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| For morphological image processing operations, see Erosion (morphology).This article may require cleanup to meet Wikipedia's quality standards.Severe soil erosion in a wheat field near Washington State University, USA.Erosion is distinguished from weathering, which is the process of chemical breakdown of the minerals in the rocks, although the two processes may be concurrent.Erosion is an intrinsic natural process but in many places it is increased by human land use.Land that is used for the production of agricultural crops generally experiences a significant greater rate of erosion than that of land under natural vegetation.This is particularly true if tillage is used, which reduces vegetation cover on the surface of the soil and disturbs both soil structure and plant roots that would otherwise hold the soil in place.Excessive erosion, however, does cause problems, such as receiving water sedimentation, ecosystem damage and outright loss of soil.Causes
2 Erosion processes
2.Causes
The rate of erosion tenses on many factors, including the amount and intensity of precipitation, the texture of the soil, the gradient of the slope, ground cover from vegetation, rocks, land use,how much water there is, and possibility of erosion from speed of a stream.The first factor, rain, is the agent for erosion, but the degree of erosion is governed by other factors.Soils with a greater proportion of clay that receive less intense precipitation and are on gentle slopes tend to erode less.But here, the impact of atmospheric sodium on erodibility of clay should be considered (Schmittner and Giresse, 1999).These layers and the underlaying soil in a forest is porous and highly permeable to rainfall.Severe fires can lead to significantly increased erosion if followed by heavy rainfall.Roads are especially likely to cause increased rates of erosion because, in addition to removing ground cover, they can significantly change drainage patterns.Logging can cause increased erosion rates due to soil compaction, exposure of mineral soil, for example roads and landings.However it is the removal of or compromise to the forest floor not the removal of the canopy that can lead to erosion.Stuart and Edwards)
Heavy grazing can reduce vegetation enough to increase erosion.Changes in the kind of vegetation in an area can also affect erosion rates.Leaf litter and low shrubs are an important part of the high infiltration rates of forested systems, the removal of which can increase erosion rates.Leaf litter also shelters the soil from the impact of falling raindrops, which is a significant agent of erosion.Vegetation can also change the speed of surface runoff flows, so grasses and shrubs can also be instrumental in this aspect.When the total ground surface is stripped of vegetation and then seared of all living organisms, the upper soils are vulnerable to both wind and water erosion.When land is overused by animal activities (including humans), there can be mechanical erosion and also removal of vegetation leading to erosion.In the case of the animal kingdom, this effect would become material primarily with very large animal herds stampeding such as the Blue Wildebeest on the Serengeti plain.These effects can also accumulate from a variety of outdoor human activities, again simply arising from too many people using a finite land resource.People's Republic of China, on the middle reaches of the Yellow River and the upper reaches of the Yangtze River.The sediment originates primarily from water erosion in the Loess Plateau region of the northwest.One of the visible topographical manifestations of a very slow form of such activity is a scree slope.In some cases, the slump is caused by water beneath the slope weakening it.In many cases it is simply the result of poor engineering along highways where it is a regular occurrence.Sheet erosion is the result of heavy rain on bare soil where water flows as a sheet down any gradient, carrying soil particles.The primary mechanism for detachment of soil particals from the surface in this type of erosion is by the impact of raindrops on the soil surface.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.Eroding rills evolve morphologically in time and space.The hydraulics is the driving mechanism for the erosion process, and therefore dynamically changing hydraulic patterns cause continually changing erosional patterns in the rill.Thus, the process of rill evolution involves a feedback loop between flow detachment, hydraulics, and bed form.Superimposed on these interactive processes, the sediment load, or amount of sediment in the flow, has a large influence on soil detachment rates in rills.Where precipitation rates exceed soil infiltration rates, runoff occurs.Surface runoff turbulence can often cause more erosion than the initial raindrop impact.Gully erosion results where water flows along a linear depression eroding a trench or gully.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.