They detach from the other soil aggregates and tend to create a crust on top of the soil, which can easily runoff when water or wind is introduced. Sheet erosion is the second stage of the erosion where a thin layer of the soil is removed. This can occur when heavy rain occurs, or the shallow surface begins to runoff from water flow.
This results in the loss of the organic matter and nutrients since the top layer of the finest soil particles are lost. This type of soil loss is very gradual and can often go unnoticed until huge amounts of soil have been lost.
When the soil has faced overgrazing or has a lack of vegetation cover, it can lead to a higher rate of erosion. It is important to learn more about the signs of erosion so that it can be prevented. These signs are:. In such cases, a vegetation cover can help to protect the particles of soil and even increase the aggregation of soil.
Rill Erosion is the third stage of soil erosion. Rills are the shallow drainage lines that are around 30cm deep into the ground. The surface water begins to collect on the soil in the form of depressions and begins to erode the soil.
It forms these rills that can make hills and the land more prone to erosion. Rill erosion is common where there is loose soil, overgrazing, and bare soil on agricultural land. People can reduce the chances of rill erosion through grassed waterways, contour drains, and mulching. Gully erosion persists more than 30cm into the soil. It is the worst type of erosion because soil conservation cannot take place through normal cultivation practices.
It can occur when runoff begins to flow strong and concentrates in one location. The water flow can be strong enough to detach and move complete soil particles along with it. For example, a spring or small waterfall may form on the soil. As the runoff flows down the land, it begins to pick up energy as it plunges over the gully head. The splashes from the water can also erode the subsoil, and the gully can eat away at the topsoil on the slope as well.
This type of erosion is very extensive and visible. It can have drastic effects on soil productivity and restrict land use. Gullies can be at least 2m deep but may go down to depths of m. Increased runoff due to changes in land such as clearing of trees. Continued water flow along a linear pathway can also cause erosion. The erosion can deepen valleys or extend the valley into the hillside. It can create steep banks or head cuts as it flows over the ground.
When it is just starting out, the erosion is mostly vertical in nature, which is why valleys usually have a V-shape. In such cases, the stream gradient can become really steep as the flowing water continues to affect the land surface. When the running water has reached the base level, the erosion can switch to lateral erosion. This can end up widening the valley floor and cause the floodplain to shrink.
When the stream gradient continues to become flat, the deposition of sediments can increase. This is due to the fact that the water begins to meander against the floor of the valley. During flooding , this can increase as the water is moving faster and is able to carry an even larger chunk of sediment.
Pebbles, boulders, and other suspended abrasive particles can also begin to erode away at the surface; this is known as traction. Tunnel erosion causes the loss of soil from the subsoil layer. This happens when water runs through small cracks or hole where roots have decayed.
The soil begins to disperse from the inside and is carried away with the water flow. These areas are subjected to high velocity floods that erode soils with insufficient surface cover.
This erosive flooding can remove the entire layer of cultivated topsoil exposing compacted subsoils. It is common for such areas to be stripped of 0.
Problems can also occur at the end of a flood event when slow moving water flows over saturated soils. Mass movement occurs on cleared slopes in coastal areas. Gravity moves earth, rock and soil material downslope both slowly millimetres per year and suddenly e. During periods of prolonged and heavy rainfall, water entering permeable soils can be stopped by a barrier such as bedrock or a clay-rich soil horizon.
The heavy weight of this saturated soil can slide downslope if it is sitting on a rock surface loosened by the build-up of water in the soil. It is better to prevent landslides than pay for expensive, time-consuming rehabilitation which may only be partially effective. As excessive water intake is the most common trigger of landslip, avoid obstructions such as dams or cross-slope drains. It is most likely to occur when strong winds blow over light-textured soils that have been heavily grazed during drought periods.
These areas, which vary from a few square metres to hundreds of hectares, are difficult to revegetate due to:. Generally, wind erosion is not a serious issue in cropping areas. Most soils cultivated in Queensland have a heavy texture—forming relatively large aggregates that are too coarse to be carried by strong winds. However, sandy soils are vulnerable to wind erosion because they cannot store very much moisture and have low fertility. The rich delta soils of the San Joaquin and Sacramento rivers in northern California, for example, have created one of the most agriculturally productive areas in the world.
Loess is an agriculturally rich sediment made almost entirely of wind-blown, eroded sediment. The Yellow River in central China gets its name from the yellow loess blown into and suspended in its water. Human activity altering the vegetation of an area is perhaps the biggest human factor contributing to erosion. Trees and plants hold soil in place. When people cut down forests or plow up grasses for agriculture and development, the soil is more vulnerable to washing or blowing away.
