptions are known. Most large-scale porphyry deposits have an age of less than 20 million years., however there are notable exceptions, such as the 438 million year old Cadia-Ridgeway deposit in New South Wales. This relatively young age reflects the preservation potential of this type of deposit; as they are typically located in zones of highly active tectonic and geological processes, such as: deformation, uplift, and erosion. It may be however, that the skewed distribution towards most deposits being less than 20 million years is at least partially an artifact of exploration methodology and model assumptions, as large examples are known in areas which were previously left only partially or under-explored partly due to their perceived older host rock ages, but which were then later found to contain large, world class examples of much older porphyry copper deposits.

text: There also appears to be discrete time periods in which porphyry deposit formation appears to be concentrated or preferred. For copper-molybdenum porphyry deposits, formation is broadly concentrated in three time periods:

text: Palaeocene

text: Eocene

text: , Eocene-

text: Oligocene

text: , and middle

text: Miocene

text: Pliocene

text: . For both porphyry and

text: epithermal

text: gold deposits, they are generally from the time period ranging from the middle Miocene to the

text: Recent

text: period., however notable exceptions are known. Most large-scale porphyry deposits have an age of less than 20 million years., however there are notable exceptions, such as the 438 million year old Cadia-Ridgeway deposit in New South Wales. This relatively young age reflects the preservation potential of this type of deposit; as they are typically located in zones of highly active tectonic and geological processes, such as: deformation, uplift, and erosion. It may be however, that the skewed distribution towards most deposits being less than 20 million years is at least partially an artifact of exploration methodology and model assumptions, as large examples are known in areas which were previously left only partially or under-explored partly due to their perceived older host rock ages, but which were then later found to contain large, world class examples of much older porphyry copper deposits.

text: Surface water is water on the surface of the planet such as  in a river, lake, wetland, or ocean. It can be contrasted with groundwater and atmospheric water.

text: Surface water is

text: water

text: on the surface of the planet such as  in a

text: river

text: lake

text: wetland

text: , or

text: ocean

text: . It can be contrasted with

text: groundwater

text: and

text: atmospheric water

text: The Pannonian Basin took shape through Miocenian thinning and subsidence of crust structures formed during Late Paleozoic Variscan orogeny. The Paleozoic and Mesozoic structures are visible in Papuk and other Slavonian mountains. The processes also led to formation of a stratovolcanic chain in the basin 17 – 12 Mya and intensified subsidence observed until 5 Mya as well as flood basalts about 7.5 Mya. Contemporary uplift of the Carpathian Mountains severed water flow to the Black Sea and Pannonian Sea formed in the basin. Sediment were transported to the basin from uplifting Carpathian and Dinaric mountains, with particularly deep fluvial sediments being deposited in the Pleistocene during uplift of the Transdanubian Mountains. Ultimately, up to  of the sediment was deposited in the basin, and the sea eventually drained through the Iron Gate gorge.

text: The

text: Pannonian Basin

text: took shape through

text: Miocenian

text: thinning and

text: subsidence

text: of crust structures formed during Late

text: Paleozoic

text: Variscan orogeny

text: . The Paleozoic and

text: Mesozoic

text: structures are visible in

text: Papuk

text: and other Slavonian mountains. The processes also led to formation of a

text: stratovolcanic

text: chain in the basin 17 – 12

text: Mya

text: and intensified subsidence observed until 5 Mya as well as

text: flood basalt

text: s about 7.5 Mya. Contemporary uplift of the

text: Carpathian Mountains

text: severed water flow to the

text: Black Sea

text: and

text: Pannonian Sea

text: formed in the basin. Sediment were transported to the basin from uplifting Carpathian and Dinaric mountains, with particularly deep fluvial sediments being deposited in the

text: Pleistocene

text: during uplift of the

text: Transdanubian Mountains

text: . Ultimately, up to  of the sediment was deposited in the basin, and the sea eventually drained through the

text: Iron Gate

text: gorge.

text: During times of rain, some of the water is retained in ponds or soil, some is absorbed by grass and vegetation, some evaporates, and the rest travels over the land as surface runoff. Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannot absorb all the water. Water then runs off the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes, and man-made reservoirs. About 30 percent of all precipitation becomes runoff and that amount might be increased by water from melting snow.  River flooding is often caused by heavy rain, sometimes increased by melting snow. A flood that rises rapidly, with little or no warning, is called a flash flood. Flash floods usually result from intense rainfall over a relatively small area, or if the area was already saturated from previous precipitation.

text: During times of rain, some of the water is retained in ponds or soil, some is absorbed by grass and vegetation, some evaporates, and the rest travels over the land as

text: surface runoff

text: . Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannot absorb all the water. Water then runs off the land in quantities that cannot be carried within

text: stream channel

text: s or retained in natural ponds, lakes, and man-made reservoirs. About 30 percent of all precipitation becomes runoff and that amount might be increased by water from melting snow.  River flooding is often caused by heavy rain, sometimes increased by melting snow. A flood that rises rapidly, with little or no warning, is called a flash flood.

text: Flash flood

text: s usually result from intense rainfall over a relatively small area, or if the area was already saturated from previous precipitation.

text: Rapids are hydrological features between a run (a smoothly flowing part of a stream) and a cascade. Rapids are characterised by the river becoming shallower with some rocks exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white colour, forming what is called "whitewater". Rapids occur where the bed material is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length. Rapids cause water aeration of the stream or river resulting in better water quality.

text: Rapids are

text: hydrological

text: features between a run (a smoothly flowing part of a

text: stream

text: ) and a

text: cascade

text: . Rapids are characterised by the river becoming shallower with some

text: rock

text: s exposed above the flow surface. As flowing water splashes over and around the rocks, air bubbles become mixed in with it and portions of the surface acquire a white colour, forming what is called "

text: whitewater

text: ". Rapids occur where the

text: bed material

text: is highly resistant to the erosive power of the stream in comparison with the bed downstream of the rapids. Very young streams flowing across solid rock may be rapids for much of their length. Rapids cause

text: water aeration

text: of the stream or river resulting in better water quality.

text: La Siberia is a land of varying terrain. The foothills of the Montes de Toledo dominate the north, and the flatter Sierra Morena runs through the south. Two major rivers flow through the region, creating vast peneplains in the less mountainous areas. Poor soil as a result of erosion in the peneplains makes the region poorly suited for agriculture, so most of the population relies on livestock as their principal economic activity. The Guadiana River flows the entire length of the comarca from northeast to southwest, going on to form most of the southern portion of the border between Spain and Portugal. The region's inhabitants have created several reservoirs along the Guadiana, providing locals with ample water resources. The largest of the reservoirs are the Cijara, the García de Sola, and the Orellana. Also, in the southern portion of La Siberia flows the Zujar River, which contains two large reservoirs -  the Zujar and the La Serena, the latter being the largest in Spain and the second largest in Europe. The combined maximum capacity of these five reservoirs is approximately 6.395×10 m (2.258×10 cu ft), or about 12% of Spain's water resources; La Serena alone holds 6% of the country's water. The region is well known for its abundant water resources; because of all the reservoirs, La Siberia contains the longest inland coastline of any region of Spain and also the largest amount of freshwater in the whole of the Iberian Peninsula.

text: La Siberia is a land of varying terrain. The foothills of the

text: Montes de Toledo

text: dominate the north, and the flatter

text: Sierra Morena

text: runs through the south. Two major rivers flow through the region, creating vast

text: peneplain

text: s in the less mountainous areas. Poor soil as a result of erosion in the peneplains makes the region poorly suited for agriculture, so most of the population relies on livestock as their principal economic activity. The

text: Guadiana River

text: flows the entire length of the comarca from northeast to southwest, going on to form most of the southern portion of the border between Spain and

text: Portugal

text: . The region's inhabitants have created several reservoirs along the Guadiana, providing locals with ample water resources. The largest of the reservoirs are the

text: Cijara

text: , the

text: García de Sola

text: , and the

text: Orellana

text: . Also, in the southern portion of La Siberia flows the

text: Zujar River

text: , which contains two large reservoirs -  the

text: Zujar

text: and the

text: La Serena

text: , the latter being the largest in Spain and the second largest in Europe. The combined maximum capacity of these five reservoirs is approximately 6.395×10 m (2.258×10 cu ft), or about 12% of Spain's water resources; La Serena alone holds 6% of the country's water. The region is well known for its abundant water resources; because of all the reservoirs, La Siberia contains the longest inland coastline of any region of Spain and also the largest amount of freshwater in the whole of the

text: Iberian Peninsula

text: The dominant bedrock of the Young Creek valley is black shale, which is cut by many dikes and sills of light-colored granitic rock and is capped in the high mountains on both sides of the valley by conglomerate and sandstone. There are also a few beds of limestone and many limestone concretions. Except for a small area of sandstone near the big bend the numerous bedrock exposures along the creek are shale or the intruded dikes. The gravel deposits of Young Creek are of three classes—highbench gravels, which lie well above the stream levels and form in part the canyon wall; low-bench gravels, which adjoin the creek channel within the canyon; and flood-plain gravels, over which the stream flows in times of high water. In addition to these deposits, which were transported and deposited chiefly by running water, or by water and ice, there is a thin veneer of morainal debris that is found throughout the valley, and even on the mountain tops. This deposit is made up of material that is in large part foreign to Young Creek and that has been transported a long distance, much of it from the upper Chitina Valley.

text: Flow velocity is especially critical for hard water or liquids containing suspensions in preventing excessive fouling. Higher cross-flow velocities can be used to enhance the sweeping effect across the membrane surface therefore preventing deposition of macromolecules and colloidal material and reducing the effects of concentration polarization. Expensive pumps are however required to achieve these conditions.

text: A spillway at the top of the dam is used to regulate the top portion of the dam, the spillway contains walls to maneuver the flow of the water, and a stilling basin is placed at the foot of the spillway to dissipate erosion from the spillway water hitting the base of the dam. The spillway is not used frequently because flooding can be regulated by other means, such as the flood control conduits.  Because of heavy rains during the first two weeks of May 2009, water poured over the spillway for the first time since 1968.

text: A

text: spillway

text: at the top of the dam is used to regulate the top portion of the dam, the spillway contains walls to maneuver the flow of the water, and a

text: stilling basin

text: is placed at the foot of the spillway to dissipate

text: erosion

text: from the spillway water hitting the base of the dam. The spillway is not used frequently because flooding can be regulated by other means, such as the flood control conduits.  Because of heavy rains during the first two weeks of May 2009, water poured over the spillway for the first time since 1968.

text: A narrow waterway known as the Split divides the island in two. Some people state that the Split was created by Hurricane Hattie in 1961 which devastated Belize City, however that is a myth.  Villagers who actually hand dredged it maintain that it is largely a man-made feature.  The Village Council Chairman at the time, Ramon Reyes, recounts that he and others dredged the waterway by hand after Hurricane Hattie opened a passage a few inches deep. This made a practical water way between the west and east sides of the island, intended at first for dugout canoes. The increased flow of tidal water has naturally dredged the opening to  deep until larger boats can now easily pass. The natural erosion continues to this day and threatens the soft sand banks of the waterway.

text: A narrow waterway known as the Split divides the island in two. Some people state that the Split was created by

text: Hurricane Hattie

text: in 1961 which devastated

text: Belize City

text: , however that is a myth.  Villagers who actually hand dredged it maintain that it is largely a man-made feature.  The Village Council Chairman at the time, Ramon Reyes, recounts that he and others dredged the waterway by hand after Hurricane Hattie opened a passage a few inches deep. This made a practical water way between the west and east sides of the island, intended at first for dugout canoes. The increased flow of tidal water has naturally dredged the opening to  deep until larger boats can now easily pass. The natural erosion continues to this day and threatens the soft sand banks of the waterway.

text: Washington County belongs to the following valleys and watersheds: Champlain Valley / Lake George Watershed—02010001  Hudson River Valley / Hudson-Hoosic Watershed—02020003   Waters in the northern part drain into Lake Champlain via Lake George (Horican) or the Mettawee River, and then flow into the Saint Lawrence River (Kaniatarowanenneh). These waters mingle in the Saint Lawrence with waters of all the Great Lakes as they flow northeast into the Gulf of Saint Lawrence, and ultimately join the Atlantic Ocean. Meanwhile, the remainder of waters drain south via the Hudson River (Muh-he-kun-ne-tuk or Muhheakantuck), and ultimately flow south into the Atlantic Ocean below New York City.  See the approximation of the watershed divide mapped in context of mountains  and valleys .

text: Washington County belongs to the following valleys and watersheds:

text: Champlain Valley

text: / Lake George Watershed—02010001

text: Hudson River

text: Valley / Hudson-Hoosic Watershed—02020003   Waters in the northern part drain into

text: Lake Champlain

text: via

text: Lake George

text: (Horican) or the

text: Mettawee River

text: , and then flow into the

text: Saint Lawrence River

text: (Kaniatarowanenneh). These waters mingle in the Saint Lawrence with waters of all the

text: Great Lakes

text: as they flow northeast into the

text: Gulf of Saint Lawrence

text: , and ultimately join the Atlantic Ocean. Meanwhile, the remainder of waters drain south via the

text: Hudson River

text: (Muh-he-kun-ne-tuk or Muhheakantuck), and ultimately flow south into the Atlantic Ocean below New York City.  See the approximation of the watershed divide mapped in context of mountains  and valleys .

text: In geology and geomorphology an erosion surface is a surface of rock or regolith that was formed by erosion and not by construction (e.g. lava flows, sediment deposition) nor fault displacement. Erosional surfaces within the stratigraphic record are known as unconformities, but not all unconformities are buried erosion surfaces. Erosion surfaces can be either small or large. Particularly large and flat erosion surfaces receive the names of peneplain, paleoplain, planation surface or pediplain.

text: In

text: geology

text: and

text: geomorphology

text: an erosion surface is a surface of

text: rock

text: or

text: regolith

text: that was formed by

text: erosion

text: and not by construction (e.g. lava flows, sediment deposition) nor

text: fault displacement

text: . Erosional surfaces within the

text: stratigraphic record

text: are known as

text: unconformities

text: , but not all unconformities are buried erosion surfaces. Erosion surfaces can be either small or large. Particularly large and flat erosion surfaces receive the names of

text: peneplain

text: paleoplain

text: planation surface

text: or

text: pediplain

text: The comparatively large quantities of water that flow quite quickly through a gat cause heavy erosion that results in a channel deeper than the rest of the surrounding seabed and also endangers neighbouring islands. When the water masses from mud flats behind the islands surge out again into the sea as ebb currents, they flow rapidly again through the narrow gat. But as these water masses break out into the open sea, they spread out and slow down. As a result, on this seaward side of the gat, the particles of sand and mud carried with the water settle and form an ebb delta with its shallower waters between the islands. The sandbanks so formed are often known in Germany as plate (pronounced "plah-ter", see Kachelotplate). The point where the water pouring out of the gat runs over these banks, which often lie in an arc between the islands, is the sand bar (). This is the shallowest part of the gat for shipping, but also the deepest point on the shallowest line between the islands. A flood delta is formed in a similar way on the landward side of the gat.

text: The comparatively large quantities of water that flow quite quickly through a gat cause heavy erosion that results in a channel deeper than the rest of the surrounding seabed and also endangers neighbouring islands. When the water masses from mud flats behind the islands surge out again into the sea as ebb currents, they flow rapidly again through the narrow gat. But as these water masses break out into the open sea, they spread out and slow down. As a result, on this seaward side of the gat, the particles of sand and mud carried with the water settle and form an ebb delta with its shallower waters between the islands. The

text: sandbank

text: s so formed are often known in Germany as plate (pronounced "plah-ter", see

text: Kachelotplate

text: ). The point where the water pouring out of the gat runs over these banks, which often lie in an arc between the islands, is the sand bar (). This is the shallowest part of the gat for shipping, but also the deepest point on the shallowest line between the islands. A flood delta is formed in a similar way on the landward side of the gat.

text: Since the 1950s the number of dams in the world has increased more than sevenfold.  The creation of reservoirs has significantly reduced the sediment yield of many rivers as sediment that was entrained in the flow is stopped by a manmade barrier and the energy required to transport the material is lost, the sediment is no longer entrained as there is no flow or the flow is too slow.

text: Since the 1950s the number of dams in the world has increased more than sevenfold.  The creation of

text: reservoir

text: s has significantly reduced the sediment yield of many rivers as sediment that was entrained in the flow is stopped by a manmade barrier and the energy required to transport the material is lost, the sediment is no longer entrained as there is no flow or the flow is too slow.

text: It was  thick which advanced and receded several times across the prairies. There were multiple glaciations affecting the Saskatchewan area during the Pre-Illinoian, Illinioan, and Wisconsin stages of the last Ice Age. These glaciations occurred during the Quaternary period which comprises the last two million years.  Northern Saskatchewan and the shield area shows the effects of glacial erosion and scour; the Western Canada Sedimentary Basin is a location of glacial deposition and collection. In southern Saskatchewan there are late Pliocene, pre-Illinoian continental glaciation sand and gravel deposits left behind from water deposition (alluvial) and glacial edge deposits (colluvial).  By the study of till, terrain, the limits of the Illinoian glaciation are evidenced around Willow Bunch Lake, Wood Mountain, Cypress Hills area.

text: It was  thick which advanced and receded several times across the prairies. There were multiple glaciations affecting the Saskatchewan area during the

text: Pre-Illinoian

text: Illinioan

text: , and

text: Wisconsin

text: stages of the last

text: Ice Age

text: . These glaciations occurred during the

text: Quaternary period

text: which comprises the last two million years.  Northern Saskatchewan and the shield area shows the effects of glacial erosion and scour; the Western Canada Sedimentary Basin is a location of glacial deposition and collection. In southern Saskatchewan there are late Pliocene, pre-Illinoian continental glaciation sand and gravel deposits left behind from water deposition (

text: alluvial

text: ) and glacial edge deposits (

text: colluvial

text: ).  By the study of till, terrain, the limits of the Illinoian glaciation are evidenced around Willow Bunch Lake, Wood Mountain, Cypress Hills area.

text: The particle-size distribution (PSD) of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amount, typically by mass, of particles present according to size. Significant energy is usually required to disintegrate soil, etc. particles into the PSD that is then called a grain size distribution.

text: The particle-size distribution (PSD) of a powder, or granular material, or particles dispersed in

text: fluid

text: , is a list of values or a mathematical function that defines the relative amount, typically by mass, of particles present according to size. Significant energy is usually required to disintegrate soil, etc. particles into the PSD that is then called a grain size distribution.

text: The San Luis Valley, contains an alluvial basin, the Alamosa Basin, which lies at the north end of the Rio Grande rift. Deeper alluvial strata, overlying Precambrian basement rock, Eocene alluvial deposits from a shallow Laramide depression, the Blanco Basin Formation; and Oligocene ash and lava flows associated with the Conejos Formation, is the Santa Fe formation, mixed alluvium and lava outflows from the San Juan volcanic field to the west; later strata comprise the Alamosa formation, alternating layers of sand, gravel, and clay. The relatively impermeable clay layers trap ground water in the "confined aquifer" which, if tapped, supplies artesian wells. Surface waters, including the Rio Grande and other streams, are hydrologically connected to the "unconfined aquifer" a shallow ground water formation which underlies much of the valley. The deeper confined aquifer also has sufficient hydrological connection with the surface waters of the valley that they are not considered for the purposes of Colorado water law "nontributary" waters which could legally be mined. Streams which flow into the valley, particularly the Rio Grande, have deposited alluvial fans where they emerge from higher terrain onto the valley floor.

text: The San Luis Valley, contains an

text: alluvial basin

text: , the Alamosa Basin, which lies at the north end of the

text: Rio Grande rift

text: . Deeper alluvial strata, overlying

text: Precambrian

text: basement rock,

text: Eocene

text: alluvial deposits from a shallow

text: Laramide

text: depression, the Blanco Basin Formation; and

text: Oligocene

text: ash and lava flows associated with the Conejos Formation, is the Santa Fe formation, mixed alluvium and lava outflows from the

text: San Juan volcanic field

text: to the west; later strata comprise the Alamosa formation, alternating layers of sand, gravel, and clay. The relatively impermeable clay layers trap ground water in the "confined

text: aquifer

text: " which, if tapped, supplies

text: artesian well

text: s. Surface waters, including the Rio Grande and other streams, are hydrologically connected to the "unconfined aquifer" a shallow ground water formation which underlies much of the valley. The deeper confined aquifer also has sufficient hydrological connection with the surface waters of the valley that they are not considered for the purposes of

text: Colorado water law

text: "nontributary" waters which could legally be mined. Streams which flow into the valley, particularly the Rio Grande, have deposited

text: alluvial fan

text: s where they emerge from higher terrain onto the valley floor.

text: Longdendale is a steep-sided V-shaped valley that is glacial in origin. Longdendale is in the Dark Peak, where a thick blanket of peat overlies the Millstone Grit sandstone, formed on a bed of shale through which flows the Etherow. Directly beneath the upper valley lie areas of Carboniferous Millstone Grit, shales and sandstone. It is on the edge of the Peak District Dome, at the southern edge of the Pennine anticline. The Variscan uplift has caused much faulting and Glossopdale was the product of glacial action in the last glaciation period that exploited the weakened rocks. The steep-sided valleys of the cloughs cause significant erosion and deposition. The layers of sandstone, mudstones and shale in the bedrock act as an aquifer to feed the springs. The valley bottoms have a thin deposit of boulder clay. The brooks are fed by the peaty soils of the moors and are, therefore, acidic (pH5.5–7.0).

text: Longdendale is a steep-sided V-shaped valley that is

text: glacial

text: in origin. Longdendale is in the

text: Dark Peak

text: , where a thick blanket of peat overlies the

text: Millstone Grit

text: sandstone, formed on a bed of

text: shale

text: through which flows the Etherow. Directly beneath the upper valley lie areas of

text: Carboniferous

text: Millstone Grit, shales and

text: sandstone

text: . It is on the edge of the

text: Peak District

text: Dome, at the southern edge of the Pennine

text: anticline

text: . The

text: Variscan uplift

text: has caused much

text: faulting

text: and Glossopdale was the product of

text: glacial

text: action in the last glaciation period that exploited the weakened rocks. The steep-sided valleys of the

text: clough

text: s cause significant

text: erosion

text: and

text: deposition

text: . The layers of sandstone, mudstones and shale in the bedrock act as an

text: aquifer

text: to feed the springs. The valley bottoms have a thin deposit of

text: boulder clay

text: . The brooks are fed by the peaty soils of the moors and are, therefore,

text: acid

text: ic (pH5.5–7.0).

text: Cenote water is often very clear, as the water comes from rain water filtering slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow. In many cases, cenotes are areas where sections of cave roof have collapsed revealing an underlying cave system, and the water flow rates may be much faster: up to  per day. Cenotes around the world attract cave divers who have documented extensive flooded cave systems through them, some of which have been explored for lengths of  or more.

text: Cenote water is often very clear, as the water comes from rain water filtering slowly through the ground, and therefore contains very little suspended particulate matter. The groundwater flow rate within a cenote may be very slow. In many cases, cenotes are areas where sections of cave roof have collapsed revealing an underlying cave system, and the water flow rates may be much faster: up to  per day. Cenotes around the world attract

text: cave divers

text: who have documented extensive flooded cave systems through them, some of which have been explored for lengths of  or more.

text: There are many sinkholes in the area, including the Bear Valley Sinkhole (), Gips Cave (''Gipsova jama''), Mary's Shaft (''Marijino brezno''), and Migut Shaft (''Migutovo brezno'') near the Grebenar farm. There is also a spring south of the settlement known as Blessed Spring ().

text: Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deprossosition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as the waves surge up river estuaries from the ocean.

text: Tide

text: s often determine the range over which

text: sediment

text: is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deprossosition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however,

text: tidal bore

text: s can erode as the waves surge up river

text: estuaries

text: from the ocean.

text: Streamflow, or channel runoff, is the flow of water in streams, rivers, and other channels, and is a major element of the water cycle. It is one component of the runoff of water from the land to waterbodies, the other component being surface runoff. Water flowing in channels comes from surface runoff from adjacent hillslopes, from groundwater flow out of the ground, and from water discharged from pipes. The discharge of water flowing in a channel is measured using stream gauges or can be estimated by the Manning equation. The record of flow over time is called a hydrograph. Flooding occurs when the volume of water exceeds the capacity of the channel.

text: Streamflow, or channel runoff, is the flow of

text: water

text: in

text: stream

text: s,

text: river

text: s, and other

text: channel

text: s, and is a major element of the

text: water cycle

text: . It is one component of the

text: runoff

text: of water from the land to

text: waterbodies

text: , the other component being

text: surface runoff

text: . Water flowing in channels comes from surface runoff from adjacent hillslopes, from

text: groundwater

text: flow out of the ground, and from water discharged from pipes. The

text: discharge

text: of water flowing in a channel is measured using

text: stream gauge

text: s or can be estimated by the

text: Manning equation

text: . The record of flow over time is called a

text: hydrograph

text: Flood

text: ing occurs when the volume of water exceeds the capacity of the channel.

text: The slow-flowing river system is known to flood and is considered to be heavily polluted, suffering from poor water quality. The Bremer does not receive enough water in its catchment to meet both human requirements and the need to flush out impurities. This results in poor water quality with high levels of turbidity, high nutrient levels and high levels of bacteria, especially where sewerage and drain runoff from the city of Ipswich is discharged into the river.

text: The slow-flowing river system is known to

text: flood

text: and is considered to be heavily

text: polluted

text: , suffering from poor

text: water quality

text: . The Bremer does not receive enough water in its catchment to meet both human requirements and the need to flush out impurities. This results in poor water quality with high levels of

text: turbidity

text: , high nutrient levels and high levels of

text: bacteria

text: , especially where

text: sewerage

text: and drain runoff from the city of Ipswich is discharged into the river.

text: Surface Water Rescue is defined as the rescue of a patient who is afloat on the surface of a body of water.

text: Surface Water Rescue is defined as the

text: rescue

text: of a patient who is afloat on the surface of a body of water.

text: The Florida peninsula appeared above sea level between 100,000 and 150,000 years ago. As sea levels at the end of the Wisconsin ice age rose, the water table appeared closer to land. Lake Okeechobee began to flood and convection thunderstorms were created. Vast peat deposits south of Lake Okeechobee indicate that regular flooding had occurred about 5,000 years ago. Plants began to migrate, subtropical ones from the northern part of Florida, and tropicals carried as seeds by birds from islands in the Caribbean. Although the limestone shelf appears to be flat, there are slight rises—called pinnacles—and depressions caused by the erosion of limestone by the acidic properties of the water. The amount of time throughout the year that water is present in a location in the Everglades determines the type of soil, of which there only two in the Everglades: peat, created by many years of decomposing plant matter, and marl, the result of dried periphyton, or chunks of algae and microorganisms that create a grayish mud. Portions of the Everglades that remain flooded for more than nine months out of the year are usually covered by peat. Areas that are flooded six months or less are covered by marl. Plant communities are determined by the type of soil and amount of water present.

text: The Florida peninsula appeared above sea level between 100,000 and 150,000 years ago. As sea levels at the end of the Wisconsin ice age rose, the water table appeared closer to land.

text: Lake Okeechobee

text: began to flood and convection thunderstorms were created. Vast

text: peat

text: deposits south of Lake Okeechobee indicate that regular flooding had occurred about 5,000 years ago. Plants began to migrate, subtropical ones from the northern part of Florida, and tropicals carried as seeds by birds from islands in the

text: Caribbean

text: . Although the limestone shelf appears to be flat, there are slight rises—called pinnacles—and depressions caused by the erosion of limestone by the acidic properties of the water. The amount of time throughout the year that water is present in a location in the Everglades determines the type of soil, of which there only two in the Everglades: peat, created by many years of decomposing plant matter, and

text: marl

text: , the result of dried

text: periphyton

text: , or chunks of algae and microorganisms that create a grayish mud. Portions of the Everglades that remain flooded for more than nine months out of the year are usually covered by peat. Areas that are flooded six months or less are covered by marl. Plant communities are determined by the type of soil and amount of water present.

text: It is very common in the construction of a qanat for the water source to be found below ground at the foot of a range of foothills of mountains, where the water table is closest to the surface. From this point, the slope of the qanat is maintained closer to level than the surface above, until the water finally flows out of the qanat above ground,i.e., the qanat is an underground tunnel, beginning from an underground water source, with a gentle slope made in such a way that water is pulled by gravity to the surface (which is at a lower level than that of the underground water source). To reach an aquifer, qanats must often extend for long distances.

text: It is very common in the construction of a qanat for the water source to be found below ground at the foot of a range of foothills of mountains, where the

text: water table

text: is closest to the surface. From this point, the slope of the qanat is maintained closer to level than the surface above, until the water finally flows out of the qanat above ground,i.e., the qanat is an underground tunnel, beginning from an underground water source, with a gentle slope made in such a way that water is pulled by gravity to the surface (which is at a lower level than that of the underground water source). To reach an aquifer, qanats must often extend for long distances.

text: Once the acidic groundwater drained from the caverns, speleothems began to be deposited within the cavern. Erosion above ground created the natural entrance to the Carlsbad Caverns within the last million years. Exposure to the surface has allowed for the influx of air into the cavern. Rainwater and snowmelt percolating downward into the ground pick up carbon dioxide; once this water reaches a cavern ceiling, it precipitates and evaporates, leaving behind a small calcium carbonate deposit. Growths from the roof downward formed through this process are known as stalactites. Additionally, water on the floor of the caverns can contain carbonic acid and generate mineral deposits by evaporation. Growths from the floor upward through this process are known as stalagmites. Different formations of speleothems include columns, soda straws, draperies, helictites, and popcorn. Changes in the ambient air temperature and rainfall affect the rate of growth of speleothems, as higher temperatures increase carbon dioxide production rates within the overlying soil. The color of the speleothems is determined by the trace constituents in the minerals of the formation.

text: Once the acidic groundwater drained from the caverns,

text: speleothems

text: began to be deposited within the cavern. Erosion above ground created the natural entrance to the Carlsbad Caverns within the last million years. Exposure to the surface has allowed for the influx of

text: air

text: into the cavern. Rainwater and snowmelt percolating downward into the ground pick up carbon dioxide; once this water reaches a cavern ceiling, it precipitates and evaporates, leaving behind a small

text: calcium carbonate

text: deposit. Growths from the roof downward formed through this process are known as

text: stalactites

text: . Additionally, water on the floor of the caverns can contain carbonic acid and generate mineral deposits by evaporation. Growths from the floor upward through this process are known as

text: stalagmites

text: . Different formations of speleothems include columns,

text: soda straws

text: , draperies,

text: helictites

text: , and

text: popcorn

text: . Changes in the ambient air temperature and rainfall affect the rate of growth of speleothems, as higher temperatures increase carbon dioxide production rates within the overlying soil. The color of the speleothems is determined by the trace constituents in the minerals of the formation.

text: Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are typically of the order of a few centimeters (about an inch) or less and along-channel slopes may be quite steep. This means that rills exhibit hydraulic physics very different from water flowing through the deeper, wider channels of streams and rivers.

text: Rill

text: erosion refers to the development of small,

text: ephemeral

text: concentrated flow paths which function as both sediment source and

text: sediment

text: delivery systems for erosion on hillslopes. Generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Flow depths in rills are typically of the order of a few centimeters (about an inch) or less and along-channel slopes may be quite steep. This means that rills exhibit

text: hydraulic

text: physics very different from water flowing through the deeper, wider channels of streams and rivers.

text: The natural build up of sedimentation can reduce downstream river flows due to the installation of irrigation systems. Sedimentation is an essential part of the ecosystem that requires the natural flux of the river flow. This natural cycle of sediment dispersion replenishes the nutrients in the soil, that will in turn, determine the livelihood of the plants and animals that rely on the sediments carried downstream. The benefits of heavy deposits of sedimentation can be seen in large rivers like the Nile River. The sediment from the delta has built up to form a giant aquifer during flood season, and retains water in the wetlands. The wetlands that are created and sustained due to built up sediment at the basin of the river is a habitat for numerous species of birds  However, heavy sedimentation can reduce downstream river water quality and can exacerbate floods up stream. This has been known to happen in the Sanmenxia reservoir in China. The Sanmenxia reservoir is part of a larger man-made project of hydro-electric dams called the Three Gorge Project  In 1998, uncertain calculations and heavy sediment greatly affected the reservoir’s ability to properly fulfill its flood-control function  This also reduces the down stream river water quality. Shifting more towards mass irrigation installments in order to meet more socioeconomic demands is going against the natural balance of nature, and use water pragmatically- use it where it is found

text: Streams flowing from higher impermeable slopes sink into the ground when they reach permeable limestone. During dry spells all water sinks very quickly on reaching the limestone, through sinkholes. In wetter conditions water flows a greater distance across the limestone as underground channels and chambers fill up. Large sinkholes are called 'swallowholes' or 'potholes'. Gaping Gill, Alum Pot and the Buttertubs are well-known examples.

text: Streams flowing from higher impermeable slopes sink into the ground when they reach permeable limestone. During dry spells all water sinks very quickly on reaching the limestone, through

text: sinkholes

text: . In wetter conditions water flows a greater distance across the limestone as underground channels and chambers fill up. Large sinkholes are called 'swallowholes' or 'potholes'.

text: Gaping Gill

text: , Alum Pot and the Buttertubs are well-known examples.

text: The cave in the tenth lake stretches under the waterfall with a width 9 m, 16 m length and 3 m water depth,it depends on the level of the lake. The entrance of the cave is 5 m wide and 3 m high. The karst cave is formed by the erosive forces of the water of Mirusha river.

text: The cave in the tenth lake stretches under the waterfall with a width 9 m, 16 m length and 3 m water depth,it depends on the level of the lake. The entrance of the cave is 5 m wide and 3 m high. The

text: karst

text: cave is formed by the

text: erosive

text: forces of the water of Mirusha river.

text: The Blue Nile (Ge'ez ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black Abay) to Ethiopians; ; transliterated: an-Nīl al-Azraq) springsfrom Lake Tana in the Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile originates in Ethiopia, with fifty-nine percent of the water from the Blue Nile (the rest being from the Tekezé, Atbarah, Sobat, and small tributaries). The erosion and transportation of silt only occurs during the Ethiopian rainy season in the summer, however, when rainfall is especially high on the Ethiopian Plateau; the rest of the year, the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, Tekezé, and Atbarah) have a weaker flow.

text: The

text: Blue Nile

text: Ge'ez

text: ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black

text: Abay

text: ) to

text: Ethiopia

text: ns; ;

text: transliterated

text: : an-Nīl al-Azraq) springsfrom

text: Lake Tana

text: in the Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile originates in Ethiopia, with fifty-nine percent of the water from the Blue Nile (the rest being from the

text: Tekezé

text: , Atbarah,

text: Sobat

text: , and small tributaries). The erosion and transportation of silt only occurs during the Ethiopian rainy season in the summer, however, when rainfall is especially high on the

text: Ethiopian Plateau

text: ; the rest of the year, the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, Tekezé, and Atbarah) have a weaker flow.

text: The river lazily winds back and forth with a slow flowage.  In its upper reaches it flows through the Cylon Marsh State Wildlife Area.  It passes south of Deer Park by about one mile.  It then passes through New Richmond, Boardman, and Burkhardt. Near Burkhardt it enters Willow River State Park.

text: The river lazily winds back and forth with a slow flowage.  In its upper reaches it flows through the

text: Cylon

text: Marsh State Wildlife Area.  It passes south of

text: Deer Park

text: by about one mile.  It then passes through

text: New Richmond

text: Boardman

text: , and

text: Burkhardt

text: . Near Burkhardt it enters

text: Willow River State Park

text: As all dams result in reduced sediment load downstream, a dammed river is said to be "hungry" for sediment. Because the rate of deposition of sediment is greatly reduced since there is less to deposit but the rate of erosion remains nearly constant, the water flow erodes the river shores and riverbed, threatening shoreline ecosystems, deepening the riverbed, and narrowing the river over time. This leads to a compromised water table, reduced water levels, homogenization of the river flow and thus reduced ecosystem variability, reduced support for wildlife, and reduced amount of sediment reaching coastal plains and deltas. This prompts coastal erosion, as beaches are unable to replenish what waves erode without the sediment deposition of supporting river systems. Downsteam channel erosion of dammed rivers is related to the morphology of the riverbed, which is different from directly studying the amounts of sedimentation because it is subject to specific long term conditions for each river system. For example, the eroded channel could create a lower water table level in the affected area, impacting bottomland crops such as alfalfa or corn, and resulting in a smaller supply.In the case of the Three Gorges Dam in China the changes described above now appears to have arrived at a new balance of erosion and sedimentation over a 10-year period in the lower reaches of the river. The impacts on the tidal region have also been linked to the upstream effects of the dam.

text: As all dams result in reduced sediment load downstream, a dammed river is said to be "hungry" for sediment. Because the rate of deposition of sediment is greatly reduced since there is less to deposit but the rate of erosion remains nearly constant, the water flow erodes the river shores and riverbed, threatening shoreline ecosystems, deepening the riverbed, and narrowing the river over time. This leads to a compromised water table, reduced water levels, homogenization of the river flow and thus reduced ecosystem variability, reduced support for wildlife, and reduced amount of sediment reaching coastal plains and deltas. This prompts coastal erosion, as beaches are unable to replenish what waves erode without the sediment deposition of supporting river systems. Downsteam channel erosion of dammed rivers is related to the morphology of the riverbed, which is different from directly studying the amounts of sedimentation because it is subject to specific long term conditions for each river system. For example, the eroded channel could create a lower water table level in the affected area, impacting bottomland crops such as

text: alfalfa

text: or

text: corn

text: , and resulting in a smaller supply.In the case of the Three Gorges Dam in China the changes described above now appears to have arrived at a new balance of erosion and sedimentation over a 10-year period in the lower reaches of the river. The impacts on the tidal region have also been linked to the upstream effects of the dam.

text: Volcanoes were active during the retreating phase of the ice age. Some geologists postulate that Lake Todos los Santos and Llanquihue were just one lake in which the Osorno volcano built up until the two water bodies were separated. From then on, lake Todos los Santos had its surface level lifted as successive lava flows from the Osorno blocked the outlet of the lake. At the Petrohue waterfalls, one sees the river flow over such a constraining andesite lava flow. The steep left bank of the river is granodiorite. These volcanoes expel large quantities of loose cinder that in depositing give the rounded conic shape. These cinders are easily washed away by rain and surface water flow, so that the Puntiagudo, an elder brother of the Osorno, is denuded to the hard core of lava frozen inside the volcanic chimney.

text: PBRs are not known on Earth. Montgomery has said that there could be landforms on Earth that are somewhat similar to PBRs, but to date there's nothing exactly like it, largely because there are not many bedrock landscapes on Earth in which wind is the main erosion agent. "There are very few places ... where you have bedrock exposed at the surface where there isn't also water that is carving valleys, that's shaping the topography. Mars is a different planet, obviously, and the biggest difference is the lack of fluvial action, the lack of water working on the surface."

text: With lower river levels in mid-summer, algal blooms have contributed to making slow-flowing areas anoxic. The algal blooms have been attributed as the cause of death of a small number of dogs swimming in the river, as well as of skin reactions in the case of swimmers.

text: With lower river levels in mid-summer,

text: algal bloom

text: s have contributed to making slow-flowing areas anoxic. The algal blooms have been attributed as the cause of death of a small number of dogs swimming in the river, as well as of skin reactions in the case of swimmers.

text: The Goyden system floods as a result of excess water overflowing the Scar House dam. This can happen not only following significant rainfall but also by wind action from a westerly or near westerly direction. The wind on a full or nearly full reservoir whips up waves on Scar House Reservoir sending water over the dam that on occasions has pushed down the valley more than one metre depth of water from the reservoir. The caves can therefore flood in a period of no rain but by wind action alone. The water flowing down the valley is typically greater than the capacity of the fissures taking water into Manchester Hole. So most of the water flows past the Manchester Hole and onwards to Goyden Pot Main entrance. At various times old abandoned inlets are re-opened and re-closed by the flood waters allowing water to enter the far reaches of Manchester Hole and Lesser Stream passage of Goyden Pot. The increased flow into Manchester Hole and a pooling effect by the constricted sump 2, with possibly reopened inlets, causes the far end (between the ‘grovel’ and the ‘duck’) of Manchester cave to flood, at times very quickly. Water flowing into Goyden Pot Main entrance falls into the Main Chamber from high level passages from the first and then second and eventually the third window. This water joins the river flowing from Manchester Hole over the cascades and along the Main Stream passage. The swollen river flows through to sump 7 which due to its constricted nature causes the water to back up and flood the system from there all the way back. The rising water enters the roof passage between sump 6 and sump 7 taking with it much debris. The water flows along this passage into Toad Hall and through the 30m sump into Frog Pot, where it joins the New Stream water from Goyden Pot, New Stream sump. The combined flood waters flow into New Goyden Pot via Main Stream inlet to join the increased water from upstream sumps 1 and 2 in New Goyden. This water backing up through the system is first seen to rise in Frog Pot then Guscott Pot, Limley Pot, Church Pot and then Goyden Pot. By this time the far end of Manchester Hole has already flooded by the mechanism mentioned before. The whole system floods completely with the exception of Manchester Hole from the entrance to the ‘grovel’. The latter has been confirmed by leaving markers in the roof of Manchester Hole amongst the flood debris. The markers remained even in very high flood conditions in the rest of the system, which suggests that the flood debris present in the roof dates from before the construction of Scarhouse reservoir. Once Goyden is full water is forced past Goyden Pot Main entrance down the valley on the surface past the village of Lofthouse through to Gouthwaite Reservoir. In severe floods water mushrooms out of Church Pot, Limley Pot and New Goyden Pot, while Guscott Pot and Frog Pot still take water. In the most severe floods the River Nidd rises enough to lap into or small flow into Manchester Hole main entrance.

text: Waterfalls are commonly formed in the upper course of the river. At these times the channel is often narrow and deep. When the river courses over resistant bedrock, erosion happens slowly, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it plucks material from the riverbed. Whirlpools created in the turbulence as well as sand and stones carried by the watercourse increase the erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one and half meters per year.

text: Waterfalls are commonly formed in the upper course of the river. At these times the channel is often narrow and deep. When the river courses over resistant

text: bedrock

text: , erosion happens slowly, while downstream the erosion occurs more rapidly. As the watercourse increases its velocity at the edge of the waterfall, it plucks material from the riverbed.

text: Whirlpool

text: s created in the turbulence as well as sand and stones carried by the watercourse increase the erosion capacity. This causes the waterfall to carve deeper into the bed and to recede upstream. Often over time, the waterfall will recede back to form a canyon or gorge downstream as it recedes upstream, and it will carve deeper into the ridge above it. The rate of retreat for a waterfall can be as high as one and half meters per year.

text: Dhoni Waterfalls is located around 15 km from Palakkad and around 34 km from Kollengode Town in Palakkad. An entry pass is required before entering the area. A fee of Rs.100/-(from Aug 15th 2016) will be charged per person. You have to walk 4 km from the bottom of the hill to reach the waterfalls. The roads are not tarred, and one can see water flowing down between the rocks on the way up. No restrictions for carrying food to the top.

text: The Cave Divers Association of Australia (CDAA) is a cave diving organisation which was formed in September 1973 to represent the interests of recreational scuba divers who dive in water‐filled caves and sinkholes principally in the Lower South East (now called the Limestone Coast) of South Australia (SA) and secondly in other parts of Australia.  Its formation occurred after a series of diving fatalities in waterfilled caves and sinkholes in the Mount Gambier region between 1969 and 1973 and in parallel to a South Australian Government inquiry into these deaths.  The CDAA’s major achievement has been the dramatic reduction of fatalities via the introduction of a site rating scheme and an associated testing system which was brought in during the mid-1970s.  While its major area of operation is in the Limestone Coast region of SA, it administers and supports cave diving activity in other parts of Australia including the Nullarbor Plain and Wellington, New South Wales.

text: The Cave Divers Association of Australia (CDAA) is a

text: cave diving

text: organisation which was formed in September 1973 to represent the interests of

text: recreational scuba divers

text: who dive in water‐filled caves and

text: sinkholes

text: principally in the Lower South East (now called the

text: Limestone Coast

text: ) of

text: South Australia

text: (SA) and secondly in other parts of

text: Australia

text: .  Its formation occurred after a series of diving fatalities in waterfilled caves and sinkholes in the Mount Gambier region between 1969 and 1973 and in parallel to a

text: South Australian Government

text: inquiry into these deaths.  The CDAA’s major achievement has been the dramatic reduction of fatalities via the introduction of a site rating scheme and an associated testing system which was brought in during the mid-1970s.  While its major area of operation is in the Limestone Coast region of SA, it administers and supports cave diving activity in other parts of Australia including the

text: Nullarbor Plain

text: and

text: Wellington, New South Wales

text: Pollutants entering surface waters during precipitation events is termed polluted runoff.  Daily human activities result in deposition of pollutants on roads, lawns, roofs, farm fields, etc.  When it rains or there is irrigation, water runs off and ultimately makes its way to a river, lake, or the ocean.  While there is some attenuation of these pollutants before entering the receiving waters, the quantity of human activity results in large enough quantities of pollutants to impair these receiving waters.

text: Pollutants entering surface waters during precipitation events is termed polluted runoff.  Daily human activities result in deposition of pollutants on

text: road

text: s,

text: lawn

text: s,

text: roof

text: s,

text: farm

text: fields, etc.  When it

text: rains

text: or there is

text: irrigation

text: water

text: runs off and ultimately makes its way to a

text: river

text: lake

text: , or the

text: ocean

text: .  While there is some

text: attenuation

text: of these pollutants before entering the receiving waters, the quantity of

text: human

text: activity results in large enough quantities of pollutants to impair these receiving waters.

text: Over 50 million years, driven by movements of compression, low relief which constitutes the Pre-Pyrenees has risen. Glaciers and streams that cascade down its slopes subject to mountain erosion which flows off from the foot of it. While continuing to rise, the mountain has erected the cluster of its deposits and thus forms the Plateau de Lannemezan, head of a gigantic  which puts its mark upon much of the southwest, up the Garonne at more than  to the north. High up and submitted to the four winds, the site already assigns itself an identity that would assist in its history and reputation.

text: Over 50 million years, driven by movements of compression, low relief which constitutes the Pre-

text: Pyrenees

text: has risen.

text: Glacier

text: s and streams that cascade down its slopes subject to mountain erosion which flows off from the foot of it. While continuing to rise, the mountain has erected the cluster of its deposits and thus forms the

text: Plateau de Lannemezan

text: , head of a gigantic  which puts its mark upon much of the southwest, up the

text: Garonne

text: at more than  to the north. High up and submitted to the four winds, the site already assigns itself an identity that would assist in its history and reputation.

text: Bank erosion at cutbanks on the outside of meanders combined with deposition of point bars on the inside of meanders cause channel migration. The greatest bank erosion often occurs just downstream of the meander apex, causing downstream migration as the high velocity flow eats away at the bank as it is forced around the meander curve. Avulsion is another process of channel migration that occurs much more rapidly than the gradual migration process of cutbank erosion and point bar deposition. Avulsion occurs when lateral migration causes two meanders to become so close that the river bank between them is breached, causing the joining of the meanders and the creation of two channels. When the original channel is cut off from the new channel by the deposition of sediments, oxbow lakes are formed. Channel migration is important to sustaining diverse aquatic and riparian habitats The migration causes sediments and woody debris to enter the river, and creates areas of new floodplain on the inside of the meander.

text: Bank erosion at cutbanks on the outside of meanders combined with deposition of point bars on the inside of meanders cause

text: channel migration

text: . The greatest bank erosion often occurs just downstream of the meander apex, causing downstream migration as the high velocity flow eats away at the bank as it is forced around the meander curve.

text: Avulsion

text: is another process of channel migration that occurs much more rapidly than the gradual migration process of cutbank erosion and point bar deposition. Avulsion occurs when lateral migration causes two meanders to become so close that the river bank between them is breached, causing the joining of the meanders and the creation of two channels. When the original channel is cut off from the new channel by the deposition of sediments, oxbow lakes are formed. Channel migration is important to sustaining diverse aquatic and riparian habitats The migration causes sediments and woody debris to enter the river, and creates areas of new floodplain on the inside of the meander.

text: The Pa'ar Cave () is a karstic sinkhole in the Upper Galilee, Israel. The cave is located between the Adir peak (part of the Meron range), and kibbutz Sasa. The sinkhole channels the water flowing from the Pa'ar stream to groundwater level.

text: The Pa'ar Cave () is a

text: karstic

text: sinkhole

text: in the

text: Upper Galilee

text: Israel

text: . The cave is located between the Adir peak (part of the

text: Meron

text: range), and

text: kibbutz

text: Sasa

text: . The sinkhole channels the water flowing from the Pa'ar stream to

text: groundwater

text: level.

text: A tuff cone, sometimes called an ash cone, is a small monogenetic volcanic cone produced by phreatic (hydrovolcanic) explosions directly associated with magma brought to the surface through a conduit from a  deep-seated magma reservoir. They are characterized by high rims that have a maximum relief of  above the crater floor and steep slopes that are greater than 25 degrees. They typically have a rim to rim diameter of . A tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column. The tuffs composing a tuff cone have commonly been altered, palagonitized, by either its interaction with groundwater or when it was deposited warm and wet. The pyroclastic deposits of tuff cones differ from the pyroclastic deposits of spatter cones by their lack or paucity of lava spatter, smaller grain-size, and excellent bedding. Typically, but not always, tuff cones lack associated lava flows.

text: A tuff cone, sometimes called an ash cone, is a small monogenetic volcanic cone produced by

text: phreatic

text: (hydrovolcanic) explosions directly associated with magma brought to the surface through a conduit from a  deep-seated magma reservoir. They are characterized by high rims that have a maximum relief of  above the crater floor and steep slopes that are greater than 25 degrees. They typically have a rim to rim diameter of . A tuff cone consists typically of thick-bedded pyroclastic flow and surge deposits created by eruption-fed density currents and bomb-scoria beds derived from fallout from its eruption column. The tuffs composing a tuff cone have commonly been altered,

text: palagonitized

text: , by either its interaction with groundwater or when it was deposited warm and wet. The pyroclastic deposits of tuff cones differ from the pyroclastic deposits of spatter cones by their lack or paucity of lava spatter, smaller grain-size, and excellent bedding. Typically, but not always, tuff cones lack associated lava flows.

text: These diversions added about  to the Kitchen Creek drainage basin, increasing it by just over 50 percent. The result was increased water flow in Kitchen Creek, which has been cutting the falls in the glens since. The gradient or slope of Kitchen Creek was fairly stable for its flow when it had a much smaller drainage basin, as Phillips Creek to the east still does. Kitchen Creek is now too steep for its present amount of water flow, and over time erosion will decrease the creek's slope and make it less steep. There are rocks with glacial striations visible within the park.

text: These diversions added about  to the Kitchen Creek drainage basin, increasing it by just over 50 percent. The result was increased water flow in Kitchen Creek, which has been cutting the falls in the glens since. The gradient or slope of Kitchen Creek was fairly stable for its flow when it had a much smaller drainage basin, as Phillips Creek to the east still does. Kitchen Creek is now too steep for its present amount of water flow, and over time erosion will decrease the creek's slope and make it less steep. There are rocks with

text: glacial striation

text: s visible within the park.

text: In north Germany there are numerous salt domes under the ground – relicts of the Zechstein Sea from the Permian period, which were later relocated and deformed tectonically. When rock salt comes into contact with ground water it leaches away; i.e. the salt is absorbed by the water and transported off. This can lead to the development of large underground caverns that finally cave in. Sometimes such an event at a depth of several hundred metres can result in the ground collapsing right up to the surface. This results in prominent, often steep-sided and deep hollows called sinkholes or dolines (although dolines can have other morphogenetic causes, particularly in karst regions). Many of these funnel-shaped hollows remain dry, in others water collects that can later become marshy. Sinkholes are geologically often very recent; it is not uncommon for them to be only a few thousand years old and many hollows only date back a few hundred years.

text: In north Germany there are numerous

text: salt domes

text: under the ground – relicts of the Zechstein Sea from the

text: Permian

text: period, which were later relocated and deformed

text: tectonically

text: . When

text: rock salt

text: comes into contact with ground water it leaches away; i.e. the salt is absorbed by the water and transported off. This can lead to the development of large underground caverns that finally cave in. Sometimes such an event at a depth of several hundred metres can result in the ground collapsing right up to the surface. This results in prominent, often steep-sided and deep hollows called

text: sinkholes

text: or dolines (although dolines can have other

text: morphogenetic

text: causes, particularly in

text: karst

text: regions). Many of these funnel-shaped hollows remain dry, in others water collects that can later become marshy. Sinkholes are geologically often very recent; it is not uncommon for them to be only a few thousand years old and many hollows only date back a few hundred years.

text: About 200 million years ago, as the continent of North America began rifting apart from Africa and Eurasia, a series of erosion and deposition episodes interspersed with basalt lava flows created this layer cake. Faulting and earthquakes tilted the layers; subsequent erosion and glacial activity exposed the tilted "layers" of sandstone, basalt, and erosion-resistant conglomerate visible today. Although not composed of basalt trap rock, Sugarloaf Mountain is a closely associated with the Metacomet Ridge by virtue of its origin via the same rifting and uplift that created those mountains.

text: About 200 million years ago, as the continent of

text: North America

text: began rifting apart from

text: Africa

text: and

text: Eurasia

text: , a series of

text: erosion

text: and

text: deposition

text: episodes interspersed with basalt

text: lava

text: flows created this layer cake. Faulting and earthquakes tilted the layers; subsequent erosion and

text: glacial

text: activity exposed the tilted "layers" of sandstone, basalt, and erosion-resistant conglomerate visible today. Although not composed of basalt

text: trap rock

text: , Sugarloaf Mountain is a closely associated with the Metacomet Ridge by virtue of its origin via the same rifting and uplift that created those mountains.

text: There are three iron ranges in northern Minnesota, the Cuyuna, the Vermilion, and the Mesabi.  Most of the world's iron ore, including that contained in northern Minnesota, was formed during the middle Precambrian period. During this period, erosion leveled mountains. This erosion released iron and silica into the waters of a new sea. Marine algae living in this new sea raised the level of atmospheric oxygen. This oxygen catastrophe caused the eroded iron to precipitate into the banded iron formations found in northern Minnesota and other members of the Animikie Group.  Over billions of years, geological forces left behind ore deposits of varied quality and concentrations – differences that would determine how the ore was mined from place to place. On the Vermilion Range, between Soudan and Ely, lay the deepest veins of ore. There, miners worked in deep underground mines, blasting the ore from volcanic bedrock.  On the Mesabi Range, stretching  from Grand Rapids to Babbitt, soft ore lay close to the surface, where it could be scooped from open pit mines.

text: There are three iron ranges in northern Minnesota, the Cuyuna, the Vermilion, and the Mesabi.  Most of the world's iron ore, including that contained in northern Minnesota, was formed during the middle

text: Precambrian

text: period. During this period, erosion leveled mountains. This erosion released iron and

text: silica

text: into the waters of a new sea.

text: Marine algae

text: living in this new sea raised the level of atmospheric oxygen. This

text: oxygen catastrophe

text: caused the eroded iron to

text: precipitate

text: into the

text: banded iron formation

text: s found in northern Minnesota and other members of the

text: Animikie Group

text: .  Over billions of years, geological forces left behind ore deposits of varied quality and concentrations – differences that would determine how the ore was mined from place to place. On the Vermilion Range, between Soudan and Ely, lay the deepest veins of ore. There, miners worked in deep underground mines, blasting the ore from volcanic bedrock.  On the Mesabi Range, stretching  from Grand Rapids to Babbitt, soft ore lay close to the surface, where it could be scooped from open pit mines.

text: Environmental issues in Kenya include deforestation, soil erosion, desertification, water shortage and degraded water quality, flooding, poaching, and domestic and industrial pollution.

text: Environmental issues

text: in

text: Kenya

text: include

text: deforestation

text: soil erosion

text: desertification

text: water shortage

text: and degraded

text: water quality

text: flooding

text: poaching

text: , and domestic and industrial

text: pollution

text: The sinkhole's name is attributed to the property of its water to turn blue in colour on an annual basis in a similar manner to the Blue Lake.  However in more recent times the sinkhole generally remains  green in colour throughout most of the year. This is believed by some to be due to groundwater pollution from agricultural fertilizers increasing the nutrient levels.   The lake is also known as Baby Blue and is referenced in caving literature by its Cave Exploration Group of South Australia (CEGSA) Inc. identification number, 5L9.

text: The sinkhole's name is attributed to the property of its water to turn

text: blue

text: in colour on an annual basis in a similar manner to the

text: Blue Lake

text: .  However in more recent times the sinkhole generally remains

text: green

text: in colour throughout most of the year. This is believed by some to be due to groundwater pollution from agricultural fertilizers increasing the nutrient levels.   The lake is also known as Baby Blue and is referenced in caving literature by its Cave Exploration Group of South Australia (CEGSA) Inc. identification number, 5L9.

text: The landslide caused by the quake blocked the flow of the Madison River. The blockage caused the water to rise and formed a new lake, which was later to be named Quake Lake. Fearing that the pressure caused by the rising water would result in a catastrophic flood, the Army Corps of Engineers began to cut a 250 ft (76.2 m) wide and 14 ft (4.3 m) deep channel into the slide. By September 10, water began to flow through the channel. To prevent more erosion by the flowing water, the Army Corps cut another  (15.2 m) channel which was completed on October 29. The construction of the two channels cost $1.7 million (1959 US$).

text: The landslide caused by the quake blocked the flow of the

text: Madison River

text: . The blockage caused the water to rise and formed a new lake, which was later to be named

text: Quake Lake

text: . Fearing that the pressure caused by the rising water would result in a catastrophic flood, the

text: Army Corps of Engineers

text: began to cut a 250 ft (76.2 m) wide and 14 ft (4.3 m) deep channel into the slide. By September 10, water began to flow through the channel. To prevent more erosion by the flowing water, the Army Corps cut another  (15.2 m) channel which was completed on October 29. The construction of the two channels cost $1.7 million (1959 US$).

text: Rising sea levels have submerged a number of different sites, such as Stingray Lagoon and Wild Cane Cay, in Belize. At Stingray Lagoon, artifacts related to the production of salt, including pottery used to boil down brine, a process known as sal cocida, were found underwater .   Evidence suggests Wild Cane Cay,  was used as a trading post with deposits submerged about a meter underwater dating from both the Classic and Post Classic periods. Similarly submerged remains extend about a meter to a meter and a half in depth at other sites in the Port Honduras, suggesting a dramatically different environment at the time of occupation.  The speed at which a site becomes inundated can have major effects on the condition of the remains.  A gradual rise in water levels partially exposes the remains to erosion through the wave force, and a fast rise in water levels could leave a completely submerged site relatively undamaged.  As a result the condition of underwater remains and the amount of decay can infer insights into the location and the cause of its abandonment, however every site is different what can be true of one archeological site may not be true for another.