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.At extremely high flows, kolks, or vortices are formed by large volumes of rapidly rushing water.Erosion due to wave pounding at Venus Bay, South Australia.Shoreline erosion, which occurrs on both exposed and sheltered coasts, primarily occurs through the action of currents and waves but sea level (tidal) change can also play a role.Hydraulic action takes place when air in a joint is suddenly compressed by a wave closing the entrance of the joint.It is the most effective and rapid form of shoreline erosion (not to be confused with corrosion).Corrosion is the dissolving of rock by carbonic acid in sea water.Limestone cliffs are particularly vulnerable to this kind of erosion.The material ends up as shingle and sand.Another significant source of erosion, particularly on carbonate coastlines, is the boring, scraping and grinding of organisms, a process termed bioerosion.Sediment is transported along the coast in the direction of the prevailing current (longshore drift).When the upcurrent amount of sediment is less than the amount being carried away, erosion occurs.Where there is a bend in the coastline, quite often a build up of eroded material occurs forming a long narrow bank (a spit).Over the years, as the shoals gradually shift, the erosion may be redirected to attack different parts of the shore.In an abrasion process, debris in the basal ice scrapes along the bed, polishing and gouging the underlying rocks, similar to sandpaper on wood.These processes, combined with erosion and transport by the water network beneath the glacier, leave moraines, drumlins and glacial erratics in their wake, typically at the terminus or during glacier retreat.Freeze Thaw is the weathering process in which water trapped in tiny rock cracks freezes and expands, breaking the rock.This can lead to gravity erosion on steep slopes.Ice expands, thus, creating a wedge in the rock.Second, these suspended particles may impact on solid objects causing erosion by abrasion.Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation.Windbreaks are often planted by farmers to reduce wind erosion.Soil Erosion and Climate Change
The consensus of atmospheric scientists is that climate change is occurring, both in terms of global air temperature and precipitation patterns.Warmer atmospheric temperatures associated with greenhouse warming are expected to lead to a more vigorous hydrological cycle, including more extreme rainfall events (IPCC, 1995).Studies on soil erosion suggest that increased rainfall amounts and intensities will lead to greater rates of erosion.Thus, if rainfall amounts and intensities increase in many parts of the world as expected, erosion will also increase, unless amelioration measures are taken.Soil erosion rates are expected to change in response to changes in climate for a variety of reasons.Studies by Pruski and Nearing (2002) indicated that, other factors such as land use not considered, we can expect approximately a 1.Tectonic effects of erosion
The removal by erosion of large amounts of rock from a particular region, and its deposition elsewhere, can result in a lightening of the load on the lower crust and mantle.Research undertaken since the early 1990s suggests that the spatial distribution of erosion at the surface of an orogen can exert a key influence on its growth and its final internal structure.Materials science
In materials science, erosion is the recession of surfaces by repeated localized mechanical trauma as, for example, by suspended abrasive particles within a moving fluid.In hard particle erosion, the hardness of the impacted material is a large factor in the mechanics of the erosion.Hardness is a correlative factor for erosion resistance, but a higher hardness does not guarantee better resistance.Factors that affect the erosion rate also include impacting particle speed, size, density, hardness, and rotation.Coatings can be applied to retard erosion, but normally can only slow the removal of material.Figurative use
The concept of erosion is commonly employed by analogy to various forms of perceived or real homogenization (i.It is a common trope of the English language to describe as erosion the gradual, organic mutation of something thought of as distinct, more complex, harder to pronounce or more refined into something indistinct, less complex, easier to pronounce or (disparagingly) less refined.Origin of term
The first known occurrence of the term "erosion" was in the 1541 translation by Robert Copland of Guy de Chauliac's medical text The Questyonary of Cyrurygens.Copland used erosion to describe how ulcers developed in the mouth.By 1774 'erosion' was used outside medical subjects.Oliver Goldsmith employed the term in the more contemporary geological context, in his book Natural History, with the quote
"Bounds are thus put to the erosion of the earth by water."Pan European Soil Erosion Assessment