Landslides become more common. Water rushes over exposed soil rather than soaking into it, causing flooding. Global warming , the current period of climate change , is speeding erosion. The change in climate has been linked to more frequent and severe storms. Storm surge s following hurricanes and typhoon s can erode kilometers of coastline and coastal habitat. These coastal areas are home to residences, businesses, and economically important industries, such as fisheries.
The rise in temperature is also quickly melting glaciers. The slower, more massive form of glacial erosion is being supplanted by the cumulative impact of rill, gully, and valley erosion. In areas downstream from glacial snouts, rapidly melting glaciers are contributing to sea level rise. The rising sea erodes beaches more quickly. Erosion control is the process of reducing erosion by wind and water.
Farmer s and engineer s must regularly practice erosion control. Sometimes, engineers simply install structures to physically prevent soil from being transported. Gabion s are huge wireframes that hold boulders in place, for instance. Gabions are often placed near cliffs. These cliffs, often near the coast, have homes, businesses, and highways near them.
When erosion by water or wind threatens to tumble the boulders toward buildings and cars, gabions protect landowners and drivers by holding the rocks in place. Erosion control also includes physically changing the landscape.
Communities often invest in windbreak s and riparian buffer s to protect valuable agricultural land. Windbreaks, also called hedgerow s or shelterbelt s, are lines of trees and shrubs planted to protect cropland from wind erosion. Riparian buffers describe plants such as trees, shrubs, grasses, and sedges that line the banks of a river. Riparian buffers help contain the river in times of increased stream flow and flooding. Living shoreline s are another form of erosion control in wetland areas.
Living shorelines are constructed by placing native plants, stone, sand, and even living organisms such as oysters along wetland coasts. These plants help anchor the soil to the area, preventing erosion.
By securing the land, living shorelines establish a natural habitat. They protect coastlines from powerful storm surges as well as erosion. Eroding Animals. Cave entrances can be on land or in water. Also called limestone and calcium carbonate. Dust Bowl. Also known as an ice age. Northern Hemisphere. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
Media If a media asset is downloadable, a download button appears in the corner of the media viewer. Text Text on this page is printable and can be used according to our Terms of Service. Interactives Any interactives on this page can only be played while you are visiting our website.
Related Resources. The Rock Cycle. View Collection. Walter's Travels - Weathering and Erosion. View Interactive. The removal of topsoil due to the fast land degradation process will inevitably affect the plants that grow there. The reduction of nutrients that were washed out from the soil by the excess water will prevent crops from receiving the necessary amount of needed elements that decreases their performance.
The absence of the topsoil surface leads to water pollution due to chemical runoff, negatively affecting animals, fish and algae in the area. Eventually, this leads to reduction of the animal population.
Severe land degradation by water can negatively impact the ecosystems by causing flooding. The washed away topsoil loses its water absorption ability , greatly increasing the possibility of flooding in areas that are predisposed to it.
It could be low-lying landscapes and soils with limited drainage ability. Ultimately, heavy flooding can be extremely disruptive to the extent of ruining roads and buildings. Apart from affecting animals, plants, and farmland, water erosion also significantly decreases the quality of water itself. The particles of the eroded soil eventually reach the water sources nearby, changing the water chemical content and reducing its oxygen levels. Besides, the water from eroded farmlands contains harmful chemicals due to previous pesticides application , washing them off to lakes, streams, and rivers.
Water erosion control is vital in battling the issue of land degradation caused by water. And the water erosion solutions differ depending on the soil type , topography, climate, crop rotation , and land use. However, there are water erosion prevention measures for its every type.
The table below shows both the common and the most useful control measures for different types of water erosion. Ultimately, ground cover maintenance is the best method of controlling splash erosion. To assist with that, Crop Monitoring offers a number of vegetation indices that help to evaluate not only the quality of the crops but distinguish covered with plant areas of the field and bare soil.
It is especially useful. Sheet erosion control starts with the maintenance of ground cover, soil structure, and soil organic matter. This prevents the development of splash erosion by preventing topsoil compaction. Another protection option is the use of mulch to cover the land surface. As the productivity of the field can decrease after such soil degradation, Crop Monitoring enables farmers to monitor the productivity of a separate field not only throughout the season but in the long run too.
Season by season, a farmer can compare the productivity areas of the field and identify the problem sites. Setting the scouting tasks helps effectively check weather water erosion processes present in the field and implement timely management strategies.
0コメント