text: Rising sea levels

text: have submerged a number of different sites, such as Stingray Lagoon and Wild Cane Cay, in

text: Belize

text: . At Stingray Lagoon, artifacts related to the production of salt, including pottery used to boil down brine, a process known as sal cocida, were found underwater .   Evidence suggests Wild Cane Cay,  was used as a trading post with deposits submerged about a meter underwater dating from both the

text: Classic

text: and

text: Post Classic

text: periods. Similarly submerged remains extend about a meter to a meter and a half in depth at other sites in the

text: Port Honduras

text: , suggesting a dramatically different environment at the time of occupation.  The speed at which a site becomes inundated can have major effects on the condition of the remains.  A gradual rise in water levels partially exposes the remains to erosion through the

text: wave force

text: , and a fast rise in water levels could leave a completely submerged site relatively undamaged.  As a result the condition of underwater remains and the amount of decay can infer insights into the location and the cause of its abandonment, however every site is different what can be true of one archeological site may not be true for another.

text: It is not known for certain when, but at some point in the distant past the St. Joseph and St. Marys Rivers jumped their banks and flooded the marshy ground of the Fort Wayne Outlet. Thedischarge of this unusual flood was enough to cut across the outlet and come into contactwith the headwaters of the Maumee River. Once this happened, the flood waters rushed tothe east into the Maumee River, and their erosive force was enough that the new channel cut across the Fort Wayne Outlet into the Maumee River was at a lower elevation thanthat of the sluiceway. This meant that when the flood waters receded, the sluiceway waspermanently abandoned by the two rivers. As a result of capturing them both, the Maumee was converted from a minor creek to a large river. Once again, riverwaters flowed through the Fort Wayne Outlet, but now they flowed eastward, towardLake Erie, instead of westward.  Following this event, the branch of the Wabash River that originates along the WabashMoraine near Bluffton became the system's main course and source.

text: It is not known for certain when, but at some point in the distant past the St. Joseph and St. Marys Rivers jumped their banks and flooded the marshy ground of the Fort Wayne Outlet. Thedischarge of this unusual flood was enough to cut across the outlet and come into contactwith the headwaters of the Maumee River. Once this happened, the flood waters rushed tothe east into the Maumee River, and their erosive force was enough that the new channel cut across the Fort Wayne Outlet into the Maumee River was at a lower elevation thanthat of the sluiceway. This meant that when the flood waters receded, the sluiceway waspermanently abandoned by the two rivers. As a result of

text: capturing

text: them both, the Maumee was converted from a minor creek to a large river. Once again, riverwaters flowed through the Fort Wayne Outlet, but now they flowed eastward, towardLake Erie, instead of westward.  Following this event, the branch of the Wabash River that originates along the WabashMoraine near Bluffton became the system's main course and source.

text: With the regular flooding of settlements in the UK, a rethink on flood risk management was initiated. One of the proposals put forward was containing flood waters at source to prevent large volumes of water flowing downstream causing soil erosion and flooding of properties.

text: On the southwestern side of the lake, a stone bridge crosses an inlet leading to the portion of the lake that is referred to as the "Lily Pond" and near the farthest end of it to the west of the base of "Shady Point" is a small dam used to draw down lake levels from October to May in order to prevent shore erosion and damage to docks during the winter. The water traveling over that dam flows south to the Lake of the Pines.

text: The hydrology of the area consists mainly of three rivers. The Dobravka River is a continuation of two non-karst streams: Grosupeljščica Creek and Podlomščica Creek. It meanders for nearly  through the karst field and then disappears into the ground. Both of the true karst streams, Zelenka Creek and Šica Creek, originate at karst springs on the edge of the karst field and then flow across it from the west toward the east. Zelenka Creek meanders through the karst field for  and is dry during periods of drought. Šica Creek is fed by two springs at its source and meanders for . During flooding all three watercourses flow together and flow into Inlet Cave () at the southeast end of the karst field. Sometimes, when the water does not drain quickly enough, a karst lake forms, reaching as far as the first houses in Velika Račna. The road connecting the region to Grosuplje also often floods, and on 24 October 1993 a flood lasting three weeks flooded the fire station in Velika Račna. All of the water that drains on the east edge of the karst field flows underground to the source of the Krka River, which is about  away as the crow flies. Because water covers potential farmland for part of the year, barriers have been built at both sinkholes into Inlet Cave to catch branches and other debris and allow the water to drain faster. Karst hydrology studies have shown that narrow areas in the depths of the cave that are inaccessible to human exploration are a significant factor in the speed of drainage through the sinkholes.

text: The hydrology of the area consists mainly of three rivers. The Dobravka River is a continuation of two non-karst streams: Grosupeljščica Creek and Podlomščica Creek. It meanders for nearly  through the karst field and then disappears into the ground. Both of the true karst streams, Zelenka Creek and Šica Creek, originate at karst springs on the edge of the karst field and then flow across it from the west toward the east. Zelenka Creek meanders through the karst field for  and is dry during periods of drought. Šica Creek is fed by two springs at its source and meanders for . During flooding all three watercourses flow together and flow into Inlet Cave () at the southeast end of the karst field. Sometimes, when the water does not drain quickly enough, a karst lake forms, reaching as far as the first houses in Velika Račna. The road connecting the region to Grosuplje also often floods, and on 24 October 1993 a flood lasting three weeks flooded the fire station in Velika Račna. All of the water that drains on the east edge of the karst field flows underground to the source of the

text: Krka River

text: , which is about  away as the crow flies. Because water covers potential farmland for part of the year, barriers have been built at both sinkholes into Inlet Cave to catch branches and other debris and allow the water to drain faster. Karst hydrology studies have shown that narrow areas in the depths of the cave that are inaccessible to human exploration are a significant factor in the speed of drainage through the sinkholes.

text: In other regions of the world (e.g. western Europe), runoff and erosion result from relatively low intensities of stratiform rainfall falling onto previously saturated soil. In such situations, rainfall amount rather than intensity is the main factor determining the severity of soil erosion by water.

text: In other regions of the world (e.g.

text: western Europe

text: ), runoff and erosion result from relatively low intensities of

text: stratiform rainfall

text: falling onto previously saturated soil. In such situations, rainfall amount rather than intensity is the main factor determining the severity of soil erosion by water.

text: In-depth analysis of surface-water components of the hydrologic cycle: hydrometeorology, evaporation/transpiration, rainfall-runoff relationships, open-channel flow, flood hydrology, fluid mechanics, and statistical and probabilistic methods in hydrology.Surface-water hydrology includes the relation between rainfall and surface runoff; this relationship is an important aspect of water resources for sewerage (wastewater) or (sewage), drinking water, agriculture (irrigation) environmental protection, and for flood control.

text: In-depth analysis of surface-water components of the hydrologic cycle: hydrometeorology, evaporation/transpiration,

text: rainfall-runoff relationships

text: , open-channel flow, flood hydrology, fluid mechanics, and statistical and probabilistic methods in hydrology.Surface-water hydrology includes the relation between rainfall and

text: surface runoff

text: ; this relationship is an important aspect of

text: water resources

text: for

text: sewerage

text: wastewater

text: ) or (

text: sewage

text: drinking water

text: , agriculture (

text: irrigation

text: ) environmental protection, and for

text: flood control

text: Changing (increasing or decreasing) the flow of water through the core is the normal and convenient method for controlling power from approximately 30% to 100% reactor power. When operating on the so-called "100% rod line," power may be varied from approximately 30% to 100% of rated power by changing the reactor recirculation system flow by varying the speed of the recirculation pumps or modulating flow control valves. As flow of water through the core is increased, steam bubbles ("voids") are more quickly removed from the core, the amount of liquid water in the core increases, neutron moderation increases, more neutrons are slowed down to be absorbed by the fuel, and reactor power increases. As flow of water through the core is decreased, steam voids remain longer in the core, the amount of liquid water in the core decreases, neutron moderation decreases, fewer neutrons are slowed down to be absorbed by the fuel, and reactor power decreases.

text: Flood control channels are a series of large and empty (except when a flood is actually present) open-air channels that extend below the street levels of some larger cities, so that if and when a flood occurs, the flood will run into the channels, and proceed to be drained to the proper body of water. Flood control channels are sometimes built on the former courses of waterways as a way to reduce flooding. They are not to be confused with watercourses which are simply confined between levees. These structures may be made entirely of concrete, with concrete sides and an exposed bottom, with riprap sides and an exposed bottom, or completely unlined. They often contain grade control sills or weirs to prevent erosion and maintain a level streambed. By definition, flood control channels range from the size of a street gutter to a few hundred or even a few thousand feet wide in some rare cases. Flood control channels are found in most heavily developed areas in the world. One city which contains many of these channels is Los Angeles, as they became mandatory with the passage of the Flood Control Act of 1941, passed in the wake of the Los Angeles Flood of 1938.

text: Flood control channels are a series of large and empty (except when a

text: flood

text: is actually present) open-air channels that extend below the street levels of some larger

text: cities

text: , so that if and when a flood occurs, the flood will run into the channels, and proceed to be drained to the proper body of

text: water

text: . Flood control channels are sometimes built on the former courses of waterways as a way to reduce flooding. They are not to be confused with watercourses which are simply confined between

text: levee

text: s. These structures may be made entirely of

text: concrete

text: , with concrete sides and an exposed bottom, with

text: riprap

text: sides and an exposed bottom, or completely unlined. They often contain grade control sills or

text: weir

text: s to prevent

text: erosion

text: and maintain a level streambed. By definition, flood control channels range from the size of a

text: street gutter

text: to a few hundred or even a few thousand feet wide in some rare cases. Flood control channels are found in most heavily developed areas in the world. One city which contains many of these channels is

text: Los Angeles

text: , as they became mandatory with the passage of the

text: Flood Control Act of 1941

text: , passed in the wake of the

text: Los Angeles Flood of 1938

text: Ma'adim Vallis is thought to have been carved by flowing water early in Mars' history. Some of the short narrow channels along the walls of Ma'adim are probably sapping channels. Sapping occurs when groundwater partially dissolves and undermines the rock, which collapses into debris deposits and is carried away by other erosion processes.

text: Ma'adim Vallis is thought to have been carved by flowing water early in Mars' history. Some of the short narrow channels along the walls of Ma'adim are probably

text: sapping channel

text: s.

text: Sapping

text: occurs when

text: groundwater

text: partially dissolves and undermines the rock, which collapses into debris deposits and is carried away by other erosion processes.

text: The retention of the fresh water may also help to maintain underground water reserves and will resist salt water incursion.  If the surface flow of the runoff is diverted and concentrated by drains that create constant flows over the beach above the sea or river level, the beach will be eroded and ultimately form an inlet unless longshore flows deposit sediments to repair the breach.

text: Since surface erosion is easier to control than bulk erosion, surface erosion is preferred in drug delivery where the release of the drug must be constant or be controlled by changing the dimensions of the material.  A zero order release of a drug can be possible with surface erosion if a very thin material is used or if surface area is kept constant.  Surface erosion is also useful for protecting water-soluble drugs until the time of desired drug release, because water will not penetrate through the polymer matrix and reach the drug until all the surrounding polymer has degraded.  However, bulk erosion can be useful in situations that do not require controlled release, such as plastic degradation.

text: Since surface erosion is easier to control than bulk erosion, surface erosion is preferred in

text: drug delivery

text: where the release of the drug must be constant or be controlled by changing the dimensions of the material.  A zero order release of a drug can be possible with surface erosion if a very thin material is used or if surface area is kept constant.  Surface erosion is also useful for protecting water-soluble drugs until the time of desired drug release, because water will not penetrate through the polymer matrix and reach the drug until all the surrounding polymer has degraded.  However, bulk erosion can be useful in situations that do not require controlled release, such as plastic degradation.

text: By discovering many geological forms that are typically formed from large amounts of water, Viking orbiters caused a revolution in our ideas about water on Mars. Huge river valleys were found in many areas. They showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers.  Large areas in the southern hemisphere contained branched valley networks, suggesting that rain once fell. The flanks of some volcanoes are believed to have been exposed to rainfall because they resemble those occurring on Hawaiian volcanoes. Many craters look as if the impactor fell into mud. When they were formed, ice in the soil may have melted, turned the ground into mud, then the mud flowed across the surface.  Normally, material from an impact goes up, then down. It does not flow across the surface, going around obstacles, as it does on some Martian craters.  Regions, called "chaotic terrain", seemed to have quickly lost great volumes of water which caused large channels to form downstream. The amount of water involved was almost unthinkable—estimates for some channel flows run to ten thousand times the flow of the Mississippi River. Underground volcanism may have melted frozen ice; the water then flowed away and the ground just collapsed to leave chaotic terrain.

text: By discovering many geological forms that are typically formed from large amounts of water,

text: Viking

text: orbiters caused a revolution in our ideas about water on Mars. Huge river valleys were found in many areas. They showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers.  Large areas in the southern hemisphere contained branched

text: valley networks

text: , suggesting that rain once fell. The flanks of some volcanoes are believed to have been exposed to rainfall because they resemble those occurring on Hawaiian volcanoes. Many craters look as if the impactor fell into mud. When they were formed, ice in the soil may have melted, turned the ground into mud, then the mud flowed across the surface.  Normally, material from an impact goes up, then down. It does not flow across the surface, going around obstacles, as it does on some Martian craters.  Regions, called "chaotic terrain", seemed to have quickly lost great volumes of water which caused large channels to form downstream. The amount of water involved was almost unthinkable—estimates for some channel flows run to ten thousand times the flow of the

text: Mississippi River

text: . Underground volcanism may have melted frozen ice; the water then flowed away and the ground just collapsed to leave chaotic

text: terrain

text: The cement industry is one of the primary producers of carbon dioxide, a major greenhouse gas. Concrete causes damage to the most fertile layer of the earth, the topsoil.Concrete is used to create hard surfaces which contribute to surface runoff that may cause soil erosion, water pollution and flooding. Conversely, concrete is one of the most powerful tools for proper flood control, by means of damming, diversion, and deflection of flood waters, mud flows, and the like.Light-colored concrete can reduce the urban heat island effect, due to its higher albedo.Concrete dust released by building demolition and natural disasters can be a major source of dangerous air pollution.The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity. Wet concrete is highly alkaline and should always be handled with proper protective equipment. Concrete recycling is increasing in response to improved environmental awareness, legislation, and economic considerations.

text: The

text: cement industry

text: is one of the primary producers of

text: carbon dioxide

text: , a major

text: greenhouse gas

text: . Concrete causes damage to the most fertile layer of the earth, the

text: topsoil

text: .Concrete is used to create hard surfaces which contribute to

text: surface runoff

text: that may cause

text: soil erosion

text: water pollution

text: and

text: flooding

text: . Conversely, concrete is one of the most powerful tools for proper flood control, by means of

text: dam

text: ming, diversion, and deflection of flood waters, mud flows, and the like.Light-colored concrete can reduce the

text: urban heat island

text: effect, due to its higher

text: albedo

text: .Concrete dust released by

text: building demolition

text: and natural disasters can be a major source of dangerous

text: air pollution

text: .The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and

text: radioactivity

text: . Wet concrete is highly

text: alkaline

text: and should always be handled with proper protective equipment. Concrete

text: recycling

text: is increasing in response to improved

text: environmental awareness

text: , legislation, and economic considerations.

text: In Viking images, the resemblance of Alba's valley networks to terrestrial pluvial (rainfall) valleys is quite striking. The valley networks show a fine-textured, parallel to dendritic pattern with well-integrated tributary valleys and drainage densities comparable to those on Earth's Hawaiian volcanoes. However, stereoscopic images from the High Resolution Stereo Camera (HRSC) on the European Mars Express orbiter show that the valleys are relatively shallow ( or less) and more closely resemble rills or gullies from intermittent runoff erosion than valleys formed from sustained erosion. It seems likely that the valleys on Alba Mons formed as a result of transient erosional processes, possibly related to snow or ice deposits melting during volcanic activity, or to short-lived periods of global climate change. (See Surface characteristics, above.) Whether the eroded material is an ice-rich dust or friable volcanic ash is still uncertain.

text: In

text: Viking

text: images, the resemblance of Alba's valley networks to terrestrial

text: pluvial

text: (rainfall) valleys is quite striking. The valley networks show a fine-textured,

text: parallel to dendritic pattern

text: with well-integrated tributary valleys and

text: drainage densities

text: comparable to those on Earth's

text: Hawaii

text: an volcanoes. However, stereoscopic images from the High Resolution Stereo Camera (HRSC) on the European

text: Mars Express

text: orbiter show that the valleys are relatively shallow ( or less) and more closely resemble

text: rill

text: s or

text: gullies

text: from intermittent runoff erosion than valleys formed from sustained erosion. It seems likely that the valleys on Alba Mons formed as a result of transient erosional processes, possibly related to snow or ice deposits melting during volcanic activity, or to short-lived periods of global climate change. (See Surface characteristics, above.) Whether the eroded material is an ice-rich dust or

text: friable

text: volcanic ash is still uncertain.

text: The brown tubular sponge is a filter feeder. The current flowing over the top of the sponge draws in water through small pores near the base called ostia. These are lined by flagellated cells called choanocytes. The food particles are engulfed by these and the water exits through the osculi. Only very small particles can enter the sponge and 80% of its nourishment comes from bacteria sized particles.

text: The brown tubular sponge is a

text: filter feeder

text: . The current flowing over the top of the sponge draws in water through small pores near the base called ostia. These are lined by

text: flagellated

text: cells called

text: choanocyte

text: s. The food particles are engulfed by these and the water exits through the osculi. Only very small particles can enter the sponge and 80% of its nourishment comes from bacteria sized particles.

text: The Amplatzer septal occluder was shown to have full closure of the ventricular defect within the 24 hours of placement.  It has a low risk of embolism after implantation.  Some tricuspid valve regurgitation was shown after the procedure that could possibly be due from the right ventricular disc.  There have been some reports that the Amplatzer septal occluder may cause life-threatening erosion of the tissue inside the heart. This occurs in one percent of people implanted with the device and requires immediate open-heart surgery.  This erosion occurs due to improper sizing of the device resulting with it being too large for the defect, causing rubbing of the septal tissue and erosion.

text: For many years it was thought that the observed remains of floods were caused by the release of water from a global water table, but research published in 2015 reveals regional deposits of sediment and ice emplaced 450 million years earlier to be the source. "Deposition of sediment from rivers and glacial melt filled giant canyons beneath primordial ocean contained within the planet's northern lowlands. It was the water preserved in these canyon sediments that was later released as great floods, the effects of which can be seen today."

text: Shafts can be sunk either dry or for methods such as the caisson method they can be sunk wet. Sinking a dry shaft means that any water that flows into the excavation is pumped out to leave no significant standing or flowing water in the base of the shaft. When wet sinking a shaft the shaft is allowed to flood and the muck is excavated out of the base of the shaft underwater using a grab on the end of a crane or similar excavation method. Because the shaft is flooded, the lining can not be constructed at the excavation level of the shaft so this method only suits methods where the lining is installed before shaft sinking (such as the use of sheet piles) or where the lining is sunk down with the shaft such as the caisson method.

text: The landscape of the reservation is very mosaic. Sandy deposits which are the core of the reservation along with tertiary clayey deposits historically arose in Pleistocene over the bed-rock - a Paleozoic limestone (Ararat Travertine). Later tectonic movements along with constant water and wind erosion of the bed rock adding even more complexity in the structure of the landscape (Baghdasarian et al., 1971, Tadevosyan, 2001). Sandy habitats of the reservation remained a pretty large and wide ash-grey shore-line, thought there are no seas or lakes around. Presence of diatomite shelves in the sand is an evidence of its lacustrine or marine origin. Today, the closest water body is the river Vedi, which is intermittent in its lower flow, and usually dries out every summer. It is situated within almost 900 meters from the reservation and separated from it by the road and a wide line of agriculture lands. Within the reservation there are no other water bodies except few small ephemeral springs on bo bottom of the deepest limestone canions.

text: Shahbuz district is located in the north of NAR. It is a mountainous area. Salvarti (3162 m), Uchgardash (3156 m), and Kechaldagh (3115 m) are the highest points. Like the rest of the republic, many underground waters flow here, such as badamli, batabat, caravansarai, bichanak and other mineral waters. There are sulfur, construction materials, peat deposits. The district has the river Nakhchivanchay River and its tributaries - Kuku, Shahbuz, Salvarti - and Ganligol and Batabat Lakes. The mountains are heavily forested. "Badamli" resort was built near the Badamli mineral water plant.

text: The caldera forming eruption commenced with a phreatoplinian eruption that generated deposits of fine ash. Several yellowish rhyolitic ignimbrites were erupted, reaching a thickness of over . These ignimbrites filled gullies around the lake and also reach thicknesses of several tens of centimetres in the Vychenkiya River and Unkanovich River valleys. This eruption phase occurred through the lake. All these deposits were formed by the same event. Subsequently, a short eruption of lapilli and pumice consisting of dacite and rhyolite occurred, most of it falling towards the northwest; their thickness reaches  north of the lake. Some basaltic scoria was also deposited during this phase. At this point, the vent had emerged abot the water level and was generating an eruption column that deposited ash over southern Kamchatka. Eventually, the vent widened and caused the eruption column to collapse. At this point, pyroclastic flows formed and deposited the Kurile Lake ignimbrite. Reaching a thickness of  close to the lake, it filled valleys, overran plateaus and ridges and reached both the Pacific Ocean and the Sea of Okhotsk. The ignimbrite was highly mobile, overrunning high topographic obstacles and flowing along valleys in a complex flow pattern. The ignimbrite covered a total surface area of . This ignimbrite consists of rocks ranging from basaltic andesite to rhyolite with colours ranging from white to dark. Unusually for such mixed-composition ignimbrites, the rhyolites overlie the more mafic deposits. These mafic ignimbrites are not found around the entire lake, indicating that the magma chamber was asymmetric or its contents were erupted in an asymmetric fashion. The ignimbrite contains remnants of vegetation, accretionary structures formed when the ignimbrite interacted with water, breccia probably formed when conditions at the vent changed, involving the formation of a ring vent. Fumaroles formed as the ignimbrite overran rivers. Some post-eruption alteration of the ignimbrite deposits also took place. In the lake itself, the ignimbrite is about  thick. The pumice deposits have been affected by erosion and possibly by fumarolic activity, forming structures resembling overturned boats that were named "Khutk's boats" by native settlers.

text: The caldera forming eruption commenced with a

text: phreatoplinian

text: eruption that generated deposits of fine ash. Several yellowish

text: rhyolitic

text: ignimbrites were erupted, reaching a thickness of over . These ignimbrites filled gullies around the lake and also reach thicknesses of several tens of centimetres in the

text: Vychenkiya River

text: and

text: Unkanovich River

text: valleys. This eruption phase occurred through the lake. All these deposits were formed by the same event. Subsequently, a short eruption of

text: lapilli

text: and pumice consisting of

text: dacite

text: and rhyolite occurred, most of it falling towards the northwest; their thickness reaches  north of the lake. Some

text: basaltic

text: scoria

text: was also deposited during this phase. At this point, the

text: vent

text: had emerged abot the water level and was generating an

text: eruption column

text: that deposited ash over southern Kamchatka. Eventually, the vent widened and caused the eruption column to collapse. At this point,

text: pyroclastic flow

text: s formed and deposited the Kurile Lake ignimbrite. Reaching a thickness of  close to the lake, it filled valleys, overran plateaus and ridges and reached both the

text: Pacific Ocean

text: and the Sea of Okhotsk. The ignimbrite was highly mobile, overrunning high topographic obstacles and flowing along valleys in a complex flow pattern. The ignimbrite covered a total surface area of . This ignimbrite consists of rocks ranging from basaltic andesite to rhyolite with colours ranging from white to dark. Unusually for such mixed-composition ignimbrites, the rhyolites overlie the more

text: mafic

text: deposits. These mafic ignimbrites are not found around the entire lake, indicating that the magma chamber was asymmetric or its contents were erupted in an asymmetric fashion. The ignimbrite contains remnants of vegetation, accretionary structures formed when the ignimbrite interacted with water,

text: breccia

text: probably formed when conditions at the vent changed, involving the formation of a ring vent.

text: Fumarole

text: s formed as the ignimbrite overran rivers. Some post-eruption alteration of the ignimbrite deposits also took place. In the lake itself, the ignimbrite is about  thick. The pumice deposits have been affected by

text: erosion

text: and possibly by

text: fumarolic

text: activity, forming structures resembling overturned boats that were named "Khutk's boats" by native settlers.

text: A washout is the sudden erosion of soft soil or other support surfaces by a gush of water, usually occurring during a heavy downpour of rain (a flash flood) or other stream flooding. These downpours may occur locally in a thunderstorm or over a large area, such as following the landfall of a tropical cyclone. If a washout occurs in a crater-like formation, it is called a sinkhole, and it usually involves a leaking or broken water main or sewerage pipes. Other types of sinkholes, such as collapsed caves, are not washouts.

text: A washout is the sudden

text: erosion

text: of soft

text: soil

text: or other support surfaces by a gush of

text: water

text: , usually occurring during a heavy downpour of

text: rain

text: (a

text: flash flood

text: ) or other

text: stream

text: flood

text: ing. These downpours may occur locally in a

text: thunderstorm

text: or over a large area, such as following the

text: landfall

text: of a

text: tropical cyclone

text: . If a washout occurs in a

text: crater

text: -like formation, it is called a

text: sinkhole

text: , and it usually involves a leaking or broken

text: water main

text: or

text: sewerage

text: pipe

text: s. Other types of sinkholes, such as collapsed

text: cave

text: s, are not washouts.

text: Prediction of erosion by turbidity currents, and of the distribution of turbidite deposits, such as their extent, thickness and grain size distribution, requires an understanding of the mechanisms of sediment transport and deposition, which in turn depends on the fluid dynamics of the currents.

text: Prediction

text: of

text: erosion

text: by turbidity currents, and of the distribution of

text: turbidite

text: deposits, such as their extent, thickness and grain size distribution, requires an understanding of the mechanisms of

text: sediment transport

text: and

text: deposition

text: , which in turn depends on the

text: fluid dynamics

text: of the currents.

text: The most famous volcanic landslide was probably the failure of a bulge that built up from intruding magma before the Mt. St. Helens eruption in 1980, this landslide "uncorked" the shallow magmatic intrusion causing catastrophic failure and an unexpected lateral eruption blast. Rock falls often occur during periods of increased deformation and can be a sign of increased activity in absence of instrumental monitoring. Mud flows (lahars) are remobilized hydrated ash deposits from pyroclastic flows and ash fall deposits, moving downslope even at very shallow angles at high speed. Because of their high density they are capable of moving large objects such as loaded logging trucks, houses, bridges, and boulders. Their deposits usually form a second ring of debris fans around volcanic edifices, the inner fan being primary ash deposits. Downstream of the deposition of their finest load, lahars can still pose a sheet flood hazard from the residual water. Lahar deposits can take many months to dry out, until they can be walked on. The hazards derived from lahar activity can exist several years after a large explosive eruption.

text: The most famous volcanic landslide was probably the failure of a bulge that built up from intruding magma before the Mt. St. Helens eruption in 1980, this landslide "uncorked" the shallow magmatic intrusion causing catastrophic failure and an unexpected lateral eruption blast. Rock falls often occur during periods of increased deformation and can be a sign of increased activity in absence of instrumental monitoring. Mud flows (

text: lahar

text: s) are remobilized hydrated ash deposits from pyroclastic flows and ash fall deposits, moving downslope even at very shallow angles at high speed. Because of their high density they are capable of moving large objects such as loaded logging trucks, houses, bridges, and boulders. Their deposits usually form a second ring of debris fans around volcanic edifices, the inner fan being primary ash deposits. Downstream of the deposition of their finest load, lahars can still pose a sheet flood hazard from the residual water. Lahar deposits can take many months to dry out, until they can be walked on. The hazards derived from lahar activity can exist several years after a large explosive eruption.

text: To the north of the town are several caves of the Mendip Hills, including Thrupe Lane Swallet which is a geological Site of Special Scientific Interest (SSSI), and the St. Dunstan's Well Catchment which is an important cave system including a series of spectacularly-decorated caves which in total extend to about  of mapped passage. The caves at Fairy Cave Quarry were formed mainly by the erosive action of water flowing beneath the water-table at considerable pressure (so called 'phreatic' development), but as the water table has fallen many of the caves now lie well above it and the system now contains a variety of cave formations (stalagmites, stalactites and calcite curtains) which in their extent and preservation are amongst the best in Britain. Shatter Cave and Withyhill Cave are generally considered to be amongst the finest decorated caves in Britain in terms of their sheer abundance of pure white and translucent calcite deposits. Small numbers of greater horseshoe bat (Rhinolophus ferrumequinum), lesser horseshoe bat (R. hipposideros) and Natterer's bat (Myotis nattereri) hibernate in the cave system. An area of nationally rare species-rich unimproved calcareous grassland of the Sheep's-fescue-Meadow Oat-grass type occurs in the field to the east of Stoke Lane Quarry.

text: To the north of the town are several

text: caves of the Mendip Hills

text: , including

text: Thrupe Lane Swallet

text: which is a

text: geological Site of Special Scientific Interest

text: (SSSI), and the

text: St. Dunstan's Well Catchment

text: which is an important cave system including a series of spectacularly-decorated caves which in total extend to about  of mapped passage. The caves at

text: Fairy Cave Quarry

text: were formed mainly by the erosive action of water flowing beneath the water-table at considerable pressure (so called '

text: phreatic

text: stalagmite

text: s,

text: stalactites

text: and

text: calcite

text: Shatter Cave

text: and

text: Withyhill Cave

text: are generally considered to be amongst the finest decorated caves in Britain in terms of their sheer abundance of pure white and translucent calcite deposits. Small numbers of

text: greater horseshoe bat

text: (Rhinolophus ferrumequinum),

text: lesser horseshoe bat

text: (R. hipposideros) and

text: Natterer's bat

text: (Myotis nattereri) hibernate in the cave system. An area of nationally rare species-rich unimproved calcareous grassland of the

text: Sheep's-fescue-Meadow Oat-grass type

text: occurs in the field to the east of Stoke Lane Quarry.

text: Above the Pre-Neogene sequence lies a major unconformity, overlain by early Miocene rocks. This unconformity is the result of the area being subjected to subaerial erosion, but then was followed by a marine transgression, which deposited the overlaying Miocene rocks. This transgression originally deposited near-shore sands, followed by shallow water siltstones. Towards the middle Miocene, the region developed into a carbonate shelf, and these carbonates make up the rest of this sequence. During the late Miocene, these carbonates were buried by large quantities of clastic sediments originating from the uplift of Sumatra during this time. These sediments deposited faster than the rate of subsidence in the region, creating a continental shelf and slope in the west of the basin. The newly formed continental slope deposited turbidites over the early-middle Miocene sediment that the shelf did not cover. This Sequence is about 1000 meters thick. After the middle Miocene, there lies an unconformity which represents a ~10 million year depositional hiatus.

text: Above the Pre-

text: Neogene

text: sequence lies a major

text: unconformity

text: , overlain by early

text: Miocene

text: rocks. This unconformity is the result of the area being subjected to subaerial erosion, but then was followed by a marine

text: transgression

text: , which deposited the overlaying

text: Miocene

text: rocks. This transgression originally deposited near-shore sands, followed by shallow water

text: siltstones

text: . Towards the middle

text: Miocene

text: , the region developed into a carbonate shelf, and these carbonates make up the rest of this sequence. During the late

text: Miocene

text: , these carbonates were buried by large quantities of clastic sediments originating from the uplift of

text: Sumatra

text: during this time. These sediments deposited faster than the rate of

text: subsidence

text: in the region, creating a

text: continental shelf

text: and slope in the west of the basin. The newly formed continental slope deposited

text: turbidites

text: over the early-middle

text: Miocene

text: sediment that the shelf did not cover. This Sequence is about 1000 meters thick. After the middle Miocene, there lies an unconformity which represents a ~10 million year depositional hiatus.

text: The area is underlain by bedrock of Silurian age. This rock is dolomite. Preglacial erosion the surface of the bedrock created an irregular surface, allows the glacial drift to vary in depth over short distances. Some areas are underlain by bedrock near the surface, in other areas it can be  deep. Some hills are solely glacial drift; others may be entirely of limestone.The water comes from the melting ‘Valparaiso glacier’, the glacier that deposited first the Manhattan moraine, part of the Valparaiso morainic system and the Valparaiso moraines to the northeast. The melt-water came from three glacial lobes of the Laurentide ice sheet. In addition to the melt-water from the Michigan lobe in the Michigan basin, melt-water came from the Huron-Erie lobe to the east in the Maumee valley in Ohio and from the Sturgis Lobe coming out of Michigan across northeast Indiana. The water backed up behind the Marseilles moraine  forming a series of lakes.  In the Morris basin was Lake Wauponsee, which reached east up the Kankakee valley into Indiana, It flowed south into the Iroquois River  into Lake Watseka over the divide (Chatsworth ridge of the Marseilles morainic system, to the Vermillion River valley past Pontiac. The volume of water was blocked at the gap in the Farm Ridge moraine, a unit of the Bloomington morainic system near  LaSalle.  This blockage created Lake Ottawa between Farm Ridge and the Marseilles moraine in the Illinois Valley, and between the Lake Pontiac between the Cropsey (unit of the Bloomington morainic system, and Marseilles moraines in the Vermilion Valley.

text: The area is underlain by bedrock of

text: Silurian

text: age. This rock is

text: dolomite

text: . Preglacial erosion the surface of the bedrock created an irregular surface, allows the glacial drift to vary in depth over short distances. Some areas are underlain by bedrock near the surface, in other areas it can be  deep. Some hills are solely glacial drift; others may be entirely of limestone.The water comes from the melting ‘Valparaiso glacier’, the glacier that deposited first the Manhattan moraine, part of the

text: Valparaiso morainic system

text: and the Valparaiso moraines to the northeast. The melt-water came from three glacial lobes of the

text: Laurentide ice sheet

text: . In addition to the melt-water from the Michigan lobe in the

text: Michigan basin

text: , melt-water came from the Huron-Erie lobe to the east in the

text: Maumee valley

text: in

text: Ohio

text: and from the Sturgis Lobe coming out of

text: Michigan

text: across northeast Indiana. The water backed up behind the

text: Marseilles moraine

text: forming a series of

text: lakes

text: .  In the Morris basin was

text: Lake Wauponsee

text: , which reached east up the Kankakee valley into Indiana, It flowed south into the

text: Iroquois River

text: into

text: Lake Watseka

text: over the divide (Chatsworth ridge of the Marseilles morainic system, to the

text: Vermillion River valley

text: past

text: Pontiac

text: . The volume of water was blocked at the gap in the Farm Ridge moraine, a unit of the

text: Bloomington morainic system

text: near

text: LaSalle

text: .  This blockage created

text: Lake Ottawa

text: between Farm Ridge and the Marseilles moraine in the

text: Illinois Valley

text: , and between the

text: Lake Pontiac

text: between the Cropsey (unit of the

text: Bloomington morainic system

text: , and Marseilles moraines in the Vermilion Valley.

text: The amount and intensity of precipitation is the main climatic factor governing soil erosion by water. The relationship is particularly strong if heavy rainfall occurs at times when, or in locations where, the soil's surface is not well protected by vegetation. This might be during periods when agricultural activities leave the soil bare, or in semi-arid regions where vegetation is naturally sparse. Wind erosion requires strong winds, particularly during times of drought when vegetation is sparse and soil is dry (and so is more erodible). Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion.

text: The amount and intensity of

text: precipitation

text: is the main

text: climatic factor

text: governing soil erosion by water. The relationship is particularly strong if heavy rainfall occurs at times when, or in locations where, the soil's surface is not well protected by

text: vegetation

text: . This might be during periods when

text: agricultural activities

text: leave the soil bare, or in

text: semi-arid

text: regions where vegetation is naturally sparse. Wind erosion requires strong winds, particularly during times of drought when vegetation is sparse and soil is dry (and so is more erodible). Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion.

text: Mesas form by weathering and erosion of horizontally layered rocks that have been uplifted by tectonic activity.  Variations in the ability of different types of rock to resist weathering and erosion cause the weaker types of rocks to be eroded away, leaving the more resistant types of rocks topographically higher than their surroundings. This process is called differential erosion. The most resistant rock types include sandstone, conglomerate, quartzite, basalt, chert, limestone, lava flows and sills. Lava flows and sills, in particular, are very resistant to weathering and erosion, and often form the flat top, or caprock, of a mesa. The less resistant rock layers are mainly made up of shale, a softer rock that weathers and erodes more easily.

text: Mesas form by

text: weathering

text: and

text: erosion

text: of horizontally layered rocks that have been uplifted by

text: tectonic

text: activity.  Variations in the ability of different types of rock to resist weathering and

text: erosion

text: cause the weaker types of rocks to be eroded away, leaving the more resistant types of rocks topographically higher than their surroundings. This process is called differential erosion. The most resistant rock types include

text: sandstone

text: conglomerate

text: quartzite

text: basalt

text: chert

text: limestone

text: lava flows

text: and

text: sills

text: . Lava flows and sills, in particular, are very resistant to weathering and erosion, and often form the flat top, or

text: caprock

text: , of a mesa. The less resistant rock layers are mainly made up of

text: shale

text: , a softer rock that weathers and erodes more easily.

text: Particle size also plays an important role in chemical concentrations, and this factor is ignored in calculating the ERL and ERM. When using these values for screening contaminated sediment, it is likely that the ERL will be exceeded more often when the sediment contains a larger proportion of fine-grained material. This is due to the inverse relationship between chemical concentration and particle size. Due to sediment concentrations being measured on a dry weight basis, other geochemical factors of sediment that may also influence contaminant bioavailibility are not considered.

text: Particle size also plays an important role in chemical concentrations, and this factor is ignored in calculating the ERL and ERM. When using these values for screening contaminated sediment, it is likely that the ERL will be exceeded more often when the sediment contains a larger proportion of fine-grained material. This is due to the inverse relationship between chemical concentration and particle size. Due to sediment concentrations being measured on a

text: dry weight

text: basis, other

text: geochemical

text: factors of sediment that may also influence contaminant bioavailibility are not considered.

text: Water no longer flows through the mill today: the flume is blocked with pre-formed concrete slabs. The spillway is similarly reinforced and conducts the flow round the boundary of the watermill to join the tailrace below. The beck then flows through a culvert under the road to meet the water coming down the road from the upper overflow channel, then out into the marshes behind the shingle bank, often flooding the car park at the end of Beach Road.

text: In the summer of 1922, and for the next seven years, Bretz conducted field research of the Columbia River Plateau. Since 1910 he had been interested in unusual erosion features in the area after seeing a newly published topographic map of the Potholes Cataract. Bretz coined the term Channeled Scablands in 1923 to describe the area near the Grand Coulee, where massive erosion had cut through basalt deposits. The area was a desert, but Bretz's theories required cataclysmic water flows to form the landscape, for which Bretz coined the term Spokane Floods in a 1925 publication.

text: In the summer of 1922, and for the next seven years, Bretz conducted field research of the

text: Columbia River Plateau

text: . Since 1910 he had been interested in unusual

text: erosion

text: features in the area after seeing a newly published

text: topographic

text: map of the

text: Potholes Cataract

text: . Bretz coined the term Channeled Scablands in 1923 to describe the area near the

text: Grand Coulee

text: , where massive erosion had cut through

text: basalt

text: deposits. The area was a

text: desert

text: , but Bretz's theories required cataclysmic water flows to form the landscape, for which Bretz coined the term

text: Spokane Floods

text: in a 1925 publication.

text: It is unusual for the general water velocity in a system to be so high that impingement attack occurs throughout the whole of the copper pipework. More commonly, the velocity is just sufficiently low for satisfactory protective films to be formed and to remain in position on most of the system, with impingement damage more likely to occur where there is an abrupt change in the direction of water flow giving rise to a high degree of turbulence, such as at tee pieces and elbow fittings. It is not generally realised how great an effect small obstructions can have on the flow pattern of water in a pipe-work system and the extent to which they can induce turbulence and cause corrosion-erosion. For example, it is most important, as far as possible, to ensure that copper tubes cut with a tube cutter are deburred before making the joint. Also a gap between the tube end and the stop in the fitting, due to the tube not having been cut to the correct length and fully inserted into the socket of the fitting, can also induce turbulence in the water stream.

text: The flood waters were expected to exceed the levels seen during the disastrous "once in a century" Central European floods of 2002 in some areas. In Bavaria and eastern Germany water levels significantly exceeded those of 2002 in many places on the Danube and Elbe. In Passau, at the confluence of the rivers Danube, Inn and Ilz, the highest water level since 1501 was recorded. In Dresden, by contrast, the old city centre was largely spared, unlike in 2002. Thanks to better flood control, fewer dykes on the upper reaches of the Elbe broke than in 2002, but this meant that the flood wave further downstream was all the higher. In Magdeburg, the floods reached a record level.

text: The flood waters were expected to exceed the levels seen during the disastrous "once in a century"

text: Central European floods of 2002

text: in some areas. In Bavaria and eastern Germany water levels significantly exceeded those of 2002 in many places on the Danube and Elbe. In Passau, at the confluence of the rivers Danube, Inn and Ilz, the highest water level since 1501 was recorded. In Dresden, by contrast, the old city centre was largely spared, unlike in 2002. Thanks to better flood control, fewer dykes on the upper reaches of the Elbe broke than in 2002, but this meant that the flood wave further downstream was all the higher. In Magdeburg, the floods reached a record level.

text: A fair number are present, often on the higher reaches of the rivers. Some are named, such as Lizzie's Linn at Caven Mill, Montgreenan, on the Lugton Water. The Cessnock Water has a number on its course through the woods at the Carnell estate near Fiveways outside Kilmarnock. A series of low waterfalls occur at Cunnighamhead on the Annick Water, these being, like many others, dykes that are more resistant to erosion than the surrounding rocks. Other notable waterfalls are on the Polbaith burn, Fenwick Water (near Rigghill), Glen water (Darvel) and Burn Anne.

text: A fair number are present, often on the higher reaches of the rivers. Some are named, such as Lizzie's Linn at Caven Mill,

text: Montgreenan

text: , on the Lugton Water. The Cessnock Water has a number on its course through the woods at the Carnell estate near Fiveways outside Kilmarnock. A series of low waterfalls occur at Cunnighamhead on the Annick Water, these being, like many others,

text: dyke

text: s that are more resistant to erosion than the surrounding rocks. Other notable waterfalls are on the Polbaith burn, Fenwick Water (near Rigghill), Glen water (Darvel) and Burn Anne.

text: Urbanization has major effects on erosion processes—first by denuding the land of vegetative cover, altering drainage patterns, and compacting the soil during construction; and next by covering the land in an impermeable layer of asphalt or concrete that increases the amount of surface runoff and increases surface wind speeds. Much of the sediment carried in runoff from urban areas (especially roads) is highly contaminated with fuel, oil, and other chemicals. This increased runoff, in addition to eroding and degrading the land that it flows over, also causes major disruption to surrounding watersheds by altering the volume and rate of water that flows through them, and filling them with chemically polluted sedimentation. The increased flow of water through local waterways also causes a large increase in the rate of bank erosion.

text: Urbanization

text: has major effects on erosion processes—first by denuding the land of vegetative cover, altering drainage patterns, and compacting the soil during construction; and next by covering the land in an impermeable layer of asphalt or concrete that increases the amount of surface runoff and increases surface wind speeds. Much of the sediment carried in runoff from urban areas (especially roads) is highly contaminated with fuel, oil, and other chemicals. This increased runoff, in addition to eroding and degrading the land that it flows over, also causes major disruption to surrounding watersheds by altering the volume and rate of water that flows through them, and filling them with chemically polluted sedimentation. The increased flow of water through local waterways also causes a large increase in the rate of bank erosion.

text: Lost World Caverns is a publicly accessible cave for those who want to experience and understand the karst topography within the Greenbrier River watershed.  Environmental interests such as local schools and the Greenbrier River Watershed Association encourage the public to take educational tours in order to understand the unique relationship between surface water and groundwater.  Surrounded by farmland on all sides, the cave interacts with a constant influx of air, water, clastic and other additives and pollutants.  As part of Greenbrier County's karst plateau or "Great Savannah" where the average number of sinkholes are 18 per square kilometer, the cave system has much to offer the curious and the ongoing scientist.

text: Lost World Caverns is a publicly accessible cave for those who want to experience and understand the

text: karst topography

text: within the

text: Greenbrier River

text: watershed

text: .  Environmental interests such as local schools and the

text: Greenbrier River Watershed Association

text: encourage the public to take educational tours in order to understand the unique relationship between

text: surface water

text: and

text: groundwater

text: .  Surrounded by farmland on all sides, the cave interacts with a constant

text: influx

text: of air, water,

text: clastic

text: and other additives and pollutants.  As part of

text: Greenbrier County

text: 's

text: karst

text: plateau

text: or "Great Savannah" where the average number of

text: sinkholes

text: are 18 per square kilometer, the cave system has much to offer the curious and the ongoing scientist.

text: A rain garden is a planted depression or a hole that allows rainwater runoff from impervious urban areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas, the opportunity to be absorbed. This reduces rain runoff by allowing stormwater to soak into the ground (as opposed to flowing into storm drains and surface waters which causes erosion, water pollution, flooding, and diminished groundwater). They should be designed for specific soils and climates. The purpose of a rain garden is to improve water quality in nearby bodies of water and to ensure that rainwater becomes available for plants as groundwater rather than being sent through stormwater drains straight out to sea. Rain gardens can cut down on the amount of pollution reaching creeks and streams by up to 30%.

text: A rain garden is a planted depression or a hole that allows rainwater

text: runoff

text: from

text: impervious

text: urban areas, like roofs, driveways, walkways, parking lots, and compacted lawn areas, the opportunity to be absorbed. This reduces rain runoff by allowing

text: stormwater

text: to soak into the ground (as opposed to flowing into

text: storm drain

text: s and

text: surface water

text: s which causes

text: erosion

text: water pollution

text: flooding

text: , and diminished

text: groundwater

text: ). They should be designed for specific soils and climates. The purpose of a rain garden is to improve water quality in nearby bodies of water and to ensure that rainwater becomes available for plants as groundwater rather than being sent through stormwater drains straight out to sea. Rain gardens can cut down on the amount of pollution reaching creeks and streams by up to 30%.

text: While usually the flood stage is set at the elevation of the floodplain, it can be higher (if there are no structures, roads, or farming areas immediately on the floodplain) or lower (if there are structures such as marinas, lake houses, or docks low on the banks or shores of the body of water) depending on the location. Because flood stage is defined by impacts to people, as opposed to the natural topography of the area, flood stages are usually only calculated for bodies of water near communities.

text: While usually the flood stage is set at the elevation of the floodplain, it can be higher (if there are no structures,

text: road

text: s, or

text: farm

text: ing areas immediately on the floodplain) or lower (if there are structures such as

text: marina

text: s, lake houses, or

text: docks

text: low on the banks or shores of the body of water) depending on the location. Because flood stage is defined by impacts to people, as opposed to the natural topography of the area, flood stages are usually only calculated for bodies of water near communities.

text: Lava dams are formed by lava flowing or spilling into a river valley in sufficient quantity and height to temporarily overcome the explosive nature (steam) of its contact with water, and the erosive force of flowing water to remove it. The latter depends on the quantity of water flow and stream gradient. The lava may flow during numerous successive or repetitive eruptions and may emanate from single or numerous vents or fissures.  Lava of this nature, like basalt, is usually associated with less explosive eruptions; more viscous lavas with lower mafic content, like dacites and rhyolites, can also flow, but tend to be more closely associated with eruptions of greater explosiveness and the formation of pyroclastics.

text: Lava dams are formed by

text: lava

text: flowing or spilling into a river valley in sufficient quantity and height to temporarily overcome the explosive nature (steam) of its contact with water, and the erosive force of flowing water to remove it. The latter depends on the quantity of water flow and stream gradient. The lava may flow during numerous successive or repetitive eruptions and may emanate from single or numerous vents or fissures.  Lava of this nature, like

text: basalt

text: , is usually associated with less explosive eruptions; more viscous lavas with lower

text: mafic

text: content, like

text: dacite

text: s and

text: rhyolite

text: s, can also flow, but tend to be more closely associated with eruptions of greater explosiveness and the formation of pyroclastics.

text: A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a water channel (stream), which is continually undergoing erosion. Cut banks are found in abundance along mature or meandering streams, they are located on the outside of a stream bend, known as a meander, opposite the slip-off slope on the inside of the bend. They are shaped much like a small cliff, and are formed by the erosion of soil as the stream collides with the river bank. As opposed to a point bar which is an area of deposition, a cut bank is an area of erosion.

text: A cut bank, also known as a river cliff or river-cut cliff, is the outside bank of a water channel (

text: stream

text: ), which is continually undergoing erosion. Cut banks are found in abundance along mature or meandering streams, they are located on the outside of a stream bend, known as a

text: meander

text: , opposite the

text: slip-off slope

text: on the inside of the bend. They are shaped much like a small

text: cliff

text: , and are formed by the erosion of soil as the stream collides with the river bank. As opposed to a

text: point bar

text: which is an area of

text: deposition

text: , a cut bank is an area of

text: erosion

text: A total of 18 bridges cross Black Hole Creek. There are also 20 pipes that flow into or run under the creek. The creek has two small dams that are made of rock. There is also an earthen dam on Black Hole Creek near the Allenwood Federal Prison. The presence of this dam raises the water temperature of the creek. A culvert on the prison grounds that is obstructed also contributes to an increase in the water temperature. As of 2003, there are also 15 instances of rip rap and 36 deposition bars. A 2003 study found that there were 98 potential sites for erosion on the creek.

text: A total of 18 bridges cross Black Hole Creek. There are also 20

text: pipes

text: that flow into or run under the creek. The creek has two small

text: dam

text: s that are made of rock. There is also an

text: earthen

text: dam on Black Hole Creek near the

text: Allenwood Federal Prison

text: . The presence of this dam raises the water temperature of the creek. A

text: culvert

text: on the prison grounds that is obstructed also contributes to an increase in the water temperature. As of 2003, there are also 15 instances of

text: rip rap

text: and 36

text: deposition bar

text: s. A 2003 study found that there were 98 potential sites for

text: erosion

text: on the creek.

text: When a forage crop breaks down, binding products are formed that act like an adhesive on the soil, which makes particles stick together, and form aggregates. The formation of soil aggregates is important for erosion control, as they are better able to resist raindrop impact, and water erosion. Soil aggregates also reduce wind erosion, because they are larger particles, and are more resistant to abrasion through tillage practices.

text: The Delaware River is deflected by ridges and travels generally southwest, along the strike of the upturned beds of shale sedimentary rock. The Delaware flows in a riverbed of glacial till in the Minisink and Walpack buried valleys, formed from erosion of softer bedrock, then passes through the Delaware Water Gap in Kittatinny Mountain,a continuation of Blue Mountain in Pennsylvania. The buried valleys extend beyond the riverbed and stretch across the state from Pennsylvania to New York.The limestones in this area also exhibit karst topography, including sinkholes and small caves.

text: The

text: Delaware River

text: is deflected by ridges and travels generally southwest, along the

text: strike

text: of the upturned beds of shale

text: sedimentary rock

text: . The Delaware flows in a

text: riverbed

text: of

text: glacial

text: till

text: in the Minisink and Walpack

text: buried valley

text: s, formed from erosion of softer

text: bedrock

text: , then passes through the

text: Delaware Water Gap

text: in

text: Kittatinny Mountain

text: ,a continuation of

text: Blue Mountain

text: in Pennsylvania. The buried valleys extend beyond the riverbed and stretch across the state from Pennsylvania to New York.The limestones in this area also exhibit

text: karst topography

text: , including sinkholes and small caves.

text: Mudrocks are sedimentary rocks composed of at least 50% silt- and clay-sized particles. These relatively fine-grained particles are commonly transported by turbulent flow in water or air, and deposited as the flow calms and the particles settle out of suspension.

text: Mudrock

text: s are sedimentary rocks composed of at least 50%

text: silt

text: - and

text: clay

text: -sized particles. These relatively fine-grained particles are commonly transported by

text: turbulent flow

text: in water or air, and deposited as the flow calms and the particles settle out of

text: suspension

text: Tourism is a diverse, growing aspect of the economy, with seaside towns such as Beachport attracting tourists for the seaside atmosphere, and others such as Coonawarra, for the wine growing industry. A niche tourism activity is cave diving in the water-filled caves and sinkholes present in the southern part of the council's area as well as in the adjoining local government area of the District Council of Grant.  This activity attracts cave divers from around the globe.  Popular sites include Fossil Cave, Pines and Tank Cave.

text: Tourism is a diverse, growing aspect of the economy, with seaside towns such as Beachport attracting tourists for the seaside atmosphere, and others such as Coonawarra, for the wine growing industry. A niche tourism activity is

text: cave diving

text: in the water-filled

text: caves

text: and

text: sinkhole

text: s present in the southern part of the council's area as well as in the adjoining local government area of the

text: District Council of Grant

text: .  This activity attracts cave divers from around the globe.  Popular sites include

text: Fossil Cave

text: , Pines and Tank Cave.

text: River flows in the Tucannon basin depend solely on precipitation and groundwater. Studies in the early 1990s suggested that these flows would not be able to meet all of the claims, public and private, on the water resources of the lower river. In particular, farm irrigation projects were competing with fisheries for limited water. The Washington Department of Ecology named the Tucannon basin a Watershed Resource Inventory Area (WRIA) and in 1995 began hearings about how to allocate the water.

text: River flows in the Tucannon basin depend solely on precipitation and groundwater. Studies in the early 1990s suggested that these flows would not be able to meet all of the claims, public and private, on the water resources of the lower river. In particular, farm irrigation projects were competing with fisheries for limited water. The

text: Washington Department of Ecology

text: named the Tucannon basin a Watershed Resource Inventory Area (WRIA) and in 1995 began hearings about how to allocate the water.

text: Heavy rainfall, snowmelt, or high levels of ground water flowing through cracked bedrock may trigger a movement of soil or sediments. Floods and debris flows  may also occur when strong rains on hill or mountain slopes cause extensive erosion and/or what is known as "channel scour". The 2006 Sidoarjo mud flow may have been caused by rogue drilling.

text: Heavy rainfall,

text: snow

text: melt, or high levels of

text: ground water

text: flowing through cracked bedrock may trigger a movement of soil or sediments.

text: Flood

text: s and

text: debris flow

text: s  may also occur when strong rains on hill or mountain slopes cause extensive

text: erosion

text: and/or what is known as "channel scour". The 2006

text: Sidoarjo mud flow

text: may have been caused by rogue drilling.

text: Colin Reader, a British geologist, agrees that the suggested evidence of weathering indicates prolonged water erosion. Reader found, inter alia, that the flow of rainwater causing the weathering had been stemmed by the construction of 'Khufu's quarries', which lie directly "upstream" of the Sphinx enclosure, and therefore concludes that the Sphinx must predate the reign of Khufu (2589 – 2566 BC), and certainly Khafra, by several hundred years. Reader disagrees with Schoch's palaeometeorological estimates, and instead concludes that the Sphinx dates to the Early Dynastic Period (c. 3150 – 2686 BC). To explain the disproportionate size of the head compared to the body, Reader, as does Schoch, also suggests the head of the Sphinx was originally that of a lion and recarved sometime later in the likeness of a pharaoh.

text: Colin Reader

text: , a British geologist, agrees that the suggested evidence of weathering indicates prolonged water erosion. Reader found,

text: inter alia

text: , that the flow of rainwater causing the weathering had been stemmed by the construction of 'Khufu's quarries', which lie directly "

text: upstream

text: " of the Sphinx enclosure, and therefore concludes that the Sphinx must predate the reign of Khufu (2589 – 2566 BC), and certainly Khafra, by several hundred years. Reader disagrees with Schoch's palaeometeorological estimates, and instead concludes that the Sphinx dates to the

text: Early Dynastic Period

text: (c. 3150 – 2686 BC). To explain the disproportionate size of the head compared to the body, Reader, as does Schoch, also suggests the head of the Sphinx was originally that of a lion and recarved sometime later in the likeness of a pharaoh.

text: Controlling river flow by use of dams has diminished the river's ability to scour rocks by substantially reducing the amount of sediment it carries. Dams on the Colorado River have also changed the character of the river water. Once both muddy and warm, the river is now clear and averages a  temperature year-round. Experimental floods approaching the  per second level mentioned above have been carried out in 1996 and 2004 to study the effects on sediment erosion and deposition.

text: In some cases, the term current source refers to a boundary where charge flows from locations where it is not measured to  locations where it is measured. In a similar fashion, a current sink may refer to the boundary where charge flows from locations where it is measured to locations where it is not measured.  By analogy to the flow of water, a current source would be like a mountain spring - water flows from its source (a hidden location underground) to the surface where it is easily observed. Using the same analogy, a current sink would be like water flowing down a drain - water travels from where it is observed to where it is not observed.

text: In some cases, the term current source refers to a boundary where charge flows from locations where it is not measured to  locations where it is measured. In a similar fashion, a current sink may refer to the boundary where charge flows from locations where it is measured to locations where it is not measured.  By analogy to the flow of water, a current source would be like a mountain

text: spring

text: - water flows from its source (a hidden location underground) to the surface where it is easily observed. Using the same analogy, a current sink would be like water flowing down a drain - water travels from where it is observed to where it is not observed.

text: Subglacial streams are streams which flow in a channel at the bottom of an ice-sheet or a glacier, and are usually close to the glacier terminus or snout. These are fed by streams on top of the glacier which descend through ducts in the ice. The pressures are very high in these streams due to the huge mass of ice above them, consequently, they have very high erosive power meaning they will increase the volume of water flowing through, maintaining the high pressure. Some subglacial streams have the strange property of 'flowing' uphill due to the colossal pressures that are present.

text: Subglacial streams are streams which flow in a channel at the bottom of an

text: ice-sheet

text: or a

text: glacier

text: , and are usually close to the

text: glacier terminus

text: or snout. These are fed by streams on top of the glacier which descend through ducts in the ice. The pressures are very high in these streams due to the huge mass of ice above them, consequently, they have very high erosive power meaning they will increase the volume of water flowing through, maintaining the high pressure. Some subglacial streams have the strange property of 'flowing' uphill due to the colossal pressures that are present.

text: At lower water levels, a high-water mark or "bathtub ring" is visible in photos that show the shoreline of Lake Mead. The bathtub ring is white because of the deposition of minerals on previously submerged surfaces.

text: Cheese Cave's natural entrance is located  from the north end of the tube. The north cave entrance is in private property and has a building over the sinkhole. There is a steel staircase from the inside of the private building down to a small rock pile on the cave floor.