Concepts about forests and water Author: Stuart, Gordon W.Runoff and soil loss responses to changes in precipitation: a computer simulation study.Technical Information relevant to interpreting Article 2 of the UN Framework Convention on Climate Change.Intergovernmental Panel on Climate Change.Soil erosion in Europe.Erich and Giresse Pierre, 1999.All text is available under the terms of the GNU Free Documentation License.For morphological image processing operations, see Erosion (morphology).Severe soil erosion in a wheat field near Washington State University, USA.Erosion is distinguished from weathering, which is the process of chemical breakdown of the minerals in the rocks, although the two processes may be concurrent.Erosion is an intrinsic natural process but in many places it is increased by human land use.Poor land use practices include deforestation, overgrazing, unmanaged construction activity and road or trail building.Land that is used for the production of agricultural crops generally experiences a significant greater rate of erosion than that of land under natural vegetation.This is particularly true if tillage is used, which reduces vegetation cover on the surface of the soil and disturbs both soil structure and plant roots that would otherwise hold the soil in place.Excessive erosion, however, does cause problems, such as receiving water sedimentation, ecosystem damage and outright loss of soil.Causes
2 Erosion processes
2.Causes
The rate of erosion tenses on many factors, including the amount and intensity of precipitation, the texture of the soil, the gradient of the slope, ground cover from vegetation, rocks, land use,how much water there is, and possibility of erosion from speed of a stream.The first factor, rain, is the agent for erosion, but the degree of erosion is governed by other factors.The first three factors can remain fairly constant over time.Soils with a greater proportion of clay that receive less intense precipitation and are on gentle slopes tend to erode less.These layers and the underlaying soil in a forest is porous and highly permeable to rainfall.Severe fires can lead to significantly increased erosion if followed by heavy rainfall.Roads are especially likely to cause increased rates of erosion because, in addition to removing ground cover, they can significantly change drainage patterns.Logging can cause increased erosion rates due to soil compaction, exposure of mineral soil, for example roads and landings.However it is the removal of or compromise to the forest floor not the removal of the canopy that can lead to erosion.However, the intact forest floor, with its layers of leaf litter and organic matter, absorbs the impact of the rainfall.Stuart and Edwards)
Heavy grazing can reduce vegetation enough to increase erosion.Changes in the kind of vegetation in an area can also affect erosion rates.Different kinds of vegetation lead to different infiltration rates of rain into the soil.Forested areas have higher infiltration rates, so precipitation will result in less surface runoff, which erodes.Leaf litter and low shrubs are an important part of the high infiltration rates of forested systems, the removal of which can increase erosion rates.Leaf litter also shelters the soil from the impact of falling raindrops, which is a significant agent of erosion.One of the main causes of erosive soil loss in the year 2006 is the result of slash and burn treatment of tropical forest.When the total ground surface is stripped of vegetation and then seared of all living organisms, the upper soils are vulnerable to both wind and water erosion.When land is overused by animal activities (including humans), there can be mechanical erosion and also removal of vegetation leading to erosion.In the case of the animal kingdom, this effect would become material primarily with very large animal herds stampeding such as the Blue Wildebeest on the Serengeti plain.Even in this case there are broader material benefits to the ecosystem, such as continuing the survival of grasslands, that are indigenous to this region.The sediment originates primarily from water erosion in the Loess Plateau region of the northwest.One of the visible topographical manifestations of a very slow form of such activity is a scree slope.In some cases, the slump is caused by water beneath the slope weakening it.In many cases it is simply the result of poor engineering along highways where it is a regular occurrence.Sheet erosion is the result of heavy rain on bare soil where water flows as a sheet down any gradient, carrying soil particles.The primary mechanism for detachment of soil particals from the surface in this type of erosion is by the impact of raindrops on the soil surface.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.The hydraulics is the driving mechanism for the erosion process, and therefore dynamically changing hydraulic patterns cause continually changing erosional patterns in the rill.Thus, the process of rill evolution involves a feedback loop between flow detachment, hydraulics, and bed form.Superimposed on these interactive processes, the sediment load, or amount of sediment in the flow, has a large influence on soil detachment rates in rills.Where precipitation rates exceed soil infiltration rates, runoff occurs.Surface runoff turbulence can often cause more erosion than the initial raindrop impact.Gully erosion results where water flows along a linear depression eroding a trench or gully.