text: Cheese Cave's natural entrance is located  from the north end of the tube. The north cave entrance is in private property and has a building over the

text: sinkhole

text: . There is a steel staircase from the inside of the private building down to a small rock pile on the cave floor.

text: The vertical hard basin drop structure, also called a dissipation wall, is the basic type of drop structure. The vertical hard basin drop consists of a vertical "cutoff wall", usually built of concrete, that is usually laid perpendicular to the stream flow; and an impact basin, not unlike a stream pool, to catch the discharged water. The purpose of the vertical hard basin drop is to force the water into a hydraulic jump (a small standing wave). Though the simplest type of drop structure, it is highest in maintenance needs and less safe, with most problems related to the impact basin. Sediment is often deposited in the basin, requiring frequent removal, and erosion downstream of the base of the structure.

text: The vertical hard basin drop structure, also called a dissipation wall, is the basic type of drop structure. The vertical hard basin drop consists of a vertical "cutoff wall", usually built of concrete, that is usually laid perpendicular to the stream flow; and an impact basin, not unlike a

text: stream pool

text: , to catch the discharged water. The purpose of the vertical hard basin drop is to force the water into a

text: hydraulic jump

text: (a small standing wave). Though the simplest type of drop structure, it is highest in maintenance needs and less safe, with most problems related to the impact basin.

text: Sediment

text: is often deposited in the basin, requiring frequent removal, and erosion downstream of the base of the structure.

text: In hydrogeology, groundwater flow is defined as the "...part of streamflow that has infiltrated the ground, has entered the phreatic zone, and has been discharged into a stream channel, via springs or seepage water".  It is governed by the groundwater flow equation.Groundwater is water that is found underground in cracks and spaces in the soil, sand and rocks. An area where water fills these spaces is called a phreatic zone or saturated zone. Groundwater is stored in and moves slowly through the layers of soil, sand and rocks called aquifers. The rate of groundwater flow depends on the permeability (the size of the spaces in the soil or rocks and how well the spaces are connected) and the hydraulic head (water pressure).

text: In

text: hydrogeology

text: , groundwater flow is defined as the "...part of

text: streamflow

text: that has infiltrated the ground, has entered the

text: phreatic zone

text: , and has been discharged into a

text: stream channel

text: , via

text: spring

text: s or

text: seepage water

text: ".  It is governed by the

text: groundwater flow equation

text: .Groundwater is water that is found underground in cracks and spaces in the soil, sand and rocks. An area where water fills these spaces is called a phreatic zone or saturated zone. Groundwater is stored in and moves slowly through the layers of soil, sand and rocks called

text: aquifer

text: s. The rate of groundwater flow depends on the

text: permeability

text: (the size of the spaces in the soil or rocks and how well the spaces are connected) and the

text: hydraulic head

text: (water pressure).

text: Melissani cave is a typical feature of karst environment in coastal carbonate aquifer. It forms a kind of "cenote" as described in the Yucatán peninsula (Mexico). The vertical shaft gives access to the water table (where you can do a round trip on a small boat!). This groundwater is brackish, mixing between fresh water recharge inland and sea water intruded in depth in the island. Huge karst conduits have been explored by speleo-divers. The bay of Sami has many cenotes, with impressive shafts, that have been inventoried in a GIS Database [see external links]. The brackish water flowing through the cenotes outflows along the sea shore, forming brackish coastal and submarine springs. The groundwater of Melissani cave outflows at the "Fridi" beach. This brackish water is part of a famous hydrogeological phenomena : seawater is sucked in the west part of the island of Kefalonia, near Argostoli, and expelled in the bay of Sami. In Argostoli, the seawater flows into sinkholes, named katavothres, where water mill turns.

text: Slow-rising floods most commonly occur in large rivers with large catchment areas. The increase in flow may be the result of sustained rainfall, rapid snow melt, monsoons, or tropical cyclones. However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be very intense in smaller areas of those basins.

text: Slow-rising floods most commonly occur in large rivers with large

text: catchment area

text: s. The increase in flow may be the result of sustained rainfall, rapid snow melt,

text: monsoon

text: s, or

text: tropical cyclones

text: . However, large rivers may have rapid flooding events in areas with dry climate, since they may have large basins but small river channels and rainfall can be very intense in smaller areas of those basins.

text: The power behind a large release of water is very great, especially if it forms a single water wave, and is well known as a strong force in coastal erosion and river erosion. Such a wave could be created by a sluice gate covering one end of the reservoir, possibly a permanent fixture such as a swinging flap or a rising gate. The size of the tank controlled the height of the wave and its volume. Hushing was most effective when used on steep ground such as the brow of a hill or mountain, the force of falling water lessening as the slope becomes smaller. The rate of attack would be controlled by the water supply, and perhaps more difficult the higher the deposit to be cleared.

text: The power behind a large release of water is very great, especially if it forms a single

text: water wave

text: , and is well known as a strong force in

text: coastal erosion

text: and

text: river erosion

text: . Such a wave could be created by a

text: sluice gate

text: covering one end of the reservoir, possibly a permanent fixture such as a swinging flap or a rising gate. The size of the tank controlled the height of the wave and its volume. Hushing was most effective when used on steep ground such as the brow of a hill or mountain, the force of falling water lessening as the slope becomes smaller. The rate of attack would be controlled by the water supply, and perhaps more difficult the higher the deposit to be cleared.

text: The Witwatersrand aka The Reef, is a 56-kilometre-long north-facing scarp in the Gauteng Province of South Africa. It consists of a hard, erosion-resistant quartzite sedimentary rock, over which several north-flowing rivers form waterfalls, which account for the name “Witwatersrand”, meaning the “ridge of white waters” in Afrikaans.  This east–west-running scarp can be traced with only one short gap from Bedfordview (about 10 km west of O.R. Tambo International Airport) in the east, through Johannesburg and Roodepoort, to Krugersdorp in the west (see the diagram bottom-left below).

text: The Witwatersrand aka The Reef, is a 56-kilometre-long north-facing

text: scarp

text: in the

text: Gauteng Province

text: of

text: South Africa

text: . It consists of a hard, erosion-resistant

text: quartzite

text: sedimentary rock, over which several north-flowing rivers form waterfalls, which account for the name “Witwatersrand”, meaning the “ridge of white waters” in

text: Afrikaans

text: .  This east–west-running scarp can be traced with only one short gap from

text: Bedfordview

text: (about 10 km west of

text: O.R. Tambo International Airport

text: ) in the east, through

text: Johannesburg

text: and

text: Roodepoort

text: , to

text: Krugersdorp

text: in the west (see the diagram bottom-left below).

text: The climate is arid with an average rainfall of only 315 mm per year between June and September. The number of days during which rain falls in a year usually does not exceed 4 or 5. Banni has almost no rivers or natural streams however, about 100 rivers and rivulets flowing northwards from the Kutch mainland drain into the grasslands of Banni along its southern boundary. This area near the boundary gets flooded during the rainy season mainly by the water brought by these rivers and local rainfall. It is this annual flooding and the old silt deposits that formed Banni, which were deposited here when the Indus River used to flow through the region until it changed its course due to the 1819 earthquake. This gave rise to what is often called Asia's finest natural grasslands.

text: The climate is

text: arid

text: with an average rainfall of only 315 mm per year between June and September. The number of days during which rain falls in a year usually does not exceed 4 or 5. Banni has almost no rivers or natural streams however, about 100 rivers and rivulets flowing northwards from the Kutch mainland drain into the grasslands of Banni along its southern boundary. This area near the boundary gets flooded during the rainy season mainly by the water brought by these rivers and local rainfall. It is this annual

text: flooding

text: and the old

text: silt

text: deposits that formed Banni, which were

text: deposited

text: here when the

text: Indus River

text: used to flow through the region until it changed its course due to the 1819 earthquake. This gave rise to what is often called Asia's finest natural grasslands.

text: Cabeço Gordo is the main geomorphological unit, corresponding to a polygenetic volcano two kilometers at the top and one kilometer at the base. The walls of the crater rim are abrupt, although their slopes increase with altitudes. The superficial cover of the volcano is covered in pyroclastic material, such as pumice rock, phreatic and phreatomagmatic deposits, evidence of pyroclastic flows and lahars. The flanks of the stratovolcano also include the Morro de Castelo Branco and peninsula of denser material that have resisted erosion.

text: The Pannonian Basin took shape through Miocenian thinning and subsidence of crust structures formed during the Late Paleozoic Variscan orogeny. The Paleozoic and Mesozoic structures are visible in Papuk and other Slavonian mountains. The processes also led to the formation of a stratovolcanic chain in the basin 12–17 Mya; intensified subsidence was observed until 5 Mya as well as flood basalts at about 7.5 Mya. The contemporary tectonic uplift of the Carpathian Mountains severed water flow to the Black Sea and the Pannonian Sea formed in the basin. Sediments were transported to the basin from the uplifting Carpathian and Dinaric mountains, with particularly deep fluvial sediments being deposited in the Pleistocene epoch during the Transdanubian Mountains' formation. Ultimately, up to  of sediment was deposited in the basin, and the sea eventually drained through the Iron Gate gorge.

text: The Pannonian Basin took shape through Miocenian thinning and

text: subsidence

text: of crust structures formed during the Late

text: Paleozoic

text: Variscan orogeny

text: . The Paleozoic and

text: Mesozoic

text: structures are visible in

text: Papuk

text: and other Slavonian mountains. The processes also led to the formation of a

text: stratovolcanic

text: chain in the basin 12–17

text: Mya

text: ; intensified subsidence was observed until 5 Mya as well as

text: flood basalt

text: s at about 7.5 Mya. The contemporary

text: tectonic uplift

text: of the

text: Carpathian Mountains

text: severed water flow to the

text: Black Sea

text: and the

text: Pannonian Sea

text: formed in the basin.

text: Sediments

text: were transported to the basin from the uplifting Carpathian and Dinaric mountains, with particularly deep

text: fluvial

text: sediments being deposited in the

text: Pleistocene

text: epoch during the

text: Transdanubian Mountains

text: ' formation. Ultimately, up to  of sediment was deposited in the basin, and the sea eventually drained through the

text: Iron Gate

text: gorge.

text: Geologists classify the falls at Ricketts Glen State Park into two types. Wedding-cake falls descend in a series of small steps, forming waterfalls that are said to resemble a wedding cake. Within the park, this type of falls usually flows over thin layers of Huntley Mountain Formation sandstone. In bridal-veil falls, the second type, water falls over a ledge and drops vertically into a plunge pool in the stream bed below. Within the park, this type of falls flows over Catskill Formation rocks or the red shale and sandstone of the Huntley Formation. In the park, the harder caprock which forms the ledge from which the bridal-veil falls drops is grey sandstone. The softer red shale below is eroded away by water, sand and gravel to form the plunge pool.

text: Geologists classify the falls at Ricketts Glen State Park into two types. Wedding-cake falls descend in a series of small steps, forming waterfalls that are said to resemble a

text: wedding cake

text: . Within the park, this type of falls usually flows over thin layers of Huntley Mountain Formation sandstone. In

text: bridal-veil

text: falls, the second type, water falls over a ledge and drops vertically into a

text: plunge pool

text: in the stream bed below. Within the park, this type of falls flows over Catskill Formation rocks or the red shale and sandstone of the Huntley Formation. In the park, the harder

text: caprock

text: which forms the ledge from which the bridal-veil falls drops is grey sandstone. The softer red shale below is eroded away by water, sand and gravel to form the plunge pool.

text: Valley or stream erosion occurs with continued water flow along a linear feature. The erosion is both downward, deepening the valley, and headward, extending the valley into the hillside, creating head cuts and steep banks. In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is relatively steep. When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain. The stream gradient becomes nearly flat, and lateral deposition of sediments becomes important as the stream meanders across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood, when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes: suspended abrasive particles, pebbles and boulders can also act erosively as they traverse a surface, in a process known as traction.

text: Valley or stream erosion occurs with continued water flow along a linear feature. The erosion is both

text: downward

text: , deepening the valley, and

text: headward

text: , extending the valley into the hillside, creating

text: head cuts

text: and steep banks. In the earliest stage of stream erosion, the erosive activity is dominantly vertical, the valleys have a typical V cross-section and the stream gradient is relatively steep. When some

text: base level

text: is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain. The stream gradient becomes nearly flat, and lateral deposition of sediments becomes important as the stream

text: meander

text: s across the valley floor. In all stages of stream erosion, by far the most erosion occurs during times of flood, when more and faster-moving water is available to carry a larger sediment load. In such processes, it is not the water alone that erodes: suspended abrasive particles,

text: pebble

text: s and

text: boulder

text: s can also act erosively as they traverse a surface, in a process known as traction.

text: Bracken Cave is the summer home to the largest colony of bats in the world. An estimated 20 million Mexican Free-tailed Bats roost in the cave from March to October making it the largest known concentration of mammals. The cave is located in southern Comal County, Texas, outside the city of San Antonio. The 100-foot-wide crescent shaped opening to the cave lies at the bottom of a sinkhole, formed when the roof of the cave collapsed.

text: Bracken Cave is the summer home to the largest colony of bats in the world. An estimated 20 million

text: Mexican Free-tailed Bat

text: s roost in the cave from March to October making it the largest known concentration of mammals. The cave is located in southern

text: Comal County, Texas

text: , outside the city of

text: San Antonio

text: . The 100-foot-wide crescent shaped opening to the cave lies at the bottom of a sinkhole, formed when the roof of the cave collapsed.

text: The Hugoton Field is a stratigraphic trap overlying a monocline, with the primary pay found in the Krider dolomite of Permian age.  This dolomite and the overlying Herington dolomite make up the Wolfcampian carbonates.  Above these carbonates is the Wichita, an anhydrite and dense dolomite forming the reservoir seal, which thins to the west.  Marine carbonates were being deposited from the Late Pennsylvanian until Early Permian when the western portion of the area was uplifted which resulted in erosion and the deposition of red clays and sands, the future red beds consisting of shales and sandstones. Marine carbonate deposition followed, resulting in the interfingering of the red beds and carbonates, the basis of the stratigraphic trap and a tilted gas-water contact.

text: The Hugoton Field is a

text: stratigraphic trap

text: overlying a

text: monocline

text: , with the primary pay found in the Krider

text: dolomite

text: of

text: Permian

text: age.  This dolomite and the overlying Herington dolomite make up the Wolfcampian carbonates.  Above these carbonates is the Wichita, an

text: anhydrite

text: and dense dolomite forming the reservoir seal, which thins to the west.  Marine carbonates were being deposited from the

text: Late Pennsylvanian

text: until

text: Early Permian

text: when the western portion of the area was uplifted which resulted in erosion and the deposition of red clays and sands, the future red beds consisting of shales and sandstones. Marine carbonate deposition followed, resulting in the interfingering of the red beds and carbonates, the basis of the stratigraphic trap and a tilted gas-water contact.

text: Middle Island Creek's most extreme meander forms a peninsula known as "the Jug," located upstream of Middlebourne. The creek rounds a 3.3 mile (5.3 km) bend only to return to within 100 feet (30 m) of itself.  Sometime prior to 1800, an early European settler named George Gregg had a raceway (mill race) carved across the narrow point of the peninsula and harnessed the resulting hydropower of the stream's 13-foot (4 m) fall for a gristmill and sawmill at the site.  These mills were destroyed by a flood in 1852; four more mills were subsequently built and respectively washed away by flooding in the later 19th century.  Flooding had the effect of widening the raceway across the peninsula such that it became the main channel of the stream, inhibiting the flow of water through the longer loop and transforming the peninsula to an island.  In 1947 the West Virginia Conservation Commission constructed a low water bridge which substantially dammed the cut-through and restored a steady flow to the bend of the creek. The low water bridge is known to be frequently impassable due to flooding.  The land encircled by the creek's loop is operated as a Wildlife Management Area by the state of West Virginia.

text: Middle Island Creek's most extreme meander forms a

text: peninsula

text: known as "the Jug," located upstream of Middlebourne. The creek rounds a 3.3 mile (5.3 km) bend only to return to within 100 feet (30 m) of itself.  Sometime prior to 1800, an early European settler named George Gregg had a

text: raceway (mill race)

text: carved across the narrow point of the peninsula and harnessed the resulting

text: hydropower

text: of the stream's 13-foot (4 m) fall for a

text: gristmill

text: and

text: sawmill

text: at the site.  These mills were destroyed by a flood in 1852; four more mills were subsequently built and respectively washed away by flooding in the later 19th century.  Flooding had the effect of widening the raceway across the peninsula such that it became the main channel of the stream, inhibiting the flow of water through the longer loop and transforming the peninsula to an island.  In 1947 the West Virginia Conservation Commission constructed a

text: low water bridge

text: which substantially dammed the cut-through and restored a steady flow to the bend of the creek. The low water bridge is known to be frequently impassable due to flooding.  The land encircled by the creek's loop is operated as a

entity_name: List of West Virginia wildlife management areas

text: Wildlife Management Area

text: by the state of West Virginia.

text: Salmon friendly gardens, also called rain gardens, would prevent overflow and surges and would absorb pollutants which would otherwise be washed directly into freshwater systems. When a storm causes rainwater to surge into rivers and streams via storm drains, the heavy flow of fast moving water commonly erodes the soil thus destroying precious salmon and steelhead habitat.  Said storm drain surges are typically warmer in temperature than the water of the streams into which they are being deposited. This causes river and stream temperatures to rise and places further stress on growing and migrating salmon and steelhead. The salmon friendly gardens are planted as depressions in the ground, and work by absorbing much of the rainwater runoff which is redirected to first flow through the gardens before ultimately ending up in the rivers and streams. The gardens therefore slow and lessen the storm surges and filter out pollutants being washed out of the city. Planting rain gardens would result in less erosion, lower and stable water temperatures, and less pollutants entering freshwater systems.

text: Salmon friendly gardens, also called

text: rain garden

text: s, would prevent overflow and surges and would absorb pollutants which would otherwise be washed directly into freshwater systems. When a storm causes rainwater to surge into rivers and streams via storm drains, the heavy flow of fast moving water commonly erodes the soil thus destroying precious salmon and steelhead habitat.  Said storm drain surges are typically warmer in temperature than the water of the streams into which they are being deposited. This causes river and stream temperatures to rise and places further stress on growing and migrating salmon and steelhead. The salmon friendly gardens are planted as depressions in the ground, and work by absorbing much of the rainwater runoff which is redirected to first flow through the gardens before ultimately ending up in the rivers and streams. The gardens therefore slow and lessen the storm surges and filter out pollutants being washed out of the city. Planting rain gardens would result in less erosion, lower and stable water temperatures, and less pollutants entering freshwater systems.

text: Prior to the ice ages the River Thames followed a path through the southern part of Hertfordshire, running from the area of modern Staines up the valley of the Colne to Hatfield and then eastward across Essex originally towards the primeval Rhine but later down the valley of the modern River Lea. This path was blocked by a mass of ice near Hatfield and a lake ponded up to the west of this around St Albans. Waters eventually overflowed near Staines to cut the path of the modern Thames through central London.  When the ice retreated about 400,000 years ago the river bed along the new route followed the lower path and so the river remained on its present-day course. The flow in the Colne valley reversed, now flowing south as a tributary into the modern Thames. Superficial gravel deposits from the primordial Thames, are found throughout the Vale of St. Albans.

text: Prior to the ice ages the

text: River Thames

text: followed a path through the southern part of Hertfordshire, running from the area of modern

text: Staines

text: up the valley of the Colne to

text: Hatfield

text: and then eastward across Essex originally towards the primeval

text: Rhine

text: but later down the valley of the modern

text: River Lea

text: . This path was blocked by a mass of ice near Hatfield and a lake ponded up to the west of this around St Albans. Waters eventually overflowed near Staines to cut the path of the modern Thames through central

text: London

text: .  When the ice retreated about 400,000 years ago the river bed along the new route followed the lower path and so the river remained on its present-day course. The flow in the Colne valley reversed, now flowing south as a tributary into the modern Thames. Superficial gravel deposits from the primordial Thames, are found throughout the Vale of St. Albans.

text: Australian water resources have always been variable but they are becoming increasingly so with changing climate conditions. Because of how limited water resources are in Australia, there needs to be an effective implementation of environmental governance conducted within the country. Water restrictions are an important policy device used in Australian environmental governance to limit the amount of water used in urban and agricultural environments (Beeton et al. 2006). There is increased pressure on surface water resources in Australia because of the uncontrolled growth in groundwater use and the constant threat of drought. These increased pressures not only affect the quantity and quality of the waterways but they also negatively affect biodiversity. The government needs to create policies that preserve, protect and monitor Australia’s inland water. The most significant environmental governance policy imposed by the Australian government is environmental flow allocations that allocate water to the natural environment. The proper implementation of water trading systems could help to conserve water resources in Australia. Over the years there has been an increase in demand for water, making Australia the third largest per capita user of water in the world (Beeton et al. 2006). If this trend continues, the gap between supply and demand will need to be addressed. The government needs to implement more efficient water allocations and raise water rates (UNEP, 2014). By changing public perception to promote the action of reusing and recycling water some of the stress of water shortages can be alleviated.  More extensive solutions like desalination plants, building more dams and using aquifer storage are all options that could be taken to conserve water levels but all these methods are controversial. With caps on surface water use, both urban and rural consumers are turning to groundwater use; this has caused groundwater levels to decline significantly. Groundwater use is very hard to monitor and regulate. There is not enough research currently being conducted to accurately determine sustainable yields. Some regions are seeing improvement in groundwater levels by applying caps on bores and the amount of water that consumers are allowed to extract. There have been projects in environmental governance aimed at restoring vegetation in the riparian zone. Restoring riparian vegetation helps increase biodiversity, reduce salinity, prevent soil erosion and prevent riverbank collapse. Many rivers and waterways are controlled by weirs and locks that control the flow of rivers and also prevent the movement of fish. The government has funded fish-ways on some weirs and locks to allow for native fish to move upstream. Wetlands have significantly suffered under restricted water resources with water bird numbers dropping and a decrease in species diversity. The allocation of water for bird breeding through environmental flows in Macquarie Marshes has led to an increase in breeding (Beeton et al. 2006). Because of dry land salinity throughout Australia there has been an increase in the levels of salt in Australian waterways. There has been funding in salt interception schemes which help to improve in-stream salinity levels but whether river salinity has improved or not is still unclear because there is not enough data available yet. High salinity levels are dangerous because they can negatively affect larval and juvenile stages of certain fish. The introduction of invasive species into waterways has negatively affected native aquatic species because invasive species compete with native species and alter natural habitats. There has been research in producing daughterless carp to help eradicate carp. Government funding has also gone into building in-stream barriers that trap the carp and prevent them from moving into floodplains and wetlands.  Investment in national and regional programmes like the Living Murray (MDBC), Healthy Waterways Partnership and the Clean Up the Swan Programme are leading to important environmental governance. The Healthy Rivers programme promotes restoration and recovery of environmental flows, riparian re-vegetation and aquatic pest control.  The Living Murray programme has been crucial for the allocation of water to the environment by creating an agreement to recover 500 billion litres of water to the Murray River environment. Environmental governance and water resource management in Australia must be constantly monitored and adapted to suit the changing environmental conditions within the country (Beeton et al. 2006). If environmental programmes are governed with transparency there can be a reduction in policy fragmentation and an increase in policy efficiency (Mclntyre, 2010).<ref>United Nations Environmental Programme, 2014, “UNEP Conference on Strengthening Transboundary Freshwater Governance – The Environmental Sustainability Challenge”, UNEP, viewed on 31/5/14,

text: Australia

text: n

text: water resources

text: have always been variable but they are becoming increasingly so with changing climate conditions. Because of how limited water resources are in Australia, there needs to be an effective implementation of environmental governance conducted within the country. Water restrictions are an important policy device used in Australian environmental governance to limit the amount of water used in urban and agricultural environments (Beeton et al. 2006). There is increased pressure on surface water resources in Australia because of the uncontrolled growth in

text: groundwater

text: Macquarie Marshes

text: has led to an increase in breeding (Beeton et al. 2006). Because of dry land salinity throughout Australia there has been an increase in the levels of salt in Australian waterways. There has been funding in salt interception schemes which help to improve in-stream salinity levels but whether river salinity has improved or not is still unclear because there is not enough data available yet. High salinity levels are dangerous because they can negatively affect larval and juvenile stages of certain fish. The introduction of invasive species into waterways has negatively affected native aquatic species because invasive species compete with native species and alter natural habitats. There has been research in producing

text: daughterless carp

text: to help eradicate carp. Government funding has also gone into building in-stream barriers that trap the carp and prevent them from moving into floodplains and wetlands.  Investment in national and regional programmes like the Living Murray (MDBC), Healthy Waterways Partnership and the Clean Up the Swan Programme are leading to important environmental governance. The Healthy Rivers programme promotes restoration and recovery of environmental flows, riparian re-vegetation and aquatic pest control.  The Living Murray programme has been crucial for the allocation of water to the environment by creating an agreement to recover 500 billion litres of water to the Murray River environment. Environmental governance and water resource management in Australia must be constantly monitored and adapted to suit the changing environmental conditions within the country (Beeton et al. 2006). If environmental programmes are governed with transparency there can be a reduction in policy fragmentation and an increase in policy efficiency (Mclntyre, 2010).<ref>United Nations Environmental Programme, 2014, “UNEP Conference on Strengthening Transboundary Freshwater Governance – The Environmental Sustainability Challenge”, UNEP, viewed on 31/5/14,

text: One generally accepted view for the formation of large outflow channels is that they were formed by catastrophic floods of water released from giant groundwater reservoirs. Perhaps, the water started to come out of the ground due to faulting or volcanic activity.  Sometimes hot magma just travels under the surface.  If that is the case, the ground will be heated, but there may be no evidence of lava at the surface. After the water escaped, the surface would collapse.  Moving across the surface, the water would have simultaneously froze and evaporated. Chunks of ice that would have rapidly formed may have enhanced the erosive power of the flood. Furthermore, the water may have frozen over at the surface, but continuing to flow underneath.  Rivers in cold climates on the Earth often become ice-covered, yet continue to flow.

text: When a river reaches a low-lying plain, often in its final course to the sea or a lake, it meanders widely. In the vicinity of a river bend, deposition occurs on the convex bank (the bank with the smaller radius). In contrast, both lateral erosion and undercutting occur on the cut bank or concave bank (the bank with the greater radius.) Continuous deposition on the convex bank and erosion of the concave bank of a meandering river cause the formation of a very pronounced meander with two concave banks getting closer. The narrow neck of land between the two neighboring concave banks is finally cut through, either by lateral erosion of the two concave banks or by the strong currents of a flood. When this happens, a new straighter river channel is created and an abandoned meander loop, called a cutoff, is formed. When deposition finally seals off the cutoff from the river channel, an oxbow lake is formed. This process can occur over a time scale from a few years to several decades and may sometimes become essentially static.

text: When a river reaches a low-lying plain, often in its final course to the

text: sea

text: or a

text: lake

text: , it

text: meander

text: s widely. In the vicinity of a

text: river

text: bend,

text: deposition

text: occurs on the

text: convex

text: bank (the bank with the smaller radius). In contrast, both lateral

text: erosion

text: and undercutting occur on the

text: cut bank

text: or concave bank (the bank with the greater radius.) Continuous deposition on the convex bank and erosion of the concave bank of a meandering river cause the formation of a very pronounced

text: meander

text: with two

text: concave

text: banks getting closer. The narrow neck of land between the two neighboring concave banks is finally cut through, either by lateral erosion of the two concave banks or by the strong currents of a

text: flood

text: . When this happens, a new straighter river

text: channel

text: is created and an abandoned meander loop, called a

text: cutoff

text: , is formed. When deposition finally seals off the cutoff from the river channel, an oxbow lake is formed. This process can occur over a time scale from a few years to several decades and may sometimes become essentially static.

text: While there is no further surface water flow out of the Ailik Lake, some water from this lake is believed to seasonally seep through ground fractures of the Kewu Fault into the nearby Small Ailik Lake (小艾里克湖, ), whose water surface is (as of 1999) at about  above sea level. Potentially, water can seep through the same fault even farther to the southwest, to the dry Alan Nur lake (the former terminus of the Manas River).

text: While there is no further surface water flow out of the Ailik Lake, some water from this lake is believed to seasonally seep through

text: ground fractures

text: of the Kewu

text: Fault

text: into the nearby Small Ailik Lake (小艾里克湖, ), whose water surface is (as of 1999) at about  above sea level. Potentially, water can seep through the same fault even farther to the southwest, to the dry Alan Nur lake (the former terminus of the

text: Manas River

text: The cause of the erosion and flooding which eventually drowned this development was the original Hampton Pier. The ebb and flow of tidal streams is powerful in the shallow Thames Estuary, where its tidal waters are caught in the vortex of the tidal push from Atlantic waters via both the north and south of the British Isles. Off Herne Bay, the running ebb current moves at 10.15 knots, and the flow at . Where strong currents meet and divide, or are disrupted by uneven coastal features, there are eddies. After Hampton Pier was first built, the flow running west along Herne Bay beach dropped its sand and pebbles on the east side of the pier instead of replenishing beach material in front of the new development. Subsequently, after being forced into a loop around the pier-end it was possibly forced into a shoreward eddy by deep-water currents. That means that at a certain point in the flow-tide it could have continued briefly westward past Hampton-on-Sea, then turned inshore and looped back strongly eastwards along the beach towards Hampton Pier Avenue, eroding land at Hampton-on-Sea and then turning north along Hampton Pier Avenue and the pier, carrying soil with it. It is said that the later shortening of the pier was not enough and that erosion will continue, so such an eddy may explain the need for today's shore defences along the north end of Hampton Pier Avenue. An additional possibility is related to the strong ebb flow's history of removing the headlands of Herne Bay's original bay before the 19th century. This current moving east, being baulked and turned north suddenly by the new sea defences of Hampton Pier Avenue and Hampton Pier, might easily erode the little Hampton-on-Sea bay in default of the Hampton Pier headland. Both the above theories allow for scoured coastal material to be removed to deeper waters to the north of Hampton-on-Sea by the ebb tide and by the occasional eddy, besides being dropped at Long Rock by an alternate normal east-west flow tide. When there are exceptional conditions on top of these tidal streams, for example a low pressure system causing higher water level coinciding with strong north-westerly winds, coastal flooding can occur.

text: The cause of the

text: erosion

text: and flooding which eventually drowned this development was the original Hampton Pier. The

text: ebb and flow

text: of

text: tidal streams

text: is powerful in the shallow

text: Thames Estuary

text: , where its tidal waters are caught in the vortex of the tidal push from

text: Atlantic

text: waters via both the north and south of the British Isles. Off Herne Bay, the running ebb current moves at 10.15

text: knots

text: , and the flow at . Where strong currents meet and divide, or are disrupted by uneven coastal features, there are

text: eddies

text: Floods take place when water overflows or submerges land that is usually parched. The most common way is when rivers or streams overflow their banks. A floodplain is produced when water from a rivers spreads through the land from excessive rain, rapid ice melting, unfortunately placed beaver dam, and ruptured dam. There are two types of floods: general and flash floods. General floods are predicted well in advance and usually cause the destruction of housing, people and crops. Flash floods come without warning and are sudden and extreme: A large volume of water flows rapidly and people have to make quick movements if they do not want to be caught in the flood. They have to find high safe ground where the water will not reach them.

text: Hesperornis was primarily marine, and lived in the waters of such contemporary shallow shelf seas as the Western Interior Seaway, the Turgai Strait, and the North Sea, which then were subtropical to tropical waters, much warmer than today. However, some of the youngest known specimens of Hesperornis have been found in inland freshwater deposits of the Foremost Formation, suggesting that some species of Hesperornis may have eventually moved, at least partially, away from a primarily marine habitat. Additionally, the species H. altus comes from the freshwater deposits at the base of the Judith River Formation.

text: Hesperornis was primarily marine, and lived in the waters of such contemporary shallow

text: shelf sea

text: s as the

text: Western Interior Seaway

text: , the

text: Turgai Strait

text: , and the

text: North Sea

text: , which then were

text: subtropical

text: to

text: tropical

text: waters, much warmer than today. However, some of the youngest known specimens of Hesperornis have been found in inland freshwater deposits of the

text: Foremost Formation

text: , suggesting that some species of Hesperornis may have eventually moved, at least partially, away from a primarily marine habitat. Additionally, the species H. altus comes from the freshwater deposits at the base of the

text: Judith River Formation

text: It is generally believed to be a basaltic shield with the lower part buried beneath plain forming lavas. Earlier interpretations suggested that it is a stratovolcano.  The slopes on Ceraunius Tholus are quite steep with an average slope of 8° with many radial erosion channels and pitted valleys extending from just below the rim of the caldera toward the base of the volcano. The current view is that the valleys were eroded by water.  Interesting features on Ceraunius Tholus are three large canyons at the northwest ﬂank of Ceraunius Tholus which are up to 2.5 km wide and 300 m deep. The biggest of these three also appears to be the youngest and protrude from the lowest point of the volcanic caldera and ends at the interesting crater Rahe (an oblique impact crater with measures of 35 × 18 km), just north from the volcano where it formed a depositional fan. Its origin is still debatable and there are four main models proposed: ﬂuvial action, volcanic flows, valley being a lava channel or some combination of previously mentioned models.

text: It is generally believed to be a basaltic shield with the lower part buried beneath plain forming lavas. Earlier interpretations suggested that it is a

text: stratovolcano

text: .  The slopes on Ceraunius Tholus are quite steep with an average slope of 8° with many radial erosion channels and pitted valleys extending from just below the rim of the

text: caldera

text: toward the base of the volcano. The current view is that the valleys were eroded by water.  Interesting features on Ceraunius Tholus are three large canyons at the northwest ﬂank of Ceraunius Tholus which are up to 2.5 km wide and 300 m deep. The biggest of these three also appears to be the youngest and protrude from the lowest point of the volcanic caldera and ends at the interesting crater

text: Rahe

text: (an oblique impact crater with measures of 35 × 18 km), just north from the volcano where it formed a depositional fan. Its origin is still debatable and there are four main models proposed: ﬂuvial action, volcanic flows, valley being a lava channel or some combination of previously mentioned models.

text: The volcanic cone of Mount Thielsen sits atop prior shield volcanoes, and has a volume of . The cone was built from basaltic andesite, a common component of other shield volcanoes in the Oregon Cascades, breccia, and tuff, and it is intruded by dikes. A coalesced volcanic cone, it formed as pyroclastics erupted and fountains spewed lava. Glaciers cut and deformed the cone, eroding its upper sector. This erosion opened the interior of Thielsen for observation. Within the cone, lava flows, pyroclastic flow deposits, and strata of tephra, and volcanic ash, are easily visible. Potassium-argon dating of deposits in the cone suggests that Thielsen is at least 290,000 years old. Since its eruption stopped about 250,000 to 100,000 years ago, the period of eruptive activity was short in time. The eruptions of the cone came in three phases: a period where lava flows built up its cone, one where more explosive pyroclastic eruptions took place, and the final period, in which pyroclastic and material of lava-based origin were erupted together forming a weak cone encircled by long deposits.

text: The volcanic cone of Mount Thielsen sits atop prior shield volcanoes, and has a volume of . The cone was built from

text: basaltic andesite

text: , a common component of other shield volcanoes in the Oregon Cascades, breccia, and

text: tuff

text: , and it is intruded by

text: dikes

text: . A coalesced volcanic cone, it formed as pyroclastics erupted and fountains spewed lava. Glaciers cut and deformed the cone, eroding its upper sector. This erosion opened the interior of Thielsen for observation. Within the cone,

text: lava flows

text: pyroclastic flow

text: deposits, and strata of

text: tephra

text: , and volcanic ash, are easily visible.

text: Potassium-argon dating

text: of deposits in the cone suggests that Thielsen is at least 290,000 years old. Since its eruption stopped about 250,000 to 100,000 years ago, the period of eruptive activity was short in time. The eruptions of the cone came in three phases: a period where lava flows built up its cone, one where more explosive pyroclastic eruptions took place, and the final period, in which pyroclastic and material of lava-based origin were erupted together forming a weak cone encircled by long deposits.

text: Pitted terrain has been observed in four craters on Vesta: Marcia, Cornelia, Numisia and Licinia. The formation of the pitted terrain is proposed to be degassing of impact-heated volatile-bearing material. Along with the pitted terrain, curvilinear gullies are found in Marcia and Cornelia craters. The curvilinear gullies end in lobate deposits, which are sometimes covered by pitted terrain, and are proposed to form by the transient flow of liquid water after buried deposits of ice were melted by the heat of the impacts. Hydrated materials have also been detected, many of which are associated with areas of dark material. Consequently, dark material is thought to be largely composed of carbonaceous chondrite, which was deposited on the surface by impacts. Carbonaceous chondrites are comparatively rich in mineralogically bound OH.

text: In some river and stream systems, small streams join together and redivide in many places. Such stream systems are said to be braided. These are often found in alluvial fans at the outlet of canyons. This is a result of heavy sediment deposition at high flows followed by re-erosion at low flows. See also river delta.

text: In some river and stream systems, small streams join together and redivide in many places. Such stream systems are said to be

text: braided

text: . These are often found in

text: alluvial fan

text: s at the outlet of

text: canyon

text: s. This is a result of heavy

text: sediment

text: deposition at high flows followed by re-erosion at low flows. See also

text: river delta

text: Deserts are formed by weathering processes as large variations in temperature between day and night put strains on the rocks which consequently break in pieces. Although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter and the resulting fragments and rubble strewn over the desert floor is further eroded by the wind. This picks up particles of sand and dust and wafts them aloft in sand or dust storms. Wind-blown sand grains striking any solid object in their path can abrade the surface. Rocks are smoothed down, and the wind sorts sand into uniform deposits. The grains end up as level sheets of sand or are piled high in billowing sand dunes. Other deserts are flat, stony plains where all the fine material has been blown away and the surface consists of a mosaic of smooth stones. These areas are known as desert pavements and little further erosion takes place. Other desert features include rock outcrops, exposed bedrock and clays once deposited by flowing water. Temporary lakes may form and salt pans may be left when waters evaporate. There may be underground sources of water in the form of springs and seepages from aquifers. Where these are found, oases can occur.

text: Deserts are formed by

text: weathering

text: processes as large variations in temperature between day and night put strains on the rocks which consequently break in pieces. Although rain seldom occurs in deserts, there are occasional downpours that can result in flash floods. Rain falling on hot rocks can cause them to shatter and the resulting fragments and rubble strewn over the desert floor is further eroded by the wind. This picks up particles of sand and dust and wafts them aloft in sand or

text: dust storm

text: s. Wind-blown sand grains striking any solid object in their path can abrade the surface. Rocks are smoothed down, and the wind sorts sand into uniform deposits. The grains end up as level sheets of sand or are piled high in billowing sand dunes. Other deserts are flat, stony

text: plain

text: s where all the fine material has been blown away and the surface consists of a

text: mosaic

text: of smooth stones. These areas are known as

text: desert pavement

text: s and little further

text: erosion

text: takes place. Other desert features include rock outcrops, exposed bedrock and clays once deposited by flowing water. Temporary lakes may form and salt pans may be left when waters evaporate. There may be underground sources of water in the form of springs and seepages from

text: aquifer

text: s. Where these are found,

text: oases

text: can occur.

text: The official RusHydro assessment, however, was deemed overly optimistic by the opposition. The dam, which has no major flood control structures upstream, must bear the brunt of spring freshets, and due to a snowy winter and late thaw, in the first week of June 2010 the amount of spring flood water influx was about twice the normal (peaking at 9,700 m/s on 5 June and expected to stay around 7,000 m/s throughout the second and third weeks of June). Due to the August 2009 accident, only 2 out of 10 turbines were operable and capable of routing only 690 m/s of water. Consequently, most of the water influx into the reservoir must be drained through a poorly designed spillway, which previously had already suffered extensive damage as a result of spring floods in 1985 and 1988. As of 8 June, drainage through the spillway was roughly 5,000 m/s. While it would be possible to increase the spillway drain to 7,000—7,500 m/s, such operation was previously deemed unsafe to the structure, and could result in further erosion of the dam's already weakened foundation even as the reservoir continues to fill. The damage would occur by direct impact of the falling water to the spill well (which, once its concrete slab lining were destroyed, would expose and erode the dam's bedrock support) as well as by intense vibrations created by the waterfall, which the concrete dam, lacking steel reinforcement, is not designed to withstand for prolonged periods. To that date, only one section of the bypass spillway had been completed, and was capable of routing only 2,000 m/s of water, meaning that the main spillway, probably already worn and torn from the 2009 winter's heavy ice deposition on the dam, must continue to be operated for some time before repairs would be possible.

text: The official RusHydro assessment, however, was deemed overly optimistic by the opposition. The dam, which has no major flood control structures upstream, must bear the brunt of spring

text: freshet

text: The primary coupling between groundwater and hydrological inputs is the unsaturated zone or vadose zone.  The soil acts to partition hydrological inputs such as rainfall or snowmelt into surface runoff, soil moisture, evapotranspiration and groundwater recharge.  Flows through the unsaturated zone that couple surface water to soil moisture and groundwater can be upward or downward, depending upon the gradient of hydraulic head in the soil, can be modeled using the numerical solution of Richards' equation  partial differential equation, or the ordinary differential equation Finite Water-Content method  as validated for modeling groundwater and vadose zone interactions.

text: The primary coupling between groundwater and hydrological inputs is the

text: unsaturated zone

text: or

text: vadose zone

text: .  The soil acts to partition hydrological inputs such as rainfall or snowmelt into

text: surface runoff

text: soil moisture

text: evapotranspiration

text: and

text: groundwater recharge

text: .  Flows through the

text: unsaturated zone

text: that couple surface water to

text: soil moisture

text: and

text: groundwater

text: can be upward or downward, depending upon the gradient of

text: hydraulic head

text: in the soil, can be modeled using the numerical solution of

text: Richards' equation

text: partial differential equation, or the ordinary differential equation Finite Water-Content method  as validated for modeling

text: groundwater

text: and

text: vadose zone

text: interactions.

text: A dam was built upstream of the waterfalls on the Ganoga Glen branch of Kitchen Creek in 1842. Ricketts strengthened the dam circa 1905 as part of a hydroelectric power generation scheme, and renamed the body of water Lake Rose (Rose is a Ricketts family name). However, both the Lake Rose and Lake Leigh dams were "poorly constructed" and could not be used to generate power; both dams were condemned by the state and Lake Rose was drained in 1969. Ganoga Glen is not as steep as Glen Leigh; both glens are almost entirely in the Huntley Mountain Formation, with a small region at the southern end, including Waters Meet, in the Catskill Formation. Ganoga Glen has ten named waterfalls in 1.1 miles (1.8 km). It is 1.8 miles (2.9 km) from PA 118 in the south to Waters Meet and the southern end of Ganoga Glen. From the north, it is 0.3 miles (0.48 km) from the Lake Rose trailhead parking lot by Lake Jean to Mohawk, the northernmost waterfall. There is also the 2.8-mile (4.5 km) Ganoga View Trail, which leads from Pennsylvania Route 487 in the west to Ganoga Falls. The Highland Trail, which meets the Falls Trail a short distance north of Mohawk Falls, is the 1.2-mile (1.9 km) connector between the northern ends of Ganoga Glen and Glen Leigh.

text: In one experiment, water runoff and soil loss on a 14% slope was compared for rototilled (RT), no-till with corn stover mulch (NTCMS), no-till in CSM+ birdsfoot trefoil living mulch (NT-BFT) and no till in CSM and crownvetch living mulch (NT-CV). The results indicated that the water runoff was 6,350 L ha-1 for NT-BFT, 6,350 L ha-1 NO-CSM, 5,925 L ha-1 for NT-CV, and 145,000 L ha-1 for RT. The soil loss for the RT was 14.22 t ha-1 while with the other treatments it was less than 0.5 tons ha-1. The least soil loss was obtained with NT-CV 0.02 tons ha-1. The reduction of water runoff and erosion is one of the greatest advantages of having a cover crop. Soil can be easily eroded with no vegetative ground cover or plant residue. Ideally soil erosion should be less than 4 to 5 tons/ha/year.

text: As for the next theory, much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smoothes the land, but in places it has a bumpy texture, resembling the surface of a basketball. The mantle may be like a glacier and under certain conditions the ice that is mixed in the mantle could melt and flow down the slopes and make gullies.  Because there are few craters on this mantle, the mantle is relatively young. An excellent view of this mantle is shown below in the picture of the Ptolemaeus Crater Rim, as seen by HiRISE.The ice-rich mantle may be the result of climate changes. Changes in Mars's orbit and tilt cause significant changes in the distribution of water ice from polar regions down to latitudes equivalent to Texas. During certain climate periods water vapor leaves polar ice and enters the atmosphere. The water comes back to ground at lower latitudes as deposits of frost or snow mixed generously with dust. The atmosphere of Mars contains a great deal of fine dust particles. Water vapor will condense on the particles, then fall down to the ground due to the additional weight of the water coating. When Mars is at its greatest tilt or obliquity, up to 2 cm of ice could be removed from the summer ice cap and deposited at midlatitudes. This movement of water could last for several thousand years and create a snow layer of up to around 10 meters thick. When ice at the top of the mantling layer goes back into the atmosphere, it leaves behind dust, which insulating the remaining ice.  Measurements of altitudes and slopes of gullies support the idea that snowpacks or glaciers are associated with gullies.  Steeper slopes have more shade which would preserve snow.Higher elevations have far fewer gullies because ice would tend to sublimate more in the thin air of the higher altitude.  Very few gullies are found in the Thaumasia region; however, a few are present in the lower elevations like the one pictured below in Ross Crater.

text: As for the next theory, much of the surface of Mars is covered by a thick smooth mantle that is thought to be a mixture of ice and dust. This ice-rich mantle, a few yards thick, smoothes the land, but in places it has a bumpy texture, resembling the surface of a basketball. The mantle may be like a glacier and under certain conditions the ice that is mixed in the mantle could melt and flow down the slopes and make gullies.  Because there are few craters on this mantle, the mantle is relatively young. An excellent view of this mantle is shown below in the picture of the Ptolemaeus Crater Rim, as seen by

text: HiRISE

text: Ross Crater

text: The original Khoikhoi people named the waterfall Ankoerebis, meaning the "place of big noises". The Trekboers who later settled in the area derived the name Augrabies. The name is sometimes spelt Aughrabies. There are many deposits of alluvial diamonds along the Orange River and legend has it that the biggest cache of diamonds in the world lies in the swirl-hole eroded into the granite at the foot of the waterfall by the thundering waters.

text: The original

text: Khoikhoi

text: people named the waterfall Ankoerebis, meaning the "place of big noises". The

text: Trekboers

text: who later settled in the area derived the name Augrabies. The name is sometimes spelt Aughrabies. There are many deposits of alluvial diamonds along the Orange River and legend has it that the biggest cache of diamonds in the world lies in the swirl-hole eroded into the granite at the foot of the waterfall by the thundering waters.

text: As the highlands erode due to weathering and water flow, the sediment from the hills is transported to the lower plain. Various creeks will carry the water further to a river, lake, bay, or ocean. As the sediments are deposited during flood conditions in the floodplain of a creek, the elevation of the floodplain will be raised. As this reduces the channel floodwater capacity, the creek will, over time, seek new, lower paths, forming a meander (a curving sinuous path). The leftover higher locations, typically natural levees at the margins of the flood channel, will themselves be eroded by lateral stream erosion and from local rainfall and possibly wind transport if the climate is arid and does not support soil-holding grasses. These processes, over geologic time, will form the plain, a region with little relief (local changes in elevation), yet with a constant but small slope.

text: As the highlands

text: erode

text: due to

text: weathering

text: and water flow, the

text: sediment

text: from the hills is

text: transported

text: to the lower

text: plain

text: . Various

text: creek

text: s will carry the water further to a river,

text: lake

text: bay

text: , or

text: ocean

text: . As the sediments are deposited during flood conditions in the

text: floodplain

text: of a creek, the elevation of the floodplain will be raised. As this reduces the channel floodwater capacity, the creek will, over time, seek new, lower paths, forming a

text: meander

text: (a curving sinuous path). The leftover higher locations, typically natural

text: levee

text: s at the margins of the flood channel, will themselves be eroded by lateral stream erosion and from local rainfall and possibly wind transport if the climate is arid and does not support soil-holding grasses. These processes, over geologic time, will form the plain, a region with little

text: relief

text: (local changes in elevation), yet with a constant but small slope.

text: Gathering of erosion products near the concave bank and transporting them to the convex bank is the work of the secondary flow across the floor of the river in the vicinity of a river bend. The process of deposition of silt, sand and gravel on the convex bank is clearly illustrated in point bars.

text: Gathering of erosion products near the concave bank and transporting them to the convex bank is the work of the

text: secondary flow

text: across the floor of the river in the vicinity of a river bend. The process of deposition of silt, sand and gravel on the convex bank is clearly illustrated in

text: point bar

text: s.

text: The Water Erosion Prediction Project (WEPP) Model is a physically based erosion simulation model built on the fundamentals of hydrology, plant science, hydraulics, and erosion mechanics. The model was developed by an interagency team of scientists to replace the Universal Soil Loss Equation (USLE) and has been widely used in the United States and the world. WEPP requires four inputs, i.e., climate, topography, soil, and management (vegetation); and provides various types of outputs, including water balance (surface runoff, subsurface flow, and evapotranspiration), soil detachment and deposition at points along the slope, sediment delivery, and vegetation growth. The WEPP model has been improved continuously since its public delivery in 1995, and is applicable for a variety of areas (e.g., cropland, rangeland, forestry, fisheries, and surface coal mining).

text: The Water Erosion Prediction Project (WEPP) Model is a

text: physically based

text: erosion

text: simulation model built on the fundamentals of

text: hydrology

text: plant science

text: hydraulics

text: , and

text: erosion

text: mechanics. The model was developed by an interagency team of scientists to replace the

text: Universal Soil Loss Equation

text: (USLE) and has been widely used in the United States and the world. WEPP requires four inputs, i.e.,

text: climate

text: topography

text: soil

text: , and management (

text: vegetation

text: ); and provides various types of outputs, including

text: water balance

text: surface runoff

text: subsurface flow

text: , and

text: evapotranspiration

text: soil detachment

text: and

text: deposition

text: at points along the slope,

text: sediment delivery

text: , and vegetation growth. The WEPP model has been improved continuously since its public delivery in 1995, and is applicable for a variety of areas (e.g.,

text: cropland

text: rangeland

text: forestry

text: fisheries

text: , and surface

text: coal mining

text: Extending north of Mount Meager almost to the Interior Plateau are the Bridge River Cones. This group of small volcanoes on the upper Bridge River includes stratovolcanoes, volcanic plugs and lava flows. These volcanoes are unlike others throughout the Garibaldi Belt in that they are mainly composed of volcanic rocks with mafic compositions, including alkaline basalt and hawaiite. The different magma compositions might be related to a smaller degree of partial melting in the Earth's mantle or a descending plate edge effect. The oldest volcano in the group, known as Sham Hill, is a  high volcanic plug with a potassium-argon date of one million years. It is about  wide and its uncovered glaciated surface is strewn with glacial erratics. Its massive level rock columns were constructed inside the main volcanic vent of a stratovolcano that has since been reduced by erosion. To the southeast, the Salal Glacier volcanic complex was constructed between 970,000 and 590,000 years ago. It consists of subaerial tephra and thin lava flow deposits that are surrounded by  thick ice-ponded lava flows. These ice-marginal lava flows were created when lava ponded against glacial ice in the nearby valleys before the Wisconsin Glaciation. North of the Salal Glacier complex lies a small basaltic stratovolcano named Tuber Hill. It began to form about 600,000 years ago when adjacent valleys were filled by glacial ice. When lava flows were erupted from Tuber Hill, they interacted with the valley-filling glaciers on its southern flank and produced a glacial meltwater lake. Here, more than  of stacked hyaloclastite, lahars and lacustrine tuff were deposited. A series of pillow lavas were also deposited during this eruptive period. The most recent volcanic activity in the Bridge River volcanic field produced a series of basaltic lava flows in the regional valleys that overlie till of the last glacial period. The age of these valley-filling lava flows is unknown but the presence of unconsolidated glacial till under the flows suggests that they are less than 1,500 years old.

text: Extending north of Mount Meager almost to the

text: Interior Plateau

text: are the

text: Bridge River Cones

text: . This group of small volcanoes on the upper

text: Bridge River

text: includes stratovolcanoes, volcanic plugs and lava flows. These volcanoes are unlike others throughout the Garibaldi Belt in that they are mainly composed of volcanic rocks with mafic compositions, including

text: alkaline

text: basalt and

text: hawaiite

text: . The different magma compositions might be related to a smaller degree of

text: partial melting

text: in the Earth's

text: mantle

text: or a descending plate edge effect. The oldest volcano in the group, known as

text: Sham Hill

text: , is a  high volcanic plug with a

text: potassium-argon date

text: of one million years. It is about  wide and its uncovered glaciated surface is strewn with glacial erratics. Its massive level

text: rock column

text: s were constructed inside the main volcanic vent of a stratovolcano that has since been reduced by erosion. To the southeast, the

text: Salal Glacier volcanic complex

text: was constructed between 970,000 and 590,000 years ago. It consists of subaerial

text: tephra

text: and thin lava flow deposits that are surrounded by  thick ice-ponded lava flows. These ice-marginal lava flows were created when lava ponded against glacial ice in the nearby valleys before the

text: Wisconsin Glaciation

text: . North of the Salal Glacier complex lies a small basaltic stratovolcano named

text: Tuber Hill

text: . It began to form about 600,000 years ago when adjacent valleys were filled by glacial ice. When lava flows were erupted from Tuber Hill, they interacted with the valley-filling glaciers on its southern flank and produced a glacial

text: meltwater

text: lake. Here, more than  of stacked hyaloclastite,

text: lahar

text: s and lacustrine tuff were deposited. A series of pillow lavas were also deposited during this eruptive period. The most recent volcanic activity in the Bridge River volcanic field produced a series of basaltic lava flows in the regional valleys that overlie till of the

text: last glacial period

text: . The age of these valley-filling lava flows is unknown but the presence of unconsolidated glacial till under the flows suggests that they are less than 1,500 years old.

text: There are two kinds of flow structures: bidirectional (multiple directions, back-and-forth) and unidirectional.  Flow regimes in single-direction (typically fluvial) flow, which at varying speeds and velocities produce different structures, are called bedforms.  In the lower flow regime, the natural progression is from a flat bed, to some sediment movement (saltation etc.), to ripples, to slightly larger dunes.  Dunes have a vortex in the lee side of the dune.  As the upper flow regime forms, the dunes become flattened out, and then produce antidunes.  At higher still velocity, the antidunes are flattened and most sedimentation stops, as erosion takes over as the dominant process.

text: There are two kinds of flow structures: bidirectional (multiple directions, back-and-forth) and unidirectional.  Flow regimes in single-direction (typically

text: fluvial

text: ) flow, which at varying speeds and velocities produce different structures, are called

text: bedform

text: s.  In the lower flow regime, the natural progression is from a flat bed, to some sediment movement (

text: saltation

text: etc.), to ripples, to slightly larger dunes.  Dunes have a vortex in the lee side of the dune.  As the upper flow regime forms, the dunes become flattened out, and then produce

text: antidune

text: s.  At higher still velocity, the antidunes are flattened and most sedimentation stops, as erosion takes over as the dominant process.

text: As an example study of soils erosion, calculations would be made of surface runoff by soil scientists. Fluvial geomorphologists would assist in examining sediment transport in overland flow. Physicists would contribute by assessing the changes in light transmission in the receiving waters. Biologists would analyze subsequent impacts to aquatic flora and fauna from increases in water turbidity.

text: As an example study of soils

text: erosion

text: , calculations would be made of

text: surface runoff

text: by soil scientists. Fluvial geomorphologists would assist in examining

text: sediment transport

text: in overland flow. Physicists would contribute by assessing the changes in light transmission in the receiving waters. Biologists would analyze subsequent impacts to aquatic flora and fauna from increases in water turbidity.

text: Erosion of the seafloor contributes to the growth of a deepwater nepheloid layer. This layer plays a key role in supplying the sediment for the deposition of contourites under appropriate flow conditions.

text: Erosion of the seafloor contributes to the growth of a deepwater

text: nepheloid layer

text: . This layer plays a key role in supplying the sediment for the deposition of contourites under appropriate flow conditions.

text: On December 6, 2006, MSSS announced that it had discovered evidence that liquid water had likely flowed on Mars within the past five years. At a press conference, NASA showed images taken by the Mars Global Surveyor that suggested that water occasionally flows on the surface of Mars. The images did not actually show flowing water. Rather, they showed changes in craters and sediment deposits, providing the strongest evidence yet that water coursed through them as recently as several years ago, and is perhaps doing so even now. The findings were published in the December 8, 2006 issue of the journal Science.

text: On December 6, 2006, MSSS announced that it had discovered evidence that liquid water had likely flowed on

text: Mars

text: within the past five years. At a press conference,

text: NASA

text: showed images taken by the

text: Mars Global Surveyor

text: that suggested that water occasionally flows on the surface of Mars. The images did not actually show flowing water. Rather, they showed changes in craters and sediment deposits, providing the strongest evidence yet that water coursed through them as recently as several years ago, and is perhaps doing so even now. The findings were published in the December 8, 2006 issue of the journal

text: Science

text: The Menuha Formation records the earliest occurrence of tectonic activity within the Ramon anticline, forming the present erosive valley known as "Makhtesh Ramon" as an outcome of a sequence of erosive events evolving since the Late Cretaceous (Avni, 1993). It consists of white and yellow/brown chalk that is often glauconitic and sometimes conglomeratic or marly. The Menuha Formation likely represents a temperate to subtropical, open shelf environment deposited during the formation of the Ramon anticline. Reworked conglomeratic chalks in the western section represent marginal facies derived from this structural uplift.

text: The Menuha Formation records the earliest occurrence of tectonic activity within the Ramon anticline, forming the present erosive valley known as "

text: Makhtesh Ramon

text: " as an outcome of a sequence of erosive events evolving since the

text: Late Cretaceous

text: (Avni, 1993). It consists of white and yellow/brown chalk that is often glauconitic and sometimes conglomeratic or marly. The Menuha Formation likely represents a temperate to subtropical, open shelf environment deposited during the formation of the Ramon anticline. Reworked conglomeratic chalks in the western section represent marginal facies derived from this structural uplift.

text: Tides often determine the range over which sediment is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however, tidal bores can erode as the waves surge up river estuaries from the ocean.

text: Tide

text: s often determine the range over which

text: sediment

text: is deposited or eroded. Areas with high tidal ranges allow waves to reach farther up the shore, and areas with lower tidal ranges produce deposition at a smaller elevation interval. The tidal range is influenced by the size and shape of the coastline. Tides do not typically cause erosion by themselves; however,

text: tidal bore

text: s can erode as the waves surge up river

text: estuaries

text: from the ocean.

text: In the July–September period, flood water from the Yangtze flows into the lake, enlarging it greatly. The lake's area, which normally is  (data before 1998), may increase to  in flood season, when vast amounts of water and sediment from the Chang Jiang flow into the lake.  The lake is also fed by four major rivers: the Xiang (湘), Zi (资), Yuan (沅) and Li (澧) rivers. Small rivers also flow in, the most famous one being Miluo River where a famous poet Qu Yuan committed suicide. In addition, the Xiao River (瀟) flows into the Xiang near Yongzhou, before the Xiang flows into the lake. Ocean-going vessels can travel through the Xiang to reach Changsha.

text: In the July–September period, flood water from the

text: Yangtze

text: flows into the lake, enlarging it greatly. The lake's area, which normally is  (data before 1998), may increase to  in flood season, when vast amounts of water and sediment from the Chang Jiang flow into the lake.  The lake is also fed by four major rivers: the

text: Xiang

text: (湘),

text: Zi

text: (资),

text: Yuan

text: (沅) and

text: Li

text: (澧) rivers. Small rivers also flow in, the most famous one being

text: Miluo River

text: where a famous poet

text: Qu Yuan

text: committed suicide. In addition, the

text: Xiao River

text: (瀟) flows into the Xiang near

text: Yongzhou

text: , before the Xiang flows into the lake. Ocean-going vessels can travel through the Xiang to reach

text: Changsha

text: The parish of Andés is located on the coastal plateau and is wedged between the Veiga d'Arenas and Frejulfe beaches, locations where the Navia and Frejulfe rivers, respectively, empty into the sea. This plain is fragmented by several rivulets, which are born near the coast, resulting in small valleys with gentle slopes. At its mouth there are small and beautiful beaches with calm waters. Some of these rivulets flow into the sea forming jets of water several meters high due to the limited erosive capacity of the flow and steady decline of the waterfront. The Rubreves, La Bragada, La Rubias, Las Cortías, La Xertal and Cereizo rivulets run from south to north, are short-haul and flow into the sea. The Travesedo Brook runs from east to west, ending at the Poza de Veiga d'Arenas. The Paderne stream, which exceeds two kilometers, also runs east-west, empties into the river Navia and in its last section it is called the Olga Faquina River.

text: Waterfall has formed on the basalt rocks of Serra Geral formation and has two cascades. Upper cascade is located approximately 100 m before the second cascade, which falls over an overhanging cliff ledge.

text: Damage to vegetation and the concentration of surface water from increased flows as a result of clearing for urban development, is a cause of erosion and sedimentation. Tracks for walking and the use of off road vehicles are also impacting the soils and contributing to their degradation. These types of activities can lead to the compaction of the soils around and within the swamp communities.

text: Damage to

text: vegetation

text: and the concentration of surface water from increased flows as a result of clearing for urban development, is a cause of erosion and sedimentation. Tracks for walking and the use of off road vehicles are also impacting the soils and contributing to their degradation. These types of activities can lead to the compaction of the soils around and within the swamp communities.

text: Rivers carry sediment down their riverbeds, allowing for the formation of depositional features such as river deltas, alluvial fans, braided rivers, oxbow lakes, levees and coastal shores. The construction of a dam blocks the flow of sediment downstream, leading to downstream erosion of these Sedimentary depositional environments, and increased sediment build-up in the reservoir. While the rate of sedimentation varies for each dam and each river, eventually all reservoirs develop a reduced water-storage capacity due to the exchange of storage space for sediment. Diminished storage capacity results in decreased ability to produce hydroelectric power, reduced availability of water for irrigation, and if left unaddressed, may ultimately result in the expiration of the dam and river.

text: A powder snow avalanche is a type of avalanche where the snow grains are largely or wholly suspended by fluid turbulence. They are particle-laden gravity currents and closely related to turbidity currents, pyroclastic flows from volcanoes and dust storms in the desert. The turbulence is typically generated by the forward motion of the current along the lower boundary of the domain, the motion being in turn driven by the action of gravity on the density difference between the particle-fluid mixture and the ambient fluid. The ambient fluid is generally of similar composition to (and miscible with) the interstitial fluid, and is water for turbidity currents and air for avalanches. These flows are non-conservative in that they may exchange particles at the lower boundary by deposition or  suspension, and may exchange fluid with the ambient by entrainment or detrainment. Such flows dissipate when the turbulence can no longer hold the particles in suspension and they are deposited on the lower boundary. When the turbulence is strong enough to suspend new material from the bed or the underlying dense flow then current is said to be auto-suspending. Particle concentrations in the suspension cloud are usually sufficiently low (0.1--7\,\% by volume) that particle-particle interactions play a small or negligible role in maintaining the suspension. In powder snow avalanches, even at these low concentrations, the extra density of the suspended particles is large relative to that of air, so the Boussinesq approximation, where density differences are considered negligible in inertia terms, is invalid, so that the snow grains carry most of the flows momentum. This is in contrast to turbidity currents and laboratory experiments in water where the extra inertia of the particles can usually be neglected. Nonetheless, due to the extreme difficulty in estimating particle concentrations in natural flows there remains considerable uncertainty --- and debate --- concerning the particle loading in large submarine turbidity currents and the validity of the Boussinesq approximation.

text: A powder snow avalanche is a type of

text: avalanche

text: where the snow grains are largely or wholly suspended by fluid turbulence. They are particle-laden gravity currents and closely related to

text: turbidity current

text: s,

text: pyroclastic flow

text: s from

text: volcanoes

text: and

text: dust storm

text: Periodically, velocities may increase dramatically or even reverse due to atmospheric storms raising the local surface eddy kinetic energy, which gets partially transmitted down to abyssal depths in episodes called benthic storms. These velocities may reach magnitudes well above 40 cm/s and vary significantly depending on the specific location. At the lower continental rise, south of Halifax, Nova Scotia, and at the lower slope around the Faeroe Islands these velocities may reach up to 73 cm/s and 75 cm/s, respectively. Bottom-current flow velocities have been measured as high as 300 cm/s in the Strait of Gibraltar. These benthic storms occur only 5 to 10 times per year and usually last between 3 and 5 days, but that is enough to heavily erode benthic sediment and keep the finer grains in suspension even after flow velocities return to normal and the bedload has been deposited. During benthic storms, the eroded sediment may be transported over thousands of kilometers and deposited rather quickly (i.e. ~1.5 cm/month) once the storm wanes. However, the net sedimentation rate over thousands of years may be much smaller (i.e. ~5.5 cm/year) due to the intense periods of erosion during benthic storms.

text: Periodically, velocities may increase dramatically or even reverse due to

text: atmospheric storms

text: raising the local

text: surface eddy kinetic energy

text: , which gets partially transmitted down to

text: abyssal

text: depths in episodes called

text: benthic storms

text: . These velocities may reach magnitudes well above 40 cm/s and vary significantly depending on the specific location. At the lower continental rise, south of

text: Halifax, Nova Scotia

text: , and at the lower slope around the

text: Faeroe Islands

text: these velocities may reach up to 73 cm/s and 75 cm/s, respectively. Bottom-current flow velocities have been measured as high as 300 cm/s in the

text: Strait of Gibraltar

text: . These benthic storms occur only 5 to 10 times per year and usually last between 3 and 5 days, but that is enough to heavily erode benthic sediment and keep the finer grains in suspension even after flow velocities return to normal and the bedload has been deposited. During benthic storms, the eroded sediment may be transported over thousands of kilometers and deposited rather quickly (i.e. ~1.5 cm/month) once the storm wanes. However, the net sedimentation rate over thousands of years may be much smaller (i.e. ~5.5 cm/year) due to the intense periods of erosion during benthic storms.

text: In aeolian processes, wind transports and deposits particles of sediment. Aeolian features form in areas where wind is the primary source of erosion. The particles deposited are of sand, silt and clay size. The particles are entrained in by one of four processes. Creep occurs when a particle rolls or slides across the surface. Lift occurs when a particle rises off the surface due to the Bernoulli effect. If the airflow is turbulent, larger particles are transported by a process known as saltation. Finally, impact transport occurs which one particle strikes another causing the second particle to move.

text: In

text: aeolian processes

text: , wind transports and deposits particles of

text: sediment

text: . Aeolian features form in areas where wind is the primary source of

text: erosion

text: . The particles deposited are of

text: sand

text: silt

text: and

text: clay

text: size. The particles are entrained in by one of four processes. Creep occurs when a particle rolls or slides across the surface. Lift occurs when a particle rises off the surface due to the

text: Bernoulli effect

text: . If the airflow is

text: turbulent

text: , larger particles are transported by a process known as

text: saltation

text: . Finally, impact transport occurs which one particle strikes another causing the second particle to move.

text: The entire area is covered by the Deccan Traps lava flows of Upper Cretaceous to Lower Eocene age. The lava flows are overlain by thin alluvial deposits along the Kham and Sukhana river. The basaltic lava flows belonging to the Deccan Trap is the only major geological formation occurring in Aurangabad. The lava flows are horizontal and each flow has two distinct units. The upper layers consist of vesiculara and amygdaloidal zeolitic basalt while the bottom layer consists of massive basalt.The lava flows are individually different in their ability to receive as well as hold water in storage and to transmit it. The difference in the productivity of groundwater in various flows arises as a result of their inherent physical properties such as porosity and permeability. The groundwater occurs under water table conditions and is mainly controlled by the extent of its secondary porosity i.e. thickness of weathered rocks and spacing of joints and fractures. The highly weathered vesicular trap and underlying weathered jointed and fractured massive trap constitutes the main water yielding zones. The soil is mostly formed from igneous rocks and are black, medium black, shallow and calcareous types having different depths and profiles.

text: The entire area is covered by the

text: Deccan Traps

text: lava flows of

text: Upper Cretaceous

text: to

text: Lower Eocene

text: age. The lava flows are overlain by thin alluvial deposits along the Kham and Sukhana river. The basaltic lava flows belonging to the Deccan Trap is the only major geological formation occurring in Aurangabad. The lava flows are horizontal and each flow has two distinct units. The upper layers consist of

text: vesicular

text: a and

text: amygdaloidal

text: zeolitic

text: basalt

text: while the bottom layer consists of massive basalt.The lava flows are individually different in their ability to receive as well as hold water in storage and to transmit it. The difference in the productivity of groundwater in various flows arises as a result of their inherent physical properties such as porosity and permeability. The groundwater occurs under water table conditions and is mainly controlled by the extent of its secondary porosity i.e. thickness of weathered rocks and spacing of joints and fractures. The highly weathered vesicular trap and underlying weathered jointed and fractured massive trap constitutes the main water yielding zones. The soil is mostly formed from igneous rocks and are black, medium black, shallow and calcareous types having different depths and profiles.

text: The view that radiolarites are mainly deposited under pelagic, deep water conditions cannot be asserted any longer. Layers enriched in radiolarians do even occur in shallow water limestones like the Solnhofen limestone and the Werkkalk Formation of Bavaria. What seems to be important for the preservation of radiolarian oozes is that they are deposited well below the storm wave base and below the jets of erosive surface currents. Radiolarites without any carbonates have most likely been sedimented below the calcite compensation depth (CCD). One has to bear in mind that the CCD has not been stationary in the geological past and that it is also a function of latitude. At present, the CCD reaches a maximum depth of about 5000 meters near the equator.

text: The view that radiolarites are mainly deposited under

text: pelagic

text: , deep water conditions cannot be asserted any longer. Layers enriched in radiolarians do even occur in shallow water

text: limestone

text: s like the

text: Solnhofen limestone

text: and the

text: Werkkalk Formation

text: of

text: Bavaria

text: . What seems to be important for the preservation of radiolarian oozes is that they are deposited well below the storm wave base and below the jets of erosive surface currents. Radiolarites without any carbonates have most likely been sedimented below the

text: calcite compensation depth

text: (CCD). One has to bear in mind that the CCD has not been stationary in the geological past and that it is also a function of

text: latitude

text: . At present, the CCD reaches a maximum depth of about 5000 meters near the

text: equator

text: In some areas of the world (e.g. the mid-western USA), rainfall intensity is the primary determinant of erosivity, with higher intensity rainfall generally resulting in more soil erosion by water. The size and velocity of rain drops is also an important factor. Larger and higher-velocity rain drops have greater kinetic energy, and thus their impact will displace soil particles by larger distances than smaller, slower-moving rain drops.

text: In some areas of the world (e.g. the

text: mid-western USA

text: ), rainfall intensity is the primary determinant of erosivity, with higher intensity rainfall generally resulting in more soil erosion by water. The size and velocity of

text: rain drop

text: s is also an important factor. Larger and higher-velocity rain drops have greater

text: kinetic energy

text: , and thus their impact will displace soil particles by larger distances than smaller, slower-moving rain drops.

text: Lucifuga is a genus of viviparous brotulas. Most of the species are native to caves and sinkholes in Cuba and the Bahamas; L. inopinata from deep water off the Galápagos Islands is the only exception. The four species rated by the IUCN are all considered vulnerable. The largest species in the genus reaches about  in length.

text: Lucifuga is a genus of

text: viviparous brotula

text: s. Most of the species are native to caves and

text: sinkhole

text: s in

text: Cuba

text: and

text: the Bahamas

text: ; L. inopinata from deep water off the

text: Galápagos Islands

text: is the only exception. The four species rated by the

entity_name: International Union for Conservation of Nature

text: IUCN

text: are all considered

text: vulnerable

text: . The largest species in the genus reaches about  in length.

text: Waterfalls are short-lived geological formations.  Their successful operation causes them to erode themselves out of existence, and they degenerate into rapids.  When Mackinac Falls was submerged, however, it ceased to erode.  The formation "froze" underwater in the form that it had been when it disappeared under the water of Lake Huron.

text: Unsustainable agricultural practices are the single greatest contributor to the global increase in erosion rates.The tillage of agricultural lands, which breaks up soil into finer particles, is one of the primary factors. The problem has been exacerbated in modern times, due to mechanized agricultural equipment that allows for deep plowing, which severely increases the amount of soil that is available for transport by water erosion. Others include mono-cropping, farming on steep slopes, pesticide and chemical fertilizer usage (which kill organisms that bind soil together), row-cropping, and the use of surface irrigation. A complex overall situation with respect to defining nutrient losses from soils, could arise as a result of the size selective nature of soil erosion events. Loss of total phosphorus, for instance, in the finer eroded fraction is greater relative to the whole soil. Extrapolating this evidence to predict subsequent behaviour within receiving aquatic systems, the reason is that this more easily transported material may support a lower solution P concentration compared to coarser sized fractions. Tillage also increases wind erosion rates, by dehydrating the soil and breaking it up into smaller particles that can be picked up by the wind. Exacerbating this is the fact that most of the trees are generally removed from agricultural fields, allowing winds to have long, open runs to travel over at higher speeds. Heavy grazing reduces vegetative cover and causes severe soil compaction, both of which increase erosion rates.

text: Unsustainable agricultural practices are the single greatest contributor to the global increase in erosion rates.The

text: tillage

text: of agricultural lands, which breaks up soil into finer particles, is one of the primary factors. The problem has been exacerbated in modern times, due to mechanized agricultural equipment that allows for

text: deep plowing

text: , which severely increases the amount of soil that is available for transport by water erosion. Others include

text: mono-cropping

text: , farming on steep slopes,

text: pesticide

text: and

text: chemical fertilizer

text: usage (which kill organisms that bind soil together), row-cropping, and the use of

text: surface irrigation

text: . A complex overall situation with respect to defining nutrient losses from soils, could arise as a result of the size selective nature of soil erosion events. Loss of total

text: phosphorus

text: , for instance, in the finer eroded fraction is greater relative to the whole soil. Extrapolating this evidence to predict subsequent behaviour within receiving aquatic systems, the reason is that this more easily transported material may support a lower solution P concentration compared to coarser sized fractions. Tillage also increases wind erosion rates, by dehydrating the soil and breaking it up into smaller particles that can be picked up by the wind. Exacerbating this is the fact that most of the trees are generally removed from agricultural fields, allowing winds to have long, open runs to travel over at higher speeds. Heavy

text: grazing

text: reduces vegetative cover and causes severe soil compaction, both of which increase erosion rates.

text: The waterfall is the beginning of the Gave de Pau stream. It is fed by a melting snow and a small glacier, located in Spain. This water seeps underground until it appears at the upper rim of waterfall. The average annual flow in the waterfall is 3 m/s. In summer, when the snowmelt is most intense, it can reach up to 200 m/s. In winter it sometimes freezes and stops flowing.

text: The waterfall is the beginning of the Gave de Pau stream. It is fed by a melting snow and a small glacier, located in

text: Spain

text: . This water seeps underground until it appears at the upper rim of waterfall. The average annual flow in the waterfall is 3 m/s. In summer, when the snowmelt is most intense, it can reach up to 200 m/s. In winter it sometimes freezes and stops flowing.

text: The Cenozoic is characterised by a further shallowing and erosion of earlier sediments. In places a reasonable thickness of Paleocene and Eocene sediments is reached, but most of the subsurface of the Netherlands lack deposits of this age.

text: The

text: Cenozoic

text: is characterised by a further shallowing and erosion of earlier sediments. In places a reasonable thickness of

text: Paleocene

text: and

text: Eocene

text: sediments is reached, but most of the subsurface of the Netherlands lack deposits of this age.

text: Detention vaults manage stormwater quantity flowing to nearby surface waters. They help prevent flooding and can reduce erosion in rivers and streams.  They do not provide treatment to improve water quality, though some are attached to a media filter bank to remove pollutants.

text: Detention vaults manage stormwater quantity flowing to nearby

text: surface water

text: s. They help prevent

text: flood

text: ing and can reduce

text: erosion

text: in rivers and streams.  They do not provide treatment to improve

text: water quality

text: , though some are attached to a

text: media filter

text: bank to remove pollutants.

text: The rocks of the Romerkhall Waterfall consist mainly of limestones. In the Upper Devonian, about 370 million years ago, the area was covered by a sea. It was divided into basins and ridges. Limes were deposited on the ridges, which were closer to the surface of the water (carbonatic threshold facies of the Upper Harz Upper Devonian). About 300 million years ago, the rocks were folded, sunk, metamophosed by intruding granites, later uplifted again, and then exposed by erosion. That is how this old limestone comes to form the rocks over which the waterfall drops as well as the Rabenklippe crags to the west. In the intervening Oker valley is argillaceous Kulm slate. There is a path up to the top of the waterfall on the hillside north of the rocks. At its foot, a few metres of dark slate-hornfels rocks of the Lower Carboniferous have been exposed. The waterfall rocks at the lookout platform consists of upper Devonian limestones, which are tectonically heavily deformed. About 290 million years ago, the molten Oker granite nearby hardened and overprinted all the nearby rocks in a process known as contact metamorphism.

text: The rocks of the Romerkhall Waterfall consist mainly of limestones. In the

text: Upper Devonian

text: , about 370 million years ago, the area was covered by a sea. It was divided into basins and ridges. Limes were deposited on the ridges, which were closer to the surface of the water (carbonatic threshold

text: facies

text: of the Upper Harz Upper Devonian). About 300 million years ago, the rocks were folded, sunk, metamophosed by intruding granites, later uplifted again, and then exposed by erosion. That is how this old limestone comes to form the rocks over which the waterfall drops as well as the Rabenklippe crags to the west. In the intervening Oker valley is argillaceous Kulm slate. There is a path up to the top of the waterfall on the hillside north of the rocks. At its foot, a few metres of dark slate-hornfels rocks of the

text: Lower Carboniferous

text: have been exposed. The waterfall rocks at the lookout platform consists of upper Devonian limestones, which are tectonically heavily deformed. About 290 million years ago, the molten Oker granite nearby hardened and overprinted all the nearby rocks in a process known as

text: contact metamorphism

text: d. The interbedding layers of fluvial sediments and basaltic lava bands imply that there was repeated occurrence of basaltic eruption and erosion and sedimentation of fluvial deposits alternatively. These events were probably caused by breaking up and rifting of Gondwanaland during the Late Jurassic to Early Cretaceous.

text: d. The interbedding layers of fluvial sediments and basaltic lava bands imply that there was repeated occurrence of basaltic eruption and

text: erosion

text: and

text: sedimentation

text: of fluvial deposits alternatively. These events were probably caused by breaking up and rifting of

text: Gondwana

text: land during the

text: Late Jurassic

text: to

text: Early Cretaceous

text: The formation, nine to eleven metres thick in total, contains two subdivisions, the Svarvare Mudstone Member, two to three metres thick, which is overlain by the Gannarve Siltstone Member, seven to eight metres in thickness.(This is also known as the Silte Siltstone, but does not form part of the Slite Group.)  The water depth was decreasing as the Gannarve member was deposited, so the member shows evidence of shallowing up. The formation is overlain with an oolite, which rests unconformably on an erosion surface – a sequence boundary – created at a time of low sea level. This erosional surface formed a flat – a rocky shore which was inundated by the sea at times, but was also subject to subaerial rainfall.  Calcium carbonate penetrated the underlying sediment (the top of the Gannarve member), altering the existing dolomitic siltstone.

text: The formation, nine to eleven metres thick in total, contains two subdivisions, the Svarvare Mudstone Member, two to three metres thick, which is overlain by the Gannarve Siltstone Member, seven to eight metres in thickness.(This is also known as the

text: Silte Siltstone

text: , but does not form part of the

text: Slite Group

text: .)  The water depth was decreasing as the Gannarve member was deposited, so the member shows evidence of shallowing up. The formation is overlain with an

text: oolite

text: , which rests

text: unconformably

text: on an erosion surface – a

text: sequence boundary

text: – created at a time of low sea level. This

text: erosional surface

text: formed a flat – a rocky shore which was inundated by the sea at times, but was also subject to subaerial rainfall.  Calcium carbonate penetrated the underlying sediment (the top of the Gannarve member), altering the existing dolomitic siltstone.

text: Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great distances through unseen aquifers. Non-porous aquifers such as clays partially purify water of bacteria by simple filtration (adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity; however, in some cases, the pollutants merely transform to soil contaminants. Groundwater that moves through open fractures and caverns is not filtered and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use natural sinkholes as dumps in areas of karst topography.

text: Groundwater pollution is much more difficult to abate than surface pollution because groundwater can move great distances through unseen

text: aquifer

text: s. Non-porous aquifers such as

text: clay

text: s partially purify water of bacteria by simple filtration (adsorption and absorption), dilution, and, in some cases, chemical reactions and biological activity; however, in some cases, the pollutants merely transform to

text: soil contaminant

text: s. Groundwater that moves through open

text: fractures

text: and

text: caverns

text: is not filtered and can be transported as easily as surface water. In fact, this can be aggravated by the human tendency to use natural

text: sinkhole

text: s as dumps in areas of

text: karst topography

text: Another characteristic of Mirusha Canyon is also the river erosion where during the process of the water flow, depending on the composition of the rocks, erodes, dissolves and carries erosive material.

text: Thermal erosion is the result of melting and weakening permafrost due to moving water. It can occur both along rivers and at the coast. Rapid river channel migration observed in the Lena River of Siberia is due to thermal erosion, as these portions of the banks are composed of permafrost-cemented non-cohesive materials. Much of this erosion occurs as the weakened banks fail in large slumps. Thermal erosion also affects the Arctic coast, where wave action and near-shore temperatures combine to undercut permafrost bluffs along the shoreline and cause them to fail. Annual erosion rates along a  segment of the Beaufort Sea shoreline averaged  per year from 1955 to 2002.

text: Thermal erosion is the result of melting and weakening

text: permafrost

text: due to moving water. It can occur both along rivers and at the coast. Rapid

text: river channel migration

text: observed in the

text: Lena River

text: of

text: Siberia

text: is due to thermal erosion, as these portions of the banks are composed of permafrost-cemented non-cohesive materials. Much of this erosion occurs as the weakened banks fail in large slumps. Thermal erosion also affects the

text: Arctic

text: coast, where wave action and near-shore temperatures combine to undercut permafrost bluffs along the shoreline and cause them to fail. Annual erosion rates along a  segment of the Beaufort Sea shoreline averaged  per year from 1955 to 2002.

text: Megafloods are paleofloods (past floods) that involved rates of water flow larger than those in the historical record. They are studied through the sedimentary deposits and the erosional and constructional landforms that individual megafloods have created. Floods that are known to us through historical descriptions are mostly related to meteorological events, such as heavy rains, rapid melting of snowpacks, or combination of these. In the geological past of the Earth, however, geological research has shown that much larger events have occurred. In the case of outburst floods, such floods are typically linked to the collapse of the barrier forming a lake. They fall in the following classification according to the mechanism responsible:

text: Megafloods are paleofloods (past floods) that involved rates of water flow larger than those in the historical record. They are studied through the

text: sedimentary deposits

text: and the erosional and constructional

text: landform

text: s that individual megafloods have created. Floods that are known to us through historical descriptions are mostly related to meteorological events, such as heavy rains, rapid melting of snowpacks, or combination of these. In the geological past of the Earth, however, geological research has shown that much larger events have occurred. In the case of outburst floods, such floods are typically linked to the collapse of the barrier forming a lake. They fall in the following classification according to the mechanism responsible:

text: Surface water is water in a river, lake or fresh water wetland.  Surface water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, evapotranspiration and groundwater recharge.

text: Surface water is water in a river,

text: lake

text: or fresh water

text: wetland

text: .  Surface water is naturally replenished by

text: precipitation

text: and naturally lost through discharge to the

text: oceans

text: evaporation

text: evapotranspiration

text: and

text: groundwater recharge

text: Tilkiler Cave, aka Tilkiler Sinkhole, ( aka Tilkiler Düdeni) is a cave located in Manavgat district of Antalya in southern Turkey. It is named after the nearby village Tilkiler.

text: Tilkiler Cave, aka Tilkiler Sinkhole, ( aka Tilkiler Düdeni) is a

text: cave

text: located in

text: Manavgat

text: district of

text: Antalya

text: in

text: southern Turkey

text: . It is named after the nearby village

text: Tilkiler

text: The geological monument has been called a "natural wonder".Its walls rise to a height of 80-100m. Rock formations are naturally carved with very unusual shapes of columns, towers and pyramids formed over centuries of erosion by rainwater. Study of the feature has revealed geological formations of gravel, quartz sands, and sandstones. The deposits are distinct "succession of red clays, grey and reddish soap-stones, friable white soap-stone." They all exhibit a reddish colour. Deep ravines are formed and during the rainy season the water flowing in the deep ravines is in the colour of the formation that is red; as the water falls into the ravines it makes a roaring sound.Râpa Roșie River flows in the vicinity.

text: The geological monument has been called a "natural wonder".Its walls rise to a height of 80-100m. Rock formations are naturally carved with very unusual shapes of columns, towers and pyramids formed over centuries of erosion by rainwater. Study of the feature has revealed geological formations of gravel, quartz sands, and sandstones. The deposits are distinct "succession of red clays, grey and reddish soap-stones, friable white soap-stone." They all exhibit a reddish colour. Deep ravines are formed and during the rainy season the water flowing in the deep ravines is in the colour of the formation that is red; as the water falls into the ravines it makes a roaring sound.

text: Râpa Roșie River

text: flows in the vicinity.

text: Between the individual lava flows may be beds of volcaniclastic sandstone, sedimentary deposits formed from the erosion of the volcanic rocks, and the map shows a small deposit of this near the summit of Sheffield Pike.

text: Between the individual lava flows may be beds of

text: volcaniclastic

text: sandstone, sedimentary deposits formed from the erosion of the volcanic rocks, and the map shows a small deposit of this near the summit of Sheffield Pike.

text: A hyperconcentrated flow is a two-phase flowing mixture of water and sediment in a channel which has properties intermediate between fluvial flow and debris flow. Large quantities of sand may be transported throughout the flow column, but the transport of suspended and bedload sediment along the channel depends on flow turbulence and high flow velocities, and coarser sediment remains as bedload. Hyperconcentrated flows do not show the characteristics of non-Newtonian flow typical of debris flows, e.g., levees, coarsening up or matrix supported deposits.

text: A hyperconcentrated flow is a two-phase flowing mixture of

text: water

text: and

text: sediment

text: in a channel which has properties intermediate between

text: fluvial

text: flow and

text: debris flow

text: . Large quantities of

text: sand

text: may be transported throughout the flow column, but the transport of

text: suspended

text: and

text: bedload

text: sediment along the channel depends on flow

text: turbulence

text: and high flow velocities, and coarser sediment remains as

text: bedload

text: . Hyperconcentrated flows do not show the characteristics of

text: non-Newtonian

text: flow typical of debris flows, e.g.,

text: levee

text: s,

text: coarsening up

text: or

text: matrix supported

text: deposits.

text: Another aspect in which Dams negatively impact the natural ecosystem deals with sediment erosion and sediment deposition. Specifically, the effects dams have on the natural flow of the river such as the natural pulses it has and as well its ability to transfer sediment else where. The fact that the river no longer flows like it used to shows that sediment is backing up. This makes sense because a dam is a large wall blocking the path of the water and sediment. Leaving the natural ecosystem without the benefits of a naturally working cycle of nutrients and water flow.

text: The construction of Shasta Dam and its afterbay (regulating downstream dam), Keswick Dam, in 1943 and 1950, respectively, severely impaired the capability of the Sacramento River to flush away pollutants from the mine. Acid mine drainage flowed, unfettered, down Spring Creek directly into the Keswick Reservoir, depositing contaminated sediment and turning a portion of the water a rusty red shade. Previously, the water would have continued down the creek into the river, and flushed to the Pacific Ocean. The pooling of the water, however, made it extremely difficult for the pollutants to be removed. From 1955 to 1962, open pit mining began on the site. At its peak, the mine discharged 5 tons of iron,  of copper, and  of zinc into the stream per day. By then, the water flowing down the drainage was so contaminated that it necessitated the construction of a holding dam, the Spring Creek Dam.

text: The construction of

text: Shasta Dam

text: and its afterbay (regulating downstream dam), Keswick Dam, in 1943 and 1950, respectively, severely impaired the capability of the Sacramento River to flush away pollutants from the mine.

text: Acid mine drainage

text: flowed, unfettered, down Spring Creek directly into the Keswick Reservoir, depositing contaminated sediment and turning a portion of the water a rusty red shade. Previously, the water would have continued down the creek into the river, and flushed to the

text: Pacific Ocean

text: . The pooling of the water, however, made it extremely difficult for the pollutants to be removed. From 1955 to 1962,

text: open pit mining

text: began on the site. At its peak, the mine discharged 5 tons of

text: iron

text: ,  of

text: copper

text: , and  of

text: zinc

text: into the stream per day. By then, the water flowing down the drainage was so contaminated that it necessitated the construction of a holding dam, the Spring Creek Dam.

text: In the middle of the bridge are sitting areas (where the historical markers are now placed) built during the construction of the bridge.  The outline of the sitting areas when viewed from the top, follows the shape of the central pier of the bridge where the eastward pointed end points toward the source of the river thus deflecting the flow of the incoming water to prevent erosion.  The center pier is about  long from the western tip to the point end.  The width of the central pier and the sitting areas is about .

text: The remainder of the ridge consists of andesite rocks of the Birker Fell Andesite Formation. These rocks are a succession of sheets of andesite lava flows which came from shallow-sided volcanoes. Here and there the map shows beds of volcaniclastic sandstone or breccia, sedimentary deposits formed from the erosion of the volcanic rocks. Around the summit of Common Fell it shows areas of hyaloclastite, a rock made up of shattered angular fragments and formed by the quenching of lava in water. However, smooth grassy turf covers these rocks from view.

text: The remainder of the ridge consists of

text: andesite

text: rocks of the Birker Fell Andesite Formation. These rocks are a succession of sheets of andesite lava flows which came from shallow-sided volcanoes. Here and there the map shows beds of

text: volcaniclastic

text: sandstone or breccia, sedimentary deposits formed from the erosion of the volcanic rocks. Around the summit of Common Fell it shows areas of

text: hyaloclastite

text: , a rock made up of shattered angular fragments and formed by the quenching of lava in water. However, smooth grassy turf covers these rocks from view.

text: A landscape evolution model is a physically based numerical model that simulates changing terrain over the course of time. This can be due to glacial erosion and deposition; erosion, sediment transport, and deposition in fluvial systems such as rivers; regolith production; the movement of material on hillslopes; more intermittent events such as rockfalls, debris flows, landslides, and other surface processes. This can also be due to surface uplift and/or subsidence. A typical landscape evolution model takes many of these factors into account.

text: A landscape evolution model is a physically based

text: numerical model

text: that simulates changing terrain over the course of time. This can be due to

text: glacial

text: erosion and deposition;

text: erosion

text: sediment transport

text: , and

text: deposition

text: in

text: fluvial

text: systems such as

text: river

text: s;

text: regolith production

text: ; the movement of material on

text: hill

text: slopes; more intermittent events such as

text: rockfall

text: s,

text: debris flow

text: s,

text: landslide

text: s, and other surface processes. This can also be due to surface

text: uplift

text: and/or

text: subsidence

text: . A typical landscape evolution model takes many of these factors into account.

text: The sinkhole formed due to volcanic pumice deposits, upon which Guatemala City is built. These deposits were unconsolidated and of low density, allowing easy erosion. According to Sam Bonis, a geologist at Dartmouth College, leaking pipes went unfixed long enough to create the conditions necessary for sinkhole formation because of lax city zoning regulations and building codes. Bonis also says that the Guatemala City sinkhole is a misnomer: sinkholes have natural causes, but this one was mainly artificial. In addition, according to Bonis, sinkholes are usually formed from limestone but there is no limestone hundreds of metres underneath Guatemala City. Bonis proposes that the sinkhole be renamed a piping feature.

text: The sinkhole formed due to volcanic

text: pumice

text: deposits, upon which Guatemala City is built. These deposits were unconsolidated and of low density, allowing easy

text: erosion

text: . According to Sam Bonis, a geologist at

text: Dartmouth College

text: , leaking pipes went unfixed long enough to create the conditions necessary for sinkhole formation because of lax city zoning regulations and building codes. Bonis also says that the Guatemala City sinkhole is a misnomer: sinkholes have natural causes, but this one was mainly artificial. In addition, according to Bonis, sinkholes are usually formed from

text: limestone

text: but there is no limestone hundreds of metres underneath Guatemala City. Bonis proposes that the sinkhole be renamed a piping feature.

text: Natural rates of erosion are controlled by the action of geomorphic drivers, such as rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical erosion proceeds fastest on steeply sloping surfaces, and rates may also be sensitive to some climatically-controlled properties including amounts of water supplied (e.g., by rain), storminess, wind speed, wave fetch, or atmospheric temperature (especially for some ice-related processes). Feedbacks are also possible between rates of erosion and the amount of eroded material that is already carried by, for example, a river or glacier. Processes of erosion that produce sediment or solutes from a place contrast with those of deposition, which control the arrival and emplacement of material at a new location.

text: Natural rates of erosion are controlled by the action of

text: geomorphic

text: drivers, such as

text: rain

text: fall; bedrock wear in

text: river

text: s; coastal erosion by the sea and

text: waves

text: glacial

text: plucking,

text: abrasion

text: , and scour; areal flooding;

text: wind

text: abrasion;

text: groundwater

text: processes; and

text: mass movement

text: processes in steep landscapes like

text: landslide

text: s and

text: debris flow

text: s. The rates at which such processes act control how fast a surface is eroded. Typically, physical erosion proceeds fastest on steeply sloping surfaces, and rates may also be sensitive to some climatically-controlled properties including amounts of water supplied (e.g., by rain), storminess, wind speed, wave

text: fetch

text: , or atmospheric temperature (especially for some ice-related processes).

text: Feedback

text: s are also possible between rates of erosion and the amount of eroded material that is already carried by, for example, a river or glacier. Processes of erosion that produce sediment or solutes from a place contrast with those of

text: deposition

text: , which control the arrival and emplacement of material at a new location.

text: Geologists and the official Ricketts Glen State Park web page classify the falls at Ricketts Glen State Park into two types. Wedding-cake falls descend in a series of small steps. Within the park, this type of falls usually flows over thin layers of Huntley Mountain Formation sandstone. In bridal-veil falls, the second type, water falls over a ledge and drops vertically into a plunge pool in the stream bed below. Within the park, this type of falls flows over Catskill Formation rocks or the red shale and sandstone of the Huntley Formation. In the park, the harder caprock which forms the ledge from which the bridal-veil falls drops is gray sandstone. The softer red shale below is eroded away by water, sand and gravel to form the plunge pool. Brown's book Pennsylvania waterfalls: a guide for hikers and photographers uses four types to classify waterfalls: falls, cascade, slide, and chute.

text: Geologists and the official Ricketts Glen State Park web page classify the falls at Ricketts Glen State Park into two types.

text: Wedding-cake

text: falls descend in a series of small steps. Within the park, this type of falls usually flows over thin layers of Huntley Mountain Formation sandstone. In

text: bridal-veil

text: plunge pool

text: caprock

text: which forms the ledge from which the bridal-veil falls drops is gray sandstone. The softer red shale below is eroded away by water, sand and gravel to form the plunge pool. Brown's book Pennsylvania waterfalls: a guide for hikers and photographers uses four types to classify waterfalls: falls, cascade, slide, and chute.

text: A plunge pool (or plunge basin or waterfall lake) is a depression at the base of a waterfall created by the erosional force of falling water and rocks where it lands.

text: A plunge pool (or plunge basin or waterfall lake) is a depression at the base of a

text: waterfall

text: created by the

text: erosional

text: force of falling water and rocks where it lands.

text: In the study of sediments, particle size is frequently bimodal. Empirically, it has been found useful to plot the frequency against the log( size ) of the particles. This usually gives a clear separation of the particles into a bimodal distribution. In geological applications the logarithm is normally taken to the base 2. The log transformed values are referred to as phi (Φ) units. This system is known as the Krumbein (or phi) scale.

text: In the study of sediments, particle size is frequently bimodal. Empirically, it has been found useful to plot the frequency against the log( size ) of the particles. This usually gives a clear separation of the particles into a bimodal distribution. In geological applications the

text: logarithm

text: is normally taken to the base 2. The log transformed values are referred to as phi (Φ) units. This system is known as the

text: Krumbein

text: (or phi) scale.

text: Straight channels (sinuosity <1.3) are relatively rare in natural systems due to the fact that sediment and flow are rarely distributed evenly across a landscape. Irregularities in the deposition and erosion of sediments leads to the formation of alternate bars that are on opposite sides of the channel in succession. Alternating bar sequences result in flow to be directed in a sinuous pattern, leading to the formation of sinuous channels (sinuosity of 1.3-1.5).

text: This shrub grows in cracks in rocks alongside flowing water. It has a fibrous mass of roots and lateral rhizomes that anchor it, and even if most of the plant is ripped away during flooding, it easily resprouts from remnants of the rhizomes. It is often found growing in sandstone bedrock, gravel bars, nooks between boulders, and in riverborne deposits of debris, rubble, and silt. It is adapted to periodic flooding, scouring, erosion, and deposition of litter. Other plants in the habitat may include hazel alder (Alnus serrulata), silky dogwood (Cornus amomum), jewelweed (Impatiens capensis), creepers (Parthenocissus), ninebark (Physocarpus opulifolius), sycamore species (Platanus), blackberries (Rubus), willow species (Salix), American elderberry (Sambucus canadensis), soapworts (Saponaria), greenbrier species (Smilax), goldenrod species (Solidago), and poison ivy (Toxicodendron radicans).

text: This shrub grows in cracks in rocks alongside flowing water. It has a fibrous mass of roots and lateral

text: rhizome

text: s that anchor it, and even if most of the plant is ripped away during

text: flood

text: ing, it easily resprouts from remnants of the rhizomes. It is often found growing in

text: sandstone

text: bedrock

text: gravel bar

text: s, nooks between boulders, and in riverborne deposits of debris, rubble, and silt. It is adapted to periodic flooding, scouring,

text: erosion

text: , and deposition of litter. Other plants in the habitat may include

text: hazel alder

text: (Alnus serrulata),

text: silky dogwood

text: (Cornus amomum),

text: jewelweed

text: (Impatiens capensis),

text: creepers

text: (Parthenocissus),

text: ninebark

text: (Physocarpus opulifolius),

text: sycamore

text: species (Platanus),

text: blackberries

text: (Rubus),

text: willow

text: species (Salix),

text: American elderberry

text: (Sambucus canadensis),

text: soapwort

text: s (Saponaria),

text: greenbrier

text: species (Smilax),

text: goldenrod

text: species (Solidago), and

text: poison ivy

text: (Toxicodendron radicans).

text: Extended systems of underwater caves, sinkholes and springs are found throughout the state and supply most of the water used by residents. The limestone is topped with sandy soils deposited as ancient beaches over millions of years as global sea levels rose and fell. During the last glacial period, lower sea levels and a drier climate revealed a much wider peninsula, largely savanna. While there are sinkholes in much of the state, modern sinkholes have tended to be in West-Central Florida.

text: Extended systems of underwater

text: cave

text: s,

text: sinkholes

text: and

text: springs

text: are found throughout the state and supply most of the water used by residents. The limestone is topped with

text: sand

text: y soils deposited as ancient

text: beach

text: es over millions of years as global sea levels rose and fell. During the

text: last glacial period

text: , lower sea levels and a drier climate revealed a much wider peninsula, largely

entity_name: Temperate grasslands, savannas, and shrublands

text: savanna

text: . While there are sinkholes in much of the state, modern sinkholes have tended to be in West-

text: Central Florida

text: In road and rail transport, a washout is the result of a natural disaster where the roadbed is eroded away by flowing water, usually as the result of a flood. When a washout destroys a railroad's right-of-way, the track is sometimes left suspended in midair across the newly formed gap, or it dips down into a ditch. This phenomenon is discussed in more detail under the term erosion. Bridges may collapse due to bridge scour around one or more bridge abutments or piers.

text: In road and

text: rail transport

text: , a washout is the result of a

text: natural disaster

text: where the

text: roadbed

text: is eroded away by flowing water, usually as the result of a

text: flood

text: . When a washout destroys a railroad's

text: right-of-way

text: , the

text: track

text: is sometimes left suspended in midair across the newly formed gap, or it dips down into a ditch. This phenomenon is discussed in more detail under the term

text: erosion

text: . Bridges may collapse due to

text: bridge scour

text: around one or more bridge

text: abutment

text: s or piers.

text: In the process of burial, it is possible that siliciclastic deposits may subsequently be uplifted as a result of a mountain building event or erosion.  When uplift occurs, it exposes buried deposits to a radically new environment. Because the process brings material to or closer to the surface, sediments that undergo uplift are subjected to lower temperatures and pressures as well as slightly acidic rain water. Under these conditions, framework grains and cement are again subjected to dissolution and in turn increasing porosity. On the other hand, telogenesis can also change framework grains to clays, thus reducing porosity. These changes are dependent on the specific conditions that the rock is exposed as well as the composition of the rock and pore waters. Specific pore waters, can cause the further precipitation of carbonate or silica cements. This process can also encourage the process of oxidation on a variety of iron bearing minerals.

text: Extended systems of underwater caves, sinkholes and springs are found throughout the state and supply most of the water used by residents. The limestone is topped with sandy soils deposited as ancient beaches over millions of years as global sea levels rose and fell. During the last glacial period, lower sea levels and a drier climate revealed a much wider peninsula, largely savanna. The Everglades, an enormously wide, slow-flowing river encompasses the southern tip of the peninsula. Sinkhole damage claims on property in the state exceeded a total of $2 billion from 2006 through 2010.

text: Extended systems of underwater caves,

text: sinkholes

text: and

text: springs

text: sand

text: y soils deposited as ancient beaches over millions of years as global sea levels rose and fell. During the

text: last glacial period

text: savanna

text: . The

text: Everglades

text: , an enormously wide, slow-flowing river encompasses the southern tip of the peninsula. Sinkhole damage claims on property in the state exceeded a total of $2 billion from 2006 through 2010.

text: Depression focused groundwater recharge also profoundly effects contaminant transport into groundwater.  This is of great concern in regions with karst geological formations because water can eventually dissolve tunnels all the way to aquifers, or otherwise disconnected streams.  This extreme form of preferential flow, accelerates the transport of contaminants and the erosion of such tunnels.  In this way depressions intended to trap runoff water—before it flows to vulnerable water resources—can connect underground over time.  Cavitation of surfaces above into the tunnels, results in pot holes or caves.

text: Depression focused groundwater recharge also profoundly effects

text: contaminant

text: transport into groundwater.  This is of great concern in regions with

text: karst

text: geological formations because water can eventually dissolve tunnels all the way to

text: aquifer

text: s, or otherwise disconnected streams.  This extreme form of

text: preferential flow

text: , accelerates the transport of contaminants and the

text: erosion

text: of such

text: tunnel

text: s.  In this way depressions intended to trap

text: runoff

text: water—before it flows to vulnerable water resources—can connect underground over time.

text: Cavitation

text: of surfaces above into the tunnels, results in

text: pot holes

text: or caves.

text: The channel of Shamokin Creek is sinuous and flows through rock formations consisting of sandstone, shale, and extensive anthracite deposits. There are some culm deposits along the creek. The creek flows between stone walls in Shamokin. The upper  of the watershed, upstream of Big Mountain, are in the Western Middle Anthracite Field, in the Coal Region. There are 34 coal veins in the watershed and nearly all have been either deep-mined or strip-mined. The creek passes through rock of the Hamilton Formation near Paxinos. The creek's valley is partly carved from Marcellus black slate. Red shale of the Mauch Chunk Formation also occurs in the watershed.

text: The

text: channel

text: of Shamokin Creek is

text: sinuous

text: and flows through

text: rock formation

text: s consisting of

text: sandstone

text: shale

text: , and extensive

text: anthracite

text: deposits. There are some

text: culm

text: deposits along the creek. The creek flows between stone walls in Shamokin. The upper  of the watershed, upstream of Big Mountain, are in the

text: Western Middle Anthracite Field

text: , in the

text: Coal Region

text: . There are 34 coal veins in the watershed and nearly all have been either

text: deep-mined

text: or

text: strip-mined

text: . The creek passes through rock of the

text: Hamilton Formation

text: near Paxinos. The creek's valley is partly carved from Marcellus black slate. Red

text: shale

text: of the

text: Mauch Chunk Formation

text: also occurs in the watershed.

text: Antidunes migrate upstream because the stream flow is shallow and fast in the trough and slows and deepens over the crest. As a result, the shear stress on the bed decreases from trough to crest, allowing sedimentation, and increases from crest to tough, causing erosion. The inertia of the flow moves the shear stress maximum and minimum slightly downstream of the trough and crest. This allows the bedform to amplify with time as erosion occurs in the trough and deposition occurs at the crest.

text: Antidunes migrate upstream because the stream flow is shallow and fast in the trough and slows and deepens over the crest. As a result, the

text: shear stress

text: on the bed decreases from trough to crest, allowing sedimentation, and increases from crest to tough, causing erosion. The inertia of the flow moves the shear stress maximum and minimum slightly downstream of the trough and crest. This allows the bedform to amplify with time as erosion occurs in the trough and deposition occurs at the crest.

text: The forcing of the spring to the surface can be the result of a confined aquifer in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources are artesian wells. This is possible even if the outlet is in the form of a  cave. In this case the cave is used like a hose by the higher elevated recharge area of groundwater to exit through the lower elevation opening.

text: The forcing of the spring to the surface can be the result of a confined

text: aquifer

text: in which the recharge area of the spring water table rests at a higher elevation than that of the outlet. Spring water forced to the surface by elevated sources are

text: artesian wells

text: . This is possible even if the outlet is in the form of a  cave. In this case the cave is used like a hose by the higher elevated recharge area of groundwater to exit through the lower elevation opening.

text: There is an abundance of geological material from the Burdigalian portion of the early Miocene, some 20 million years ago. Materials of marine origin were deposited for some 7 million years, after which the basin became totally isolated from the sea. From that time, further deposits are exclusively continental, carried by flowing rivers. The current configuration of the Hoya began to take form some 500,000 years ago in a strong paleogeographic restructuring. Small rivers formed in the reliefs that surrounded the basin began a process of erosion that gave the landscape its now-characteristic gullies and badlands.

text: There is an abundance of geological material from the

text: Burdigalian

text: portion of the early

text: Miocene

text: , some 20 million years ago. Materials of marine origin were deposited for some 7 million years, after which the basin became totally isolated from the sea. From that time, further deposits are exclusively continental, carried by flowing rivers. The current configuration of the Hoya began to take form some 500,000 years ago in a strong

text: paleogeographic

text: restructuring. Small rivers formed in the reliefs that surrounded the basin began a process of

text: erosion

text: that gave the landscape its now-characteristic

text: gullies

text: and

text: badlands

text: The River Lossie () is a river in north east Scotland.  Ptolemy (c.90 – c.168), the Greco-Roman geographer, named it as ost. Loxa Fl.  The river originates in the hills above Dallas, in Moray, and has its source 400 metres above sea-level.  It enters the sea at Lossiemouth on the Moray Firth. By the time it moves through Elgin its rate of flow, in normal conditions, is best described as very slow.  The gradient between Elgin and Lossiemouth is almost imperceptible with a total fall of less than 5 metres.

text: The River Lossie () is a river in north east

text: Scotland

text: Ptolemy

text: (c.90 – c.168), the

text: Greco-Roman

text: geographer, named it as ost. Loxa Fl.  The river originates in the hills above

text: Dallas

text: , in

text: Moray

text: , and has its source 400 metres above sea-level.  It enters the sea at

text: Lossiemouth

text: on the

text: Moray Firth

text: . By the time it moves through

text: Elgin

text: its rate of flow, in normal conditions, is best described as very slow.  The gradient between Elgin and Lossiemouth is almost imperceptible with a total fall of less than 5 metres.

text: The bottom is at the groundwater level, so the amount of water depends on current hydrological conditions. Usually, the lake fills after the heavy rains in late autumn and again in spring. On average, the area is flooded for around three months every year. The lake's main inflow is the estavelle Matija's Cave (''Matijeva jama'') out of which the water flowing from the Javornik Hills erupts.

text: The bottom is at the

text: groundwater

text: level, so the amount of water depends on current

text: hydrological

text: conditions. Usually, the lake fills after the heavy rains in late autumn and again in spring. On average, the area is flooded for around three months every year. The lake's main

text: inflow

text: is the

text: estavelle

text: Matija's Cave (''Matijeva jama'') out of which the water flowing from the

text: Javornik Hills

text: erupts.

text: A stream bed is the channel bottom of a stream, river or creek, the physical confine of the normal water flow.  The lateral confines or channel margins are known as the stream banks or river banks, during all but flood stage. In fact, a flood occurs when a stream overflows its banks and flows onto its flood plain. As a general rule, the bed is that part of the channel up to the normal water line, and the banks are that part above the normal water line. However, because water flow varies, this differentiation is subject to local interpretation. Usually, the bed is kept clear of terrestrial vegetation, whereas the banks are subjected to water flow only during unusual or perhaps infrequent high water stages and therefore might support vegetation some or much of the time.

text: A stream bed is the channel bottom of a

text: stream

text: river

text: or creek, the physical confine of the normal water flow.  The lateral confines or channel margins are known as the stream

text: bank

text: s or river banks, during all but

text: flood stage

text: . In fact, a

text: flood

text: occurs when a stream overflows its banks and flows onto its

text: flood plain

text: . As a general rule, the bed is that part of the

text: channel

text: up to the normal water line, and the banks are that part above the normal water line. However, because water flow varies, this differentiation is subject to local interpretation. Usually, the bed is kept clear of terrestrial

text: vegetation

text: , whereas the banks are subjected to water flow only during unusual or perhaps infrequent high water stages and therefore might support vegetation some or much of the time.

text: Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces then a sudden collapse of the land surface can occur. These collapses can be small or they can be huge and can occur where a house or road is on top.

text: Sinkhole

text: s are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces then a sudden collapse of the land surface can occur. These collapses can be small or they can be huge and can occur where a house or road is on top.

text: The site at which various sizes of particles are deposited is critical to an understanding of any aspect of their toxic action. The fractional regional deposition of particles shows that between 10 and 1 μm, the portion of particles that is deposited in the upper airways falls off from 80% to 20%, whereas the pulmonary deposition increases from near zero to about 20%. Pulmonary deposition, after falling off near 1 μm, peaks again near 40% for particles of 0.03 μm, whereas upper airway deposition remains low until a new peak deposition is found at less than 0.01 μm. The portion and pattern of deposition can be modified under conditions of reduced gravity; however, human data during flights of the gravity research aircraft show that particles in the 0.5 to 1 μm range are deposited less in the respiratory system at lunar gravity than at Earth gravity. This finding is consistent with the reduced sedimentation of the particles when the gravity is less. However, a larger portion of the particles is deposited peripherally in reduced gravity.

text: Volcanism can cause flows such as lava on the surface of geologically active bodies (the largest being the Amirani (volcano) flow on Io).  Many of Earth's Igneous rocks are formed through processes rare elsewhere, such as the presence of volcanic magma and water.  Surface mineral deposits such as olivine and hematite discovered on Mars by lunar rovers provide direct evidence of past stable water on the surface of Mars.

text: Volcanism

text: can cause flows such as

text: lava

text: on the surface of geologically active bodies (the largest being the

text: Amirani (volcano)

text: flow on Io).  Many of Earth's

text: Igneous rock

text: s are formed through processes rare elsewhere, such as the presence of volcanic magma and water.  Surface mineral deposits such as

text: olivine

text: and

text: hematite

text: discovered on Mars by lunar rovers provide direct evidence of past stable

text: water on the surface of Mars

text: The West Branch rises in Schoharie County, New York at  above sea level, near Mount Jefferson, and flows tortuously through the plateau in a deep trough. The branch flows generally southwest, entering Delaware County and flowing through the towns of Stamford and Delhi. In southwestern Delaware County it flows in an increasingly winding course through the mountains, generally southwest. At Stilesville the West Branch was impounded in the 1960s to form the Cannonsville Reservoir, the westernmost of the reservoirs in the New York City water system. It is the most recently constructed New York City reservoir and began serving the city in 1964. Draining a large watershed of , the reservoir's capacity is . This water flows over halfway through the reservoir to enter the  West Delaware Tunnel in Tompkins, New York. Then it flows through the aqueduct into the Rondout Reservoir, where the water enters the  Delaware Aqueduct, that contributes to roughly 50% of the city's drinking water supply. At Deposit, on the border between Broome and Delaware counties, it turns sharply to the southeast and is paralleled by New York State Route 17. It joins the East Branch at  above sea level at Hancock to form the Delaware.

text: The West Branch rises in

text: Schoharie County, New York

text: at  above sea level, near

text: Mount Jefferson

text: , and flows tortuously through the plateau in a deep trough. The branch flows generally southwest, entering

text: Delaware County

text: and flowing through the towns of

text: Stamford

text: and

text: Delhi

text: . In southwestern Delaware County it flows in an increasingly winding course through the mountains, generally southwest. At

text: Stilesville

text: the West Branch was impounded in the 1960s to form the

text: Cannonsville Reservoir

text: , the westernmost of the reservoirs in the New York City water system. It is the most recently constructed New York City reservoir and began serving the city in 1964. Draining a large watershed of , the reservoir's capacity is . This water flows over halfway through the reservoir to enter the

text: West Delaware Tunnel

text: in

text: Tompkins, New York

text: . Then it flows through the aqueduct into the

text: Rondout Reservoir

text: , where the water enters the

text: Delaware Aqueduct

text: , that contributes to roughly 50% of the city's drinking water supply. At

text: Deposit

text: , on the border between

text: Broome

text: and Delaware counties, it turns sharply to the southeast and is paralleled by

text: New York State Route 17

text: . It joins the East Branch at  above sea level at

text: Hancock

text: to form the Delaware.

text: Groundwater is a critical element of the California water supply. During a normal year, 30% of the state's water supply comes from groundwater (underground water). In times of intense drought, groundwater consumption can rise to 60% or more. Over  of water is stored in California's 450 known groundwater reservoirs. However, not all the water is usable. Over half of the groundwater is unavailable due to poor quality and the high cost of pumping the water from the ground. While surface water is concentrated mostly in the northern part of the state, groundwater is more evenly distributed.

text: Groundwater

text: is a critical element of the California water supply. During a normal year, 30% of the state's water supply comes from groundwater (underground water). In times of intense

text: drought

text: , groundwater consumption can rise to 60% or more. Over  of water is stored in California's 450 known groundwater reservoirs. However, not all the water is usable. Over half of the groundwater is unavailable due to poor quality and the high cost of pumping the water from the ground. While surface water is concentrated mostly in the northern part of the state, groundwater is more evenly distributed.

text: The source of virtually all freshwater is precipitation from the atmosphere, in the form of mist, rain and snow, as part of the water cycle over eons, millennia and in the present day. Freshwater constitutes only 3% of all water on Earth, and of that, slightly over two thirds is stored frozen in glaciers and polar ice caps. The remaining unfrozen freshwater is mainly found as groundwater, with only a small fraction present in the air, or on the ground surface.  Surface water is stored in wetlands or lakes or flows in a stream or river, and is the most commonly utilized resource for water.  In places, surface water can be stored in a reservoir behind a dam, and then used for municipal and industrial water supply, for irrigation and to generate power in the form of hydroelectricity. Sub-surface groundwater, although stored in the pore space of soil and rock; it is utilized most as water flowing within aquifers below the water table. Groundwater can exist both as a renewable water system closely associated with surface water and as a separate, deep sub-surface water system in an aquifer. This latter case is sometimes called "fossil water", and is realistically non-renewable.  Normally, groundwater is utilized where surface sources are unavailable or when surface supply distribution is limited.

text: The source of virtually all

text: freshwater

text: is

text: precipitation

text: from the

text: atmosphere

text: , in the form of

text: mist

text: rain

text: and

text: snow

text: , as part of the

text: water cycle

text: over

text: eons

text: millennia

text: and in the present day. Freshwater constitutes only 3% of all water on Earth, and of that, slightly over two thirds is stored frozen in

text: glacier

text: s and

text: polar

text: ice cap

text: s. The remaining unfrozen freshwater is mainly found as

text: groundwater

text: , with only a small fraction present in the air, or on the ground surface.

text: Surface water

text: is stored in

text: wetland

text: s or

text: lake

text: s or flows in a stream or

text: river

text: , and is the most commonly utilized resource for water.  In places, surface water can be stored in a

text: reservoir

text: behind a

text: dam

text: , and then used for municipal and industrial

text: water supply

text: , for

text: irrigation

text: and to generate power in the form of

text: hydroelectricity

text: . Sub-surface groundwater, although stored in the

text: pore

text: space of

text: soil

text: and

text: rock

text: ; it is utilized most as water flowing within

text: aquifer

text: s below the

text: water table

text: . Groundwater can exist both as a renewable water system closely associated with surface water and as a separate, deep sub-surface water system in an aquifer. This latter case is sometimes called "fossil water", and is realistically non-renewable.  Normally, groundwater is utilized where surface sources are unavailable or when surface supply distribution is limited.