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.When some base level is reached, the erosive activity switches to lateral erosion, which widens the valley floor and creates a narrow floodplain.At extremely high flows, kolks, or vortices are formed by large volumes of rapidly rushing water.Erosion due to wave pounding at Venus Bay, South Australia.Shoreline erosion, which occurrs on both exposed and sheltered coasts, primarily occurs through the action of currents and waves but sea level (tidal) change can also play a role.It is the most effective and rapid form of shoreline erosion (not to be confused with corrosion).Limestone cliffs are particularly vulnerable to this kind of erosion.Another significant source of erosion, particularly on carbonate coastlines, is the boring, scraping and grinding of organisms, a process termed bioerosion.When the upcurrent amount of sediment is less than the amount being carried away, erosion occurs.When the upcurrent amount of sediment is greater, sand or gravel banks will tend to form.Over the years, as the shoals gradually shift, the erosion may be redirected to attack different parts of the shore.In an abrasion process, debris in the basal ice scrapes along the bed, polishing and gouging the underlying rocks, similar to sandpaper on wood.These processes, combined with erosion and transport by the water network beneath the glacier, leave moraines, drumlins and glacial erratics in their wake, typically at the terminus or during glacier retreat.Freeze Thaw is the weathering process in which water trapped in tiny rock cracks freezes and expands, breaking the rock.This can lead to gravity erosion on steep slopes.The scree which forms at the bottom of a steep mountainside is mostly formed from pieces of rock broken away by this means.In some places, water seeps into rocks during the daytime, then freezes at night.There are two main effects.This is called deflation.Second, these suspended particles may impact on solid objects causing erosion by abrasion.Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation.Windbreaks are often planted by farmers to reduce wind erosion.Soil Erosion and Climate Change
The consensus of atmospheric scientists is that climate change is occurring, both in terms of global air temperature and precipitation patterns.Karl and Knight (1998) reported that from 1910 to 1996 total precipitation over the contiguous U.Studies on soil erosion suggest that increased rainfall amounts and intensities will lead to greater rates of erosion.Thus, if rainfall amounts and intensities increase in many parts of the world as expected, erosion will also increase, unless amelioration measures are taken.Soil erosion rates are expected to change in response to changes in climate for a variety of reasons.Studies by Pruski and Nearing (2002) indicated that, other factors such as land use not considered, we can expect approximately a 1.Tectonic effects of erosion
The removal by erosion of large amounts of rock from a particular region, and its deposition elsewhere, can result in a lightening of the load on the lower crust and mantle.This can cause tectonic or isostatic uplift in the region.Research undertaken since the early 1990s suggests that the spatial distribution of erosion at the surface of an orogen can exert a key influence on its growth and its final internal structure.Materials science
In materials science, erosion is the recession of surfaces by repeated localized mechanical trauma as, for example, by suspended abrasive particles within a moving fluid.In hard particle erosion, the hardness of the impacted material is a large factor in the mechanics of the erosion.Harder material will typically erode fastest from perpendicular impacts.Hardness is a correlative factor for erosion resistance, but a higher hardness does not guarantee better resistance.Factors that affect the erosion rate also include impacting particle speed, size, density, hardness, and rotation.Coatings can be applied to retard erosion, but normally can only slow the removal of material.Figurative use
The concept of erosion is commonly employed by analogy to various forms of perceived or real homogenization (i.It is a common trope of the English language to describe as erosion the gradual, organic mutation of something thought of as distinct, more complex, harder to pronounce or more refined into something indistinct, less complex, easier to pronounce or (disparagingly) less refined.Origin of term