text: In the 1990s, cold spraying (often called gas dynamic cold spray) was introduced. The method was originally developed in Russia, with the accidental observation of the rapid formation of coatings. This occurred while experimenting with particle erosion of a target exposed to a high velocity flow loaded with fine powder in a wind tunnel. In cold spraying, particles are accelerated to very high speeds by the carrier gas forced through a converging–diverging de Laval type nozzle. Upon impact, solid particles with sufficient kinetic energy deform plastically and bond mechanically to the substrate to form a coating. The critical velocity needed to form bonding depends on the material's properties, powder size and temperature. Metals, polymers, ceramics, composite materials and nanocrystalline powders can be deposited using cold spraying.Soft metals such as Cu and Al are best suited for cold spraying, but coating of other materials (W, Ta, Ti, MCrAlY, WC–Co, etc.) by cold spraying has been reported.

text: In the 1990s, cold spraying (often called

text: gas dynamic cold spray

text: ) was introduced. The method was originally developed in Russia, with the accidental observation of the rapid formation of coatings. This occurred while experimenting with particle erosion of a target exposed to a high velocity flow loaded with fine powder in a wind tunnel. In cold spraying, particles are accelerated to very high speeds by the carrier gas forced through a converging–diverging

text: de Laval type nozzle

text: . Upon impact, solid particles with sufficient kinetic energy deform plastically and bond mechanically to the substrate to form a coating. The critical velocity needed to form bonding depends on the material's properties, powder size and temperature.

text: Metal

text: s,

text: polymer

text: s,

text: ceramic

text: s,

text: composite material

text: s and

text: nanocrystalline

text: powders can be deposited using cold spraying.Soft metals such as Cu and Al are best suited for cold spraying, but coating of other materials (W, Ta, Ti, MCrAlY, WC–Co, etc.) by cold spraying has been reported.

text: The rocks  found in and around Wichita Falls result from southwesterly-flowing Permian streams that deposited sands in channels and silts and clays on the surrounding floodplains.  Calcium-carbonate rich soils concurrently developed adjacent to these streams.  These were likely buried by further Permian sedimentation and then lithified.  Pleistocene erosion removed the younger rocks, exposing the current strata.  Exposures of sediments indicate that northeast-flowing streams locally deposited silts, clays, sands, and some gravels on the Permian rocks.  These are subsequently modified by modern (Holocene) stream erosion and deposition.

text: The rocks  found in and around Wichita Falls result from southwesterly-flowing

text: Permian

text: streams that deposited sands in channels and silts and clays on the surrounding floodplains.  Calcium-carbonate rich soils concurrently developed adjacent to these streams.  These were likely buried by further Permian sedimentation and then

text: lithified

text: Pleistocene

text: erosion removed the younger rocks, exposing the current strata.  Exposures of sediments indicate that northeast-flowing streams locally deposited silts, clays, sands, and some gravels on the Permian rocks.  These are subsequently modified by modern (

text: Holocene

text: ) stream erosion and deposition.

text: Subsea trees are available in either vertical or horizontal configurations with further speciality available such as dual bore, monobore, concentric, drill-through, mudline, guidlineless or guideline.  Subsea trees may range in size and weight from a few tons to approximately 70 tons for high pressure, deepwater (>3000 feet) guidelineless applications.  Subsea trees contain many additional valves and accessories compared to Surface trees.  Typically a subsea tree would have a choke (permits control of flow), a flowline connection interface (hub, flange or other connection), subsea control interface (direct hydraulic, electro hydraulic, or electric) and sensors for gathering data such as pressure, temperature, sand flow, erosion, multiPhase flow, single phase flow such as water or gas.

text: Altogether, this fauna is massively dominated by large herbivores and generally lacks terrestrial carnivores. It can thus be assumed that the habitat was mostly low-lying rainforest that was seasonally flooded, as well as floodplains and swampland. The rivers must have been wide and slow-moving, as the fossil-rich rocks are alluvial deposits and do not show evidence of fast-flowing riverbeds that would have dug into the sediment deeply while depositing little of their own.

text: Altogether, this fauna is massively dominated by large herbivores and generally lacks terrestrial carnivores. It can thus be assumed that the habitat was mostly low-lying

text: rainforest

text: that was seasonally flooded, as well as

text: floodplain

text: s and

text: swamp

text: land. The rivers must have been wide and slow-moving, as the fossil-rich rocks are

text: alluvial

text: deposits and do not show evidence of fast-flowing riverbeds that would have dug into the sediment deeply while depositing little of their own.

text: When water is supplied to the hose, it flows through the nozzle body to the opening, where it would normally flow straight forward in a stream. Just after leaving the opening it encounters the plug, which deflects the water sideways through an angle. After travelling a short distance the water encounters the outside of the nozzle opening, which deflects it forward again. This two-step process causes the water to be ejected in a ring-shaped pattern, which causes less water to strike any one location, and thereby reduces erosion while also making it easier to water larger areas.

text: In 1979, this lawsuit resulted in a Consent Decree, amended in 1981, which imposed several conditions on development of the freeway, including additional public hearings, preparation of an environmental report, alterations to the design to reduce lanes and intersections, improve carpooling and provide for a transit way, which became the Los Angeles Metro Rail Green Line.  A portion of the right-of-way was also to be constructed below grade to buffer adjacent areas from the effects of traffic noise. After construction began in the 1980s, failure to perform a full survey of the area's groundwater deposits, combined with the 20–30 foot below-grade trench through the city of Downey, resulted in buckling and cracking along the eastern portions of the route. At one point a large sinkhole opened in the Bellflower Boulevard on-ramp. This resulted in construction of an elaborate pump system along the freeway between the interchanges with I-710 and I-605.

text: In 1979, this lawsuit resulted in a Consent Decree, amended in 1981, which imposed several conditions on development of the freeway, including additional public hearings, preparation of an environmental report, alterations to the design to reduce lanes and intersections, improve carpooling and provide for a transit way, which became the

text: Los Angeles Metro Rail

text: Green Line

text: .  A portion of the right-of-way was also to be constructed below grade to buffer adjacent areas from the effects of

text: traffic noise

text: . After construction began in the 1980s, failure to perform a full survey of the area's

text: groundwater

text: deposits, combined with the 20–30 foot below-grade trench through the city of

text: Downey

text: , resulted in buckling and cracking along the eastern portions of the route. At one point a large sinkhole opened in the Bellflower Boulevard on-ramp. This resulted in construction of an elaborate pump system along the freeway between the interchanges with

text: and

text: All three mechanisms operate simultaneously, but one mechanism or another may be most important for a particular nutrient. For example, in the case of calcium, which is generally plentiful in the soil solution, mass flow alone can usually bring sufficient amounts to the root surface. However, in the case of phosphorus, diffusion is needed to supplement mass flow. For the most part, nutrient ions must travel some distance in the soil solution to reach the root surface. This movement can take place by mass flow, as when dissolved nutrients are carried along with the soil water flowing toward a root that is actively drawing water from the soil. In this type of movement, the nutrient ions are somewhat analogous to leaves floating down a stream. In addition, nutrient ions continually move by diffusion from areas of greater concentration toward the nutrient-depleted areas of lower concentration around the root surface. That process is due to random motion of molecules. By this means, plants can continue to take up nutrients even at night, when water is only slowly absorbed into the roots as transpiration has almost stopped. Finally, root interception comes into play as roots continually grow into new, undepleted soil.

text: Many check dams tend to form stream pools. Under low-flow circumstances, water either infiltrates into the ground, evaporates, or seeps through or under the dam. Under high flow - flood - conditions, water flows over or through the structure. Coarse and medium-grained sediment from runoff tends to be deposited behind check dams, while finer grains flow through. Extra nutrients, phosphorus, nitrogen, heavy metals, and floating garbage are also trapped by check dams, increasing their effectiveness as water quality control measures.

text: Many check dams tend to form

text: stream pool

text: s. Under low-flow circumstances, water either

text: infiltrates

text: into the ground,

text: evaporates

text: , or seeps through or under the dam. Under high flow -

text: flood

text: - conditions, water flows over or through the structure. Coarse and medium-grained sediment from

text: runoff

text: tends to be deposited behind check dams, while finer grains flow through. Extra nutrients,

text: phosphorus

text: nitrogen

text: heavy metals

text: , and floating garbage are also trapped by check dams, increasing their effectiveness as water quality control measures.

text: Cat Ba island is the largest island within the Cat Ba archipelago, with 366 smaller islands and tidally exposed rocks surrounding it. As all members of the Trachypithecus francoisi species group, this social, diurnal lutung is found in limestone forests. Critically endangered, the white-headed Langur resides near Ha Long Bay, specifically in Cat Ba Island, hence its common name "Cat Ba Langur". This landscape is known as a karst formation that has been invaded by the ocean. The topography is of limestone that has been worn away through erosion, which later formed ridges, towers, fissures, sinkholes and other types of landforms. The Cat Ba Langur are diurnal animals, adapted to living in limestone habitat.The sleeping caves, ledges, and overhangs used by the langurs are thought to be used as protection from predators and extreme weather. Accessible caves were used as a hunting ground for humans to capture or kill langurs as they slept.

text: Cat Ba island is the largest island within the Cat Ba archipelago, with 366 smaller islands and tidally exposed rocks surrounding it. As all members of the

text: Trachypithecus francoisi

text: species group, this social,

text: diurnal

text: lutung

text: is found in limestone forests. Critically endangered, the white-headed Langur resides near Ha Long Bay, specifically in Cat Ba Island, hence its common name "Cat Ba Langur". This landscape is known as a karst formation that has been invaded by the ocean. The topography is of limestone that has been worn away through erosion, which later formed ridges, towers, fissures, sinkholes and other types of landforms. The Cat Ba Langur are diurnal animals, adapted to living in limestone habitat.The sleeping caves, ledges, and overhangs used by the langurs are thought to be used as protection from predators and extreme weather. Accessible caves were used as a hunting ground for humans to capture or kill langurs as they slept.

text: Given that the turbine blades in a water turbine are constantly exposed to water and dynamic forces, they need to have high corrosion resistance and strength. The most common material used in overlays on carbon steel runners in water turbines are austenitic steel alloys that have 17% to 20% chromium to increase stability of the film which improves aqueous corrosion resistance. The chromium content in these steel alloys exceed the minimum of 12% chromium required to exhibit some atmospheric corrosion resistance. Having a higher chromium concentration in the steel alloys allows for a much longer lifespan of the turbine blades. Currently, the blades are made of martensitic stainless steels which have high strength compared to austenitic stainless steels by a factor of 2. Besides corrosion resistance and strength as the criteria for material selection, weld-ability and density of the turbine blade.  Greater weld-ability allows for easier repair of the turbine blades. This also allows for higher weld quality which results in a better repair. Selecting a material with low density is important to achieve higher efficiency because the lighter blades rotate more easily. The most common material used in Kaplan Turbine blades are stainless steel alloys (SS). The different alloys used are SS(16Cr-5Ni), SS(13Cr-4Ni), SS(13Cr-1Ni). The martensitic stainless steel alloys have high strength, thinner sections than standard carbon steel, and reduced mass that enhances the hydrodynamic flow conditions and efficiency of the water turbine. The SS(13Cr-4Ni) has been shown to have improved erosion resistance at all angles of attack through the process of laser hardening. It is important to minimize erosion in order to maintain high efficiencies because erosion negatively impacts the hydraulic profile of the blades which reduces the relative ease to rotate.

text: Rocks in the area are limestones and dolomites from the Ordovician Period, which implies deposition about 470 million years ago.  The carbonates of the Natural Bridge occur within the Chepultepec Formation, making the buttress of the bridge, and the Beekmantown Formation, deposited conformably over the Chepultepec and comprising the span and the upper part of the bridge. Strata at Natural Bridge are close to horizontal, in contrast with dipping and folded beds as close as 300 ft away along Highway 11, which points to the fact that structurally the rocks making the Natural Bridge are the bottom part of a syncline.<br>The process of formation of the bridge is less certain, but the ideas proposed by different individuals have in common the importance of three elements: the southeast dipping of the strata, the capability of water to slowly dissolve carbonates and the existence of numerous fractures.  Spencer  has provided a summary of the most respected interpretations and produced the presently most widely accepted hypothesis. According to him, the Natural Bridge would be the remnant of an underground river tunnel that diverted water to the south. Initially, the underground river started capturing water from the Poague Run about two miles to the north, contributing to enlarge the incipient Cedar Creek drainage basin.  Over time, through weathering and erosion, the underground river collapsed and disappeared almost completely, the Natural Bridge being the only surviving relic of the roof of the ancient underground river. The creek’s larger flow contributed to form the present day gorge, significantly increasing the distance from the bottom of the water flow to the roof of the underground channel.  Today, the “Lost River”, about half a mile upstream from the Natural Bridge, is a vivid example supporting the hypothesis of the underground river.  Water from the side of the gorge flows into the Cedar Creek, similarly as the ancestral Cedar Creek underground river allegedly flew into the Cascade Creek, presently entering the Cedar Creek approximately 500 ft below the Natural Bridge.

text: Rocks in the area are

text: limestones

text: and

text: dolomites

text: from the

text: Ordovician

text: Period, which implies deposition about 470 million years ago.  The

text: carbonates

text: of the Natural Bridge occur within the

text: Chepultepec Formation

text: , making the

text: buttress

text: of the bridge, and the Beekmantown Formation, deposited

text: conformably

text: over the Chepultepec and comprising the span and the upper part of the bridge.

text: Strata

text: at Natural Bridge are close to horizontal, in contrast with dipping and folded beds as close as 300 ft away along Highway 11, which points to the fact that

text: structurally

text: the rocks making the Natural Bridge are the bottom part of a

text: syncline

text: .<br>The process of formation of the bridge is less certain, but the ideas proposed by different individuals have in common the importance of three elements: the southeast dipping of the strata, the capability of water to slowly dissolve carbonates and the existence of numerous fractures.  Spencer  has provided a summary of the most respected interpretations and produced the presently most widely accepted

text: hypothesis

text: . According to him, the Natural Bridge would be the remnant of an underground river tunnel that diverted water to the south. Initially, the underground river started capturing water from the Poague Run about two miles to the north, contributing to enlarge the incipient Cedar Creek

text: drainage basin

text: .  Over time, through

text: weathering

text: and

text: erosion

text: , the underground river collapsed and disappeared almost completely, the Natural Bridge being the only surviving relic of the roof of the ancient underground river. The creek’s larger flow contributed to form the present day

text: gorge

text: , significantly increasing the distance from the bottom of the water flow to the roof of the underground channel.  Today, the “Lost River”, about half a mile upstream from the Natural Bridge, is a vivid example supporting the hypothesis of the underground river.  Water from the side of the gorge flows into the Cedar Creek, similarly as the ancestral Cedar Creek underground river allegedly flew into the Cascade Creek, presently entering the Cedar Creek approximately 500 ft below the Natural Bridge.

text: Bodies of fine to very fine grained sand that fill symmetrical, cone shaped, depressions centered on tree trunks by swirling flood water. The fill is generally organized into form-concordant, concentric laminae that dip towards the tree. Centroclinal cross strata form from the infilling of scours created around trees by swirling flood water.  Studies and piers show us just how the scouring process works.  In front of these piers, decelerating flow and friction with the bed material causes a downward pressure gradient that leads to erosive downflow. Downflow is accompanied by horseshoe shaped sediment deposits that generate a U-shaped scour around the front and sides of the obstruction.

text: Bodies of fine to very fine grained sand that fill

text: symmetrical

text: , cone shaped, depressions centered on tree trunks by swirling flood water. The fill is generally organized into form-concordant, concentric laminae that dip towards the tree. Centroclinal cross strata form from the infilling of scours created around trees by swirling flood water.  Studies and piers show us just how the scouring process works.  In front of these piers, decelerating flow and friction with the bed material causes a downward pressure gradient that leads to erosive downflow. Downflow is accompanied by horseshoe shaped sediment deposits that generate a U-shaped scour around the front and sides of the obstruction.

text: The Portage River is an  tributary of the Moose Horn River in eastern Minnesota, United States. It flows west to the Moose Horn River, joining it at Moosehead Lake next to the city of Moose Lake. By the Moose Horn River, its waters flow to the Kettle River, St. Croix River, and ultimately the Mississippi River. Just to the east of the Portage River, Nemadji Creek flows east to the Nemadji River, a tributary of Lake Superior and part of the Saint Lawrence River basin.

text: The Portage River is an  tributary of the

text: Moose Horn River

text: in eastern

text: Minnesota

text: , United States. It flows west to the Moose Horn River, joining it at Moosehead Lake next to the city of

text: Moose Lake

text: . By the Moose Horn River, its waters flow to the

text: Kettle River

text: St. Croix River

text: , and ultimately the

text: Mississippi River

text: . Just to the east of the Portage River, Nemadji Creek flows east to the

text: Nemadji River

text: , a tributary of

text: Lake Superior

text: and part of the

text: Saint Lawrence River

text: basin.

text: In many cases, sedimentation occurs slowly. In a desert, for example, the wind deposits siliciclastic material (sand or silt) in some spots, or catastrophic flooding of a wadi may cause sudden deposits of large quantities of detrital material, but in most places eolian erosion dominates. The amount of sedimentary rock that forms is not only dependent on the amount of supplied material, but also on how well the material consolidates. Erosion removes most deposited sediment shortly after deposition.

text: In many cases, sedimentation occurs slowly. In a

text: desert

text: , for example, the wind deposits siliciclastic material (sand or silt) in some spots, or catastrophic flooding of a

text: wadi

text: may cause sudden deposits of large quantities of detrital material, but in most places eolian erosion dominates. The amount of sedimentary rock that forms is not only dependent on the amount of supplied material, but also on how well the material consolidates. Erosion removes most deposited sediment shortly after deposition.

text: Deposition of the Cadomin Formation marked the renewal of subsidence and sedimentation following a long period of uplift, exposure and erosion of older strata. The Cadomin sediments were derived from sources in the mountains to the west, and were deposited across the pediment surface by systems of alluvial fans and braided streams. It is postulated that the streams flowed generally northeastward, turning northwestward at the Fox Creek Escarpment.

text: Deposition of the Cadomin Formation marked the renewal of subsidence and sedimentation following a long period of uplift, exposure and erosion of older strata. The Cadomin sediments were derived from sources in the mountains to the west, and were deposited across the

text: pediment

text: surface by systems of

text: alluvial fan

text: s and

text: braided streams

text: . It is postulated that the streams flowed generally northeastward, turning northwestward at the Fox Creek Escarpment.

text: The topography of the area was greatly influenced by glacial processes, followed by fluvial erosion. The reserve is characterized by a till moraine and other glacial features, such as kames and kettles. A deeply cut tributary valley to the Nottawasaga River bisects the reserve through its centre. The Niagara Escarpment's dolostone caprock (the Amabel Formation) can be seen in the upper parts of the gorge; rapids and waterfalls expose stratigraphic succession down to the Queenston Shale.

text: The

text: topography

text: of the area was greatly influenced by

text: glacial

text: processes, followed by

text: fluvial

text: erosion. The reserve is characterized by a

text: till

text: moraine

text: and other glacial features, such as

text: kame

text: s and

text: kettles

text: . A deeply cut tributary valley to the

text: Nottawasaga River

text: bisects the reserve through its centre. The Niagara Escarpment's

text: dolostone

text: caprock

text: (the Amabel Formation) can be seen in the upper parts of the gorge; rapids and waterfalls expose stratigraphic succession down to the

text: Queenston Shale

text: The water surface profile displays how the flow depth changes over a distance between critical depth and normal depth. For a steep reach, the water surface profile downstream of the lake is called an S2 curve. When a lake discharges to a mild reach there is no profile. The flow in the reach is immediately at normal depth. When the lake discharges to a steep reach, there is an S2 profile from the lake outlet to normal depth. As the slope decreases, the S2 curve increases in length. Figure 5 shows the S2 curve for the channel profile given above when Fr=1.18. The Standard Step Method was used for calculating the water surface profiles.

text: The water surface profile displays how the flow depth changes over a distance between critical depth and normal depth. For a steep reach, the water surface profile downstream of the lake is called an S2 curve. When a lake discharges to a mild reach there is no profile. The flow in the reach is immediately at normal depth. When the lake discharges to a steep reach, there is an S2 profile from the lake outlet to normal depth. As the slope decreases, the S2 curve increases in length. Figure 5 shows the S2 curve for the channel profile given above when Fr=1.18. The

text: Standard Step Method

text: was used for calculating the water surface profiles.

text: More than 200 methods are used worldwide to prescribe river flows needed to maintain healthy rivers.  However, very few of these are comprehensive and holistic, accounting for seasonal and inter-annual flow variation needed to support the whole range of ecosystem services that healthy rivers provide. Such comprehensive approaches include DRIFT (Downstream Response to Imposed Flow Transformation), BBM (Building Block Methodology), and the "Savannah Process" for site-specific environmental flow assessment, and ELOHA (Ecological Limits of Hydrologic Alteration) for regional-scale water resource planning and management.  The "best" method, or more likely, methods, for a given situation depends on the amount of resources and data available, the most important issues, and the level of certainty required.  To facilitate environmental flow prescriptions, a number of computer models and tools have been developed by groups such as the USACE's Hydrologic Engineering Center to capture flow requirements defined in a workshop setting (e.g., HEC-RPT) or to evaluate the implications of environmental flow implementation (e.g., HEC-ResSim, HEC-RAS, and HEC-EFM).Additionally, a 2D model is developed from a 3D turbulence model based on Smagorinsky large eddy closure to more appropriately model environmental large scale flows. This model is based on a slow manifold of the turbulent Smagorinsky large eddy closure instead of conventional depth-averaging flow equations.

text: More than 200 methods are used worldwide to prescribe river flows needed to maintain healthy rivers.  However, very few of these are comprehensive and holistic, accounting for seasonal and inter-annual flow variation needed to support the whole range of ecosystem services that healthy rivers provide. Such comprehensive approaches include DRIFT (Downstream Response to Imposed Flow Transformation), BBM (Building Block Methodology), and the "Savannah Process" for site-specific environmental flow assessment, and ELOHA (Ecological Limits of Hydrologic Alteration) for regional-scale water resource planning and management.  The "best" method, or more likely, methods, for a given situation depends on the amount of resources and data available, the most important issues, and the level of certainty required.  To facilitate environmental flow prescriptions, a number of computer models and tools have been developed by groups such as the USACE's Hydrologic Engineering Center to capture flow requirements defined in a workshop setting (e.g., HEC-RPT) or to evaluate the implications of environmental flow implementation (e.g., HEC-ResSim, HEC-RAS, and HEC-EFM).Additionally, a

text: model is developed from a

text: turbulence model based on Smagorinsky large eddy closure to more appropriately model environmental large scale flows. This model is based on a

text: slow manifold

text: of the turbulent Smagorinsky large eddy closure instead of conventional depth-averaging flow equations.

text: In the town there are three Caves, a Venetian Castle and the Monastery of Orphan Mary.  The gorge where the 22 mills are found starts from a magnificent waterfall named "Fonisa",(Φόνισσα, female killer), the only one on the island.  The stream above the waterfall springs from the mountain in the middle of town, by the "platea" square,during the summer coming right out from the mountain.  Upstream from town to the distant mountains there is no water during the summer.  During the rainy season water flows from the distant mountains to town, filling up the up-stream portion of the stream.  The stream from town flows about 200 meters to the waterfall.  The mills start from the base of the water fall and go down stream to the sea.  On a cliff by the gorge, is the church, Saint Catherine, which was built into the mountain.  At the end of the gorge, before the water reaches the sea, is the Monastery of Orphan Mary with its cave, the second biggest cave on the island.  The gorge concludes with one of the many beautiful beaches on the island called "Kalami" (Καλάμι, reed).

text: Sediment size is measured on a log base 2 scale, called the "Phi" scale, which classifies particles by size from "colloid" to "boulder".

text: The floodplain is the natural place for a river to dissipate its energy. Meanders form over the floodplain to slow down the flow of water and when the channel is at capacity the water spills over the floodplain where it is temporarily stored. In terms of flood management the upper part of the floodplain (piedmont zone) is crucial as this is where the flood water control starts. Artificial canalisation of the river here will have a major impact on wider flooding. This is the basis of sustainable flood management.

text: A buffer strip is an area of land maintained in permanent vegetation that helps to control air, soil, and water quality, along with other environmental problems, dealing primarily on land that is used in agriculture. Buffer strips trap sediment, and enhance filtration of nutrients and pesticides by slowing down runoff that could enter the local surface waters. The root systems of the planted vegetation in these buffers hold soil particles together which alleviate the soil of wind erosion and stabilize stream banks providing protection against substantial erosion and landslides. Farmers can also use buffer strips to square up existing crop fields to provide safety for equipment while also farming more efficiently.

text: A buffer strip is an area of land maintained in permanent

text: vegetation

text: that helps to control

text: air

text: soil

text: , and

text: water quality

text: , along with other environmental problems, dealing primarily on land that is used in

text: agriculture

text: . Buffer strips trap

text: sediment

text: , and enhance

text: filtration

text: of

text: nutrient

text: s and

text: pesticide

text: s by slowing down

text: runoff

text: that could enter the local

text: surface water

text: s. The

text: root systems

text: of the planted vegetation in these buffers hold soil particles together which alleviate the soil of

text: wind erosion

text: and stabilize

text: stream banks

text: providing protection against substantial

text: erosion

text: and

text: landslide

text: s. Farmers can also use buffer strips to square up existing

text: crop

text: fields to provide safety for equipment while also farming more efficiently.

text: After rills begin forming, they are subjected to variety of other erosional forces which may increase their size and output volume. Up to 37% of erosion in a rill-ridden area may derive from mass movement, or collapse, of rill sidewalls. As water flows through a rill, it will undercut into the walls, triggering collapse. Also, as water seeps into the soil of the walls, they weaken, amplifying the chance of wall collapse. The erosion created by these forces increases the size of the rill while also swelling its output volume.

text: Actually the valley of Swat starts from the foothill of Malakand but we are concerned with portion from Landakay to Gabral (Gulabad), the area within the administrative boundaries of Swat.The length of the valley from Landakay to Gabral is 91 miles. Two narrow strips of plains run along the banks of Swat River from Landakay to Madyan. Beyond Madyan in Kohistan-e-Swat, the plan is too little to be mentioned. So for as the width concerns, it is not similar, it varies from place to place. We can say that the average width is 5 miles. The widest portion of the valley is between Barikot and khwaza khela. The widest view point and the charming sight where a major portion of the valley is seen is at Gulibagh on main road, which leads to Madyan.There are some subsidiary valleys, which help to increase the width of the main valley. These subsidiary valleys are called "Daras". A Dara a narrow passage between mountains, and sometimes, the upper course of a river is also called Dara. If we imagine the main valley as a stem of a tree the subsidiary valleys form its branches. Swat River and its tributaries drain Swat. Therefore, the whole valley is the outcome of running water. This flowing water cuts the upper courses deeply, and flows the load of washed away materials. As the gradient is greater in the upper course so the erosion is on large scale, particularly in the summer rains, when all the rivers are in flood. The big boulders and stones are rolled, which causes more destruction in the upper courses. When the loaded water reaches to the areas of low gradient, the heavier materials are deposited. The deposition takes place according to the slope, generally, we observe, that the upper course is made up of big boulders, the middle course is of relatively small stones, pebbles, and debris, while the lower course is made of fine clay. Anyhow, the whole plain of Swat valley is strewn by the running water, and is made up of fine alluvial soil.

text: Klingen are small, narrow, steep V-shaped valleys formed by the erosive forces of water and suspended abrasive particles, gravel and pebbles. They are usually side valleys without a discernible valley floor that lead into a main valley. Further incision through ablation and headward erosion is mainly caused by the waters of small, steep, fast flowing, streams or becks and their processes are still visible today. Erosion, sedimentation and transport are mutually dependent. The term klinge is German and is used to refer to European stream landforms, especially in southern Germany and eastern France.

text: Klingen are small, narrow, steep

text: V-shaped valley

text: s formed by the

text: erosive forces

text: of water and suspended abrasive particles,

text: gravel

text: and

text: pebble

text: s. They are usually

text: side valley

text: s without a discernible

text: valley floor

text: that lead into a main

text: valley

text: . Further incision through

text: ablation

text: and

text: headward erosion

text: is mainly caused by the waters of small, steep, fast flowing, streams or becks and their processes are still visible today. Erosion,

text: sedimentation

text: and transport are mutually dependent. The term klinge is German and is used to refer to European stream landforms, especially in southern Germany and eastern France.

text: In addition to the Grijalva, there are other flows of water in the area in and around the canyon, many of which are seasonal. These consists of streams, some of which form waterfalls on the canyon’s sides and underground movements which have created caves and karst formations.  The last important water formation in the area is the reservoir of the Chicoasén Dam, which is manmade.

text: In addition to the Grijalva, there are other flows of water in the area in and around the canyon, many of which are seasonal. These consists of streams, some of which form waterfalls on the canyon’s sides and underground movements which have created caves and karst formations.  The last important water formation in the area is the reservoir of the

text: Chicoasén Dam

text: , which is manmade.

text: Silverthrone Caldera is the largest and best-preserved of the two caldera complexes in the northern Garibaldi chain, the other being the Franklin Glacier complex  to the east-southeast. The caldera has a diameter of  and contains breccia, lava flows and lava domes. Like Franklin to the east-southeast, the geology of Silverthrone is poorly known due to minimal studies. The region surrounding the Silverthrone complex is significantly jagged due to the mountainous terrain of the Coast Mountains. Near vertical flanks extend from near sea level to more than  in elevation. Silverthrone is significantly younger than the Franklin Glacier complex to the east-southeast and its volcanics likely have ages comparable to other volcanics throughout the Garibaldi chain. The oldest volcanics at the Silverthrone Caldera complex are composed of volcanic breccias, some of which became fused together by intense volcanic heat from when the deposits were first erupted. After these volcanics were deposited, a series of dacite, andesite and rhyolite lava flows were erupted upon volcanic breccia from the first volcanic phase. These eroded lava flows in total are  thick. Volcanics in the lower portion of this series of lava flows give a potassium-argon date of 750,000 years while volcanics slightly above the lava flows are 400,000 years old. The most recent volcanic activity produced a series of andesite and basaltic andesite lava flows down Pashleth Creek and the Machmell and Kingcome river valleys. The lava flow extending from near Pashleth Creek to down the Machmell River valley is over  in length. Its small amount of erosion indicates that it could be 1,000 years old or younger.

text: Machmell

text: and

text: Kingcome

text: river valleys. The lava flow extending from near Pashleth Creek to down the Machmell River valley is over  in length. Its small amount of erosion indicates that it could be 1,000 years old or younger.

text: These tubes form when calcium carbonate or calcium sulfate dissolved in the water comes out of solution and is deposited. In soda straws, as each drop hovers at the tip, it deposits a ring of mineral at its edge. It then falls and a new drop takes its place. Each successive drop of water deposits a little more mineral before falling, and eventually a tube is built up. Stalagmites or flowstone may form where the water drops hit the cave floor.

text: These tubes form when

text: calcium carbonate

text: or

text: calcium sulfate

text: dissolved in the water comes out of solution and is deposited. In soda straws, as each drop hovers at the tip, it deposits a ring of mineral at its edge. It then falls and a new drop takes its place. Each successive drop of water deposits a little more mineral before falling, and eventually a tube is built up.

text: Stalagmite

text: s or

text: flowstone

text: may form where the water drops hit the cave floor.

text: In terms of particle size as used by geologists, sand particles range in diameter from 0.0625 mm (or  mm) to 2 mm. An individual particle in this range size is termed a sand grain. Sand grains are between gravel (with particles ranging from 2 mm up to 64 mm) and silt (particles smaller than 0.0625 mm down to 0.004 mm).  The size specification between sand and gravel has remained constant for more than a century, but particle diameters as small as 0.02 mm were considered sand under the Albert Atterberg standard in use during the early 20th century. A 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A 1938 specification of the United States Department of Agriculture was 0.05 mm.  Sand feels gritty when rubbed between the fingers (silt, by comparison, feels like flour).

text: In terms of

text: particle size

text: as used by

text: geologist

text: s, sand particles range in diameter from 0.0625 mm (or  mm) to 2 mm. An individual particle in this range size is termed a sand grain. Sand grains are between

text: gravel

text: (with particles ranging from 2 mm up to 64 mm) and

text: silt

text: (particles smaller than 0.0625 mm down to 0.004 mm).  The size specification between sand and gravel has remained constant for more than a century, but particle diameters as small as 0.02 mm were considered sand under the

text: Albert Atterberg

text: standard in use during the early 20th century. A 1953 engineering standard published by the

entity_name: American Association of State Highway and Transportation Officials

text: American Association of State Highway and Transportation Officials

text: set the minimum sand size at 0.074 mm. A 1938 specification of the

text: United States Department of Agriculture

text: was 0.05 mm.  Sand feels gritty when rubbed between the fingers (

text: silt

text: , by comparison, feels like

text: flour

text: At Loe Pool a barrier dammed the ria of the River Cober causing the formation of Cornwall's largest lake. Very little of the Loe Bar shingle is locally derived (compared with nearby Gunwalloe beach material to the south) and the deposits have been tentatively dated as Eocene. The composition of the bar deposits are: chalk flint 86%, quartz 9%, grit 2.6%, greensand chert 2% and serpentine 0.5%. The shingle coming from drowned terraces of the former river that flowed down the English Channel; the nearest onshore source is  away in East Devon. Longshore drift is unlikely to have caused the formation because the bar is situated between two headlands but it plays an important part in the maintenance of the bar, with a strong current flowing to the south-east from Porthleven to Gunwalloe, depositing shingle along the bar. The ebb flow is not a simple reverse flow and is not strong enough to remove all the deposits.*

text: At

text: Loe Pool

text: a barrier dammed the

text: ria

text: of the

text: River Cober

text: causing the formation of Cornwall's largest lake. Very little of the Loe Bar shingle is locally derived (compared with nearby

text: Gunwalloe beach material

text: to the south) and the deposits have been tentatively dated as

text: Eocene

text: . The composition of the bar deposits are:

text: chalk

text: flint

text: quartz

text: grit

text: greensand

text: chert

text: 2% and

text: serpentine

text: 0.5%. The shingle coming from drowned terraces of the former river that flowed down the

text: English Channel

text: ; the nearest onshore source is  away in East Devon.

text: Longshore drift

text: is unlikely to have caused the formation because the bar is situated between two headlands but it plays an important part in the maintenance of the bar, with a strong current flowing to the south-east from Porthleven to Gunwalloe, depositing shingle along the bar. The ebb flow is not a simple reverse flow and is not strong enough to remove all the deposits.*

text: Eagle Rock participates in the Austin Bluffs area’s soil type of the "Travessilla-Rock outcrop complex," as mapped at the scale of 1:24,000-ft., (ref. USDA, 1974.) To understand the area’s soil characteristics in more detail, we may consider a field-study lecture on site at the Heller Ranch, where Prof. Thomas P. Huber explained the geomorphological origins of Eagle Rock. The Eagle Rock cliff resulted from several long cycles of mountain-building (termed "orogenies,") followed by erosion. Heat and pressure energies that had thrust up the mountains produced igneous rock, such as the Pikes Peak pink granite, which eventually degraded. Natural forces dispersed and deposited particles of the rock debris. Over time, the sediment collected and consolidated into new sandstone at the Garden of the Gods, producing a geologic layer known as the Dakota Formation. The Dakota sedimented sandstone later came to be inundated by the waters of a shallow inland sea. From some 66 to 70 million years ago and episodically continuing for millions of years, uplift from the Laramide Orogeny exposed the old sandstone seabed, by tilting up to 90-degree angles the steep red megaliths which we now see in the Garden of the Gods (Huber, 1998, pp. 7 and 130.) Portions of the Dakota Formation again cycled into episodes of erosion, allowing a detritus of coarse-grained sedimentary sand to be displaced some three miles (5 km) eastwards, to land at the site which we now know as Austin Bluffs. The feldspar-rich sedimented particles of "arkose" sand consolidated into new sandstone, i.e. the Dawson Formation, which shows Eagle Rock’s characteristic color, ranging from grey to reddish. At Eagle Rock, the sandstone cliff we see today has survived further erosion for a longer time, than the less-resistant background soils could have withstood. Eagle Rock lies exposed to view, as a weather-sculpted geological form (Huber, pp. 6 and 55.)

text: Eagle Rock participates in the Austin Bluffs area’s soil type of the "Travessilla-Rock outcrop complex," as mapped at the scale of 1:24,000-ft., (ref. USDA, 1974.) To understand the area’s soil characteristics in more detail, we may consider a field-study lecture on site at the Heller Ranch, where Prof. Thomas P. Huber explained the geomorphological origins of Eagle Rock. The Eagle Rock cliff resulted from several long cycles of mountain-building (termed "orogenies,") followed by erosion. Heat and pressure energies that had thrust up the mountains produced igneous rock, such as the

text: Pikes Peak

text: pink granite, which eventually degraded. Natural forces dispersed and deposited particles of the rock debris. Over time, the sediment collected and consolidated into new sandstone at the Garden of the Gods, producing a geologic layer known as the

text: Dakota Formation

text: . The Dakota sedimented sandstone later came to be inundated by the waters of a shallow inland sea. From some 66 to 70 million years ago and episodically continuing for millions of years, uplift from the Laramide Orogeny exposed the old sandstone seabed, by tilting up to 90-degree angles the steep red megaliths which we now see in the Garden of the Gods (Huber, 1998, pp. 7 and 130.) Portions of the Dakota Formation again cycled into episodes of erosion, allowing a detritus of coarse-grained sedimentary sand to be displaced some three miles (5 km) eastwards, to land at the site which we now know as Austin Bluffs. The feldspar-rich sedimented particles of "arkose" sand consolidated into new sandstone, i.e. the Dawson Formation, which shows Eagle Rock’s characteristic color, ranging from grey to reddish. At Eagle Rock, the sandstone cliff we see today has survived further erosion for a longer time, than the less-resistant background soils could have withstood. Eagle Rock lies exposed to view, as a weather-sculpted geological form (Huber, pp. 6 and 55.)

text: The way in which "size" is expressed is open to a wide range of interpretations. A simple treatment assumes the particles are spheres that will just pass through a square hole in a "sieve". In practice, particles are irregular – often extremely so, for example in the case of fibrous materials – and the way in which such particles are characterized during analysis is very dependent on the method of measurement used.

text: There are 2 possible scenarios when the path of a stream is blocked by an uplifted block of rock. First scenario: the stream poses stream power that is high enough to cut through the uplifted rocks, so that the river course will not be significantly altered. A channel is opened in the uplifted rocks due to erosion, a landform known as water gap. It continues to flow until the rock is further uplifted and the river no longer has enough erosive power to cut through it, leading to the second scenario. Second scenario: the stream does not have enough erosive power to cut through the rocks, so it deflected to flow along the boundary of the uplifted block as aforementioned. The abandoned river channel is known as wind gap. From here, the river either flows along the boundary of the fold and bends around the fold tip, or it may cut through the rocks at some points despite the block, due to either, acquisition of enough stream power through stream capture of small tributaries along its flow, or the presence of a particularly weak spot in the rock.  In either way the river continues to flow until further uplift of rocks makes the rock too difficult for the river to cut through, which results in, again, the deflection of the channel and formation of a new wind gap.

text: There are 2 possible scenarios when the path of a stream is blocked by an uplifted block of rock. First scenario: the stream poses stream power that is high enough to cut through the uplifted rocks, so that the river course will not be significantly altered. A channel is opened in the uplifted rocks due to erosion, a landform known as

text: water gap

text: . It continues to flow until the rock is further uplifted and the river no longer has enough erosive power to cut through it, leading to the second scenario. Second scenario: the stream does not have enough erosive power to cut through the rocks, so it deflected to flow along the boundary of the uplifted block as aforementioned. The abandoned river channel is known as

text: wind gap

text: . From here, the river either flows along the boundary of the fold and bends around the fold tip, or it may cut through the rocks at some points despite the block, due to either, acquisition of enough stream power through stream capture of small tributaries along its flow, or the presence of a particularly weak spot in the rock.  In either way the river continues to flow until further uplift of rocks makes the rock too difficult for the river to cut through, which results in, again, the deflection of the channel and formation of a new wind gap.

text: In karst areas, a sinkhole, sink, or doline is a closed depression draining underground. It can be cylindrical, conical, bowl-shaped or dish-shaped. The diameter ranges from a few to many hundreds of metres. The name "doline" comes from dolina, the Slovenian word for this very common feature. The term "foiba" may also refer to a deep wide chasm of a river at the place where it goes underground.

text: In

text: karst

text: areas, a

text: sinkhole

text: , sink, or doline is a closed depression draining underground. It can be cylindrical, conical, bowl-shaped or dish-shaped. The diameter ranges from a few to many hundreds of metres. The name "doline" comes from dolina, the

text: Slovenian

text: word for this very common feature. The term "foiba" may also refer to a deep wide chasm of a river at the place where it goes underground.

text: Dave plans to dynamite the local dam and flood the nearby salt flats, creating a large supply of salt water.  Because the dam is private property, however, Dan attempts to contact the governor for permission to blow up the dam. Knowing they must halt the monoliths at the canyon's edge, Dave disregards the governor's concerns, and places dynamite charges within the dam; with only minutes left, the dynamite is detonated. The group watches as a huge torrent of water flows over the salt deposits at the canyon's edge, reaching the monoliths; their growth is finally halted when the last huge formation of monoliths crashes down into the salty water. Dan then reveals to the group that the governor actually said to use dynamite "only" if Dave was absolutely certain of success. As they all laugh, Dave then comments, first repeating Martin's earlier assertion that the region's salt flat was "Mother Nature's worst mistake", then pointing out, ironically, that this near-disaster has just proved otherwise.

text: Dave plans to dynamite the local dam and flood the nearby

text: salt flat

text: s, creating a large supply of salt water.  Because the dam is private property, however, Dan attempts to contact the governor for permission to blow up the dam. Knowing they must halt the monoliths at the canyon's edge, Dave disregards the governor's concerns, and places dynamite charges within the dam; with only minutes left, the dynamite is detonated. The group watches as a huge torrent of water flows over the salt deposits at the canyon's edge, reaching the monoliths; their growth is finally halted when the last huge formation of monoliths crashes down into the salty water. Dan then reveals to the group that the governor actually said to use dynamite "only" if Dave was absolutely certain of success. As they all laugh, Dave then comments, first repeating Martin's earlier assertion that the region's salt flat was "Mother Nature's worst mistake", then pointing out, ironically, that this near-disaster has just proved otherwise.

text: Following the glacier's retreat and allowing for the lake to be released, the river carved out most of the clay and silt deposits, leaving the former delta "hanging" approximately  above the current valley floor When the sand portion of a deposit has very little clay or "fines" to cement it together, it is structurally weak, leaving the area around it vulnerable. Such an area is also sensitive to water accumulation, increasing the internal "pore" pressure and subsequently contributing to ground failure. Water infiltrating from the surface will flow through the surface, save for contact with the less permeable clay, allowing the water to accumulate and form a zone of stability weakness.

text: Compacted fine sediments will form a smooth beach surface that resists wind and water erosion. During hot calm seasons, a crust may form on the surface of ocean beaches as the heat of the sun evaporates the water leaving the salt which crystallises around the sand particles.  This crust forms an additional protective layer that resists wind erosion unless disturbed by animals, or dissolved by the advancing tide.

text: Often, the rock stratum just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a rock shelter under and behind the waterfall. Eventually, the outcropping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by attrition as they collide with each other, and they also erode the base of the waterfall by abrasion, creating a deep plunge pool or gorge.

text: Often, the rock

text: stratum

text: just below the more resistant shelf will be of a softer type, meaning that undercutting due to splashback will occur here to form a shallow cave-like formation known as a

text: rock shelter

text: under and behind the waterfall. Eventually, the

text: outcrop

text: ping, more resistant cap rock will collapse under pressure to add blocks of rock to the base of the waterfall. These blocks of rock are then broken down into smaller boulders by

text: attrition

text: as they collide with each other, and they also erode the base of the waterfall by

text: abrasion

text: , creating a deep plunge pool or gorge.

text: The Merced River (pronounced mɜːsɛd), in the central part of the U.S. state of California, is a -long tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through the southern part of Yosemite National Park, and the world-famous Yosemite Valley. The river's character changes dramatically once it reaches the foothills and the lowlands, becoming a slow-moving waterway meandering through irrigated fields.

text: The Merced River (pronounced

text: mɜːsɛd

text: ), in the central part of the

text: U.S. state

text: of

text: California

text: , is a -long

text: tributary

text: of the

text: San Joaquin River

text: flowing from the

text: Sierra Nevada

text: into the

text: San Joaquin Valley

text: . It is most well known for its swift and steep course through the southern part of

text: Yosemite National Park

text: , and the world-famous

text: Yosemite Valley

text: . The river's character changes dramatically once it reaches the

text: foothills

text: and the lowlands, becoming a slow-moving waterway meandering through irrigated fields.

text: The contact between the Tapeats Sandstone and Bass Formation and the rest of the folded and faulted Unkar Group is a prominent angular unconformity, which is part of the Great Unconformity. The differential erosion of the Unkar Group left resistant beds of the Cardenas Basalt and Shinumo Quartzite as topographic highs, ancient monadnocks, that are now buried by sandstones, shales, and conglomerates of the Tapeats Sandstone. These monadnocks served locally as sources of coarse-grained sediments during the marine transgression that deposited the Tapeats Sandstone and other members of the Tonto Group. The contact between the Bass Formation and the Tapeats Sandstone forms part of a relative flat surface that lies between the monadnocks.

text: The contact between the

text: Tapeats Sandstone

text: and Bass Formation and the rest of the

text: folded

text: and faulted Unkar Group is a prominent

text: angular unconformity

text: , which is part of the

text: Great Unconformity

text: . The differential

text: erosion

text: of the Unkar Group left resistant beds of the Cardenas Basalt and Shinumo Quartzite as topographic highs, ancient

text: monadnock

text: s, that are now buried by sandstones, shales, and conglomerates of the Tapeats Sandstone. These monadnocks served locally as sources of coarse-grained sediments during the

text: marine transgression

text: that deposited the Tapeats Sandstone and other members of the

text: Tonto Group

text: . The contact between the Bass Formation and the Tapeats Sandstone forms part of a relative flat surface that lies between the monadnocks.

text: It has the largest drainage basin of all of the NYC reservoirs, at . The reservoir's capacity is . This water flows over halfway through the reservoir to enter the  West Delaware Tunnel in the town of Tompkins, just east of the town of Deposit. Then it flows through the aqueduct into the Rondout Reservoir, where the water enters the  Delaware Aqueduct.

text: It has the largest drainage basin of all of the NYC reservoirs, at . The reservoir's capacity is . This water flows over halfway through the reservoir to enter the  West Delaware Tunnel in the town of

text: Tompkins

text: , just east of the town of Deposit. Then it flows through the aqueduct into the

text: Rondout Reservoir

text: , where the water enters the

text: Delaware Aqueduct

text: Obrh Creek () is a losing stream that originates and terminates in the Lož Karst Field in the Municipality of Loška Dolina. It is a watercourse in the Ljubljanica watershed. It is created by the confluence of Little Obrh Creek () and Big Obrh Creek (); the latter is fed by two tributaries: Brežiček Creek and Viševek Brežiček Creek (). The confluence, at which point it is simply named Obrh, lies west of the village of Pudob. In the northwest, limestone part of the karst field, Obrh Creek starts to drain into many sinkholes, and higher water flows into  Golobina Cave. The stream re-emerges at a spring  to the northwest on the southeast edge of the Cerknica Karst Field.

text: Obrh Creek () is a

text: losing stream

text: that originates and terminates in the

text: Lož Karst Field

text: in the

text: Municipality of Loška Dolina

text: . It is a watercourse in the

text: Ljubljanica

text: watershed. It is created by the confluence of Little Obrh Creek () and Big Obrh Creek (); the latter is fed by two tributaries: Brežiček Creek and Viševek Brežiček Creek (). The confluence, at which point it is simply named Obrh, lies west of the village of

text: Pudob

text: . In the northwest, limestone part of the karst field, Obrh Creek starts to drain into many

text: sinkhole

text: s, and higher water flows into  Golobina Cave. The stream re-emerges at a spring  to the northwest on the southeast edge of the

text: Cerknica Karst Field

text: Literally translated, chauka means ‘rectangular enclosure’. It’s a small gradient enclosed by earthen bunds on three sides, which effectively traps rain water helping in recharging ground water. The ground velocity of rain water is checked in a chauka, leading to a significant reduction in soil erosion. When the water level in a chauka touches 9 inches, the rain water flows to the chauka at the immediately lower gradient. The water from the chaukas eventually drains into a channel that empties into a pond called nadi providing drinking water to the cattle.

text: The formation of the uplands goes back to the last glaciation phase in northern Germany, the Weichselian. The Dornbusch was created about 12,500 years ago by a small finger of the ice front that left its mark in the present day straits of the Little Belt and Great Belt. During the retreat of the glacier, the uplands were left behind as a push moraine and for about 4,000 years they were part of a large area of the mainland, south of the present Baltic Sea. During the first flooding phase of the Baltic Sea, the water did not reach the area of Hiddensee; it was only about 3,900 years ago that the Littorina Sea lapped the three island cores of Dornbusch, Fährinsel and Gellen. And it was just 2,900 years ago that coastal erosion (land erosion, dispersal and deposition) and the formation of the elongated shape of the Hiddensee through sand-accretion began.

text: The formation of the uplands goes back to the last glaciation phase in northern Germany, the

text: Weichselian

text: . The Dornbusch was created about 12,500 years ago by a small finger of the

text: ice front

text: that left its mark in the present day straits of the

text: Little Belt

text: and

text: Great Belt

text: . During the retreat of the glacier, the uplands were left behind as a

text: push moraine

text: and for about 4,000 years they were part of a large area of the mainland, south of the present Baltic Sea. During the first flooding phase of the Baltic Sea, the water did not reach the area of Hiddensee; it was only about 3,900 years ago that the

text: Littorina Sea

text: lapped the three island cores of Dornbusch,

text: Fährinsel

text: and

text: Gellen

text: . And it was just 2,900 years ago that

text: coastal erosion

text: (land erosion, dispersal and deposition) and the formation of the elongated shape of the Hiddensee through sand-accretion began.

text: Hydrology considers quantifying surface water flow and solute transport, although the treatment of flows in large rivers is sometimes considered as a distinct topic of hydraulics or hydrodynamics. Surface water flow can include flow both in recognizable river channels and otherwise. Methods for measuring flow once water has reached a river include the stream gauge (see: discharge), and tracer techniques. Other topics include chemical transport as part of surface water, sediment transport and erosion.

text: Hydrology considers quantifying surface water flow and solute transport, although the treatment of flows in large rivers is sometimes considered as a distinct topic of hydraulics or hydrodynamics. Surface water flow can include flow both in recognizable river channels and otherwise. Methods for measuring flow once water has reached a river include the

text: stream gauge

text: (see:

text: discharge

text: ), and tracer techniques. Other topics include chemical transport as part of surface water, sediment transport and erosion.

text: Natural surface water can be augmented by importing surface water from another watershed through a canal or pipeline. It can also be artificially augmented from any of the other sources listed here, however in practice the quantities are negligible. Humans can also cause surface water to be "lost" (i.e. become unusable) through pollution.

text: Natural surface water can be augmented by importing surface water from another watershed through a

text: canal

text: or

text: pipeline

text: . It can also be artificially augmented from any of the other sources listed here, however in practice the quantities are negligible. Humans can also cause surface water to be "lost" (i.e. become unusable) through

text: pollution

text: The Sherabad River, Shirabad River, Sherabad Darya or Shirabad Darya. It is a right tributary of the Amu Darya in south-central Uzbekistan. It is about  long and drains an area of . The river rises in the arid foothills of the Gissar Range and flows south through steppe before flowing through a mountain ridge to empty into the Central Asia plain near Shirabad. The river turns south and flows past Akkürgon, to flow into the Amu Darya near Shuro-obod. Because of irrigation water use, most of the water in the Sherabad no longer reaches the Amu Darya and its eventual destination in the Aral Sea. After flowing out of the mountains the remaining water in the river is usually salty so it is unsuitable for further water use. In dry years, most of the river dries up before reaching the Amu Darya.

text: The Sherabad River, Shirabad River, Sherabad Darya or Shirabad Darya. It is a right tributary of the

text: Amu Darya

text: in south-central

text: Uzbekistan

text: . It is about  long and drains an area of . The river rises in the arid foothills of the

text: Gissar Range

text: and flows south through

text: steppe

text: before flowing through a mountain ridge to empty into the

text: Central Asia

text: plain near

text: Shirabad

text: . The river turns south and flows past

text: Akkürgon

text: , to flow into the Amu Darya near

text: Shuro-obod

text: . Because of

text: irrigation

text: water use, most of the water in the Sherabad no longer reaches the Amu Darya and its eventual destination in the

text: Aral Sea

text: . After flowing out of the mountains the remaining water in the river is usually salty so it is unsuitable for further water use. In dry years, most of the river dries up before reaching the Amu Darya.

text: The underlying geology in the Pack River watershed is largely granitic, which decomposes into fine particles.  Glaciation in the Pack River valley formed ice dams upstream of the confluence of many tributaries, resulting in large deposits of glacial till.  Fine sandy sediments deposited in the dammed water are known as glacial fluvial deposits. These sandy areas today appear on mountain side slopes, forming very erosive soils.

text: Examples of sinkhole lakes and marshes include very large lakes like the Arendsee and the Zwischenahner Meer – both at least 500 hectares in area – the Seeburger See, the Sager Meer in Oldenburg district, the Rudower See in Westprignitz district or the "bottomless marsh" (Grundloses Moor) in Soltau-Fallingbostel district and Maujahn in Lüchow-Dannenberg district. The Bullenkuhle belongs to this group, albeit considerably smaller. This sinkhole has a diameter of about  and attains a depth of . Exactly when the Bullenkuhle was formed is not known. This would need a stratigraphic investigation and pollen analysis of the vertical profile of the sinkhole (see Maujahn Moor).

text: Examples of sinkhole lakes and marshes include very large lakes like the

text: Arendsee

text: and the

text: Zwischenahner Meer

text: – both at least 500 hectares in area – the

text: Seeburger See

text: , the Sager Meer in

text: Oldenburg district

text: , the

text: Rudower See

text: in

text: Westprignitz district

text: or the "bottomless marsh" (

text: Grundloses Moor

text: ) in

text: Soltau-Fallingbostel district

text: and

text: Maujahn

text: in

text: Lüchow-Dannenberg district

text: . The Bullenkuhle belongs to this group, albeit considerably smaller. This sinkhole has a diameter of about  and attains a depth of . Exactly when the Bullenkuhle was formed is not known. This would need a

text: stratigraphic

text: investigation and

text: pollen analysis

text: of the vertical profile of the sinkhole (see

text: Maujahn Moor

text: The Pocumtuck Range is composed of Sugarloaf arkose, a weather resistant sedimentary rock capped in places by a thin ridge of volcanic trap rock. The arkose is most apparent on Sugarloaf Mountain and the western cliff of Pocumtuck Ridge, while the trap rock is most apparent on the north and east side of Pocumtuck Ridge and throughout the summit ridge of Rocky Mountain in Greenfield. The range is a non-contiguous extension of the Metacomet Ridge that extends through New England from Long Island Sound to the Vermont border. The Pocumtuck Range forms the bottom and middle layers of a geologic layercake. The arkose is the oldest (bottom) layer, followed by the middle trap rock layer, which in turn gives way to a conglomerate rock top layer most visible across the Connecticut River as Mount Toby. These layers were formed between 190 and 210 million years ago as the continent of North America began rifting apart from Africa and Eurasia. A series of erosion and deposition (geology) episodes interspersed with heavy basalt lava flows created the layered strata; faulting and earthquakes tilted the layers diagonally while subsequent erosion and glacial activity exposed the tilted "layers" of sandstone, basalt, and erosion-resistant conglomerate rock visible today.

text: The Pocumtuck Range is composed of Sugarloaf

text: arkose

text: , a weather resistant

text: sedimentary rock

text: capped in places by a thin ridge of

text: volcanic

text: trap rock

text: . The arkose is most apparent on Sugarloaf Mountain and the western cliff of Pocumtuck Ridge, while the trap rock is most apparent on the north and east side of Pocumtuck Ridge and throughout the summit ridge of Rocky Mountain in Greenfield. The range is a non-contiguous extension of the

text: Metacomet Ridge

text: that extends through

text: New England

text: from

text: Long Island Sound

text: to the

text: Vermont

text: border. The Pocumtuck Range forms the bottom and middle layers of a geologic layercake. The arkose is the oldest (bottom) layer, followed by the middle trap rock layer, which in turn gives way to a

text: conglomerate rock

text: top layer most visible across the Connecticut River as

text: Mount Toby

text: . These layers were formed between 190 and 210 million years ago as the continent of

text: North America

text: began

text: rifting

text: apart from

text: Africa

text: and

text: Eurasia

text: . A series of

text: erosion

text: and

text: deposition (geology)

text: episodes interspersed with heavy basalt

text: lava

text: flows created the layered strata;

text: faulting

text: and

text: earthquake

text: s tilted the layers diagonally while subsequent erosion and

text: glacial

text: activity exposed the tilted "layers" of sandstone, basalt, and erosion-resistant conglomerate rock visible today.

text: FAC has to be distinguished from erosion corrosion because the  fundamental mechanisms for the two corrosion modes are different. FAC does not involve impingement of particles, bubbles, or cavitation which cause the mechanical (often crater-like) wear on the surface. By contrast to mechanical erosion, FAC involves dissolution of normally poorly soluble oxide by combined electrochemical, water chemistry and mass-transfer phenomena. Nevertheless, the terms FAC and erosion are sometimes used interchangeably because the actual mechanism may, in some cases, be unclear.

text: FAC has to be distinguished from

text: erosion corrosion

text: because the  fundamental mechanisms for the two corrosion modes are different. FAC does not involve impingement of particles, bubbles, or

text: cavitation

text: which cause the mechanical (often crater-like) wear on the surface. By contrast to mechanical erosion, FAC involves dissolution of normally poorly soluble oxide by combined electrochemical, water chemistry and mass-transfer phenomena. Nevertheless, the terms FAC and erosion are sometimes used interchangeably because the actual mechanism may, in some cases, be unclear.

text: During periods where the well floods, water flows out onto the park forming a shallow pond area adjacent to the well building. Algae flourishes in the overflow water which stand stationary exposed to light and oxygen, of which there is little in the thermal waters inside the well building. Filamentous algae Melosira variants and Spirogyra have both been identified  and are very abundant in the flooded pool area outside of the well building.

text: During periods where the well floods, water flows out onto the park forming a shallow pond area adjacent to the well building.

text: Algae

text: flourishes in the overflow water which stand stationary exposed to light and

text: oxygen

text: , of which there is little in the thermal waters inside the well building. Filamentous algae

text: Melosira

text: variants and

text: Spirogyra

text: have both been identified  and are very abundant in the flooded pool area outside of the well building.

text: Piccaninnie Ponds is a popular site for both snorkelling and cave diving.  It contains three main features of interest to cave divers. The ‘First Pond’ is an open depression about  deep with a silt floor and much aquatic life, the ‘Chasm’ is a sinkhole with a depth of over , and the ‘Cathedral’ is an enclosed area with limestone formations and a depth of about . Underwater visibility is excellent and may exceed . Snorkelling and cave diving at Piccaninnie Ponds is by permit only.

text: Piccaninnie Ponds is a popular site for both

text: snorkelling

text: and

text: cave diving

text: .  It contains three main features of interest to cave divers. The ‘First Pond’ is an open depression about  deep with a silt floor and much aquatic life, the ‘Chasm’ is a

text: sinkhole

text: with a depth of over , and the ‘Cathedral’ is an enclosed area with

text: limestone

text: formations and a depth of about . Underwater visibility is excellent and may exceed . Snorkelling and cave diving at Piccaninnie Ponds is by permit only.

text: Deforestation and overgrazing along the river's heavily populated course have caused soil erosion problems.  Sediments have reduced river flow, reservoir size, and water quality.  Water quality has also deteriorated due to pesticide runoff.

text: The term "particle" is usually applied differently to three classes of sizes. The term macroscopic particle, usually refers to particles much larger than atoms and molecules. These are usually abstracted as point-like particles, even though they have volumes, shapes, structures, etc. Examples of macroscopic particles would include powder, dust, sand, pieces of debris during a car accident, or even objects as big as the stars of a galaxy.

text: The term "particle" is usually applied differently to three classes of sizes. The term

text: macroscopic particle

text: , usually refers to particles much larger than

text: atom

text: s and

text: molecule

text: s. These are usually

text: abstracted

text: as

text: point-like particles

text: , even though they have volumes, shapes, structures, etc. Examples of macroscopic particles would include

text: powder

text: dust

text: sand

text: , pieces of

text: debris

text: during a

text: car accident

text: , or even objects as big as the

text: star

text: s of a

text: galaxy

text: In a slow-flowing stream or river, the difference in speed between one bank and the other is not sufficient to provide a credible explanation as to why all the deposition occurs on one bank, and none on the other.  Similarly, the fallacy has no explanation as to why all the deposition occurs at a stream bend, and little or none occurs where the stream is following a straight course.  (The speed of water in a stream does not slow just because the stream enters a bend.)

text: The material of the floor of the canyon system between Candor and Melas chasmata is grooved. This is interpreted to be alluvial deposits and/or material that has collapsed or contracted by the removal of ice or water. There are also portions of older and younger massive floor material of volcaniclastic origin - only separated in age by crater distribution. Also there is etched massive floor material that is like the younger and older massive material except that it has wind erosion features on it. There are also a few spires of undivided material composed of the same material as the canyon walls.

text: The material of the floor of the canyon system between Candor and Melas chasmata is grooved. This is interpreted to be

text: alluvial

text: deposits and/or material that has collapsed or contracted by the removal of ice or water. There are also portions of older and younger massive floor material of

text: volcaniclastic

text: origin - only separated in age by crater distribution. Also there is etched massive floor material that is like the younger and older massive material except that it has wind erosion features on it. There are also a few spires of undivided material composed of the same material as the canyon walls.

text: Water is almost nonexistent on Venus, and thus the only erosive process to be found (apart from thermal erosion by lava flows) is the interaction produced by the atmosphere with the surface.  This interaction is present in the ejecta of impact craters expelled onto the surface of Venus.  The material ejected during a meteorite impact is lifted to the upper atmosphere, where winds transport the material toward the west.  As the material is deposited on the surface, it forms parabola-shaped patterns.  This type of deposit can be established on top of various geologic features or lava flows.  Therefore, these deposits are the youngest structures on the planet.  Images from Magellan reveal the existence of more than 60 of these parabola-shaped deposits that are associated with crater impacts.

text: Water is almost nonexistent on Venus, and thus the only

text: erosive

text: process to be found (apart from thermal erosion by lava flows) is the interaction produced by the atmosphere with the surface.  This interaction is present in the ejecta of impact craters expelled onto the surface of Venus.  The material ejected during a

text: meteorite

text: impact is lifted to the upper atmosphere, where winds transport the material toward the west.  As the material is deposited on the surface, it forms

text: parabola

text: -shaped patterns.  This type of deposit can be established on top of various geologic features or lava flows.  Therefore, these deposits are the youngest structures on the planet.  Images from Magellan reveal the existence of more than 60 of these parabola-shaped deposits that are associated with crater impacts.

text: Klein & Vieira (1980a; b), Klein et al. (1984), Geraldes & Netto (2004a), Silveira et al. (2005), Valente et al. (2005), etc., concluded the pyroclastic rocks and their neighbours present at the Contenda Rock are pyroclastic flows, using the layered structure as proof. Motoki et al. (2007c) concluded the development degree and horizontal continuity of the pyroclastic textures are too poor for a pyroclastic flow deposit. The pyroclastic rocks along the Eugênia River are exposed, forming pyroclastic dykes, presenting underground subvolcanic fissures. If the pyroclastic rocks originated from pyroclastic flows, the deposits should have been widely present in the Fluminense lowland, such as Mesquita, Nilopolis, Nova Iguaçu, and Duque de Caxias. Welded pyroclastic rocks resist weathering and are therefore easily identified. Such volcanic deposits are not found in the Fluminense lowland. This confirms that these pyroclastic rocks were not created in pyroclastic flows.

text: Klein & Vieira (1980a; b), Klein et al. (1984), Geraldes & Netto (2004a), Silveira et al. (2005), Valente et al. (2005), etc., concluded the

text: pyroclastic rock

text: s and their neighbours present at the Contenda Rock are

text: pyroclastic flow

text: s, using the layered structure as proof. Motoki et al. (2007c) concluded the development degree and horizontal continuity of the pyroclastic textures are too poor for a

text: pyroclastic flow

text: deposit. The

text: pyroclastic rock

text: s along the Eugênia River are exposed, forming pyroclastic dykes, presenting underground subvolcanic fissures. If the pyroclastic rocks originated from pyroclastic flows, the deposits should have been widely present in the Fluminense lowland, such as Mesquita, Nilopolis, Nova Iguaçu, and Duque de Caxias. Welded pyroclastic rocks resist weathering and are therefore easily identified. Such volcanic deposits are not found in the Fluminense lowland. This confirms that these pyroclastic rocks were not created in pyroclastic flows.

text: The main cave consists of a massive structure with a big open chamber of about 5m high, 10m wide and 30m long at the entrance. There are ten tunnels at the main chamber leading to different directions. Within the tunnels are big chambers and other tunnels of varying lengths, some of which are inter connected. The caves are occupied by a large colony of bats of various sizes. There are streams and body of water at various places. A stream flows out from one of the tunnels into a rapid flowing river (River Nkissa). At the meeting point of the river and the stream one can feel the warm water from the caves and the cold river water.Beside this portion of the river is a table land of about 5 X 5 square meters used as a relaxation spot by visitors to the caves. The immediate environment of the caves up to about 200 meters radius is a thick tropical rainforest type of vegetation. The site has sufficient boundaries (20 hectares) to protect its values from direct effects of human encroachment.

text: In the U.S., the most well-known place for travertine formation is Yellowstone National Park, where the geothermal areas are rich in travertine deposits.  Oklahoma has two parks dedicated to this natural wonder. Turner Falls, the tallest waterfall in Oklahoma, is a  cascade of spring water flowing over a travertine cave. Honey Creek feeds this waterfall and creates miles of travertine shelves both up and downstream.  Many small waterfalls upstream in the dense woods repeat the travertine-formation effect.  The city of Davis now owns thousands of acres of this land and has made it a tourist attraction. Another travertine resource is in Sulphur, Oklahoma,  east of Turner Falls. Travertine Creek flows through a spring-water nature preserve within the boundaries of the Chickasaw National Recreation Area.

text: In the U.S., the most well-known place for travertine formation is

text: Yellowstone National Park

text: , where the

text: geothermal areas

text: are rich in travertine deposits.

text: Oklahoma

text: has two parks dedicated to this natural wonder.

text: Turner Falls

text: , the tallest waterfall in Oklahoma, is a  cascade of spring water flowing over a travertine cave. Honey Creek feeds this waterfall and creates miles of travertine shelves both up and downstream.  Many small waterfalls upstream in the dense woods repeat the travertine-formation effect.  The city of Davis now owns thousands of acres of this land and has made it a tourist attraction. Another travertine resource is in

text: Sulphur, Oklahoma

text: ,  east of Turner Falls. Travertine Creek flows through a spring-water nature preserve within the boundaries of the

text: Chickasaw National Recreation Area

text: Its usually quoted source is a combination of several streams, which rise on slopes of hills (Przejmowa Góra – 213.4m, Jastrzębia Góra – 230.8m, Słupowa Góra – 247.9 m, Lisia Góra – 259.5 m) southward of an old forest, Puszcza Romincka located southeast of Gołdap. The river proper rises from a lake called Jezioro Czarne and flows in a south and south-eastern direction through a series of nine postglacial lakes: Rospuda Filipowska, Kamienne, Długie, Garbas, Głębokie, Sumowo, Okrągłe, Bolesty, and The Rospuda Augustowska into which it finally empties. The Rospuda flows through typical young glacial landforms: postglacial channel lakes, eskers (long, narrow, winding ridges composed of stratified sand and gravel), and flat outwash plains. This landscape results from Scandinavian ice sheet activity during the Baltic glaciation: the postglacial channel in which the Rospuda flows was dug by a stream flowing underneath the ice sheet; eskers were composed of material accumulated by flowing water, and the outwash is a vast alluvial cone of sand and gravel deposited by a subglacial meltwater stream. In the upper reaches of the river, in the stretches between lakes, the Rospuda has a narrow winding channel of a rocky bed with rapids, for which it slightly resembles a mountain stream. The Rospuda flows through forests and meadows, within a narrow steep-sided valley with numerous bends, gorges, and felled trees. Narrow postglacial channel lakes flow for miles: Rospuda Filipowska and Bolesty, the longest two, are  long and only  wide. Their banks are high and forested or covered in meadows and cut across with ravines. These interesting landforms are attributable to erosion, the outcome of flowing rainwaters. In the lower reaches of the river, where it enters Augustów Primeval Forest, the Rospuda changes into a typically lowland river. It meanders through reeds within a boggy riparian valley, passing Święte Miejsce and Młyńsko, sacred sites in the region. The channel of the river gets wider forming a basin of peat bog, i.e. the Rospuda Valley (Pol. Dolina Rospudy).

text: Its usually quoted source is a combination of several streams, which rise on slopes of hills (Przejmowa Góra – 213.4m, Jastrzębia Góra – 230.8m, Słupowa Góra – 247.9 m, Lisia Góra – 259.5 m) southward of an old forest,

text: Puszcza Romincka

text: located southeast of

text: Gołdap

text: . The river proper rises from a lake called Jezioro Czarne and flows in a south and south-eastern direction through a series of nine postglacial lakes: Rospuda Filipowska, Kamienne, Długie, Garbas, Głębokie, Sumowo, Okrągłe, Bolesty, and The Rospuda Augustowska into which it finally empties. The Rospuda flows through typical young

text: glacial

text: landforms: postglacial

text: channel lakes

text: eskers

text: (long, narrow, winding ridges composed of stratified sand and gravel), and flat outwash plains. This landscape results from Scandinavian

text: ice sheet

text: activity during the Baltic glaciation: the postglacial channel in which the Rospuda flows was dug by a stream flowing underneath the ice sheet; eskers were composed of material accumulated by flowing water, and the outwash is a vast alluvial cone of sand and gravel deposited by a subglacial meltwater stream. In the upper reaches of the river, in the stretches between lakes, the Rospuda has a narrow winding channel of a rocky bed with rapids, for which it slightly resembles a mountain stream. The Rospuda flows through forests and meadows, within a narrow steep-sided valley with numerous bends, gorges, and felled trees. Narrow postglacial channel lakes flow for miles: Rospuda Filipowska and Bolesty, the longest two, are  long and only  wide. Their banks are high and forested or covered in meadows and cut across with ravines. These interesting landforms are attributable to erosion, the outcome of flowing rainwaters. In the lower reaches of the river, where it enters

text: Augustów Primeval Forest

text: , the Rospuda changes into a typically lowland river. It meanders through reeds within a boggy riparian valley, passing Święte Miejsce and Młyńsko, sacred sites in the region. The channel of the river gets wider forming a basin of peat bog, i.e. the Rospuda Valley (Pol. Dolina Rospudy).

text: Badab Soort's terraces are made of travertine, a sedimentary rock deposited by flowing water from the two distinct mineral springs; they were formed during Pleistocene and Pliocene geological periods. When the water, supersaturated with calcium carbonate and iron carbonate, reaches the surface, carbon dioxide degases from it, and mineral carbonates are deposited. The depositing continues until the carbon dioxide in the water balances the carbon dioxide in the air. Iron carbonate and calcium carbonate are deposited by the water as soft jellies, but they eventually harden into travertine.

text: Badab Soort's terraces are made of travertine, a

text: sedimentary

text: rock deposited by flowing water from the two distinct mineral springs; they were formed during

text: Pleistocene

text: and

text: Pliocene

text: geological periods. When the water, supersaturated with

text: calcium carbonate

text: and

text: iron carbonate

text: , reaches the surface,

text: carbon dioxide

text: degases from it, and mineral carbonates are deposited. The depositing continues until the carbon dioxide in the water balances the carbon dioxide in the air. Iron carbonate and calcium carbonate are deposited by the water as soft jellies, but they eventually harden into travertine.

text: Suttle Lake is located on the east side of the Cascade Range in central Oregon,  east of Santiam Pass.  Most of the lake water comes from groundwater seepage.  Link Creek is the only year around tributary flowing into the lake.  It drains into the west end of the lake, with water from Blue Lake.  The lake's only outlet is Lake Creek, which begins at the east end of the lake, eventually flowing into the Metolius River near Camp Sherman, Oregon.

text: Suttle Lake is located on the east side of the Cascade Range in central Oregon,  east of

text: Santiam Pass

text: .  Most of the lake water comes from groundwater seepage.  Link Creek is the only year around tributary flowing into the lake.  It drains into the west end of the lake, with water from

text: Blue Lake

text: .  The lake's only outlet is Lake Creek, which begins at the east end of the lake, eventually flowing into the

text: Metolius River

text: near

text: Camp Sherman, Oregon

text: On May 7, 2015, the city of Lincoln experienced its worst flood in recent history, following over six inches of rain beginning the night of May 6, 2015. In areas near the waterway, rain water and flood water was largely contained in the waterway, as was intended by its design. Though flooding in other areas of the city submerged cars and prevented driving, traffic flowed freely on the bridges and roads along the waterway. The waterway also channels excess flow from Salt Creek, mitigating the chances of the water level of Salt Creek from exceeding the levee height. On May 7, Salt Creek water levels were declared dangerously near its maximum; it is likely that without the Antelope Valley waterway providing this channel, water from Salt Creek may have spilled over and led to much heavier flooding in a large track of land along the Creek, which contains many residences. Though critics of the project decried its high price tag, the waterway's worth was tested and proven by the response to this storm.

text: Extended systems of underwater caves, sinkholes and springs are found throughout the state and supply most of the water used by residents. The limestone is topped with sandy soils deposited as ancient beaches over millions of years as global sea levels rose and fell. During the last glacial period, lower sea levels and a drier climate revealed a much wider peninsula, largely savanna. The Everglades, a wide, slow-flowing river, encompasses the southern tip of the peninsula.

text: Extended systems of underwater caves,

text: sinkholes

text: and

text: springs

text: sand

text: y soils deposited as ancient

text: beach

text: last glacial period

text: savanna

text: . The

text: Everglades

text: , a wide, slow-flowing river, encompasses the southern tip of the peninsula.

text: In much of the island, access to a year-round supply of water is difficult. This is traditionally attributed to deforestation which damaged the island's drainage system through erosion, but Grove and Rackham question this view. A network of winter rivers rises in the Troodos Mountains and flows out from them in all directions. The Yialias River and the Pedhieos River flow eastward across the Mesaoria into Famagusta Bay; the Serraghis River flows northwest through the Morphou plain. All of the island's rivers, however, are dry in the summer. An extensive system of dams and waterways has been constructed to bring water to farming areas.

text: In much of the island, access to a year-round supply of water is difficult. This is traditionally attributed to deforestation which damaged the island's drainage system through erosion, but Grove and Rackham question this view. A network of winter rivers rises in the Troodos Mountains and flows out from them in all directions. The Yialias River and the

text: Pedhieos River

text: flow eastward across the Mesaoria into Famagusta Bay; the Serraghis River flows northwest through the

text: Morphou

text: plain. All of the island's rivers, however, are dry in the summer. An extensive system of dams and waterways has been constructed to bring water to farming areas.

text: As mentioned above, Crystal Cave is a Solutional cave, of Multi-level Maze Type (consisting of 3 levels total). It extends to a depth of 69 ft. (21 m.) and is 4600 ft. (1.4 km.) in length, contained completely in the Prairie Du Chen group. The Bedrock forming the cave walls formed during the Ordovician Period of Earth’s History.The third level is the most extensive of the three having developed along existing Northeast to Southwest trending joints in the bedrock.Dating the period that the cave began to form has proven difficult due to erosion by Glacial waters, and  the deposit of debris during the Wisconsin Glaciation, from the nearby Terminus of the Laurentide Ice Sheet’s Superior Lobe.the commonly accepted theory of the cave's formation is that The cave was formed by a weak carbonic acid solution formed from rainwater/snowmelt that mixed with biogenic carbon dioxide found in the topsoil, which then infiltrated existing joints and fractures in the bed rock expanding them into the openings that make up the cave’s passageways. Some have advanced that the cave's formation is actually hypogenic in origin.

text: As mentioned above, Crystal Cave is a Solutional cave, of Multi-level Maze Type (consisting of 3 levels total). It extends to a depth of 69 ft. (21 m.) and is 4600 ft. (1.4 km.) in length, contained completely in the Prairie Du Chen group. The Bedrock forming the cave walls formed during the Ordovician Period of Earth’s History.The third level is the most extensive of the three having developed along existing Northeast to Southwest trending joints in the bedrock.Dating the period that the cave began to form has proven difficult due to erosion by Glacial waters, and  the deposit of debris during the

text: Wisconsin Glaciation

text: , from the nearby Terminus of the

text: Laurentide Ice Sheet

text: ’s Superior Lobe.the commonly accepted theory of the cave's formation is that The cave was formed by a weak carbonic acid solution formed from rainwater/snowmelt that mixed with biogenic carbon dioxide found in the topsoil, which then infiltrated existing joints and fractures in the bed rock expanding them into the openings that make up the cave’s passageways. Some have advanced that the cave's formation is actually

text: hypogenic

text: in origin.

text: After the first major pyroclastic flow, a hot block-and-ash flow was erupted off the face of an advancing lava dome. This deposited  of brittlely jointed welded breccia on top of the first major pyroclastic flow deposit. The slightly divided joints associated with the block-and-ash flow deposit range in a pattern from irregular to radial, indicating that the block-and-ash flow was rapidly quenched by water. These features might represent the first evidence of water reaction during the eruption and are mainly located near the  high Keyhole Falls along the Lillooet River. The welded block-and-ash flow deposit is enclosed by a grey weathering glassy matrix.

text: After the first major pyroclastic flow, a hot block-and-ash flow was erupted off the face of an advancing lava dome. This deposited  of brittlely jointed welded breccia on top of the first major pyroclastic flow deposit. The slightly divided joints associated with the block-and-ash flow deposit range in a pattern from irregular to radial, indicating that the block-and-ash flow was rapidly quenched by water. These features might represent the first evidence of water reaction during the eruption and are mainly located near the  high

text: Keyhole Falls

text: along the Lillooet River. The welded block-and-ash flow deposit is enclosed by a grey weathering glassy matrix.

text: The river was named Nabaganga (New Ganges in Bengali) in the belief that the Ganges also derived from Mathabhanga. The Nabaganga originates near the town of Chuadanga, in Chuadanga District. It flows east, where the Kumar and the Chitra rivers join it at Magura and Narail, respectively. From here, the river turns southward, where it merges into the Bhairab River. This is a recent change, as it was once a tributary of the Ichamati River. Silt deposits changed the river's course. Efforts to steer the river back to its original course proved futile when dredging in the 1930, at Gaznavi Ghat, failed to produce the desired results. Today, the Nabaganga merges into the Kumar River after flowing through Chuadanga and Jhenaidah Districts. Most of the water in the Nabaganga River from this point on comes from the Kumar.

text: The river was named Nabaganga (New Ganges in

text: Bengali

text: ) in the belief that the Ganges also derived from Mathabhanga. The Nabaganga originates near the town of Chuadanga, in

text: Chuadanga District

text: . It flows east, where the

text: Kumar

text: and the Chitra rivers join it at

text: Magura

text: and Narail, respectively. From here, the river turns southward, where it merges into the

text: Bhairab River

text: . This is a recent change, as it was once a tributary of the

text: Ichamati River

text: Silt

text: deposits changed the river's course. Efforts to steer the river back to its original course proved futile when dredging in the 1930, at Gaznavi Ghat, failed to produce the desired results. Today, the Nabaganga merges into the Kumar River after flowing through Chuadanga and

text: Jhenaidah District

text: s. Most of the water in the Nabaganga River from this point on comes from the Kumar.

text: The reduced permeability of compacted soil can result in local flooding. When water cannot infiltrate, ponding and water logging pose a general risk for soil erosion by water. On compacted soils, wheel tracks are often the starting point for runoff and erosion. Soil erosion is likely to appear on sloping fields or especially hilly land.This might lead to a transfer of sediments [56] . Except for direct negative effects for farmers, the risk of surface runoff close to wheel tracks affects the off-farm environment indirectly, as it for example redistributes “sediment, nutrients and pesticides within the field and beyond”. Especially when the risk of surface soil erosion is heightened, eutrophication of surface waters becomes a big problem due to an increased amount of nutrients.  On high risk areas, such as wet soils on slopes, applied slurry can runoff easily. This results in a loss of ammonia, which is polluting surface waters, as it creates a lack of oxygen. Leading so to the death of many species, soil erosion caused by compaction is responsible for a decline in habitat quality and therefore species loss.

text: As it flows, the amount of runoff may be reduced in a number of possible ways: a small portion of it may evapotranspire; water may become temporarily stored in microtopographic depressions; and a portion of it may infiltrate as it flows overland. Any remaining surface water eventually flows into a receiving water body such as a river, lake, estuary or ocean.

text: As it flows, the amount of runoff may be reduced in a number of possible ways: a small portion of it may

text: evapotranspire

text: ; water may become temporarily stored in microtopographic depressions; and a portion of it may

text: infiltrate

text: as it flows overland. Any remaining surface water eventually flows into a

text: receiving water

text: body such as a

text: river

text: lake

text: estuary

text: or

text: ocean

text: The Periyar river which flows westward of kerala  Arabian sea was diverted eastwards to flow towards the Bay of Bengal to provide water to the arid rain shadow region of Madurai in Madras Presidency which was in dire need of a greater supply of water than the small Vaigai River could provide. The dam created the Periyar Thekkady reservoir, from which water was diverted eastwards via a tunnel to augment the small flow of the Vaigai River. The Vaigai was dammed by the Vaigai Dam to provide a source for irrigating large tracts around Madurai. Initially the dam waters were used only for the irrigation of .

text: The Periyar river which flows westward of kerala

text: Arabian sea

text: was diverted eastwards to flow towards the

text: Bay of Bengal

text: to provide water to the arid

text: rain shadow

text: region of

text: Madurai

text: in

text: Madras Presidency

text: which was in dire need of a greater supply of water than the small

text: Vaigai River

text: could provide. The dam created the Periyar Thekkady reservoir, from which water was diverted eastwards via a tunnel to augment the small flow of the Vaigai River. The Vaigai was dammed by the

text: Vaigai Dam

text: to provide a source for irrigating large tracts around

text: Madurai

text: . Initially the dam waters were used only for the irrigation of .

text: The fluvial cirque or makhtesh, found in karst landscapes, is formed by intermittent river flow cutting through layers of limestone and chalk leaving sheer cliffs. A common feature for all fluvial-erosion cirques is a terrain which includes erosion resistant upper structures overlying materials which are more easily eroded.

text: The fluvial cirque or

text: makhtesh

text: , found in

text: karst

text: landscapes, is formed by intermittent river flow cutting through layers of limestone and chalk leaving sheer cliffs. A common feature for all

text: fluvial

text: -erosion cirques is a terrain which includes erosion resistant upper structures overlying materials which are more easily eroded.

text: While flowing, the groundwater loses energy due to friction of flow, i.e. hydraulic energy is converted into heat. At the same time, energy may be added with the recharge of water coming into the aquifer through the water table. Thus one can make an hydraulic energy balance of a block of soil between two nearby cross-sections. In steady state, i.e. without change in energy status and without accumulation or depletion of water stored in the soil body, the energy flow in the first section plus the energy added by groundwater recharge between the sections minus the energy flow in the second section must equal the energy loss due to friction of flow.

text: While flowing, the groundwater loses energy due to friction of flow, i.e. hydraulic energy is converted into heat. At the same time, energy may be added with the recharge of water coming into the aquifer through the water table. Thus one can make an hydraulic energy balance of a block of soil between two nearby cross-sections. In steady state, i.e. without change in energy status and without accumulation or depletion of water stored in the soil body, the energy flow in the first section plus the energy added by

text: groundwater recharge

text: between the sections minus the energy flow in the second section must equal the energy loss due to friction of flow.

text: Soil separates are specific ranges of particle sizes. The smallest particles are clay particles and are classified as having diameters of less than 0.002 mm. The next smallest particles are silt particles and have diameters between 0.002 mm and 0.05 mm  (in USDA soil taxonomy). The largest particles are sand particles and are larger than 0.05 mm in diameter.  Furthermore, large sand particles can be described as coarse, intermediate as medium, and the smaller as fine.  Other countries have their own particle size classifications.

text: Soil separates are specific ranges of particle sizes. The smallest particles are clay particles and are classified as having diameters of less than 0.002 mm. The next smallest particles are silt particles and have diameters between 0.002 mm and 0.05 mm  (in

text: USDA soil taxonomy

text: ). The largest particles are sand particles and are larger than 0.05 mm in diameter.  Furthermore, large sand particles can be described as coarse, intermediate as medium, and the smaller as fine.  Other countries have their own particle size classifications.

text: The pump's primary components consist of the pump handle, the riser main which carries the water to the surface, the pump cylinder which pushes water up the riser main, and the connecting rod which connects the pump handle to the pump cylinder at the bottom of the well.  After a borehole is drilled, a well casing is inserted into the hole to prevent the erosion of the borehole walls.  The India Mark II needs a borehole with a  minimum diameter of 10 cm. The casing has a well screen to allow water to pass into the casing but keeps rocks and dirt out.  A pump cylinder is attached to the bottom of a series of pipes call riser mains or riser pipes and sits below the water surface in the well once installed.  The riser main will carry the water from the pump cylinder to the surface.  Inside the riser main, a series of rods connect the pump handle to the top of the pump cylinder at the bottom of the well.  The reciprocating up and down movement of the pump handle raises and lowers the connecting rod thus raising and lowering the plunger of the pump cylinder.  Two one-way water valves inside the cylinder suck water into the cylinder on the upstroke and force the water into the riser main on the down stroke.  Water flows up the riser main and out of the spout at the top of the well head assembly.

text: The pump's primary components consist of the pump handle, the riser main which carries the water to the surface, the pump cylinder which pushes water up the riser main, and the connecting rod which connects the pump handle to the pump cylinder at the bottom of the well.  After a

text: borehole

text: is drilled, a well casing is inserted into the hole to prevent the erosion of the borehole walls.  The India Mark II needs a borehole with a  minimum diameter of 10 cm. The casing has a well screen to allow water to pass into the casing but keeps rocks and dirt out.  A pump cylinder is attached to the bottom of a series of pipes call riser mains or riser pipes and sits below the water surface in the well once installed.  The riser main will carry the water from the pump cylinder to the surface.  Inside the riser main, a series of rods connect the pump handle to the top of the pump cylinder at the bottom of the well.  The reciprocating up and down movement of the pump handle raises and lowers the connecting rod thus raising and lowering the plunger of the pump cylinder.  Two one-way water valves inside the cylinder suck water into the cylinder on the upstroke and force the water into the riser main on the down stroke.  Water flows up the riser main and out of the spout at the top of the well head assembly.

text: Limestone dissolves under the action of rainwater and groundwater charged with HCO (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes, and underground drainage. Solutional caves in this landform—topography are often called karst caves.

text: Limestone dissolves under the action of rainwater and groundwater charged with HCO (

text: carbonic acid

text: ) and naturally occurring

text: organic acid

text: karst

text: , characterized by

text: sinkhole

text: s, and underground drainage. Solutional caves in this landform—topography are often called karst caves.

text: These streams are very strong, especially during the rainy seasons spring, autumn, and at the end of winter, and cause erosion along the stream and river beds. The water in these streams is potable, especially at the beginning of their flows. The many rivers and streams contribute to sports and tourism in these regions.

text: The particle sizes range from submicrometer- and micrometer-sized (created by condensation of plasma in the fireball), through 10–500 micrometers (surface material agitated by the blast wave and raised by the afterwinds), to millimeter and above (crater ejecta). The size of particles together with the altitude they are carried to, determines the length of their stay in the atmosphere, as larger particles are subject to dry precipitation. Smaller particles can be also scavenged by precipitation, either from the moisture condensing in the cloud itself or from the cloud intersecting with a rain cloud. The fallout carried down by rain is known as rain-out if scavenged during raincloud formation, washout if absorbed into already formed falling raindrops.

text: The particle sizes range from submicrometer- and micrometer-sized (created by condensation of plasma in the fireball), through 10–500 micrometers (surface material agitated by the blast wave and raised by the afterwinds), to millimeter and above (crater ejecta). The size of particles together with the altitude they are carried to, determines the length of their stay in the atmosphere, as larger particles are subject to

text: dry precipitation

text: . Smaller particles can be also scavenged by

text: precipitation

text: , either from the moisture condensing in the cloud itself or from the cloud intersecting with a

text: rain cloud

text: . The fallout carried down by rain is known as rain-out if scavenged during raincloud formation, washout if absorbed into already formed falling raindrops.

text: The upper limit to particle size depends on the amount of flow required before the composite sets (the gravel in paving concrete can be fairly coarse, but fine sand must be used for tile mortar), whereas the lower limit is due to the thickness of matrix material at which its properties change (clay is not included in concrete because it would "absorb" the matrix, preventing a strong bond to other aggregate particles). Particle size distribution is also the subject of much study in the fields of ceramics and powder metallurgy.

text: The upper limit to particle size depends on the amount of flow required before the composite sets (the gravel in paving concrete can be fairly coarse, but fine sand must be used for

text: tile

text: mortar

text: ), whereas the lower limit is due to the thickness of matrix material at which its properties change (clay is not included in concrete because it would "absorb" the matrix, preventing a strong bond to other aggregate particles). Particle size distribution is also the subject of much study in the fields of

text: ceramic

text: s and

text: powder metallurgy

text: Headward erosion is a fluvial process of erosion that lengthens a stream, a valley or a gully at its head and also enlarges its drainage basin. The stream erodes away at the rock and soil at its headwaters in the opposite direction that it flows. Once a stream has begun to cut back, the erosion is sped up by the steep gradient the water is flowing down. As water erodes a path from its headwaters to its mouth at a standing body of water, it tries to cut an ever-shallower path. This leads to increased erosion at the steepest parts, which is headward erosion. If headward erosion continues long enough, it can cause a stream to break through into a neighboring watershed and capture drainage that previously flowed to another stream.

text: Headward erosion is a

text: fluvial

text: process of

text: erosion

text: that lengthens a

text: stream

text: , a

text: valley

text: or a

text: gully

text: at its

text: head

text: and also enlarges its

text: drainage basin

text: . The stream erodes away at the rock and soil at its headwaters in the opposite direction that it flows. Once a stream has begun to cut back, the erosion is sped up by the steep gradient the water is flowing down. As water erodes a path from its headwaters to its mouth at a standing body of water, it tries to cut an ever-shallower path. This leads to increased erosion at the steepest parts, which is headward erosion. If headward erosion continues long enough, it can cause a stream to break through into a neighboring

text: watershed

text: and

text: capture

text: drainage that previously flowed to another stream.

text: Duration of exposure and field strength, gradient, rate of change, and orientation along or perpendicular to flow are variously cited as important to the results. Magnetic water treatment proponent Klaus Kronenberg proposed that the shapes of solute lime molecules are modified by strong magnetic fields, leading them to precipitate as spherical or round crystals rather than deposit as sheets or platelets of hard crystals.  Simon Parsons of the School of Water Sciences at Cranfield University proposed that the magnetic field reduces the surface charge on small particles, increasing the tendency to coagulate as large particles that stay with the flow rather than depositing as scale. However, an internal study in 1996 at Lawrence Livermore National Laboratory found no difference in preferred crystal structure of scale deposited in magnetic water treatment systems.

text: Duration of exposure and field strength, gradient, rate of change, and orientation along or perpendicular to flow are variously cited as important to the results. Magnetic water treatment proponent Klaus Kronenberg proposed that the shapes of solute

text: lime

text: molecules are modified by strong magnetic fields, leading them to precipitate as spherical or round crystals rather than deposit as sheets or platelets of hard crystals.  Simon Parsons of the School of Water Sciences at

text: Cranfield University

text: proposed that the magnetic field reduces the surface charge on small particles, increasing the tendency to coagulate as large particles that stay with the flow rather than depositing as scale. However, an internal study in 1996 at

text: Lawrence Livermore National Laboratory

text: found no difference in preferred crystal structure of scale deposited in magnetic water treatment systems.

text: Curly pondweed is widespread and common across most of its native range, growing in standing and slow-flowing water including small ponds and ditches. It is strictly a lowland plant and requires fine substrates in standing or slow-flowing calcareous water. However, it is tolerant of significant nutrient pollution, and this has allowed it to persist in intensively farmed areas where more sensitive pondweeds have declined. Its production of both seed and turions makes it resistant to disturbance such as dredging, in contrast to some of the larger broad-leaved pondweeds.

text: The cottonwoods are exceptionally tolerant of flooding, erosion, and flood deposits filling around the trunk.

text: The cottonwoods are exceptionally tolerant of flooding,

text: erosion

text: , and flood deposits filling around the trunk.

text: The artificial lift irrigation based diversion of the river from its natural delta area into Nalgonda district caused erosion of the Florine rich volcanic rocks in Nalgonda and contaminated its ground water supply. It also caused uncertain flows of water into the Krishna river delta area and a shrinkage of the natural wonder "The Kolleru Lake". The use of erosion resistant canals interfered with the natural silting process of a river to the deltas and created long term ecological issues to the health of the delta lands. Reduced flows into the sea resulted in land salination and sea encroachment of coastal lands in Diviseema. The diversion of Krishna water for 200 km to Hyderabad resulted in massive evaporation losses especially in summer and reduced the size of Krishna river. The river water needs to be lifted 1600 ft above its natural flow for it to reach Hyderabad, power consumption that is unjustifiable given that there are cheaper ways to get water to Hydearabad.  Nagarjuna sagar, Srisailam, Almati  and Ujjani dams together successfully halted the flow of Krishna River before it reaches the delta and is good case study of how to kill a mighty river with poor environmental oversight - the fourth largest in the country. Hamsaladeevi the point where Krishna used to meet the ocean does not have Hamsalu (swan) and the Deevi (island) will merge into the ocean in the next decade. Desertification of various flood plains is already recorded. Many forest preserves along the natural Krishna flow are now categorized as "completely  degraded" forest areas. Krishna river once home to an ecological wonderland of fresh water fish and aquatic population is now completely depopulated. The river stopped being navigable since the year of Nagarjuna sagar construction. The death of river Krishna is now a matter of time.

text: The artificial lift irrigation based diversion of the river from its natural delta area into

text: Nalgonda district

text: caused erosion of the Florine rich volcanic rocks in Nalgonda and contaminated its ground water supply. It also caused uncertain flows of water into the Krishna river delta area and a shrinkage of the natural wonder "The Kolleru Lake". The use of erosion resistant canals interfered with the natural silting process of a river to the deltas and created long term ecological issues to the health of the delta lands. Reduced flows into the sea resulted in land salination and sea encroachment of coastal lands in Diviseema. The diversion of Krishna water for 200 km to Hyderabad resulted in massive evaporation losses especially in summer and reduced the size of Krishna river. The river water needs to be lifted 1600 ft above its natural flow for it to reach Hyderabad, power consumption that is unjustifiable given that there are cheaper ways to get water to Hydearabad.  Nagarjuna sagar, Srisailam, Almati  and

text: Ujjani dams

text: together successfully halted the flow of Krishna River before it reaches the delta and is good case study of how to kill a mighty river with poor environmental oversight - the fourth largest in the country.

text: Hamsaladeevi

text: the point where Krishna used to meet the ocean does not have Hamsalu (swan) and the Deevi (island) will merge into the ocean in the next decade. Desertification of various flood plains is already recorded. Many forest preserves along the natural Krishna flow are now categorized as "completely  degraded" forest areas. Krishna river once home to an ecological wonderland of fresh water fish and aquatic population is now completely depopulated. The river stopped being navigable since the year of Nagarjuna sagar construction. The death of river Krishna is now a matter of time.

text: Usually what happens is the frazil ice accumulates on the upstream side of objects and sticks to them. The frazil ice accumulates as more gets deposited. The growth will extend upstream and increase in width until the point where the frazil ice accumulations bridge together and block the water. As more and more water flows against this block, the pressure on the upstream side increases and causes a differential pressure (difference in pressure from the upstream side and the downstream side). This will cause the growth of the bridge to extend downstream. Once this happens, flooding and damage is likely unless otherwise prevented.

text: Usually what happens is the frazil ice accumulates on the

text: upstream

text: side of objects and sticks to them. The frazil ice accumulates as more gets deposited. The growth will extend upstream and increase in width until the point where the frazil ice accumulations bridge together and block the water. As more and more water flows against this block, the pressure on the upstream side increases and causes a differential pressure (difference in pressure from the upstream side and the downstream side). This will cause the growth of the bridge to extend downstream. Once this happens, flooding and damage is likely unless otherwise prevented.

text: A river is continually picking up and dropping solid particles of rock and soil from its bed throughout its length. Where the river flow is fast, more particles are picked up than dropped. Where the river flow is slow, more particles are dropped than picked up. Areas where more particles are dropped are called alluvial or flood plains, and the dropped particles are called alluvium.

text: A river is continually picking up and dropping solid particles of rock and soil from its bed throughout its length. Where the river flow is fast, more particles are picked up than dropped. Where the river flow is slow, more particles are dropped than picked up. Areas where more particles are dropped are called

text: alluvial

text: or flood plains, and the dropped particles are called

text: alluvium

text: A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. An example of a hydraulic structure would be a  dam, which slows the normal flow rate of the river in order to power turbines. A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water.

text: A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. An example of a hydraulic structure would be a

text: dam

text: , which slows the normal

text: flow rate

text: of the river in order to power

text: turbines

text: . A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water.

text: The original land surface was some 350 to  above the current sea level.  The surface had sandy deposits from an ancient sea, laid over sedimentary clay (this is the Blue London Clay). All the erosion down from this higher land surface and sorting action by these changes of water flow and direction, formed what is known as the Thames River Gravel Terraces. Since Roman times and perhaps earlier, however, the isostatic rebound from the weight of previous ice sheets, and its interplay with the eustatic change in sea level, means that the old valley of the river Brent, together with that of the Thames, has been silting up again. Thus, along much of the Brent's present day course one can make out the water meadows of rich alluvium, which is augmented by frequent floods.

text: The original land surface was some 350 to  above the current sea level.  The surface had sandy deposits from an ancient sea, laid over sedimentary clay (this is the Blue

text: London Clay

text: ). All the erosion down from this higher land surface and sorting action by these changes of water flow and direction, formed what is known as the Thames

text: River Gravel Terraces

text: . Since Roman times and perhaps earlier, however, the

text: isostatic

text: rebound from the weight of previous ice sheets, and its interplay with the eustatic change in sea level, means that the old valley of the river Brent, together with that of the Thames, has been silting up again. Thus, along much of the Brent's present day course one can make out the water meadows of rich alluvium, which is augmented by frequent floods.

text: The water level in the reservoir was lowered by  from February to April in 2010, in order for the works to be carried out on the eastern dam. To reduce the risk of internal erosion filters were installed at the downstream toe of the embankment to control and monitor seepage through the dam. To meet regulations the reservoir has to be able to withstand a 1 in 10,000-year storm event. To increase the overflow capacity culverts were installed through the causeway carrying Chasewater Railway, this was to increase water flows from Jeffries Swag into the main body of the reservoir. A new bridge, weir and spillway were built at the southeastern end of the reservoir. The drawdown culvert which runs from the reservoir bed to the canal was inspected and restored for the first time in 200 years. The £5.5 million repairs were completed in April 2012.

text: The water level in the reservoir was lowered by  from February to April in 2010, in order for the works to be carried out on the eastern dam. To reduce the risk of internal erosion filters were installed at the downstream toe of the embankment to control and monitor seepage through the dam. To meet regulations the reservoir has to be able to withstand a 1 in 10,000-year storm event. To increase the overflow capacity culverts were installed through the causeway carrying

text: Chasewater Railway

text: , this was to increase water flows from Jeffries Swag into the main body of the reservoir. A new bridge, weir and spillway were built at the southeastern end of the reservoir. The drawdown culvert which runs from the reservoir bed to the canal was inspected and restored for the first time in 200 years. The £5.5 million repairs were completed in April 2012.

text: Geomorphically relevant processes generally fall into(1) the production of regolith by weathering and erosion, (2) the transport of that material, and (3) its eventual deposition. Primary surface processes responsible for most topographic features include wind, waves, chemical dissolution, mass wasting, groundwater movement, surface water flow, glacial action, tectonism, and volcanism. Other more exotic geomorphic processes might include periglacial (freeze-thaw) processes, salt-mediated action, marine currents activity, seepage of fluids through the seafloor or extraterrestrial impact.

text: Geomorphically relevant processes generally fall into(1) the production of

text: regolith

text: by

text: weathering

text: and

text: erosion

text: , (2) the

text: transport

text: of that material, and (3) its eventual

text: deposition

text: . Primary surface processes responsible for most topographic features include

text: wind

text: wave

text: s,

text: chemical dissolution

text: mass wasting

text: groundwater

text: movement,

text: surface water

text: flow,

text: glacial action

text: tectonism

text: , and

text: volcanism

text: . Other more exotic geomorphic processes might include

text: periglacial

text: (freeze-thaw) processes, salt-mediated action, marine currents activity, seepage of fluids through the seafloor or extraterrestrial impact.

text: The gradient of a river is the rate at which it loses elevation along its course. This loss determines the river's slope, and to a large extent its rate of flow. Shallow gradients produce gentle, slow rivers while steep gradients are associated with raging torrents.

text: The

text: gradient

text: of a river is the rate at which it loses

text: elevation

text: along its course. This loss determines the river's slope, and to a large extent its rate of flow. Shallow gradients produce gentle, slow rivers while steep gradients are associated with raging torrents.

text: In surface erosion, the erosion rate is directly proportional to the surface area of the material. For very thin materials, the surface area remains relatively constant when the material degrades, which allows surface erosion to be characterized as zero order release since the rate of degradation is constant. In bulk erosion, the erosion rate depends on the volume of the material.  Due to degradation, the volume of the material decreases during bulk erosion causing the erosion rate to decrease over time. Therefore, bulk erosion rates are difficult to control since it is not zero order. To determine whether a polymer will undergo surface or bulk erosion, the degradation rate of the polymer in water (how fast the polymer reacts to water) and the rate of diffusion of water penetrating through the material must be considered. If the degradation process is faster than the diffusion process, surface erosion will occur since the material’s surface will quickly degrade before water has time to diffuse and penetrate through the material. If the diffusion process is faster than the degradation process bulk erosion will occur because water penetrates through the material before significant erosion occurs on the surface.  A kinetics of the erosion of a polymer can be modified by changing the diffusion process or the degradation process.  For example, blending a polymer with another polymer that is very reactive to water will speed up the degradation process and cause surface erosion.  On the other hand, decreasing the dimensions of a material will allow water to travel to the center of the material more quickly, which speeds up the diffusion process and causes bulk erosion.

text: In surface erosion, the erosion rate is directly proportional to the surface area of the material. For very thin materials, the surface area remains relatively constant when the material degrades, which allows surface erosion to be characterized as zero order release since the rate of degradation is constant. In bulk erosion, the erosion rate depends on the volume of the material.  Due to degradation, the volume of the material decreases during bulk erosion causing the erosion rate to decrease over time. Therefore, bulk erosion rates are difficult to control since it is not zero order. To determine whether a polymer will undergo surface or bulk erosion, the degradation rate of the polymer in water (how fast the polymer reacts to water) and the rate of

text: diffusion

text: of

text: water

text: penetrating through the material must be considered. If the degradation process is faster than the diffusion process, surface erosion will occur since the material’s surface will quickly degrade before water has time to diffuse and penetrate through the material. If the diffusion process is faster than the degradation process bulk erosion will occur because water penetrates through the material before significant erosion occurs on the surface.  A kinetics of the erosion of a polymer can be modified by changing the diffusion process or the degradation process.  For example, blending a polymer with another polymer that is very reactive to water will speed up the degradation process and cause surface erosion.  On the other hand, decreasing the dimensions of a material will allow water to travel to the center of the material more quickly, which speeds up the diffusion process and causes bulk erosion.

text: A project of the mid 1960s: on 26 June 1960 the first public meeting was held. The dam was built in the 3 years from 1969 to 1971. To do this 65 to 67 hectares of land were expropriated and Jamet island disappeared - an expanse of 12.58 hectares. The structure was built on a layer of clay (called "blue earth") in order to cope with the frequent flooding of the Rhône and support water speeds up to 7500 m3/s. The largest known flood occurred in 1856 when there were speeds of 6,100 m3/s. The largest observed flood was in 1957 with flows around 5,300 m3/s. The dam is 152 metres long and has 6 spillways 22 metres long and 12.8 metres high. Four sluice gates with shutters allow a water flow of 1,800 m3 per second. The lake to retain water for the dam extends for 20 km and it can store 3.24 million m3. It produces an average of 700 million kWh annually.

text: A project of the mid 1960s: on 26 June 1960 the first public meeting was held. The dam was built in the 3 years from 1969 to 1971. To do this 65 to 67 hectares of land were expropriated and Jamet island disappeared - an expanse of 12.58 hectares. The structure was built on a layer of

text: clay

text: (called "blue earth") in order to cope with the frequent flooding of the Rhône and support water speeds up to 7500 m3/s. The largest known flood occurred in 1856 when there were speeds of 6,100 m3/s. The largest observed flood was in 1957 with flows around 5,300 m3/s. The dam is 152 metres long and has 6 spillways 22 metres long and 12.8 metres high. Four sluice gates with shutters allow a water flow of 1,800 m3 per second. The lake to retain water for the dam extends for 20 km and it can store 3.24 million m3. It produces an average of 700 million kWh annually.

text: A detention basin or retarding basin is an excavated area installed on, or adjacent to, tributaries of rivers, streams, lakes or bays to protect against flooding and, in some cases, downstream erosion by storing water for a limited period of time.  These basins are also called "dry ponds", "holding ponds" or "dry detention basins" if no permanent pool of water exists. Some detention ponds are also "wet ponds" in that they are designed to permanently retain some volume of water at all times. In its basic form, a detention basin is used to manage water quantity while having a limited effectiveness in protecting water quality, unless it includes a permanent pool feature.

text: A detention basin or retarding basin is an excavated area installed on, or adjacent to, tributaries of

text: river

text: s,

text: stream

text: s,

text: lake

text: s or

text: bay

text: s to protect against

text: flood

text: ing and, in some cases, downstream

text: erosion

text: by storing water for a limited period of time.  These basins are also called "dry ponds", "holding ponds" or "dry detention basins" if no permanent pool of water exists. Some detention ponds are also "wet ponds" in that they are designed to permanently retain some volume of water at all times. In its basic form, a detention basin is used to manage water quantity while having a limited effectiveness in protecting

text: water quality

text: , unless it includes a permanent pool feature.

text: Some geologists would restrict the term subaqueous pyroclastic flow deposits to volcaniclastic units that show characteristics of emplacement in a hot state deposited underwater—however, this can’t always be done because of the subsequent process of alteration/diagenesis such as active hot springs and associated hydrothermal alteration. Deposits from pyroclastic flows that interact with water and are transformed into water-supported mass flows are called subaqueous pyroclastic debris flow deposits by some geologists. On the other hand, processes that are associated with eruption, transportation and deposition are notably different because of the presence of water. Such differences that the presence of water entails is the ability to vaporize when in contact with water, a high density and resulting confining pressure, high viscosity relative to air and differences in the thermal conductivities/heat capacities in the air relative to water.

text: Some geologists would restrict the term subaqueous pyroclastic flow deposits to volcaniclastic units that show characteristics of emplacement in a hot state deposited underwater—however, this can’t always be done because of the subsequent process of alteration/diagenesis such as active hot springs and associated

text: hydrothermal alteration

text: . Deposits from pyroclastic flows that interact with water and are transformed into water-supported mass flows are called subaqueous pyroclastic debris flow deposits by some geologists. On the other hand, processes that are associated with eruption, transportation and deposition are notably different because of the presence of water. Such differences that the presence of water entails is the ability to vaporize when in contact with water, a high density and resulting confining pressure, high viscosity relative to air and differences in the thermal conductivities/heat capacities in the air relative to water.

text: The daily El Comercio said that the impressive waterfall had remained unknown to outsiders until now, because local people feared the curse of a beautiful blond mermaid who lived in its waters, if they revealed its whereabouts. "The falls are supposed to be protected by a white-haired mermaid like spirit whose hair can be seen flowing down the massive U-shaped walls at the bottom of the falls."On 13 March 2006, the Peruvian government announced to the press that the area surrounding the falls would be developed as a tourist attraction, with a target date for sometime in mid-2007. A small hotel was built  from the base of the waterfall, with all rooms having views of the waterfall. Tourists can now hike the trails by foot or horse to the misty base of the waterfall. The nearby town of Chachapoyas is located at an altitude of . The waterfall is at a slightly higher altitude and thus clouds can be seen to occasionally eclipse part of the view.

text: The daily

text: El Comercio

text: said that the impressive waterfall had remained unknown to outsiders until now, because local people feared the curse of a beautiful blond mermaid who lived in its waters, if they revealed its whereabouts. "The falls are supposed to be protected by a white-haired mermaid like spirit whose hair can be seen flowing down the massive U-shaped walls at the bottom of the falls."On 13 March 2006, the Peruvian government announced to the press that the area surrounding the falls would be developed as a tourist attraction, with a target date for sometime in mid-2007. A small hotel was built  from the base of the waterfall, with all rooms having views of the waterfall. Tourists can now hike the trails by foot or horse to the misty base of the waterfall. The nearby town of

text: Chachapoyas

text: is located at an altitude of . The waterfall is at a slightly higher altitude and thus clouds can be seen to occasionally eclipse part of the view.

text: The main braided channels of Skeiðarársandur are the Gígjukvísl and Skeiðará rivers, which incurred net gains of  respectively during the 1996 jökulhlaup. In the Gígjukvísl there was massive sediment deposition of up to , which occurred closest to the terminus of the glacier. The erosional patterns of Skeiðarársandur can be seen by looking at the centimetre-scale elevation differences measured with repeat-pass laser altimetry (LIDAR) flown in 1996 (pre-flood), 1997, and 2001. Of the overall deposition during the 1996 jökulhlaup, nearly half of the net gain had been eroded 4 years after the flood. These two rivers on the sandur display drastically different erosional patterns. The difference in sediment erosion can be attributed to the  wide trench near the terminus where the Gígjukvísl flows, in contrast with the Skeiðará, which has braided flows directly onto the outwash plain. The Gígjukvísl river is where some of the highest level of sediment deposit occurred and also where the largest erosion happened afterward. This indicates that these massive jökulhlaup deposits may have a large geomorphic impact in the short term, but the net change on the surface relief could be minimal after a couple years to a decade.

text: The main braided channels of Skeiðarársandur are the Gígjukvísl and Skeiðará rivers, which incurred net gains of  respectively during the 1996 jökulhlaup. In the Gígjukvísl there was massive sediment deposition of up to , which occurred closest to the terminus of the glacier. The erosional patterns of Skeiðarársandur can be seen by looking at the centimetre-scale elevation differences measured with repeat-pass laser altimetry (

text: LIDAR

text: ) flown in 1996 (pre-flood), 1997, and 2001. Of the overall deposition during the 1996 jökulhlaup, nearly half of the net gain had been eroded 4 years after the flood. These two rivers on the sandur display drastically different erosional patterns. The difference in sediment erosion can be attributed to the  wide trench near the terminus where the Gígjukvísl flows, in contrast with the Skeiðará, which has braided flows directly onto the outwash plain. The Gígjukvísl river is where some of the highest level of sediment deposit occurred and also where the largest erosion happened afterward. This indicates that these massive jökulhlaup deposits may have a large geomorphic impact in the short term, but the net change on the surface relief could be minimal after a couple years to a decade.

text: Twelve culverts were noted and they vary in date and design.  They include circular concrete pipes, larger rectangular pipes and modern rectangular section pipes.  Some are single, some double depending on the expected water flow.  Around each of the inlets is a rock channel and wings to guide the water into the mouth of the pipe and these have been individually designed for the particular site.  Many have concrete end walls and loose concrete added to the surface.  On the outlet side there is mostly a rock surround around the pipe and, if space, a concrete apron to prevent erosion.  As with any functional road, there is evidence of a continuous upgrade of surface and culverts as required for safety but many of the original culverts survive.

text: Twelve culverts were noted and they vary in date and design.  They include circular concrete pipes, larger rectangular pipes and modern rectangular section pipes.  Some are single, some double depending on the expected water flow.  Around each of the inlets is a rock channel and wings to guide the water into the mouth of the pipe and these have been individually designed for the particular site.  Many have concrete end walls and loose concrete added to the surface.  On the outlet side there is mostly a rock surround around the pipe and, if space, a concrete

text: apron

text: to prevent erosion.  As with any functional road, there is evidence of a continuous upgrade of surface and culverts as required for safety but many of the original culverts survive.

text: There is evidence that the drainage divide between the Norwegian Sea and the  south-east flowing rivers were once further west. Glacial erosion is thought to have contributed to the shift of the divide, which in some cases ought to have in excess of 50 km. Much of the Scandinavian Mountains has been sculpted by glacal erosion. The mountain chain is dotted with glacial cirques usually separated from each other by pre-glacial surfaces. At some locations coalesced cirques form arêtes and pyramidal peaks. Glacial reshaping of valleys is more marked in the western part of the mountain chain where drowned glacier-shaped valleys constitute the fjords of Norway. In the eastern part of the mountain chain glacial reshaping of valleys is weaker. Many mountain tops contain blockfields which escaped glacial erosion either by having constituted nunataks in the glacial periods or by being protected from erosion under cold-based glacier ice. Karst systems, with their characteristic caves and sinkholes occur at various locations in the Scandinavian Mountains but are more common in the northern parts. Present-day karst systems might have long histories dating back to the Pleistocene or even earlier times.

text: There is evidence that the

text: drainage divide

text: between the

text: Norwegian Sea

text: and the  south-east flowing rivers were once further west. Glacial erosion is thought to have contributed to the shift of the divide, which in some cases ought to have in excess of 50 km. Much of the Scandinavian Mountains has been sculpted by

text: glacal erosion

text: . The mountain chain is dotted with

text: glacial cirques

text: usually separated from each other by

text: pre-glacial

text: surfaces

text: . At some locations coalesced cirques form

text: arête

text: s and

text: pyramidal peak

text: s. Glacial reshaping of valleys is more marked in the western part of the mountain chain where drowned glacier-shaped valleys constitute the

text: fjords of Norway

text: . In the eastern part of the mountain chain glacial reshaping of valleys is weaker. Many mountain tops contain

text: blockfield

text: s which escaped glacial erosion either by having constituted

text: nunatak

text: s in the glacial periods or by being protected from erosion under

text: cold-based glacier ice

text: Karst

text: systems, with their characteristic

text: cave

text: s and

text: sinkhole

text: s occur at various locations in the Scandinavian Mountains but are more common in the northern parts. Present-day karst systems might have long histories dating back to the

text: Pleistocene

text: or even earlier times.

text: However, humans have modified the natural paths of rivers. This process, known as channelization, has serious consequences for wetland ecosystems which include drainage of wetlands, degradation of natural habitats, and elimination of natural flow patterns. With levees, canals, and set channels for water to flow through, the river no longer floods and reroutes naturally and seasonally. The river is not able to deposit sediment in diverse areas to help create wetlands. Instead, the river flows through its artificially determined path and deposits the valuable sediment off the edge of the continental shelf. This lack of natural wetland restoration combined with the continued erosion from hurricanes causes a rapid loss in wetland area. Before human channelization of waterways, the river’s natural process of sediment deposition was enough to sustain the wetland habitat, but currently wetland area is on a downward trend. Since 1932, the Mississippi River Delta Basin has lost 70 percent of its land area. At this rate, it is predicted that less than 5 percent of the original land area from 1932 will exist in 2064. Additionally, levees and waterway barriers can trap storm surge and prevent proper draining. This oftentimes will cause long periods of severe flooding that has its own consequences for wetlands. For example, after Hurricane Rita in 2005, the enclosed marshes of Chenier plain were flooded for over nine months following the storm.

text: However, humans have modified the natural paths of rivers. This process, known as

text: channelization

text: , has serious consequences for wetland ecosystems which include drainage of wetlands, degradation of natural habitats, and elimination of natural flow patterns. With levees, canals, and set channels for water to flow through, the river no longer floods and reroutes naturally and seasonally. The river is not able to deposit sediment in diverse areas to help create wetlands. Instead, the river flows through its artificially determined path and deposits the valuable sediment off the edge of the continental shelf. This lack of natural wetland restoration combined with the continued erosion from hurricanes causes a rapid loss in wetland area. Before human channelization of waterways, the river’s natural process of sediment deposition was enough to sustain the wetland habitat, but currently wetland area is on a downward trend. Since 1932, the Mississippi River Delta Basin has lost 70 percent of its land area. At this rate, it is predicted that less than 5 percent of the original land area from 1932 will exist in 2064. Additionally, levees and waterway barriers can trap storm surge and prevent proper draining. This oftentimes will cause long periods of severe flooding that has its own consequences for wetlands. For example, after

text: Hurricane Rita

text: in 2005, the enclosed marshes of Chenier plain were flooded for over nine months following the storm.