The first known occurrence of the term "erosion" was in the 1541 translation by Robert Copland of Guy de Chauliac's medical text The Questyonary of Cyrurygens.Copland used erosion to describe how ulcers developed in the mouth.By 1774 'erosion' was used outside medical subjects.Oliver Goldsmith employed the term in the more contemporary geological context, in his book Natural History, with the quote
"Bounds are thus put to the erosion of the earth by water."World Bank 2001: China: Air, Land, and Water.Pan European Soil Erosion Assessment
Concepts about forests and water Author: Stuart, Gordon W.Soil erosion in Europe.The impact of atmospheric sodium on erodibility of clay in a coastal Mediterranean region.Click your browser's Refresh button to try reconnecting.Click your browser's Refresh button to try reconnecting.Erosion occurs when rock and soil are broken loose from
the earth's surface in one place, and carried to another place.Erosion is usually a slow and gradual process that takes
thousands or even millions of years.But man's activities such a
farming, mining, and urban development can speed up the erosion
process.How does erosion occur?Erosion begins with the weathering, or breaking down, of
rocks and soil.Water runoff is the major cause of erosion.It picks up and carries weathered
rocks and soils to other places.Do rivers cause erosion?Rivers cause erosion by transporting weathered rock and soil
downstream.The Grand Canyon is one spectacular feature that was created
by river erosion.How do floods affect erosion?Floods can cause brief periods of heavy erosion.These same
waters can deposit soils in wide, flat areas on both sides of the
river in the aftermath of a flood.While these flood plains are
often very fertile, the flooding potential can make flood plain
areas a dangerous place to live and a risky place to grow crops.What are some features of erosion?Chemical weathering can actually dissolve rocks, and erosion can
carry the dissolved particles away.Caves and depressions in rock
faces may be formed in this way.How is erosion helpful?When erosion occurs, broken down rocks form soils and
are deposited in very fertile layers on valley floors and river
deltas.How is erosion harmful?Erosion can be harmful when this same kind of fertile
topsoil is washed away.Urban development results in replacement of
vegetation with concrete and highways, increasing runoff and
erosion in surrounding areas.What can prevent erosion?Natural deterrents of erosion are the root systems of
plants and trees.The roots help hold topsoil in place.Contour
plowing and terracing are also ways that farmers can help prevent
erosion.Urban developers can help reduce erosion by including
green areas and by replanting vegetation that may have been lost
during the building process.HomeEducationGeography
Search over 1.The process known as weathering breaks up rocks so that they can be carried away by the process known as erosion.Water, wind, ice, and waves are the agents of erosion that wear away at the surface of the earth.Water Erosion
Water is the most important erosional agent and erodes most commonly as running water in streams.However, water in all its forms is erosional.In streams, water is a very powerful erosional agent.This is known as critical erosion velocity.The water of streams can erode in three different places: 1) lateral erosion erodes the sediment on the sides of the stream channel, 2) down cutting erodes the stream bed deeper, and 3) headward erosion erodes the channel upslope.Wind Erosion
Erosion by wind is known as aeolian (or eolian) erosion (named after Aeolus, the Greek god of winds) and occurs almost always in deserts.Aeolian erosion of sand in the desert is partially responsible for the formation of sand dunes.Ice Erosion
The erosive power of moving ice is actually a bit greater than the power of water but since water is much more common, it is responsible for a greater amount of erosion on the earth's surface.Abrasion cuts into the rock under the glacier, scooping rock up like a bulldozer and smoothing and polishing the rock surface.Wave Erosion
Waves in oceans and other large bodies of water produce coastal erosion.The power of oceanic waves is awesome, large storm waves can produce 2000 pounds of pressure per square foot.The pure energy of waves along with the chemical content of the water is what erodes the rock of the coastline.Maps and Geography of the WorldFree Blank Outline Maps of the Countries and Continents of t...What's HotWhat is the largest landlocked country?Guano Island ActWhat time is it at the North and South P...Why does the earth tilt?HomeEducationGeography
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Add to: iGoogleMy Yahoo!Loess soil has unique properties
since it can be cut vertically without any need for bank stabilization.Over sixty years later erosion continues to
take a toll.The steep bluffs and rugged ravines compound problems as they
create extreme difficulties for personnel and equipment.Regardless of the quantity and type of erosion control devices utilized,
combatting erosion remains a constant battle with the forces of nature. |
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