text: Surface mining may impair groundwater in numerous ways: by drainage of usable water from shallow aquifers; lowering of water levels in adjacent areas and changes in flow direction within aquifers; contamination of usable aquifers below mining operations due to infiltration (percolation) of poor-quality mine water; and increased infiltration of precipitation on spoil piles. Where coal or carbonaceous shale is present, increased infiltration may result in: increased runoff of poor-quality water and erosion from spoil piles, recharge of poor-quality water to shallow groundwater aquifers and poor-quality water flow to nearby streams.

text: Surface mining may impair groundwater in numerous ways: by drainage of usable water from shallow aquifers; lowering of water levels in adjacent areas and changes in flow direction within aquifers; contamination of usable aquifers below mining operations due to infiltration (percolation) of poor-quality

text: mine water

text: ; and increased infiltration of precipitation on spoil piles. Where coal or carbonaceous shale is present, increased infiltration may result in: increased runoff of poor-quality water and erosion from spoil piles, recharge of poor-quality water to shallow groundwater aquifers and poor-quality water flow to nearby streams.

text: The coast at Hornsea is subject to erosion. The rate of erosion varies, but has been inferred at around  per year in the later part of the 16th century; estimated (George Poulson) at  per year in the late 18th century, though recorded at up to  in some years in the same period. The rate of erosion may have been influenced by the presence or absence of erosion limiting groynes or a pier. South, at Hornsea Burton erosion rates rose from  pa between the periods 1845–76 and 1876–82, thought to be due to the construction of groynes north of the beach at Hornsea. The current (2008) rate of erosion is  north of and  south of Hornsea – the difference due to the defences at Hornsea preventing the renewing flow of sediment southwards.

text: The name Selfors was first mentioned in 1430. It has been interpreted as Sel-foss (Norwegian for "the pinniped waterfall"), meaning a waterfall where pinnipeds lived. It also has been connected with the Sami word saelhtie, meaning "ocean".  This interpretation of "Sel-foss", however, is doubtful. In the old dialect of Rana they never used the name "sel" for pinnipeds, but rather used "købbe". Købbforsen which literally means "the pinniped waterfall", is located in another place in Rana municipality.  The name could also be seen in connection with sele ("silent flowing and deep water"), similar to  the Swedish place names of Lycksele, Sorsele, and Åsele. Selfors may then mean "a waterfall in a river with silent flowing, deep water". The waterfall is located at Fossetangen, and the "silent flowing, deep water" might be to river Ranelva.

text: The name Selfors was first mentioned in 1430. It has been interpreted as Sel-foss (

text: Norwegian

text: for "the pinniped waterfall"), meaning a waterfall where

text: pinniped

text: s lived. It also has been connected with the

text: Sami

text: word saelhtie, meaning "ocean".  This interpretation of "Sel-foss", however, is doubtful. In the old dialect of

text: Rana

text: they never used the name "sel" for

text: pinniped

text: s, but rather used "købbe". Købbforsen which literally means "the pinniped waterfall", is located in another place in Rana municipality.  The name could also be seen in connection with sele ("silent flowing and deep water"), similar to  the Swedish place names of

text: Lycksele

text: Sorsele

text: , and

text: Åsele

text: . Selfors may then mean "a waterfall in a river with silent flowing, deep water". The waterfall is located at

text: Fossetangen

text: , and the "silent flowing, deep water" might be to river

text: Ranelva

text: Hosie was born on 30 June 1967. He gained his Cave Diving qualification in 1997.  Over the past ten years, Hosie has been involved in the discovery and mapping of over 10,000m of new cave passages in Australia. This has included the exploration of remote cave diving sites in Australia including Kija Blue Sinkhole in Australia's Kimberley region (ADM Issue 24/2006 ). Hosie has been recognised as a member of the World Exploration Team of Divers in Advanced Diver Magazine and was the recipient of the 2003 Oztek Diver of the Year Award.  In 2007, Hosie was awarded the National Speleological Society (USA) Cave Diving Section - Exploration Award along with his team members for the exploration of Kija Blue Sinkhole  Hosie has been active in the caving community in WA. He is currently exploring the area of Eneabba to find new caves and pay homage to Jeff Butt, who was the inspiration for the inaugural Australian Speleological Federation Award for Exploration that he was awarded in 2007 from the Australian Speleological Federation.

text: Hosie was born on 30 June 1967. He gained his Cave Diving qualification in 1997.  Over the past ten years, Hosie has been involved in the discovery and mapping of over 10,000m of new cave passages in Australia. This has included the exploration of remote cave diving sites in Australia including Kija Blue Sinkhole in Australia's

text: Kimberley

text: region (ADM Issue 24/2006 ). Hosie has been recognised as a member of the World Exploration Team of Divers in Advanced Diver Magazine and was the recipient of the 2003 Oztek Diver of the Year Award.  In 2007, Hosie was awarded the National Speleological Society (USA) Cave Diving Section - Exploration Award along with his team members for the exploration of Kija Blue Sinkhole  Hosie has been active in the caving community in WA. He is currently exploring the area of Eneabba to find new caves and pay homage to Jeff Butt, who was the inspiration for the inaugural

text: Australian Speleological Federation

text: Award for Exploration that he was awarded in 2007 from the Australian Speleological Federation.

text: The Riviera Maya is completely within the state of Quintana Roo on the Yucatan Peninsula of Mexico. The terrain is flat and covered by low tropical jungle. The geology is high purity carbonates down to a depth of 0.5 - 1.5 km below the surface. Mean annual rainfall is 1.5 m per year and the efficient infiltration results in the complete absence of any surface rivers. As is common in karst, underground river networks have formed by dissolution, and these have been explored and mapped by cave diving through sinkhole collapses locally called cenotes. The whole of the Yucatan Peninsula is underlain by a density stratified coastal aquifer system with a lens shaped fresh water body floating on top of intruding saline water. The formation of caves (speleogenesis) within this coastal carbonate aquifer is principally associated with carbonate dissolution at the fresh-saline water contact within the aquifer. By 2008, the Quintana Roo Speleological Society (QRSS) reported more than  of flooded cave passages within the limits of the Riviera Maya including the two longest underwater cave systems in the world of Sac Actun and Ox Bel Ha. These groundwater resources, accessed via the thousands of cenotes throughout the landscape, once supported the Maya civilizations and today remain the only natural sources of potable water in the area.

text: The Riviera Maya is completely within the state of

text: Quintana Roo

text: on the

text: Yucatan Peninsula

text: of Mexico. The terrain is flat and covered by low tropical jungle. The geology is high purity carbonates down to a depth of 0.5 - 1.5 km below the surface. Mean annual rainfall is 1.5 m per year and the efficient infiltration results in the complete absence of any surface rivers. As is common in

text: karst

text: , underground river networks have formed by dissolution, and these have been explored and mapped by

text: cave diving

text: through

text: sinkhole

text: collapses locally called

text: cenotes

text: . The whole of the Yucatan Peninsula is underlain by a density stratified coastal aquifer system with a lens shaped fresh water body floating on top of intruding saline water. The formation of caves (

text: speleogenesis

text: ) within this coastal carbonate aquifer is principally associated with carbonate dissolution at the fresh-saline water contact within the aquifer. By 2008, the Quintana Roo Speleological Society (QRSS) reported more than  of flooded

text: cave

text: passages within the limits of the Riviera Maya including the two longest underwater cave systems in the world of

text: Sac Actun

text: and

text: Ox Bel Ha

text: . These groundwater resources, accessed via the thousands of cenotes throughout the landscape, once supported the

text: Maya

text: civilizations and today remain the only natural sources of potable water in the area.

text: The concept of the habitable zone (or Liquid Water Zone) defining a region where water can exist on the surface, is based on the properties of both the Earth and Sun. Under this model, Earth orbits roughly at the centre of this zone or in the "Goldilocks" position. Earth is the only planet in the universe confirmed to possess large bodies of surface water. Venus is on the hot side of the zone while Mars is on the cold side. Neither are known to have persistent surface water, though evidence exists that Mars did have in its ancient past, and it is speculated that the same was the case for Venus.<ref name='Venus Hashimoto'/> Thus extrasolar planets (or moons) in the Goldilocks position with substantial atmospheres may possess oceans and water clouds like those on Earth. In addition to surface water, a true Earth analog would require a mix of oceans or lakes and areas not covered by water, or land.

text: The environmental impact of mining includes erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned close to its original state. Some mining methods may have significant environmental and public health effects. Nuss and Eckelman (2014) provide an overview of the life-cycle wide environmental impacts of metals production associated with 62 metals in year 2008.

text: The environmental impact of mining includes

text: erosion

text: , formation of

text: sinkhole

text: s, loss of

text: biodiversity

text: , and

text: contamination of soil

text: groundwater

text: and

text: surface water

text: by chemicals from

text: mining

text: processes. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned close to its original state. Some mining methods may have significant environmental and public health effects. Nuss and Eckelman (2014) provide an overview of the life-cycle wide environmental impacts of metals production associated with 62 metals in year 2008.

text: These photographs were all taken on the Caaf Water, Lynn Glen, Dalry, Ayrshire, Scotland. The water conditions must be precisely right to create a fully formed kolk as shown by their absence or partial formation in sub-optimal parts of the same river system. Large basins form where the water flow is forceful and many small basins occur where the flow is fast, but the water shallower, such as near the edge of a waterfall. The stone substrate is made of fossiliferous limestone in these photographs.

text: These photographs were all taken on the

text: Caaf Water

text: , Lynn Glen,

text: Dalry

text: , Ayrshire, Scotland. The water conditions must be precisely right to create a fully formed kolk as shown by their absence or partial formation in sub-optimal parts of the same river system. Large basins form where the water flow is forceful and many small basins occur where the flow is fast, but the water shallower, such as near the edge of a waterfall. The stone substrate is made of fossiliferous limestone in these photographs.

text: Immediately following the multiple fatality in The Shaft on 28 May 1973, Des Corcoran, the SA Deputy Premier, announced the appointment of a committee to ‘investigate safety precautions for Scuba Divers in Fresh water Sinkholes and Underwater Caves’ and which consisted of three government officers - L.D. Draper (Chair), R.J. Wight (Secretary), G .C. Cornwall, and three representatives from the SA recreational diving community - D.G. Burchell, P.G. Christopher and R.C. Pulford.  In January 1974, the Committee offered five recommendations.  Firstly, the creation of a government advisory body to essentially encourage a higher standard of cave diving practice by the recreational diving community; secondly, the publication and distribution of educational material to improve the awareness of cave diving safety; thirdly, the installation of warning signs at sinkhole and cave sites; fourthly, the sealing of Alleyns Cave (also known as the Death Cave) to prevent access and finally, in the case of the failure of the first three recommendations to reduce fatalities, consideration of control by legislative measures.  The fifth recommendation suggested measures such as the licensing of instructors, an access permit system and the use of patrol officers to manage sites.  In April 1974, the SA Government announced that it would proceed with the recommendations of the committee including the creation of an advisory body.

text: Immediately following the multiple fatality in The Shaft on 28 May 1973,

text: Des Corcoran

text: , the SA Deputy Premier, announced the appointment of a committee to ‘investigate safety precautions for Scuba Divers in Fresh water Sinkholes and Underwater Caves’ and which consisted of three government officers - L.D. Draper (Chair), R.J. Wight (Secretary), G .C. Cornwall, and three representatives from the SA recreational diving community -

text: D.G. Burchell

text: P.G. Christopher

text: and R.C. Pulford.  In January 1974, the Committee offered five recommendations.  Firstly, the creation of a government advisory body to essentially encourage a higher standard of cave diving practice by the recreational diving community; secondly, the publication and distribution of educational material to improve the awareness of cave diving safety; thirdly, the installation of warning signs at sinkhole and cave sites; fourthly, the sealing of Alleyns Cave (also known as the Death Cave) to prevent access and finally, in the case of the failure of the first three recommendations to reduce fatalities, consideration of control by legislative measures.  The fifth recommendation suggested measures such as the licensing of instructors, an access permit system and the use of patrol officers to manage sites.  In April 1974, the SA Government announced that it would proceed with the recommendations of the committee including the creation of an advisory body.

text: The Ili, Chu and Talas are three steppe rivers that flow west and then north-west.  The Ili River rises in Xinjiang, flows west to a point north of Lake Issyk Kul and then turns north-west to reach Lake Balkash.  The Chu River rises west of Lake Issyk Kul, flows out into the steppe and dries up before reaching the Syr Darya. The Talas River starts west and south of the Chu, flows west and north-west, but dries up before reaching the Chu.

text: The Ili, Chu and Talas are three steppe rivers that flow west and then north-west.  The

text: Ili River

text: rises in

text: Xinjiang

text: , flows west to a point north of Lake

text: Issyk Kul

text: and then turns north-west to reach

text: Lake Balkash

text: .  The

text: Chu River

text: rises west of Lake Issyk Kul, flows out into the steppe and dries up before reaching the

text: Syr Darya

text: . The Talas River starts west and south of the Chu, flows west and north-west, but dries up before reaching the Chu.

text: The concave bank is often a cut bank and an area of erosion.  The eroded material is swept and rolled across the floor of the stream by the secondary flow and may be deposited on the point bar only a small distance downstream from its original location in the concave bank.

text: The concave bank is often a

text: cut bank

text: and an area of

text: erosion

text: .  The eroded material is swept and rolled across the floor of the stream by the

text: secondary flow

text: and may be deposited on the point bar only a small distance downstream from its original location in the concave bank.

text: Some areas of Mars show inverted relief, where features that were once depressions, like streams, are now above the surface. It is believed that materials like large rocks were deposited in low-lying areas. Later, wind erosion removed much of the surface layers, but left behind the more resistant deposits. Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water. On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces. Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River, Utah. Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times. Inverted relief in the form of stream channels suggest that the climate was different—much wetter—when the inverted channels were formed.

text: Some areas of Mars show inverted relief, where features that were once depressions, like streams, are now above the surface. It is believed that materials like large rocks were deposited in low-lying areas. Later, wind erosion removed much of the surface layers, but left behind the more resistant deposits. Other ways of making inverted relief might be lava flowing down a stream bed or materials being cemented by minerals dissolved in water. On Earth, materials cemented by silica are highly resistant to all kinds of erosional forces. Examples of inverted channels on Earth are found in the Cedar Mountain Formation near Green River,

text: Utah

text: . Inverted relief in the shape of streams are further evidence of water flowing on the Martian surface in past times. Inverted relief in the form of stream channels suggest that the climate was different—much wetter—when the inverted channels were formed.

text: The traffic on the river is a significant factor concerning shoreline erosion due to waves produced, especially by large vessels using the St. Lawrence Seaway. Channel Seaway changed the course of the natural flow of the river. In places, the flow distribution in the lake due to some stagnation of water near the banks, creating a silting.

text: The traffic on the river is a significant factor concerning shoreline erosion due to waves produced, especially by large vessels using the

text: St. Lawrence Seaway

text: . Channel Seaway changed the course of the natural flow of the river. In places, the flow distribution in the lake due to some stagnation of water near the banks, creating a silting.

text: Kaziranga National Park’s landscape is the creation of natural forces of silt deposition and erosion that has been effected by the river Brahmaputra over hundreds of years. This ongoing process of erosion and deposition becomes more severe during the floods which occur at regular intervals during the monsoon season. The Brahmaputra river in its  flow through Assam receives more than a hundred tributaries flowing down from the adjoining hills. Once the tributaries hit the river valley, they lose their momentum; deposit the silt they carry, form ox-bow lakes and alluvial fans and branch out before picking up their courses again to join the Brahmaputra.

text: Kaziranga National Park’s landscape is the creation of natural forces of

text: silt deposition

text: and

text: erosion

text: that has been effected by the river Brahmaputra over hundreds of years. This ongoing process of erosion and deposition becomes more severe during the floods which occur at regular intervals during the monsoon season. The

text: Brahmaputra

text: river in its  flow through Assam receives more than a hundred tributaries flowing down from the adjoining hills. Once the tributaries hit the river valley, they lose their momentum; deposit the silt they carry, form

text: ox-bow lake

text: s and

text: alluvial fans

text: and branch out before picking up their courses again to join the Brahmaputra.

text: The lava flows formed the conditions for the creation of Lake Superior agates. As the lava solidified, gas trapped within the flows formed an amygdaloidal texture (literally, rock filled with small vesicles). Later, groundwater transported dissolved minerals through the vesicles depositing concentric bands of fine-grained quartz called chalcedony.  The color scheme is caused by the concentration of iron present in the groundwater at the time that each new layer was being deposited.  The process went on until the cavity had been completely filled. Over time erosion freed the agates from the solidified lava, which is not as hard as quartz.

text: The lava flows formed the conditions for the creation of

text: Lake Superior agate

text: s. As the lava solidified, gas trapped within the flows formed an

text: amygdaloidal texture

text: (literally, rock filled with small vesicles). Later, groundwater transported dissolved minerals through the vesicles depositing concentric bands of fine-grained

text: quartz

text: called

text: chalcedony

text: .  The color scheme is caused by the concentration of iron present in the groundwater at the time that each new layer was being deposited.  The process went on until the cavity had been completely filled. Over time erosion freed the agates from the solidified lava, which is not as hard as quartz.

text: An antidune is a bedform found in fluvial and other channeled environments. Antidunes occur in supercritical flow, meaning that the Froude number is greater than 1.0 or the flow velocity exceeds the wave velocity; this is also known as upper flow regime. In antidunes, sediment is deposited on the upstream (stoss) side and eroded from the downstream (lee) side, opposite lower flow regime bedforms. As a result, antidunes migrate in an upstream direction, counter to the current flow. Antidunes are called in-phase bedforms, meaning that the water surface elevation mimics the bed elevation; this is due to the supercritical flow regime. Antidune bedforms evolve rapidly, growing in amplitude as they migrate upstream. The resultant wave at the water's surface also increases in amplitude. When that wave becomes unstable, breaks and washes downstream, much of the antidune bedform may be destroyed.

text: An antidune is a

text: bedform

text: found in

text: fluvial

text: and other channeled environments. Antidunes occur in

text: supercritical flow

text: , meaning that the

text: Froude number

text: is greater than 1.0 or the flow velocity exceeds the wave velocity; this is also known as

text: upper flow regime

text: . In antidunes, sediment is deposited on the upstream (stoss) side and eroded from the downstream (lee) side, opposite lower flow regime bedforms. As a result, antidunes migrate in an upstream direction, counter to the current flow. Antidunes are called in-phase bedforms, meaning that the water surface elevation mimics the bed elevation; this is due to the supercritical flow regime. Antidune bedforms evolve rapidly, growing in amplitude as they migrate upstream. The resultant wave at the water's surface also increases in amplitude. When that wave becomes unstable, breaks and washes downstream, much of the antidune bedform may be destroyed.

text: As the boulders tumble down slope, they will tend to cause erosion wherever they hit, and this forms small waterfalls.  Over time, as boulders fall over the waterfall, they erode deeply at the base of the waterfall, forming a plunge pool.  During normal low flows, these make for excellent swimming holes, and are notable features of all the waterfalls on Mauna Kea.

text: As the boulders tumble down slope, they will tend to cause

text: erosion

text: wherever they hit, and this forms small waterfalls.  Over time, as boulders fall over the waterfall, they erode deeply at the base of the waterfall, forming a

text: plunge pool

text: .  During normal low flows, these make for excellent

text: swimming hole

text: s, and are notable features of all the waterfalls on Mauna Kea.

text: The major mechanism of canyon erosion is now thought to be turbidity currents and underwater landslides. Turbidity currents are dense, sediment-laden currents which flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes. There is a spectrum of turbidity- or density-current types ranging from "muddy water" to massive mudflow, and evidence of both these end members can be observed in deposits associated with the deeper parts of submarine canyons and channels, such as lobate deposits (mudflow) and levees along channels.

text: The major mechanism of canyon erosion is now thought to be turbidity currents and underwater

text: landslide

text: s. Turbidity currents are

text: dense

text: , sediment-laden

text: current

text: s which flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes. There is a spectrum of turbidity- or density-current types ranging from "

text: mud

text: dy water" to massive mudflow, and evidence of both these end members can be observed in deposits associated with the deeper parts of submarine canyons and channels, such as

text: lobate

text: deposits (mudflow) and

text: levee

text: s along channels.

text: Kandovan (, also Romanized as Kandovān and Kandavān; also known as Kanvān) is a village in Sahand Rural District, in the Central District of Osku County, East Azerbaijan Province, Iran.This village exemplifies manmade cliff dwellings which are still inhabited. The troglodyte homes, excavated inside volcanic rocks and tuffs similar to dwellings in the Turkish region of Cappadocia, are locally called "Karaan". Karaans were cut into the Lahars (volcanic mudflow or debris flow) of Mount Sahand. The cone form of the houses is the result of lahar flow consisting of porous round and angular pumice together with other volcanic particles that were positioned in a grey acidic matrix. After the eruption of Sahand these materials were naturally moved and formed the rocks of Kandovan. Around the village the thickness of this formation exceeds 100 m and with time due to water erosion the cone shaped cliffs were formed.At the 2006 census, the village population was 601, in 168 families.

text: Kandovan (, also

text: Romanize

text: d as Kandovān and Kandavān; also known as Kanvān) is a village in

text: Sahand Rural District

text: , in the

text: Central District

text: of

text: Osku County

text: East Azerbaijan Province

text: Iran

text: .This village exemplifies manmade cliff dwellings which are still inhabited. The troglodyte homes, excavated inside volcanic rocks and tuffs similar to dwellings in the Turkish region of

text: Cappadocia

text: , are locally called "Karaan". Karaans were cut into the Lahars (volcanic mudflow or debris flow) of

text: Mount Sahand

text: . The cone form of the houses is the result of lahar flow consisting of porous round and angular pumice together with other volcanic particles that were positioned in a grey acidic matrix. After the eruption of Sahand these materials were naturally moved and formed the rocks of Kandovan. Around the village the thickness of this formation exceeds 100 m and with time due to water erosion the cone shaped cliffs were formed.At the 2006 census, the village population was 601, in 168 families.

text: Ten of the many natural satellites in the Solar System are known to have atmospheres: Europa, Io, Callisto, Enceladus, Ganymede, Titan, Rhea, Dione, Triton and Earth's Moon. Ganymede and Europa both have very tenuous oxygen atmospheres, thought to be produced by radiation splitting the water ice present on the surface of these moons into hydrogen and oxygen. Io has an extremely thin atmosphere consisting mainly of sulfur dioxide (), arising from volcanism and sunlight-driven sublimation of surface sulfur dioxide deposits. The atmosphere of Enceladus is also extremely thin and variable, consisting mainly of water vapor, nitrogen, methane, and carbon dioxide vented from the moon's interior through cryovolcanism. The extremely thin carbon dioxide atmosphere of Callisto is thought to be replenished by sublimation from surface deposits.

text: Ten of the many natural satellites in the Solar System are known to have atmospheres:

text: Europa

text: Io

text: Callisto

text: Enceladus

text: Ganymede

text: Titan

text: Rhea

text: Dione

text: Triton

text: and

text: Earth

text: 's

text: Moon

text: . Ganymede and Europa both have very tenuous oxygen atmospheres, thought to be produced by radiation splitting the water ice present on the surface of these moons into hydrogen and oxygen. Io has an extremely thin atmosphere consisting mainly of sulfur dioxide (), arising from volcanism and sunlight-driven sublimation of surface sulfur dioxide deposits. The atmosphere of Enceladus is also extremely thin and variable, consisting mainly of water vapor, nitrogen, methane, and carbon dioxide vented from the moon's interior through

text: cryovolcanism

text: . The extremely thin carbon dioxide atmosphere of Callisto is thought to be replenished by sublimation from surface deposits.

text: During the last glacial period (110,000 to 10,000 years ago), especially in the Wisconsinian glaciation (31,000 to 10,000 years ago), the climate of Southern California changed radically from arid to wet, to a climate likely similar to the present-day Pacific Northwest. Prodigious rainfall gradually turned the small streams of the region into large and powerful rivers. It was this surge in volume that allowed Aliso Creek and other rivers to cut through the San Joaquin Hills. A  drop in sea level escalated the process, allowing the rivers to flow more rapidly and have more erosive power. As sea levels rose after the Wisconsinian glaciation, the water gaps the rivers had cut through the San Joaquin Hills, including Aliso Canyon, became fjord-like inlets. Aliso Creek and these other streams deposited sediments into the inlets, turning them into flat-floored alluvial valleys with an elevation very close to sea level. Eventually, the sediment deposited met the coastline. By then, the rivers and streams had diminished to their original flow before the glaciation.

text: During the

text: last glacial period

text: (110,000 to 10,000 years ago), especially in the

text: Wisconsinian glaciation

text: (31,000 to 10,000 years ago), the climate of Southern California changed radically from arid to wet, to a climate likely similar to the present-day

text: Pacific Northwest

text: . Prodigious rainfall gradually turned the small streams of the region into large and powerful rivers. It was this surge in volume that allowed Aliso Creek and other rivers to cut through the San Joaquin Hills. A  drop in sea level escalated the process, allowing the rivers to flow more rapidly and have more erosive power. As sea levels rose after the Wisconsinian glaciation, the water gaps the rivers had cut through the San Joaquin Hills, including Aliso Canyon, became

text: fjord

text: -like inlets. Aliso Creek and these other streams deposited sediments into the inlets, turning them into flat-floored alluvial valleys with an elevation very close to sea level. Eventually, the sediment deposited met the coastline. By then, the rivers and streams had diminished to their original flow before the glaciation.

text: Ribbon Fall, located in Yosemite National Park in California, flows off a cliff on the west side of El Capitan and is the longest single-drop waterfall in North America. The fall is fed by melting winter snow; while therefore dry for much of the year, the fall is a spectacular 1,612 feet (491 m) in the spring. In exceptional years, an ice cone develops at its base during the winter months similar to that which usually forms beneath Upper Yosemite Fall. This deposit can reach a depth of 200 feet, versus 322 feet for the greatest depth of the ice cone beneath the Upper Fall and Lower Fall. It is the tallest, continuous falls waterfall in the United States.

text: Ribbon Fall, located in

text: Yosemite National Park

text: in

text: California

text: , flows off a cliff on the west side of

text: El Capitan

text: and is the longest single-drop

text: waterfall

text: in North America. The fall is fed by melting winter snow; while therefore dry for much of the year, the fall is a spectacular 1,612 feet (491 m) in the spring. In exceptional years, an ice cone develops at its base during the winter months similar to that which usually forms beneath Upper

text: Yosemite Fall

text: . This deposit can reach a depth of 200 feet, versus 322 feet for the greatest depth of the ice cone beneath the Upper Fall and Lower Fall. It is the tallest, continuous falls waterfall in the United States.

text: The island became a peninsula in the early 20th century when the Gallaudet Aircraft Company constructed America's first seaplane-only factory at Chepiwanoxet cc. 1916. For truck access to the factory, fill was dumped into the marsh, making a causeway from Alger Avenue that still remains. As a result of blocking water circulation around the island, Arnold Cove lost its boat channel from silt deposits in the tidal marsh located on the North side of the island. With the island made of sand deposits it was subject to shore erosion. The Gallaudet Company built wood bulkheads around the North, East and South shores with rock rip-rap on the waterside and fill behind. With many factory workers living north of the old cove, a narrow wood plank bridge was built across the marsh to allow quicker access to/from work.

text: The island became a peninsula in the early 20th century when the

text: Gallaudet Aircraft Company

text: constructed America's first seaplane-only factory at Chepiwanoxet cc. 1916. For truck access to the factory, fill was dumped into the marsh, making a causeway from Alger Avenue that still remains. As a result of blocking water circulation around the island, Arnold Cove lost its boat channel from silt deposits in the tidal marsh located on the North side of the island. With the island made of sand deposits it was subject to shore erosion. The Gallaudet Company built wood bulkheads around the North, East and South shores with rock rip-rap on the waterside and fill behind. With many factory workers living north of the old cove, a narrow wood plank bridge was built across the marsh to allow quicker access to/from work.

text: Prior to the arrival of European settlers in the 18th century, the Anacostia River was a fast-flowing and relatively silt-free river with very few mudflats or marshes. White settlers cleared much of the surrounding forest for farmland, however, and extensive soil erosion led to a heavy load of silt and effluent in the Anacostia. In 1805, local landowner Benjamin Stoddert built a wooden bridge over the Anacostia River at the present site of Ethel Kennedy Bridge. The bridge was sold Thomas Ewell, who in the 1820s sold it to William Benning. Thereafter the structure was known as Benning's Bridge (or Benning Bridge). The wooden bridge was rebuilt several times after 1805. This included construction of a steel bridge in 1892. The construction of Benning and other bridges and the diversion of inflowing streams to agricultural use also slowed the river's current, allowing much of the silt to settle and be deposited.

text: Prior to the arrival of European settlers in the 18th century, the Anacostia River was a fast-flowing and relatively silt-free river with very few mudflats or marshes. White settlers cleared much of the surrounding forest for farmland, however, and extensive soil erosion led to a heavy load of silt and effluent in the Anacostia. In 1805, local landowner

text: Benjamin Stoddert

text: built a wooden bridge over the Anacostia River at the present site of Ethel Kennedy Bridge. The bridge was sold Thomas Ewell, who in the 1820s sold it to William Benning. Thereafter the structure was known as Benning's Bridge (or Benning Bridge). The wooden bridge was rebuilt several times after 1805. This included construction of a steel bridge in 1892. The construction of Benning and other bridges and the diversion of inflowing streams to agricultural use also slowed the river's current, allowing much of the silt to settle and be deposited.

text: This process continues today. Due to their exposure to the open ocean, the Cape and islands are subject to considerable coastal erosion. Geologists say that due to erosion, the Cape will be completely submerged by the sea within several thousand years. This erosion causes the washout of beaches and the destruction of the barrier islands; for example, the ocean broke through the barrier island at Chatham during Hurricane Bob in 1991, allowing waves and storm surges to hit the coast with no obstruction. Consequently, the sediment and sand from the beaches is being washed away and deposited elsewhere. While this destroys land in some places, it creates land elsewhere, most noticeably in marshes where sediment is deposited by flowing water.

text: This process continues today. Due to their exposure to the open ocean, the Cape and islands are subject to considerable

text: coastal erosion

text: . Geologists say that due to erosion, the Cape will be completely submerged by the sea within several thousand years. This erosion causes the washout of beaches and the destruction of the barrier islands; for example, the ocean broke through the barrier island at Chatham during

text: Hurricane Bob

text: in 1991, allowing waves and storm surges to hit the coast with no obstruction. Consequently, the sediment and sand from the beaches is being washed away and deposited elsewhere. While this destroys land in some places, it creates land elsewhere, most noticeably in marshes where sediment is deposited by flowing water.

text: The terms river morphology and its synonym fluvial geomorphology are used to describe the shapes of river channels and how they change in shape and direction over time. The morphology of a river channel is a function of a number of processes and environmental conditions, including the composition and erodibility of the bed and banks (e.g., sand, clay, bedrock); erosion comes from the power and consistency of the current, and can effect the formation of the river's path.  Also, vegetation and the rate of plant growth; the availability of sediment; the size and composition of the sediment moving through the channel; the rate of sediment transport through the channel and the rate of deposition on the floodplain, banks, bars, and bed; and regional aggradation or degradation due to subsidence or uplift. River morphology can also be effected by human interaction, which is a way the river responds to a new factor in how the river can change its course. A river regime is a dynamic equilibrium  system, which is a way of classifying rivers into different categories. The four categories of river regimes are Sinuous canali- form rivers, Sinuous point bar rivers, Sinuous braided rivers, and Non-sinuous braided rivers.

text: The terms river morphology and its synonym

text: fluvial

text: geomorphology

text: are used to describe the shapes of

text: river

text: channels

text: and how they change in shape and direction over time. The morphology of a river channel is a function of a number of processes and environmental conditions, including the composition and

text: erodibility

text: of the

text: bed

text: and

text: banks

text: (e.g., sand, clay, bedrock);

text: erosion

text: comes from the power and consistency of the current, and can effect the formation of the river's path.  Also,

text: vegetation

text: and the rate of plant growth; the availability of

text: sediment

text: ; the size and composition of the sediment moving through the channel; the rate of

text: sediment transport

text: through the channel and the rate of deposition on the

text: floodplain

text: , banks,

text: bars

text: , and bed; and regional

text: aggradation

text: or

text: degradation

text: due to

text: subsidence

text: or

text: uplift

text: . River morphology can also be effected by human interaction, which is a way the river responds to a new factor in how the river can change its course. A

text: river regime

text: is a dynamic equilibrium  system, which is a way of classifying rivers into different categories. The four categories of river regimes are Sinuous canali- form rivers, Sinuous point bar rivers, Sinuous braided rivers, and Non-sinuous braided rivers.

text: Cathedral Cave - opened for guided tours since 1885. Cathedral Cave is famous for its huge stalagmite known as Altar Rock which is 32 metres in circumference at its base and over 15 metres high.Gaden Cave - opened for guided tours since 1909. Gaden Cave is noted for its unusual and beautiful cave coral. It is named after the shire president at the time that the cave was discovered.Phosphate Mine - opened for guided tours since 1996. Apart from viewing the old workings, visitors can see 800,000-year-old deposits containing fossil bones.Other Caves (not open for tourism) - Lime Kiln Cave and McCavity - Lime Kiln Cave is the name given to the dry part of a large cave system, most of which is completely water-filled. McCavity is the under-water section of the cave which was discovered by members of the Sydney University Speleological Society.Water Cave (Anticline Cave) - this is a small doline cave leading to water. It is in the process of being re-opened.Big Sink - this is an old collapsed doline. It appears to be the route through which fossil-bearing sediments washed into the chambers below.Mitchell's Cave - this is the site from which the first Australian fossils for scientific study were collected by George Ranken

text: Cathedral Cave - opened for guided tours since 1885. Cathedral Cave is famous for its huge stalagmite known as Altar Rock which is 32 metres in circumference at its base and over 15 metres high.Gaden Cave - opened for guided tours since 1909. Gaden Cave is noted for its unusual and beautiful

text: cave coral

text: . It is named after the shire president at the time that the cave was discovered.Phosphate Mine - opened for guided tours since 1996. Apart from viewing the old workings, visitors can see 800,000-year-old deposits containing fossil bones.Other Caves (not open for tourism) - Lime Kiln Cave and McCavity - Lime Kiln Cave is the name given to the dry part of a large cave system, most of which is completely water-filled. McCavity is the under-water section of the cave which was discovered by members of the

text: Sydney University Speleological Society

text: .Water Cave (Anticline Cave) - this is a small doline cave leading to water. It is in the process of being re-opened.Big Sink - this is an old collapsed doline. It appears to be the route through which fossil-bearing sediments washed into the chambers below.Mitchell's Cave - this is the site from which the first Australian fossils for scientific study were collected by George Ranken

text: To the east of the Shannon, the limestone is often covered by great thicknesses of glacial drift deposited during the Ice Age but in many areas to the west of the Shannon where the limestone is pure and the drift cover is thin, there is no proper surface river network. In these areas, rainfall disappears underground, flows through openings in the rock and then rises at springs: large springs can be found to the west of the area, flowing into Lough Corrib and Galway Bay. In winter, when the underground water level (or water table) rises, and when the underground flow rises, and when the underground flow routes to the springs are not capable of dealing with the amount of water entering them, groundwater may appear temporarily at the surface in the form of a turlough.

text: To the east of the Shannon, the limestone is often covered by great thicknesses of

text: glacial

text: drift deposited during the

text: Ice Age

text: but in many areas to the west of the Shannon where the limestone is pure and the drift cover is thin, there is no proper surface river network. In these areas, rainfall disappears underground, flows through openings in the rock and then rises at

text: springs

text: : large springs can be found to the west of the area, flowing into

text: Lough Corrib

text: and

text: Galway Bay

text: . In winter, when the underground water level (or

text: water table

text: ) rises, and when the underground flow rises, and when the underground flow routes to the springs are not capable of dealing with the amount of water entering them, groundwater may appear temporarily at the surface in the form of a turlough.

text: The lower waters mass of NADW form from overflow of the Greenland-Iceland-Scotland Ridge.  They are Iceland-Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW).  The overflows are a combination of dense Arctic Ocean water (18%), modified Atlantic water (32%), and intermediate water from the Nordic seas (20%), that entrain and mix with other water masses (contributing 30%) as they flow over the Greenland-Iceland-Scotland Ridge.  The formation of both of these waters involves the conversion of warm salty northward flowing surface waters to cold dense deep waters behind the Greenland-Iceland-Scotland Ridge.  Water flow from the North Atlantic current enters the Arctic Ocean through the Norwegian Current which splits into the Fram Strait and Barents Sea Branch.  Water from the Fram Strait recirculates, reaching a density of DSOW, sinks, and flows towards the Denmark Strait.  Water flowing into the Barent Sea feeds ISOW.

text: The lower waters mass of NADW form from overflow of the Greenland-Iceland-Scotland Ridge.  They are Iceland-Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW).  The overflows are a combination of dense Arctic Ocean water (18%), modified Atlantic water (32%), and intermediate water from the Nordic seas (20%), that entrain and mix with other water masses (contributing 30%) as they flow over the Greenland-Iceland-Scotland Ridge.  The formation of both of these waters involves the conversion of warm salty northward flowing surface waters to cold dense deep waters behind the Greenland-Iceland-Scotland Ridge.  Water flow from the North Atlantic current enters the Arctic Ocean through the

text: Norwegian Current

text: which splits into the

text: Fram Strait

text: and

text: Barents Sea

text: Branch.  Water from the Fram Strait recirculates, reaching a density of DSOW, sinks, and flows towards the Denmark Strait.  Water flowing into the Barent Sea feeds ISOW.

text: Surface runoff can cause erosion of the Earth's surface; eroded material may be deposited a considerable distance away. There are four main types of soil erosion by water: splash erosion, sheet erosion, rill erosion and gully erosion. Splash erosion is the result of mechanical collision of raindrops with the soil surface: soil particles which are dislodged by the impact then move with the surface runoff. Sheet erosion is the overland transport of sediment by runoff without a well defined channel. Soil surface roughness causes may cause runoff to become concentrated into narrower flow paths: as these incise, the small but well-defined channels which are formed are known as rills. These channels can be as small as one centimeter wide or as large as several meters. If runoff continue to incise and enlarge rills, they may eventually grow to become gullies. Gully erosion can transport large amounts of eroded material in a small time period.

text: Surface runoff can cause

text: erosion

text: of the Earth's surface;

text: eroded material

text: may be

text: deposited

text: a considerable distance away. There are four main types of

text: soil erosion by water

text: : splash erosion, sheet erosion,

text: rill

text: erosion and

text: gully

text: erosion. Splash erosion is the result of mechanical collision of raindrops with the soil surface: soil particles which are dislodged by the impact then move with the surface runoff. Sheet erosion is the overland transport of

text: sediment

text: by runoff without a well defined channel. Soil surface roughness causes may cause runoff to become concentrated into narrower flow paths: as these incise, the small but well-defined channels which are formed are known as

text: rill

text: s. These channels can be as small as one centimeter wide or as large as several meters. If runoff continue to incise and enlarge rills, they may eventually grow to become

text: gullies

text: . Gully erosion can transport large amounts of eroded material in a small time period.

text: Flooding normally begins in May, sometimes at the end of April, peaking in two weeks and will end in the second half of June. The average duration of approximately two months, from mid-May to mid-July. The biggest difference between the water level in the lower reaches is approximately . The average water flow is about , and the total annual runoff is about , of which half runs during floods. In summer and autumn are generally low rainfall floods. The most abounding month - June, the low - March and April. River freezes usually in the second - the third decade of October, an average of 18 - 20 numbers, opened at the end of May. Freeze and an autopsy is accompanied by short ice. The average length of ice about 220 days. The average thickness of the ice at the end of winter 80 – 85 cm River are some deposits of hydrocarbon raw materials (Umseyskoe, Gubkinskoe, Purpeyskoe Southern, Eastern Purpeyskoe, Novopur-peyskoe, Komsomolskaya, North Komsomolskaya etc.)

text: Part of the Atlantic coastal plain, Broxton Rocks' sandstone layers were created by the slow erosion of the Altamaha Formation, dating from the Middle Miocene era.  Fractures have opened up throughout the feature, some wide enough to allow a person to walk through, some narrow but deep.  Where the waters of Rocky Creek, a first-order intermittent stream, drop to a lower level, a 10-foot (3 meter) waterfall has formed a pool in the sandstone before it flows out and through the lower reaches of the feature before draining into the Ocmulgee River.

text: Part of the

text: Atlantic coastal plain

text: , Broxton Rocks' sandstone layers were created by the slow erosion of the

text: Altamaha Formation

text: , dating from the

text: Middle Miocene

text: era.  Fractures have opened up throughout the feature, some wide enough to allow a person to walk through, some narrow but deep.  Where the waters of Rocky Creek, a first-order intermittent stream, drop to a lower level, a 10-foot (3 meter) waterfall has formed a pool in the sandstone before it flows out and through the lower reaches of the feature before draining into the

text: Ocmulgee River

text: Sannur Cave is a classic karst cave created by groundwater percolating through the Eocene limestone of the Galala Plateau. It is the best example of this type of cave in Egypt. As the water percolates downwards, excess calcium carbonates are deposited on the roof and floor of the cave forming spectacular stalactites and stalagmites of various forms. When a light is shone on them, they glitter like a wonderland. Above ground, there are deposits of the red soil (terra rossa) associated with such formations, as well as several swallow-holes (dolines).

text: Periodic flash floods carry rocky debris (sediment) eroded from Mosaic Canyon and the surrounding hillsides toward the valley below. At the canyon mouth water spreads out and deposits its sediment load, gradually building up a large wedge-shaped alluvial fan that extends down toward Stovepipe Wells. This canyon was formed through a process of cut and fill which included periodic erosive floods followed by long periods of deposition and uplift. But due to the uplift when the next flood hit the area it would deeply cut the streambed which forms stairstep-shaped banks.

text: Periodic

text: flash flood

text: s carry rocky debris (sediment) eroded from Mosaic Canyon and the surrounding hillsides toward the valley below. At the canyon mouth water spreads out and deposits its sediment load, gradually building up a large wedge-shaped

text: alluvial fan

text: that extends down toward Stovepipe Wells. This canyon was formed through a process of

text: cut and fill

text: which included periodic erosive floods followed by long periods of deposition and uplift. But due to the uplift when the next flood hit the area it would deeply cut the streambed which forms stairstep-shaped banks.

text: As flow enters the bank of an alluvial river, the centrifugal force created by the bend instigates helicoidal flow, a corkscrew like pattern of flow, which drives the hydraulic action acting on the opposing bank. This is where the primary process in river channel migration of bank erosion occurs. Often the bank is undercut, another result of the helicoidal flow, which leads to the creation of cut banks. Factors that limit the rate of bank erosion include the rate of deposition of the point bar, stream power, and the critical shear stress of the stream bed.

text: As flow enters the bank of an

text: alluvial river

text: , the centrifugal force created by the bend instigates

text: helicoidal flow

text: , a corkscrew like pattern of flow, which drives the

text: hydraulic action

text: acting on the opposing bank. This is where the primary process in river channel migration of

text: bank erosion

text: occurs. Often the bank is undercut, another result of the helicoidal flow, which leads to the creation of cut banks. Factors that limit the rate of bank erosion include the rate of deposition of the point bar,

text: stream power

text: , and the critical

text: shear stress

text: of the stream bed.

text: Additionally, the pyroclastic dam was still hot and poorly indurated when the flood waters rapidly cut through the pyroclastic material. Headward erosion of the dam created a  wide and  long canyon. The flood was significant enough to leave volcanic blocks  above the pre-existing valley floor  downstream of the dam failure. However, the flood was not long or large enough to complete headward erosion through the entire sequence of pyroclastic material. Subsequent erosion by the Lillooet River has created a  wide and  deep gorge in the competent portion of the pyroclastic dam from which Keyhole Falls cascades down.

text: Additionally, the pyroclastic dam was still hot and poorly indurated when the

text: flood

text: waters rapidly cut through the pyroclastic material.

text: Headward erosion

text: of the dam created a  wide and  long canyon. The flood was significant enough to leave volcanic blocks  above the pre-existing valley floor  downstream of the dam failure. However, the flood was not long or large enough to complete headward erosion through the entire sequence of pyroclastic material. Subsequent erosion by the Lillooet River has created a  wide and  deep gorge in the competent portion of the pyroclastic dam from which Keyhole Falls cascades down.

text: Flooding is a natural part of a river's cycle. The majority of the erosion of river channels and the erosion and deposition on the associated floodplains occur during the flood stage. In many developed areas, human activity has changed the form of river channels, altering magnitudes and frequencies of flooding. Some examples of this are the building of levees, the straightening of channels, and the draining of natural wetlands. In many cases human activities in rivers and floodplains have dramatically increased the risk of flooding. Straightening rivers allows water to flow more rapidly downstream, increasing the risk of flooding places further downstream. Building on flood plains removes flood storage, which again exacerbates downstream flooding. The building of levees only protects the area behind the levees and not those further downstream. Levees and flood-banks can also increase flooding upstream because of the back-water pressure as the river flow is impeded by the narrow channel banks.

text: Flooding is a natural part of a river's cycle. The majority of the erosion of river channels and the erosion and deposition on the associated floodplains occur during the

text: flood stage

text: . In many developed areas, human activity has changed the form of river channels, altering magnitudes and frequencies of flooding. Some examples of this are the building of

text: levee

text: s, the straightening of channels, and the draining of natural

text: wetland

text: s. In many cases human activities in rivers and floodplains have dramatically increased the risk of flooding. Straightening rivers allows water to flow more rapidly downstream, increasing the risk of flooding places further downstream. Building on flood plains removes flood storage, which again exacerbates downstream flooding. The building of levees only protects the area behind the levees and not those further downstream. Levees and flood-banks can also increase flooding upstream because of the back-water pressure as the river flow is impeded by the narrow channel banks.

text: The sinkhole, which has a depth of , has been known since antiquity and is located towards the north end of the plateau of Palaiochora at a height of 750 m above sea level on mount Parnon. It is about 45 minutes on unsurfaced road from the nearest town of Tyros in the Kynouria region of Arcadia. The sinkhole was first explored in August 1974 to a depth of  by a French team (in collaboration with the Hellenic Speleological Society). Since 2003, SELAS caving club in Greece has been exploring the cave, doubling the depth and more than tripling the length of the sinkhole. The new discoveries were made in 2003 by cave diving the first sump and emptying it by siphoning the water and in 2005 by emptying sumps in side passages of the sinkhole.

text: The sinkhole, which has a depth of , has been known since antiquity and is located towards the north end of the

text: plateau

text: of

text: Palaiochora

text: at a height of 750 m above sea level on mount

text: Parnon

text: . It is about 45 minutes on unsurfaced road from the nearest town of

text: Tyros

text: in the

text: Kynouria

text: region of Arcadia. The sinkhole was first explored in August 1974 to a depth of  by a French team (in collaboration with the Hellenic Speleological Society). Since 2003, SELAS caving club in Greece has been exploring the

text: cave

text: , doubling the depth and more than tripling the length of the sinkhole. The new discoveries were made in 2003 by

text: cave diving

text: the first

text: sump

text: and emptying it by

text: siphon

text: ing the water and in 2005 by emptying sumps in side passages of the sinkhole.

text: Two caves, Key Cave and Collier Cave, lie within the refuge, approximately  apart. Both caves are closed to the public. Each is on the northern shore of Pickwick Lake on the Tennessee River. The area also contains several sinkholes and underground cave systems, including a  sinkhole lake. The sinkholes and cave systems provide a source of groundwater for the caves. The refuge is set up to minimize the pollution of this groundwater.

text: Two caves, Key Cave and Collier Cave, lie within the refuge, approximately  apart. Both caves are closed to the public. Each is on the northern shore of

text: Pickwick Lake

text: on the

text: Tennessee River

text: . The area also contains several

text: sinkhole

text: s and underground cave systems, including a

text: sinkhole lake

text: . The sinkholes and cave systems provide a source of

text: groundwater

text: for the caves. The refuge is set up to minimize the pollution of this groundwater.

text: When sinkholes are very deep or connected to caves, they may offer challenges for experienced cavers or, when water-filled, divers. Some of the most spectacular are the Zacatón cenote in Mexico (the world's deepest water-filled sinkhole), the Boesmansgat sinkhole in South Africa, Sarisariñama tepuy in Venezuela, the Sótano del Barro in Mexico, and in the town of Mount Gambier, South Australia. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as blue holes and often become popular diving spots.

text: When sinkholes are very deep or connected to caves, they may offer challenges for experienced

text: caver

text: s or, when water-filled,

text: divers

text: . Some of the most spectacular are the

text: Zacatón

text: cenote in Mexico (the world's deepest water-filled sinkhole), the

text: Boesmansgat

text: sinkhole in South Africa,

text: Sarisariñama

text: tepuy

text: in Venezuela, the Sótano del Barro in Mexico, and in the town of

text: Mount Gambier, South Australia

text: . Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as

text: blue hole

text: s and often become popular diving spots.

text: Researchers in December 2016 announced the discovery of the element boron byCuriosity in mineral veins.  No other mission to Mars has found boron.  However, boron was found in the Martian meteorite MIZ 09030 in 2013.   For boron to be present in the veins there must have been a temperature between 0-60 degrees Celsius and a neutral-to-alkaline pH.  The temperature, pH, and dissolved minerals of the groundwater support a habitable environment.  Moreover, boron has been suggested to be necessary for life to form. Its presence stabilizes the sugar ribose which is an ingredient in RNA.     Initial measurements reveal that the Gale Crater veins have between 10–100 ppm Boron. One possible explanation forborates in veins is that Gale Lake evaporated, depositing evaporates, including borates. Later, Gale Crater was partially buried, and then it turned to rock.  Cracks developed in the rock and water flowed through the deposits, partially dissolving them. This mineral-rich solution  moved through the fractures, and produced veins made up of  borates and sulfates as veins.

text: Researchers in December 2016 announced the discovery of the element

text: boron

text: by

text: Curiosity

text: in mineral veins.  No other mission to Mars has found boron.  However, boron was found in the Martian meteorite MIZ 09030 in 2013.   For boron to be present in the veins there must have been a temperature between 0-60 degrees Celsius and a neutral-to-alkaline

text: pH

text: .  The temperature, pH, and dissolved minerals of the groundwater support a habitable environment.  Moreover, boron has been suggested to be necessary for life to form. Its presence stabilizes the sugar ribose which is an ingredient in

text: RNA

text: .     Initial measurements reveal that the

text: Gale Crater

text: veins have between 10–100 ppm Boron. One possible explanation for

text: borate

text: s in veins is that Gale Lake evaporated, depositing

text: evaporates

text: , including borates. Later, Gale Crater was partially buried, and then it turned to rock.  Cracks developed in the rock and water flowed through the deposits, partially dissolving them. This mineral-rich solution  moved through the fractures, and produced veins made up of  borates and sulfates as veins.

text: According to the government of Indian state of Haryana, research and satellite imagery of the region has confirmed to have found the lost river when water was detected during digging of the dry river bed at Yamunanagar. The government constituted Saraswati Heritage Development Board (SHDB) had conducted a trial run on July 30, 2016 filling the river bed with 100 cusecs of water which was pumped into a dug-up channel from tubewells at Uncha Chandna village in Yamunanagar. The water is expected to fill the channel uptil Kurukshetra, a distnce of 40 kilometres. Once confirmed that there is no obstructions in the flow of water, the government proposes to flow in another 100 cusecs after a fortnight. There also are plans to build three dams on the river route to keep it flowing perennially.

text: According to the government of Indian state of

text: Haryana

text: , research and satellite imagery of the region has confirmed to have found the lost river when water was detected during digging of the dry river bed at

text: Yamunanagar

text: . The government constituted

text: Saraswati

text: Heritage Development Board (SHDB) had conducted a trial run on July 30, 2016 filling the river bed with 100 cusecs of water which was pumped into a dug-up channel from tubewells at Uncha Chandna village in

text: Yamunanagar

text: . The water is expected to fill the channel uptil

text: Kurukshetra

text: , a distnce of 40 kilometres. Once confirmed that there is no obstructions in the flow of water, the government proposes to flow in another 100 cusecs after a fortnight. There also are plans to build three dams on the river route to keep it flowing perennially.

text: Water flows from areas where the water table is higher to areas where it is lower. This flow can be either surface runoff in rivers and streams, or subsurface runoff infiltrating rocks and soil. The amount of runoff reaching surface and groundwater can vary significantly, depending on rainfall, soil moisture, permeability, groundwater storage, evaporation, upstream use, and whether or not the ground is frozen. The movement of subsurface water is determined largely by the water gradient, type of substrate, and any barriers to flow.

text: Water flows from areas where the

text: water table

text: is higher to areas where it is lower. This flow can be either

text: surface runoff

text: in rivers and streams, or subsurface runoff infiltrating rocks and soil. The amount of runoff reaching surface and groundwater can vary significantly, depending on rainfall, soil moisture,

text: permeability

text: , groundwater storage, evaporation, upstream use, and whether or not the ground is frozen. The movement of subsurface water is determined largely by the water gradient, type of substrate, and any barriers to flow.

text: The geological record is very discontinuous, and deposition is episodic at all scales. At the largest scale, a sedimentological high-stand period may mean that no deposition may occur for tens of thousands of years and, in fact, erosion of the deposit may occur. Such a hiatus is called an unconformity. Conversely, a catastrophic event such as a mudslide may overrepresent a time period. At a shorter scale, scouring processes such as the formation of ripples and dunes and the passing of turbidity currents may cause layers to be removed. Thus the fossil record is biased towards periods of greatest sedimentation; periods of time that have less sedimentation are consequently less well represented in the fossil record.

text: The geological record is very discontinuous, and deposition is episodic at all scales. At the largest scale, a sedimentological high-stand period may mean that no deposition may occur for tens of thousands of years and, in fact, erosion of the deposit may occur. Such a hiatus is called an unconformity. Conversely, a catastrophic event such as a mudslide may overrepresent a time period. At a shorter scale, scouring processes such as the formation of ripples and dunes and the passing of

text: turbidity current

text: s may cause layers to be removed. Thus the fossil record is biased towards periods of greatest sedimentation; periods of time that have less sedimentation are consequently less well represented in the fossil record.

text: Erosion of soil is caused by water, wind, ice, and movement in response to gravity. More than one kind of erosion can occur simultaneously. Erosion is distinguished from weathering, since erosion also transports eroded soil away from its place of origin (soil in transit may be described as sediment). Erosion is an intrinsic natural process, but in many places it is greatly increased by human activity, especially poor land use practices. These include agricultural activities which leave the soil bare during times of heavy rain or strong winds, overgrazing, deforestation, and improper construction activity. Improved management can limit erosion. Soil conservation techniques which are employed include changes of land use (such as replacing erosion-prone crops with grass or other soil-binding plants), changes to the timing or type of agricultural operations, terrace building, use of erosion-suppressing cover materials (including cover crops and other plants), limiting disturbance during construction, and avoiding construction during erosion-prone periods.

text: Erosion

text: of soil is caused by

text: water

text: wind

text: ice

text: , and

text: movement in response to gravity

text: . More than one kind of erosion can occur simultaneously. Erosion is distinguished from

text: weathering

text: , since erosion also transports eroded soil away from its place of origin (soil in transit may be described as

text: sediment

text: ). Erosion is an intrinsic natural process, but in many places it is greatly increased by human activity, especially poor

text: land use

text: practices. These include

text: agricultural

text: activities which leave the soil bare during times of heavy rain or strong winds,

text: overgrazing

text: deforestation

text: , and improper

text: construction

text: activity. Improved management can limit erosion.

text: Soil conservation techniques

text: which are employed include changes of land use (such as replacing erosion-prone

text: crop

text: s with

text: grass

text: or other soil-binding plants), changes to the timing or type of agricultural operations,

text: terrace

text: building, use of erosion-suppressing cover materials (including

text: cover crops

text: and

text: other plants

text: ), limiting disturbance during construction, and avoiding construction during erosion-prone periods.

text: The Wisconsin glacier that entered into New Jersey around 21,000 BCE and then melted around 13,000 BCE did not reach Hunterdon County. However, there are glacial outwash deposits from streams and rivers that flowed from the glacier southward depositing rock and sediment.

text: The Wisconsin glacier that entered into New Jersey around 21,000

text: BCE

text: and then melted around 13,000 BCE did not reach Hunterdon County. However, there are glacial outwash deposits from streams and rivers that flowed from the glacier southward depositing rock and sediment.

text: Log jams alter flow hydraulics by: diverting flow towards the bed or banks, increasing flow resistance and creating upstream pools, diverting flow onto the floodplain and damming the channel causing water to spill over the structure. These altered channel hydraulics change local patterns of erosion and deposition, which can create greater variety in local geomorphology and thus create provision and variety of habitat for in stream biota. The formation of a logjam against one bank typically concentrates flow in the wood free portion of the channel, increasing velocity through this section and promoting scour of the river bed, the formation of channel spanning logjams can lead to the formation of an upstream pool, water spilling over the structure generating a "plunge pool" immediately downstream.

text: Log jams alter

text: flow

text: hydraulics by: diverting flow towards the bed or banks, increasing flow resistance and creating upstream pools, diverting flow onto the floodplain and damming the channel causing water to spill over the structure. These altered channel hydraulics change local patterns of erosion and

text: deposition

text: , which can create greater variety in local geomorphology and thus create provision and variety of habitat for in stream biota. The formation of a logjam against one bank typically concentrates flow in the wood free portion of the channel, increasing velocity through this section and promoting scour of the river bed, the formation of channel spanning logjams can lead to the formation of an upstream pool, water spilling over the structure generating a "plunge pool" immediately downstream.

text: Like other arms of Prince William Sound, Orca Inlet is a fjord. There are large areas on its coast with large rounded rocks as well as many cirques and hanging valleys. Glacial erosion created steep walls on the sides of the fjord. In one area the elevation rises to  within  of the coastline. The southern and central areas are filled with sediment making the area very shallow. These deposits resulted from the receded glacier that once filled the fjord as well as current inflow through the seaward end of the inlet from the Copper River and other smaller glacial streams. These deposits drift westward along the coast until they reach the entrance of Orca Inlet. Orca Inlet can serve as an entrance to Prince William Sound from the Gulf of Alaska but the shallow water limits the size of vessels that can use the route. In 1914, the southern rds of the inlet was generally  deep or less with a few, discontinuous channels, while the north part was  deep.

text: Like other arms of Prince William Sound, Orca Inlet is a

text: fjord

text: . There are large areas on its coast with large rounded rocks as well as many

text: cirques

text: and

text: hanging valleys

text: . Glacial erosion created steep walls on the sides of the fjord. In one area the elevation rises to  within  of the coastline. The southern and central areas are filled with sediment making the area very shallow. These deposits resulted from the receded glacier that once filled the fjord as well as current inflow through the seaward end of the inlet from the

text: Copper River

text: and other smaller glacial streams. These deposits drift westward along the coast until they reach the entrance of Orca Inlet. Orca Inlet can serve as an entrance to Prince William Sound from the Gulf of Alaska but the shallow water limits the size of vessels that can use the route. In 1914, the southern rds of the inlet was generally  deep or less with a few, discontinuous channels, while the north part was  deep.

text: The Black Tiger Spring () is a culturally significant artesian karst spring located in the city of Jinan, Shandong Province, China. The spring is ranked as the second most significant among the 72 named springs in Jinan (after the Baotu Spring). The water of spring stems from moderately-deep circulation<ref name=Fangetal1988>Fang, P., Cao, Y., Tang, K., Li, X., Wang, S. (1988) Age Dating of the Groundwater in the Spring Area of Jinan City in: Karst Hydrogeology and Karst Environment Protection. Volume 2. Proceedings of the 21st Congress of the International Association of Hydrogeologists, Guilin, China October 10-15, 1988. IAHS Publication No. 176, (1988). p 597-605</ref> and emerges from a water-filled limestone cave in a steep cliff. From the mouth of the cave, the water is funneled to flow out of the mouths of three ornamental stone-carved tiger heads into a square-shaped spring pool. From there it runs into the old city moat, next to which the spring is located. According to the tradition, there was a black rock lying in front of the cave in ancient time. The name of the spring is said to be derived from the shape and color of the rock, which resembled a black tiger, and the sound of the water gushing past the rock being reminiscent of the roar of a tiger. The ancient layout of the spring is described in a poem by the Ming Dynasty poet, Yan Bizeng.

text: The Black Tiger Spring () is a culturally significant

text: artesian

text: karst spring

text: located in the city of

text: Jinan

text: Shandong

text: Province

text: China

text: . The spring is ranked as the second most significant among the 72 named springs in Jinan (after the

text: Baotu Spring

text: ). The water of spring stems from moderately-deep circulation<ref name=Fangetal1988>Fang, P., Cao, Y., Tang, K., Li, X., Wang, S. (1988) Age Dating of the Groundwater in the Spring Area of Jinan City in: Karst Hydrogeology and Karst Environment Protection. Volume 2. Proceedings of the 21st Congress of the International Association of Hydrogeologists, Guilin, China October 10-15, 1988. IAHS Publication No. 176, (1988). p 597-605</ref> and emerges from a water-filled limestone cave in a steep cliff. From the mouth of the cave, the water is funneled to flow out of the mouths of three ornamental stone-carved tiger heads into a square-shaped spring pool. From there it runs into the old city moat, next to which the spring is located. According to the tradition, there was a black rock lying in front of the cave in ancient time. The name of the spring is said to be derived from the shape and color of the rock, which resembled a black tiger, and the sound of the water gushing past the rock being reminiscent of the roar of a tiger. The ancient layout of the spring is described in a poem by the

text: Ming Dynasty

text: poet, Yan Bizeng.

text: Regulation causes flooding to be decreased during the winter and spring months, and water more consistently flows during the summer and autumn months. Since the river red gum disperses its seed during spring, regulating the water may affect the species' ability to disperse using water as a dispersing agent, especially in floodplain red gum forests. Natural water run-off can also be affected, leaving some trees permanently flooded due to the build-up of water behind dams, or the permanent water flow. Neither can seeds germinate in constantly flooded areas.

text: The interception of precipitation from the atmosphere by the canopy is modeled using the Rutter Interception Model. The land surface evaporation and vegetation transpiration are computed separately using the Two Source Model of Shuttleworth and Gurney, which is based on the energy balance above canopy, within canopy and at soil surface. This model solves the non-linear equations based on the energy balance for the canopy, surface, and air temperatures at canopy height, evaporation from soil surface and transpiration from vegetation. A soil profile of three homogeneous layers (active, transmission and saturated layers) is used to model the soil moisture on the basis of water balance between layers. The active layer is 15–30 cm thick and it simulates the rapid changes of soil moisture content under high frequency atmospheric forcing. The transmission zone lies between the base of the active layer and the top of the capillary fringe and so it more characterizes the seasonal (instead of transient) changes of soil moisture. In modeling the unsaturated flow component of soil water, the water transport is assumed vertical and non-interactive between sub-basins. The lower boundary of the unsaturated zone is the top of capillary fringe controlled by the local average ground water table derived from the catchment average water table and topographic soil index which include the spatial variability of the topographic and soil parameters. Starting with an observed value from the surrounding wells of the modeled basin, the temporal changes in the average ground water depth is based on the water balance analysis for the whole catchment, and the rate of change of the average ground water table is assumed to be the rate of change of local water table.

text: The interception of

text: precipitation

text: from the

text: atmosphere

text: by the canopy is modeled using the

text: Rutter Interception Model

text: . The

text: land surface

text: evaporation

text: and

text: vegetation

text: transpiration

text: are computed separately using the

text: Two Source Model

text: of Shuttleworth and Gurney, which is based on the

text: energy balance

text: above canopy, within canopy and at soil surface. This model solves the

text: non-linear equation

text: s based on the energy balance for the canopy, surface, and air temperatures at canopy height, evaporation from soil surface and transpiration from vegetation. A soil profile of three homogeneous layers (active, transmission and saturated layers) is used to model the soil moisture on the basis of water balance between layers. The active layer is 15–30 cm thick and it simulates the rapid changes of soil moisture content under high frequency atmospheric forcing. The transmission zone lies between the base of the active layer and the top of the

text: capillary fringe

text: and so it more characterizes the seasonal (instead of transient) changes of soil moisture. In modeling the unsaturated flow component of soil water, the water transport is assumed vertical and non-interactive between sub-basins. The lower boundary of the unsaturated zone is the top of capillary fringe controlled by the local average ground water table derived from the catchment average

text: water table

text: and topographic soil index which include the spatial variability of the topographic and soil parameters. Starting with an observed value from the surrounding wells of the modeled basin, the temporal changes in the average ground water depth is based on the water balance analysis for the whole catchment, and the rate of change of the average ground water table is assumed to be the rate of change of local water table.

text: The sediment-transport capacity and sediment load in subglacial stream glaciers in which the water is not supercooled and for a glacier far into the supercooling regime vary significantly. When a moraine or moraine shoal (bedrock) has developed, the overdeepening terminates in a growing sediment-floored feature. When there is a significant increase in the elevation on the adverse slope, ice grows from supercooling of streams flowing up the overly steep face of the moraine shoal causes transport capacity to drop below loaddelivered, producing deposition to fill the adverse face of the overdeepening back towards the supercooling threshold. When the flow is able to remove all the sediment delivered but not able to erode bedrock asrapidly as the upstream glacier erodes bedrock in the overdeepened area, then the ice forms onbedrock, and subglacial erosion lowers the glacier bed in the overdeepened region while leaving a bedrock sill.

text: The sediment-transport capacity and sediment load in subglacial stream glaciers in which the water is not supercooled and for a glacier far into the supercooling regime vary significantly. When a

text: moraine

text: or moraine shoal (bedrock) has developed, the overdeepening terminates in a growing sediment-floored feature. When there is a significant increase in the elevation on the adverse slope, ice grows from supercooling of streams flowing up the overly steep face of the moraine shoal causes transport capacity to drop below loaddelivered, producing deposition to fill the adverse face of the overdeepening back towards the supercooling threshold. When the flow is able to remove all the sediment delivered but not able to erode bedrock asrapidly as the upstream glacier erodes bedrock in the overdeepened area, then the ice forms onbedrock, and subglacial erosion lowers the glacier bed in the overdeepened region while leaving a bedrock sill.

text: The environmental impact of mining includes erosion, formation of sinkholes, loss of biodiversity, and contamination of soil, groundwater and surface water by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to increase the available room for the storage of the created debris and soil. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned to close to its original state. Some mining methods may have significant environmental and public health effects.

text: erosion

text: , formation of

text: sinkhole

text: s, loss of

text: biodiversity

text: , and contamination of soil,

text: groundwater

text: and

text: surface water

text: by chemicals from mining processes. In some cases, additional forest logging is done in the vicinity of mines to increase the available room for the storage of the created debris and soil. Besides creating environmental damage, the contamination resulting from leakage of chemicals also affect the health of the local population. Mining companies in some countries are required to follow environmental and rehabilitation codes, ensuring the area mined is returned to close to its original state. Some mining methods may have significant environmental and public health effects.

text: A sinkhole is a localized depression in the surface topography, usually caused by the collapse of a subterranean structure such as a cave. Although rare, large sinkholes that develop suddenly in populated areas can lead to the collapse of buildings and other structures.

text: A

text: sinkhole

text: is a localized depression in the surface topography, usually caused by the collapse of a subterranean structure such as a

text: cave

text: . Although rare, large sinkholes that develop suddenly in populated areas can lead to the collapse of buildings and other structures.

text: Reservoirs can be used to balance the flow in highly managed systems, taking in water during high flows and releasing it again during low flows. In order for this to work without pumping requires careful control of water levels using spillways.When a major storm approaches, the dam operators calculate the volume of water that the storm will add to the reservoir. If forecast storm water will overfill the reservoir, water is slowly let out of the reservoir prior to, and during, the storm. If done with sufficient lead time, the major storm will not fill the reservoir and areas downstream will not experience damaging flows.Accurate weather forecasts are essential so that dam operators can correctly plan drawdowns prior to a high rainfall event. Dam operators blamed a faulty weather forecast on the 2010–2011 Queensland floods.Examples of highly managed reservoirs are Burrendong Dam in Australia and Bala Lake (Llyn Tegid) in North Wales. Bala Lake is a natural lake whose level was raised by a low dam and into which the River Dee flows or discharges depending upon flow conditions, as part of the River Dee regulation system. This mode of operation is a form of hydraulic capacitance in the river system.

text: Reservoirs can be used to balance the flow in highly managed systems, taking in water during high flows and releasing it again during low flows. In order for this to work without pumping requires careful control of water levels using spillways.When a major storm approaches, the dam operators calculate the volume of water that the storm will add to the reservoir. If forecast storm water will overfill the reservoir, water is slowly let out of the reservoir prior to, and during, the storm. If done with sufficient lead time, the major storm will not fill the reservoir and areas downstream will not experience damaging flows.Accurate weather forecasts are essential so that dam operators can correctly plan drawdowns prior to a high rainfall event. Dam operators blamed a faulty weather forecast on the

text: 2010–2011 Queensland floods

text: .Examples of highly managed reservoirs are

text: Burrendong Dam

text: in Australia and

text: Bala Lake

text: (Llyn Tegid) in

text: North Wales

text: . Bala Lake is a natural lake whose level was raised by a low dam and into which the

text: River Dee

text: flows or discharges depending upon flow conditions, as part of the

text: River Dee regulation system

text: . This mode of operation is a form of hydraulic

text: capacitance

text: in the river system.

text: Cenotes are surface connections to subterranean water bodies. While the best-known cenotes are large open water pools measuring tens of meters in diameter, such as those at Chichén Itzá in Mexico, the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water. The term cenote has also been used to describe similar karst features in other countries such as Cuba and Australia, in addition to the more generic term of sinkholes.

text: Cenotes are surface connections to subterranean water bodies. While the best-known cenotes are large open water pools measuring tens of meters in diameter, such as those at

text: Chichén Itzá

text: in

text: Mexico

text: , the greatest number of cenotes are smaller sheltered sites and do not necessarily have any surface exposed water. The term cenote has also been used to describe similar

text: karst

text: features in other countries such as

text: Cuba

text: and

text: Australia

text: , in addition to the more generic term of

text: sinkhole

text: s.

text: Improved health may be indicated by expanded habitat for diverse species (e.g. fish, aquatic insects, other wildlife) and reduced stream bank erosion. Enhancements may also include improved water quality (i.e. reduction of pollutant levels and increase of dissolved oxygen levels) and achieving a self-sustaining, functional flow regime in the stream system that does not require periodic human intervention, such as dredging or construction of flood control structures. Stream restoration projects can also yield increased property values in adjacent areas.

text: Improved health may be indicated by expanded

text: habitat

text: for diverse species (e.g. fish, aquatic insects, other wildlife) and reduced stream bank

text: erosion

text: . Enhancements may also include improved

text: water quality

text: (i.e. reduction of

text: pollutant

text: levels and increase of

text: dissolved oxygen

text: levels) and achieving a self-sustaining, functional

text: flow regime

text: in the stream system that does not require periodic human intervention, such as

text: dredging

text: or construction of

text: flood

text: control structures. Stream restoration projects can also yield increased property values in adjacent areas.

text: There are a total of seven different water masses in the Brazil–Malvinas Confluence Zone.  These various water masses help contribute even more to this very complex dynamical confluence zone.  Starting at the surface (<800m) where the Brazil Current is carrying Subtropical Surface Water and the Malvinas Current is carrying Subantarctic Surface Water, after these two surfaces collide they mix some, but in general they develop strong thermohaline fronts due to the strong difference in temperature and salinity.  Below the surface from about 800 meters to 1500 meters there is Antarctic Intermediate Water that is flowing equatorward.  At the very bottom of the Brazil–Malvinas Confluence Zone there is equatorward flowing Weddell Sea Deep Water.  Between the Antarctic Intermediate Water and the Weddel Sea Deep Water there are three different water masses flowing poleward: North Atlantic Deep Water, Lower Circumpolar Deep Water, and Upper Circumpolar Deep Water.

text: There are a total of seven different

text: water mass

text: es in the Brazil–Malvinas Confluence Zone.  These various water masses help contribute even more to this very complex dynamical confluence zone.  Starting at the surface (<800m) where the Brazil Current is carrying Subtropical Surface Water and the Malvinas Current is carrying Subantarctic Surface Water, after these two surfaces collide they mix some, but in general they develop strong thermohaline fronts due to the strong difference in

text: temperature

text: and salinity.  Below the surface from about 800 meters to 1500 meters there is

text: Antarctic Intermediate Water

text: that is flowing equatorward.  At the very bottom of the Brazil–Malvinas Confluence Zone there is equatorward flowing

text: Weddell Sea

text: Deep Water.  Between the Antarctic Intermediate Water and the Weddel Sea Deep Water there are three different water masses flowing poleward:

text: North Atlantic Deep Water

text: , Lower Circumpolar Deep Water, and Upper Circumpolar Deep Water.

text: Surface detritus facilitates the capture and infiltration of rainwater into lower soil layers. Soil litter protects soil aggregates from raindrop impact, preventing the release of clay and silt particles from plugging soil pores. Releasing clay and silt particles reduces the capacity for soil to absorb water and increases cross surface flow, accelerating soil erosion. In addition soil litter reduces wind erosion by preventing soil from losing moisture and providing cover preventing soil transportation.

text: Surface detritus facilitates the capture and infiltration of rainwater into lower soil layers. Soil litter protects soil aggregates from raindrop impact, preventing the release of clay and silt particles from plugging soil pores. Releasing clay and silt particles reduces the capacity for soil to absorb water and increases cross surface flow, accelerating soil

text: erosion

text: . In addition soil litter reduces

text: wind erosion

text: by preventing soil from losing moisture and providing cover preventing soil transportation.

text: The word 'malpaís' in Spanish translates to "badland," and this describes the area as being extremely rough and difficult to traverse and unusable for crops. Although a malpaís is often another word for the badlands that form by erosion of sedimentary rocks in the same environment, a malpaís is often associated with such types of lava plain terrain as found in a volcanic field. The geology of malpaís terrain is bare to thin layers of soil over lava with sparse vegetation. The lava fields usually consist of lava tube cave systems, sinkholes, pyroclastic deposits from cinder cone volcanoes, and ʻaʻā  and pāhoehoe lava flows. The lava tubes can vary from intact caves to partial or completely collapsed passages. The collapsed tubes, sinkholes, and jagged ʻaʻā surfaces are what make malpaís terrain so difficult to navigate and cultivate, thereby earning their name.

text: The word 'malpaís' in Spanish translates to "

text: badland

text: ," and this describes the area as being extremely rough and difficult to traverse and unusable for crops. Although a malpaís is often another word for the

text: badlands

text: that form by erosion of sedimentary rocks in the same environment, a malpaís is often associated with such types of

text: lava plain

text: terrain as found in a

text: volcanic field

text: . The geology of malpaís terrain is bare to thin layers of soil over lava with sparse vegetation. The lava fields usually consist of

text: lava tube

text: cave systems,

text: sinkhole

text: s,

text: pyroclastic

text: deposits from

text: cinder cone

text: volcanoes, and

text: ʻaʻā

text: and

text: pāhoehoe

text: lava flows. The lava tubes can vary from intact caves to partial or completely collapsed passages. The collapsed tubes, sinkholes, and jagged ʻaʻā surfaces are what make malpaís terrain so difficult to navigate and cultivate, thereby earning their name.

text: The site contains the entrance to St Cuthbert's Swallet cave, and overlies a large part of the cave complex reached through St Cuthbert's Swallet. This cave is an integral part of the Priddy Caves system which contains over 10 miles of surveyed cave passages divided between two major systems and four minor systems, all interconnected. All the caves are sink hole systems, fed by sink holes at the ground surface, and 3 of them exceed 100 metres in depth; in all the caves the detailed disposition and form of the passages can be seen clearly to have followed marked lines of natural weakness in the rocks. St Cuthbert's Swallet was formed by the erosive action of water flowing beneath the water-table at considerable depth (so called "phreatic development"). St Cuthbert's Swallet is a classic example of a deep phreatic cave system, containing inclined bedding plane mazes at many levels, fault-guided rifts and some significant chambers. Nine successive phases of sediment deposition, stalagmite deposition and stream erosion have been recognised in St Cuthbert's Swallet, providing an exceptional record of environmental change through thewarm and cold phases of the Ice Age.

text: The site contains the entrance to

text: St Cuthbert's Swallet

text: cave, and overlies a large part of the cave complex reached through St Cuthbert's Swallet. This cave is an integral part of the

text: Priddy Caves

text: system which contains over 10 miles of surveyed cave passages divided between two major systems and four minor systems, all interconnected. All the caves are sink hole systems, fed by sink holes at the ground surface, and 3 of them exceed 100 metres in depth; in all the caves the detailed disposition and form of the passages can be seen clearly to have followed marked lines of natural weakness in the rocks. St Cuthbert's Swallet was formed by the erosive action of water flowing beneath the water-table at considerable depth (so called "phreatic development"). St Cuthbert's Swallet is a classic example of a deep

text: phreatic

text: cave system, containing inclined bedding plane mazes at many levels, fault-guided rifts and some significant chambers. Nine successive phases of

text: sediment

text: deposition,

text: stalagmite

text: deposition and stream erosion have been recognised in St Cuthbert's Swallet, providing an exceptional record of environmental change through thewarm and cold phases of the

text: Ice Age

text: From 1850 to 1950 open water decreased from 490 km^2 to 290 km^2.  From 1950 to 2005 the amount of open water decreased to 190 km^2.  When the Atchafalaya Basin flow plan was implemented (1950-1974), 30 percent of the total Atchafalaya River flow was designated to be directed off the main channel, 15 percent to the east and 15 percent to the west side.  As a result of the Atchafalaya River channel bed incision, in the early 21st century the flow distribution is 13 percent of the total flow, with a flow distribution of 7 percent to the east side and 6 percent to the west side as reported by the USGS. This decrease in flow across the floodplain, in conjunction with high organic deposition from trees and floating vegetation and high water temperature, has resulted in large areas of low-dissolved oxygen water.  Where once the water was black (1850), the water became brown (1927).  Where the water was formerly brown (1927), it is now black (2009).

text: The Construction of the Kenny Dam in the 1950s on the Nechako River, reversed water flow and sent water westward to generate electricity for use and sale by the Alcan corporation, devastated the area around Cheslatta Lake, flooding the Cheslatta Carrier Nation village and cemetery and forcing the First Nations to be relocated with little time for preparation and no consultation. Prior to the flooding, Cheslatta Lake was at the centre of the CCN traditional hunting and trapping territory. Before 1957 the Cheslatta River was a small stream with an average annual flow of about . Alcan began releasing water flows far above the Cheslatta's natural capacity, resulting in a deep channel being carved out and large-scale erosion filling the Cheslatta and upper Nechako Rivers with sediment. In addition, the area between the Skins Lake spillway and the headwaters of the Cheslatta River was not a river but rather a series of meadows, pastures, and small lakes. Water released from the reservoir scoured the area between Skins Lake and Cheslatta Lake. Soil, gravel, grass, moss, shrubs, and trees were washed away, down into the Cheslatta River and into the Nechako River.

text: The Construction of the

text: Kenny Dam

text: in the 1950s on the Nechako River, reversed water flow and sent water westward to generate electricity for use and sale by the Alcan corporation, devastated the area around Cheslatta Lake, flooding the

text: Cheslatta Carrier Nation

text: village and cemetery and forcing the First Nations to be relocated with little time for preparation and no consultation. Prior to the flooding, Cheslatta Lake was at the centre of the CCN traditional hunting and trapping territory. Before 1957 the Cheslatta River was a small stream with an average annual flow of about . Alcan began releasing water flows far above the Cheslatta's natural capacity, resulting in a deep channel being carved out and large-scale erosion filling the Cheslatta and upper Nechako Rivers with sediment. In addition, the area between the

text: Skins Lake

text: spillway and the headwaters of the Cheslatta River was not a river but rather a series of meadows, pastures, and small lakes. Water released from the reservoir scoured the area between Skins Lake and Cheslatta Lake. Soil, gravel, grass, moss, shrubs, and trees were washed away, down into the Cheslatta River and into the Nechako River.

text: The above mentioned river plains have rich subterranean reservoirs of water. Other important water deposits include the deposits in Dudince.

text: The above mentioned river plains have rich subterranean reservoirs of water. Other important water deposits include the deposits in

text: Dudince

text: In some states Surface water, lakes, rivers, and springs, are treated differently from ground water underground water that is extracted by drilling wells; however, In other states surface and ground water are managed conjunctively. For example, in New Mexico, surface and ground water have been managed together since the 1950s. This trend comes from a growing scientific understanding of the formerly mysterious behavior of underground water systems. For instance, gradual contamination of some water supplies with salt has been explained with the knowledge that drawing water from a well creates a gradual seepage into the well area, potentially contaminating it and surrounding areas with seawater from a nearby coast. Such knowledge is useful for understanding the effects of human activity on water supplies but can also create new sources of conflict.

text: In some states

text: Surface water

text: , lakes, rivers, and springs, are treated differently from

text: ground water

text: underground water that is extracted by drilling

text: wells

text: ; however, In other states surface and ground water are managed conjunctively. For example, in New Mexico, surface and ground water have been managed together since the 1950s. This trend comes from a growing scientific understanding of the formerly mysterious behavior of underground water systems. For instance, gradual

text: contamination

text: of some water supplies with

text: salt

text: has been explained with the knowledge that drawing water from a well creates a gradual seepage into the well area, potentially contaminating it and surrounding areas with

text: seawater

text: from a nearby coast. Such knowledge is useful for understanding the effects of human activity on water supplies but can also create new sources of conflict.

text: The common logperch is currently not a threatened or endangered fish species.  Consequently, no apparent steps are being taken to manage the species.  While logperches are not currently a threatened species, several human-created changes are negatively influencing the common logperch.  One of these human-induced changes is the construction of dams.  Dams are detrimental to logperch for numerous reasons.  One reason is that dams typically create less oxygen their tailwaters.  This is because the water pushed into the tailwaters comes from oxygen-poor parts of the reservoir.  The lack of oxygen this creates can cause undue stress on common logperch larvae, because their simple lungs are evolved for high oxygen availability.  Another reason dams are detrimental to logperch species is that the constant change of water flow caused by hydroelectric generation creates a large amount of silt deposition on the river floor.  Logperch are benthic hunters evolved to hunt and spawn in rocky substrate, and the silt deposited by the hydroelectric generators covers and masks this substrate.  Human-initiated erosion also affects logperch in this way.  As a result, the common logperch obtains food less efficiently, and cannot spawn as efficiently.    The overuse of pesticides and fertilizers near watersheds can also have a deleterious effect on the common logperch by killing or altering aquatic insect life, and by increasing nitrite levels.  But perhaps the most deleterious impact on the common logperch comes from the introduction of the round goby, Neogobius melanostomus,which outcompetes it.  Through careful farm and land management the introduction of chemicals to watersheds could be greatly reduced.  Erosion can largely be avoided by halting deforestation, and the induction of invasive species may be reduced simply by better informing the public of the detrimental effects caused by releasing non-native species into the wild.

text: In the Yucatán Peninsula, any surface opening where groundwater can be reached is called cenote, which is a Spanish form of the Maya word d’zonot. The cave systems formed as normal caves underwater, but upper sections drained becoming air filled during past low sea levels. During this vadose, or air filled state, abundant speleothem deposits formed. The caves and the vadose speleothem were reflooded and became hydraulically reactivated as rising sea levels also raised the water table. These caves are therefore polygenetic, having experienced more than one cycle of formation below the water table. Polygenetic coastal cave systems with underwater speleothem are globally common, with notable examples being on the Balearic Islands (Mallorca, Menorca) of Spain, the islands of the Bahamas, Bermuda, Cuba, and many more.

text: In the Yucatán Peninsula, any surface opening where groundwater can be reached is called

text: cenote

text: , which is a Spanish form of the Maya word d’zonot. The cave systems formed as normal caves underwater, but upper sections drained becoming air filled during past low sea levels. During this vadose, or air filled state, abundant speleothem deposits formed. The caves and the vadose speleothem were reflooded and became hydraulically reactivated as rising sea levels also raised the water table. These caves are therefore polygenetic, having experienced more than one cycle of formation below the water table. Polygenetic coastal cave systems with underwater speleothem are globally common, with notable examples being on the Balearic Islands (

text: Mallorca

text: Menorca

text: ) of Spain, the islands of the Bahamas, Bermuda, Cuba, and many more.

text: High Force was formed where the River Tees crosses the Whin Sill – a hard layer of igneous rock (also seen at Hadrian's Wall and other locations). The waterfall itself consists of three different types of rock. The upper band is made up of whinstone, or dolerite, a hard igneous rock which the waterfall takes a lot of time to erode. The lower section is made up of Carboniferous Limestone, a softer rock which is more easily worn away by the waterfall. Between these two layers is a thinner layer of Carboniferous sandstone, which was baked hard when the Whin Sill was molten 295 million years ago. The wearing away of rock means that the waterfall is slowly moving upstream, leaving a narrow, deep gorge in front of it. The length of the gorge is currently about 700 metres. The bedload (rocks that the river is carrying) is mainly composed of large boulders, which are rolled along the river bed. Upstream of the waterfall, the river is narrow; downstream, it widens and meanders.

text: High Force was formed where the River Tees crosses the

text: Whin Sill

text: – a hard layer of

text: igneous rock

text: (also seen at

text: Hadrian's Wall

text: and other locations). The

text: waterfall

text: itself consists of three different types of rock. The upper band is made up of

text: whinstone

text: , or

text: dolerite

text: , a hard igneous rock which the waterfall takes a lot of time to erode. The lower section is made up of

text: Carboniferous Limestone

text: , a softer rock which is more easily worn away by the waterfall. Between these two layers is a thinner layer of Carboniferous sandstone, which was baked hard when the Whin Sill was molten 295 million years ago. The wearing away of rock means that the waterfall is slowly moving upstream, leaving a narrow, deep

text: gorge

text: in front of it. The length of the gorge is currently about 700 metres. The

text: bedload

text: (rocks that the river is carrying) is mainly composed of large boulders, which are rolled along the river bed. Upstream of the waterfall, the river is narrow; downstream, it widens and meanders.

text: The surface of Venus contains over 200 channel systems, named valles, that resemble terrestrial rivers. These channels vary in length and width and are commonly found in planar regions of the planet. Channel length and width ranges from the minimum resolution of Magellan imaging to over 6800 km long (Baltis Vallis) and up to 30 km wide. There global distribution is not uniform, and tend to concentrate around the equatorial region, near volcanic structures. Venusian valles also show characteristics of flows, such as levees on the margins and downstream narrowing and shallowing. Channels also do not contain tributaries, despite their large scale. However, because of the high surface temperature of Venus, liquid water is unstable, making their comparison with terrestrial rivers difficult.  These features are similar to lava flows on other terrestrial planets, which has led to the conclusion that these valleys likely formed from volcanic flows. This is also suggested by the evidence of cooled lava flows filling the valles. Channels  likely formed in very short timescales (1–100 years), indicating very fast movement and erosion of lavas. Venusian channels are classified by morphology and include three types: simple, complex, and compound.

text: The surface of Venus contains over 200 channel systems, named valles, that resemble terrestrial rivers. These channels vary in length and width and are commonly found in planar regions of the planet. Channel length and width ranges from the minimum resolution of Magellan imaging to over 6800 km long (

text: Baltis Vallis

text: ) and up to 30 km wide. There global distribution is not uniform, and tend to concentrate around the equatorial region, near volcanic structures. Venusian valles also show characteristics of flows, such as levees on the margins and downstream narrowing and shallowing. Channels also do not contain tributaries, despite their large scale. However, because of the high surface temperature of Venus, liquid water is unstable, making their comparison with terrestrial rivers difficult.  These features are similar to lava flows on other terrestrial planets, which has led to the conclusion that these valleys likely formed from volcanic flows. This is also suggested by the evidence of cooled lava flows filling the valles. Channels  likely formed in very short timescales (1–100 years), indicating very fast movement and erosion of lavas. Venusian channels are classified by

text: morphology

text: and include three types: simple, complex, and compound.

text: A team from the U.S. Army Corps of Engineers dammed the American Falls in June 1969 to clear rock from the base of the falls. Rockslides caused a significant buildup of rock at the bottom of the American side of the falls, and the engineers were to clean up the rock and repair some faults to prevent eventual erosion of the American side of the waterfall. A temporary dam was built to divert the flow of water to the Canadian side; the dam measured  across and was made of nearly 30,000 tons of rock. The engineers cleared the rock debris and tested for safety, finishing the project in November of that year. Water flow was restored on November 25, 1969.

text: A team from the

text: U.S. Army Corps of Engineers

text: dammed the American Falls in June 1969 to clear rock from the base of the falls. Rockslides caused a significant buildup of rock at the bottom of the American side of the falls, and the engineers were to clean up the rock and repair some faults to prevent eventual erosion of the American side of the waterfall. A temporary dam was built to divert the flow of water to the Canadian side; the dam measured  across and was made of nearly 30,000 tons of rock. The engineers cleared the rock debris and tested for safety, finishing the project in November of that year. Water flow was restored on November 25, 1969.

text: In December 2010, an independent panel of engineers published a study that determined the cause of the failure "was internal erosion in the embankment coupled with overtopping flow". The study believes that a malfunctioning spillway gate and increase reservoir size may have exacerbated an existing problem with the dam's design. The embankment was constructed in such a way that its fill did not settle correctly. Within the embankment section, a concrete wall, designed to reinforce it, was not constructed up to the height of the dam's crest. That sped up internal erosion and allowed the water to over-top the dam.

text: Even well managed loess farmland can experience dramatic erosion of well over 2.5 kg /m per year. In China the loess deposits which give the Yellow River its color have been farmed and have produced phenomenal yields for over one thousand years. Winds pick up loess particles, contributing to the Asian Dust pollution problem. The largest deposit of loess in the United States, the Loess Hills along the border of Iowa and Nebraska, has survived intensive farming and poor farming practices. For almost 150 years this loess deposit was farmed with mouldboard ploughs and fall tilled, both intensely erosive. At times it suffered erosion rates of over 10 kilograms per square meter per year. Today this loess deposit is worked as low till or no till in all areas and is aggressively terraced.

text: Even well managed loess

text: farmland

text: can experience dramatic

text: erosion

text: of well over 2.5 kg /m per year. In China the

text: loess deposits

text: which give the

text: Yellow River

text: its color have been farmed and have produced phenomenal yields for over one thousand years. Winds pick up loess particles, contributing to the

text: Asian Dust

text: pollution problem. The largest deposit of loess in the United States, the

text: Loess Hills

text: along the border of

text: Iowa

text: and Nebraska, has survived intensive farming and

text: poor farming practices

text: . For almost 150 years this loess deposit was farmed with

text: mouldboard plough

text: s and fall tilled, both intensely erosive. At times it suffered erosion rates of over 10 kilograms per square meter per year. Today this loess deposit is worked as low till or

text: no till

text: in all areas and is aggressively

text: terraced

text: Erosion is greatest along the headwall. This is attributed to the seasonal entry of water in those areas via moulins, resulting in varying but periodically high pressures, high flow rates, and large temperature variations.  This variation is thought to contribute to quarrying of blocks from the headwall combined with the erosive powers of rapidly moving debris streams entrained in flowing water.

text: In the Frasch process, three concentric tubes are introduced into the sulfur deposit. Superheated water (165 °C, 2.5-3 MPa) is injected into the deposit via the outermost tube. Sulfur (m.p. 115 °C) melts and flows into the middle tube. Water pressure alone is unable to force the sulfur into the surface due to the molten sulfur's greater density, so hot air is introduced via the innermost tube to froth the sulfur, making it less dense, and pushing it to the surface.

text: Like the Yellow River, the Hai is exceedingly muddy because of the powdery soil through which it flows. The silt carried by the water deposits in the lower reaches, sometimes causing flooding. The waters from the five major tributaries only have one shallow outlet to the sea, which makes such floods stronger. Because China's capital (and second largest city), Beijing, and the third largest city, Tianjin, both lie in the Hai He Basin, Hai He floods cause a significant loss. To alleviate flooding, reservoirs have been built and artificial channels dug to divert excess water directly into the sea. For example, the Chaobai River is diverted to the Chaobai Xin River and no longer joins with the Northern Canal.

text: Like the Yellow River, the Hai is exceedingly muddy because of the powdery soil through which it flows. The silt carried by the water deposits in the lower reaches, sometimes causing flooding. The waters from the five major tributaries only have one shallow outlet to the sea, which makes such floods stronger. Because China's capital (and second largest city), Beijing, and the third largest city, Tianjin, both lie in the Hai He Basin, Hai He floods cause a significant loss. To alleviate flooding, reservoirs have been built and artificial channels dug to divert excess water directly into the sea. For example, the

text: Chaobai River

text: is diverted to the

text: Chaobai Xin River

text: and no longer joins with the Northern Canal.

text: Wallula Gap is a large water gap through basalt anticlines in the Columbia River basin just south of the confluence of the Walla Walla River and the Columbia River. The Wallula Gap, which has existed for many millions of years, was widened by the historic flow of the Salmon-Snake and Columbia Rivers combined with the glacial waters that poured across the Channeled Scablands during the Missoula Floods. The Wallula Gap constrained the flow such that less than 1/5 of the 800 km³ of water per day entering could be discharged. As a result, the floods filled the Pasco Basin and formed, for a short period, Lake Lewis. The large volumes of flood water passing through the gap contributed substantially to the erosion of the gap, as is evidenced by the shear walls and of scab-features such as the "Sisters."

text: Wallula Gap is a large

text: water gap

text: through basalt

text: anticline

text: s in the

text: Columbia River

text: basin just south of the confluence of the

text: Walla Walla River

text: and the Columbia River. The Wallula Gap, which has existed for many millions of years, was widened by the historic flow of the Salmon-Snake and Columbia Rivers combined with the glacial waters that poured across the

text: Channeled Scablands

text: during the Missoula Floods. The Wallula Gap constrained the flow such that less than 1/5 of the 800 km³ of water per day entering could be discharged. As a result, the floods filled the Pasco Basin and formed, for a short period, Lake Lewis. The large volumes of flood water passing through the gap contributed substantially to the erosion of the gap, as is evidenced by the shear walls and of scab-features such as the "Sisters."

text: G. palleucus lives in caves and is dependent on the quality of the water in the streams that flow through them. Threats it faces include pollution, siltation, flooding, increased water flow and the filling of sinkholes and dumping of trash. This salamander is known from about two dozen sites but probably occurs in other cave systems. Its total area of occupancy is less than  and its population in Custard Hollow Cave in Tennessee seems to be decreasing. For these reasons, the International Union for Conservation of Nature has rated its conservation status as "threatened" and advocates protection of the watersheds that drain into the caverns in which it lives.

text: G. palleucus lives in caves and is dependent on the quality of the water in the streams that flow through them. Threats it faces include pollution, siltation, flooding, increased water flow and the filling of sinkholes and dumping of trash. This salamander is known from about two dozen sites but probably occurs in other cave systems. Its total area of occupancy is less than  and its population in Custard Hollow Cave in Tennessee seems to be decreasing. For these reasons, the

text: International Union for Conservation of Nature

text: has rated its conservation status as "

text: threatened

text: " and advocates protection of the

text: watersheds

text: that drain into the caverns in which it lives.

text: The river has a history of flooding, mainly due to the high sides of its banks in its earlier stages, which cause rapid runoff of water following heavy rain. Much of the lower part of the river has been urbanised, therefore trapping flowing water within the engineered river channels. Fast flows of water cause the deposition of sediment collected from the river banks, raising the river height further.

text: The river has a history of flooding, mainly due to the high sides of its banks in its earlier stages, which cause rapid runoff of water following heavy rain. Much of the lower part of the river has been

text: urbanised

text: , therefore trapping flowing water within the engineered river channels. Fast flows of water cause the deposition of sediment collected from the river banks, raising the river height further.

text: The climate of the tract is extreme. In winter it is very cold and summer is very hot. The average rainfall varies from 48 to 69 m.m per annum which is much below the required quantity but in the rainy season the water torrents flow from north to the river Jhelum with a very fast speed and cause damages to the crops, bridges, roads and are responsible for the soil erosion in the District.

text: The cave was host to Texas’ only cavern with a natural interior waterfall. Originally, there were 7 waterfalls in the Cathedral Room of the cavern. Recent droughts in Texas tended to limit and even stop the flow of water supplying this feature. It is now artificially pumped through a series of pipes to imitate what it would have looked like naturally. This very feature: the cascading waterfall is what had earned the cave its name. The cave is much alive and water droplets persistently fall upon the cave formations.

text: The Flood-Marine Excellence Centre has been established by Prof. Ir. Dr. Junaidah Ariffin. Members of the centre includes Assoc. Prof. Dr. Wardah Tahir, Dr Mohd Fozi Ali and from different disciplines such as Assoc. Prof. Dr. Azlinah Mohamed and Assoc. Prof. Zaidah Ibrahim. The aim of establishing this centre is to promote research in the field of hydrology, hydraulics and coastal engineering. The members affiliated to this research centre had secured grants worth a million Malaysian ringgit of which six (6) research are still on-going. The research areas include water resources development, evaluation techniques of channel stability and erosion control, local bed changes of restoration areas, channel distributaries, hydraulic structures such as sills, small dams, weirs and water intakes, flood forecasting, evacuation scenarios, flood hazard reduction and flood protection, the application of numerical methods in water resources and sedimentation, flood analysis, prediction, forecasting and warning, risk and management.  The other activities of the centre are organising workshop, seminar, training and conference in promoting knowledge in the area.  The centre is aggressively pursuing opportunities to work with other institutions, public and private sectors (both local and abroad) on issues related to flood analysis, management and coastal engineering. This centre has published more than 250 publications including 65 in refereed journals.  Currently, there are ten (10) students pursuing their postgraduate degree by research  working under the supervision of this centre.

text: The minimum water speed at which copper pipes suffer impingement attack depends also to some extent on water composition. Aggressive waters that tend to be cupro-solvent are the most likely to give rise to impingement attack. Installations in large buildings where flow rates may be high and water is in continuous circulation are much more susceptible to attack than ordinary domestic installations. A high mineral content or a pH below 7 is likely to increase the possibility of corrosion-erosion occurring while a positive Langelier Index and consequent tendency to deposit a calcium carbonate scale is generally beneficial. The presence or absence of colloidal organic matter is also probably of some importance.

text: The minimum water speed at which copper pipes suffer impingement attack depends also to some extent on water composition. Aggressive waters that tend to be cupro-solvent are the most likely to give rise to impingement attack. Installations in large buildings where flow rates may be high and water is in continuous circulation are much more susceptible to attack than ordinary domestic installations. A high mineral content or a pH below 7 is likely to increase the possibility of corrosion-erosion occurring while a positive

text: Langelier Index

text: and consequent tendency to deposit a calcium carbonate scale is generally beneficial. The presence or absence of colloidal organic matter is also probably of some importance.

text: With the uplift of the Cadell, a large lake was also formed south of the Northern Lake, that was the predecessor of present-day Lake Kanyapella, the remnant of the larger prehistoric lake.   Wind-blown, or Aeolian, movement of surface soils created the Barmah Sandhills on the northeastern edge of this lake.  Over time, water flowed from this lake into the Campaspe River, and the Goulburn River changed its course to follow this path.  Erosive water flows eventually drained the prehistoric Lake Kanyapella along the course of the current Murray River.

text: With the uplift of the Cadell, a large lake was also formed south of the Northern Lake, that was the predecessor of present-day

text: Lake Kanyapella

text: , the remnant of the larger prehistoric lake.   Wind-blown, or

text: Aeolian

text: , movement of surface soils created the Barmah Sandhills on the northeastern edge of this lake.  Over time, water flowed from this lake into the Campaspe River, and the Goulburn River changed its course to follow this path.  Erosive water flows eventually drained the prehistoric Lake Kanyapella along the course of the current Murray River.

text: When turbidity currents interact with other currents, such as contour currents, they can change their direction. This ultimately shifts submarine canyons and sediment deposition locations. One example of this is located in the western part of the Gulf of Cadiz, where the Mediterranean outflow water (MOW) current strongly influences turbidity currents, ultimately causing shifting of valleys and canyons in the direction of the MOW flow. This changes the erosion and depositional zones, ultimately changing the ocean floor topography.

text: When turbidity currents interact with other currents, such as contour currents, they can change their direction. This ultimately shifts submarine canyons and sediment deposition locations. One example of this is located in the western part of the

text: Gulf of Cadiz

text: , where the Mediterranean outflow water (MOW) current strongly influences turbidity currents, ultimately causing shifting of valleys and canyons in the direction of the MOW flow. This changes the erosion and depositional zones, ultimately changing the ocean floor topography.

text: Extensive soil erosion and landslides in its upper catchment have produced a silt yield of about 19 m/ha/year (10 cu yd/acre/yr), one of the highest in the world. Of major tributaries, the Arun brings the greatest amount of coarse silt in proportion to its total sediment load. The river transports sediment down the steep gradients and narrow gorges in the mountains and foothills where the gradient is at least ten metres per km. On the plains beyond Chatra, the gradient falls below one metre per km to as little as 6 cm per km as the river approaches the Ganges. Current slows and the sediment load settles out of the water and is deposited on an immense alluvial fan that has grown to an area of about 15 000 km. This fan extends some 180 km from its apex where it leaves the foothills, across the international border into Bihar state and on to the Ganges. The river has numerous interlacing channels that shift laterally over the fan from time to time. Without channelisation, floods spread out very widely. The record flow of 24 200 m/s is equivalent to water a metre deep and more than 24 km wide, flowing at one metre per second.

text: Extensive soil

text: erosion

text: and

text: landslide

text: s in its upper catchment have produced a silt yield of about 19 m/ha/year (10

text: cu yd

text: /acre/yr), one of the highest in the world. Of major tributaries, the Arun brings the greatest amount of coarse silt in proportion to its total sediment load. The river transports sediment down the steep gradients and narrow gorges in the mountains and foothills where the gradient is at least ten metres per km. On the plains beyond Chatra, the gradient falls below one metre per km to as little as 6 cm per km as the river approaches the Ganges. Current slows and the sediment load settles out of the water and is deposited on an immense

text: alluvial fan

text: that has grown to an area of about 15 000 km. This fan extends some 180 km from its apex where it leaves the foothills, across the international border into Bihar state and on to the

text: Ganges

text: . The river has numerous interlacing channels that shift laterally over the fan from time to time. Without channelisation, floods spread out very widely. The record flow of 24 200 m/s is equivalent to water a metre deep and more than 24 km wide, flowing at one metre per second.

text: In most areas, the spatial variation reflects the irregularities of the flows deep in the Earth; in some areas, deposits of iron ore or magnetite in the Earth's crust may contribute strongly to the declination. Similarly, secular changes to these flows result in slow changes to the field strength and direction at the same point on the Earth.

text: In most areas, the spatial variation reflects the irregularities of the flows deep in the Earth; in some areas, deposits of

text: iron

text: ore

text: or

text: magnetite

text: in the Earth's crust may contribute strongly to the declination. Similarly,

text: secular

text: changes to these flows result in slow changes to the field strength and direction at the same point on the Earth.

text: Because of erosion on the downstream face of the incomplete dam and its lack of a spillway, it is believed that a flood destroyed it. In addition, there was no evidence of a trench or tunnel that would have diverted water in the wadi around the construction site. Construction on the upstream side of the dam was mostly complete but the downstream side was much less developed. The crest of the dam sloped towards the center which the engineers may have intended to use as a spillway. However, as the top of the dam was not beheaded it was not protected from flood water that would over-top the crest. The dam's proximity to the fertile Nile River and distance from populations indicates it was built for protection against such events, similar to those that still occur today. If complete, the dam would have stored  –  of water and flooding would have caused the reservoir to flood into adjacent parallel wadis.  The dam's failure likely made Egyptian engineers reluctant to construct another for nearly eight centuries.

text: Because of erosion on the downstream face of the incomplete dam and its lack of a

text: spillway

text: , it is believed that a flood destroyed it. In addition, there was no evidence of a trench or tunnel that would have diverted water in the wadi around the construction site. Construction on the upstream side of the dam was mostly complete but the downstream side was much less developed. The crest of the dam sloped towards the center which the engineers may have intended to use as a spillway. However, as the top of the dam was not beheaded it was not protected from flood water that would over-top the crest. The dam's proximity to the fertile

text: Nile River

text: and distance from populations indicates it was built for protection against such events, similar to those that still occur today. If complete, the dam would have stored  –  of water and flooding would have caused the reservoir to flood into adjacent parallel wadis.  The dam's failure likely made Egyptian engineers reluctant to construct another for nearly eight centuries.

text: Hydraulic pressure forces the groundwater to the surface. It is not known exactly where this enormous volume of water comes from. The spring's pool bowl is similar to other sinkholes except it is connected with an aquifer (underground stream) to Indian Lake. The small spring pool was created when the top layer of limestone dissolved away and collapsed into the cave already created by the underground water.

text: Hydraulic pressure forces the groundwater to the surface. It is not known exactly where this enormous volume of water comes from. The spring's pool bowl is similar to other

text: sinkhole

text: s except it is connected with an

text: aquifer

text: (underground stream) to Indian Lake. The small spring pool was created when the top layer of

text: limestone

text: dissolved away and collapsed into the cave already created by the underground water.

text: Hydraulic processes at or below the surface of the water may entrain sediment and directly cause erosion. Non-cohesive banks are particularly vulnerable to this type of failure, due to bank undercutting, bed degradation, and basal clean-out.

text: This is an old village in history.From the time of the British it has presence in Birbhum.But then its name was then Binuri. After 30 years of getting independence of India it changed to Binuria officially.

text: This is an old village in history.From the time of the British it has presence in

text: Birbhum

text: .But then its name was then Binuri. After 30 years of getting independence of

text: India

text: it changed to Binuria officially.

text: Svartifoss (Black Falls) is a waterfall in Skaftafell in Vatnajökull National Park in Iceland, and is one of the most popular sights in the park. It is surrounded by dark lava columns, which gave rise to its name. Other well-known columnar jointing formations are seen at the Giant's Causeway in Northern Ireland, Devil's Tower in Wyoming, United States and on the island of Staffa in Scotland.  There are also similar formations throughout Iceland, including a small cave on the beach of Reynisdrangar.

text: Svartifoss (Black Falls) is a waterfall in

text: Skaftafell

text: in

text: Vatnajökull National Park

text: in

text: Iceland

text: , and is one of the most popular sights in the park. It is surrounded by dark lava columns, which gave rise to its name. Other well-known columnar jointing formations are seen at the

text: Giant's Causeway

text: in

text: Northern Ireland

text: Devil's Tower

text: in

text: Wyoming

text: , United States and on the island of

text: Staffa

text: in Scotland.  There are also similar formations throughout Iceland, including a small cave on the beach of

text: Reynisdrangar

text: Salbia plicata is a moth in the Crambidae family. It was described by Hampson in 1912. It is found in Brazil.

text: Salbia plicata is a

text: moth

text: in the

text: Crambidae

text: family. It was described by

text: Hampson

text: in 1912. It is found in

text: Brazil

text: Much of the stone, plaster and metal work in the interior of the building was designed and executed by architectural sculptor Corrado Parducci. The three figures over the main entrance were by Leo Friedlander, while the rest of the considerable architectural sculpture on the exterior was by Bill Gehrke.

text: Much of the stone, plaster and metal work in the interior of the building was designed and executed by

text: architectural sculptor

text: Corrado Parducci

text: . The three figures over the main entrance were by

text: Leo Friedlander

text: , while the rest of the considerable architectural sculpture on the exterior was by Bill Gehrke.

text: The superficial formations and Mesozoic formations discharge large volumes of groundwater to the sea. Much of this discharge flows through karstic solution channels in the Tamala limestone, a calcareous and siliceous formation deposited in the middle to late Pleistocene (1,500,000-10,000  years  ago). Many karst features of the Tamala Limestone, the result of karst processes and include subterranean drainage through caverns and tunnels, dolines and sinkholes, residual cone hills and circular depressions, limestone pillars and root concretions, can be linked directly to the Nambung River. Caves have evolved in relation to the movement of weakly acidic water groundwater that gradually dissolves calcium carbonate in the limestone, which can be locally redeposited within caves and cavities.

text: The superficial

text: formations

text: and Mesozoic formations discharge large volumes of groundwater to the sea. Much of this discharge flows through karstic solution channels in the

text: Tamala limestone

text: , a calcareous and siliceous formation deposited in the middle to late

text: Pleistocene

text: (1,500,000-10,000  years  ago). Many karst features of the Tamala Limestone, the result of karst processes and include subterranean drainage through caverns and tunnels,

text: dolines

text: and

text: sinkhole

text: s, residual cone hills and circular depressions, limestone pillars and root concretions, can be linked directly to the Nambung River. Caves have evolved in relation to the movement of weakly acidic water groundwater that gradually dissolves calcium carbonate in the limestone, which can be locally redeposited within caves and cavities.

text: By mathematically modeling the rate of diffusion of water in the material and the rate of degradation of the material, it is possible to predict whether a certain material will undergo surface or bulk erosion by looking at the ratio between the two rates.

text: It improves environment by reducing erosion of the banks and flooding of low-lying areas of the city by the walls constructed on the both banks. The new integrated sewage and storm-water system intercepts 38 former sewage and industrial effluent discharge points and route it to sewage treatment plants south of Vasna Barrage. Thus it reduced the water pollution in the river. The water level in the river is retained through Vasna Barrage and the losing water is replenished by the Narmada Canal. It enabled the groundwater recharge and the recreational facilities like boating in the river. There are also plans to replenish river by treated sewage water.

text: One of the most serious and long-running water erosion problems worldwide is in the People's Republic of China, on the middle reaches of the Yellow River and the upper reaches of the Yangtze River. From the Yellow River, over 1.6 billion tons of sediment flows into the ocean each year. The sediment originates primarily from water erosion in the Loess Plateau region of the northwest.

text: One of the most serious and long-running water erosion problems worldwide is in the

text: People's Republic of China

text: , on the middle reaches of the

text: Yellow River

text: and the upper reaches of the

text: Yangtze River

text: . From the

text: Yellow River

text: , over 1.6 billion tons of sediment flows into the ocean each year. The

text: sediment

text: originates primarily from water erosion in the

text: Loess Plateau

text: region of the northwest.

text: Balaké died on August 27, 2014 in Ouagadougou. His last album, recorded in 2013, was released posthumously by Sterns Music in 2015.

text: Stream channelization is the process of engineering straighter, wider, and deeper stream channels, usually for improved navigation, wetland drainage, and/or faster transport of flood waters downstream. Levees are often constructed in conjunction with channelization to protect human development and agricultural fields from flooding. Riparian vegetation can be directly removed or damaged during and after the channelization process. In addition, channelization and levee construction modify the natural hydrology of a stream system. As water flows through a natural stream, meanders are created when faster flowing water erodes outer banks and slower flowing water deposits sediment on inner banks. Many riparian plant species depend on these areas of new sediment deposition for germination and establishment of seedlings. Channel straightening and levee construction eliminate these areas of deposition, creating unfavorable conditions for riparian vegetation recruitment.

text: Stream

text: channelization

text: is the process of engineering straighter, wider, and deeper stream channels, usually for improved navigation, wetland drainage, and/or faster transport of flood waters downstream.

text: Levee

text: s are often constructed in conjunction with channelization to protect human development and agricultural fields from flooding. Riparian vegetation can be directly removed or damaged during and after the channelization process. In addition, channelization and levee construction modify the natural hydrology of a stream system. As water flows through a natural stream, meanders are created when faster flowing water erodes outer banks and slower flowing water deposits sediment on inner banks. Many riparian plant species depend on these areas of new sediment deposition for germination and establishment of seedlings. Channel straightening and levee construction eliminate these areas of deposition, creating unfavorable conditions for riparian vegetation recruitment.

text: At , the Kadishi Tufa waterfall is the second tallest tufa waterfall on earth. A tufa waterfall is formed when water running over dolomite rock absorbs calcium, and deposits rock formations more rapidly than they erode the surrounding rock. In the case of the Kadishi Tufa fall, the formation that has been produced strikingly resembles a face which is crying profusely, and is thus sometimes known as 'the weeping face of nature'.

text: At , the Kadishi Tufa waterfall is the second tallest

text: tufa

text: waterfall on earth. A tufa waterfall is formed when water running over dolomite rock absorbs calcium, and deposits rock formations more rapidly than they erode the surrounding rock. In the case of the Kadishi Tufa fall, the formation that has been produced strikingly resembles a face which is crying profusely, and is thus sometimes known as 'the weeping face of nature'.

text: Surface and groundwater are two separate entities, so they must be regarded as such. However, there is an ever-increasing need for management of the two as they are part of an interrelated system that is paramount when the demand for water exceeds the available supply (Fetter 464). Depletion of surface and ground water sources for public consumption (including industrial, commercial, and residential) is caused by over-pumping. Aquifers near river systems that are over-pumped have been known to deplete surface water sources as well. Research supporting this has been found in numerous water budgets for a multitude of cities.

text: Surface and groundwater are two separate entities, so they must be regarded as such. However, there is an ever-increasing need for management of the two as they are part of an interrelated system that is paramount when the demand for water exceeds the available supply (Fetter 464). Depletion of surface and ground water sources for public consumption (including industrial, commercial, and residential) is caused by over-pumping.

text: Aquifer

text: s near river systems that are over-pumped have been known to deplete surface water sources as well. Research supporting this has been found in numerous water budgets for a multitude of cities.

text: denote the dilation and erosion, respectively.

text: There are a variety of ways in which humans are trying to prevent the flooding of coastal environments. Typically this is through so called hard engineering structures such as seawalls and levees.  This armouring of the coast is typically to protect towns and cities which have developed right up to the beachfront. Enhancing depositional processes along the coast can also help prevent coastal flooding. Structures such as groynes (Fig. 1), breakwaters and artificial headlands promote the deposition of sediment on the beach thus helping to buffer against storm waves and surges as the wave energy is spent on moving the sediments in the beach than on moving water inland.

text: There are a variety of ways in which humans are trying to prevent the flooding of coastal environments. Typically this is through so called hard engineering structures such as

text: seawalls

text: and

text: levees

text: .  This armouring of the coast is typically to protect towns and cities which have developed right up to the beachfront. Enhancing depositional processes along the

text: coast

text: can also help prevent coastal flooding. Structures such as

text: groynes

text: (Fig. 1),

text: breakwaters

text: and artificial headlands promote the deposition of sediment on the beach thus helping to buffer against storm waves and surges as the wave energy is spent on moving the sediments in the beach than on moving water inland.

text: Bank erosion is a natural process: without it, rivers would not meander and change course. However, land management patterns that change the hydrograph and/or vegetation cover can act to increase or decrease channel migration rates. In many places, whether or not the banks are unstable due to human activities, people try to keep a river in a single place. This can be done for environmental reclamation or to prevent a river from changing course into land that is being used by people. One way that this is done is by placing riprap or gabions along the bank. A common natural method to reduce bank erosion is the re-introduction of native plant species in the area. The expansive root systems of these plants provide support within the soil and prevents erosion due to rain runoff.

text: Bank erosion is a natural process: without it, rivers would not

text: meander

text: and change course. However, land management patterns that change the

text: hydrograph

text: and/or vegetation cover can act to increase or decrease channel migration rates. In many places, whether or not the banks are unstable due to human activities, people try to keep a river in a single place. This can be done for environmental reclamation or to prevent a river from changing course into land that is being used by people. One way that this is done is by placing

text: riprap

text: or

text: gabion

text: s along the bank. A common natural method to reduce bank erosion is the re-introduction of native plant species in the area. The expansive root systems of these plants provide support within the soil and prevents erosion due to rain runoff.

text: Rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow, depending on the balance between the upwards velocity on the particle (drag and lift forces), and the settling velocity of the particle. These relationships are shown in the following table for the Rouse number, which is a ratio of sediment fall velocity to upwards velocity.

text: Rivers and streams carry sediment in their flows. This sediment can be in a variety of locations within the flow, depending on the balance between the upwards velocity on the particle (drag and lift forces), and the

text: settling velocity

text: of the particle. These relationships are shown in the following table for the

text: Rouse number

text: , which is a ratio of sediment fall velocity to upwards velocity.

text: John Wesley stated that the term 'water of separation' indicated that the water was 'appointed for the cleansing of them that are in a state of separation, who for their uncleanness are separated from the congregation'. Thomas Coke noted that 'the heathens had their water of lustration with which to sprinkle themselves in token of purification', and thought this was probably borrowed from the Mosaic law. Albert Barnes used both terms: 'the water of purification' to describe the purifying effect of the water, and 'the water of separation' to refer to the state of legal separation from the community, for which the water was to act as a remedy.

text: John Wesley

text: stated that the term 'water of separation' indicated that the water was 'appointed for the cleansing of them that are in a state of separation, who for their uncleanness are separated from the congregation'.

text: Thomas Coke

text: noted that 'the heathens had their water of lustration with which to sprinkle themselves in token of purification', and thought this was probably borrowed from the

text: Mosaic law

text: Albert Barnes

text: used both terms: 'the water of purification' to describe the purifying effect of the water, and 'the water of separation' to refer to the state of legal separation from the community, for which the water was to act as a remedy.