What makes erosion

Urban areas and parking lots result in less water entering the ground. Water runs off the parking lot onto nearby lands and speeds up erosion in those areas. Recreational activities may accelerate soil erosion.

Off-road vehicles disturb the landscape and the area eventually develops bare spots where no plants can grow. Figure 7. Soil erosion is as natural as any other type of erosion, but human activities have greatly accelerated soil erosion.

In some locations soil erosion may occur about 10 times faster than its natural rate. Since Europeans settled in North America, about one-third of the topsoil in the area that is now the United States has eroded away.

Improve this page Learn More. Skip to main content. Module 4: Weathering and Soil Formation. Search for:. Reading: Causes of Soil Erosion The agents of soil erosion are the same as the agents of all types of erosion: water, wind, ice, or gravity. Farming Agriculture is probably the most significant activity that accelerates soil erosion because of the amount of land that is farmed and how much farming practices disturb the ground Figure 1.

Figure 3. Logging exposes large areas of land to erosion. Did you have an idea for improving this content? In many cases, rills are filled in each year as part of tillage operations. Figure 4. The distinct path where the soil has been washed away by surface water runoff is an indicator of rill erosion.

Gully erosion is an advanced stage of rill erosion where surface channels are eroded to the point where they become a nuisance factor in normal tillage operations Figure 5. There are farms in Ontario that are losing large quantities of topsoil and subsoil each year due to gully erosion. Surface water runoff, causing gully formation or the enlarging of existing gullies, is usually the result of improper outlet design for local surface and subsurface drainage systems.

The soil instability of gully banks, usually associated with seepage of groundwater, leads to sloughing and slumping caving-in of bank slopes. Such failures usually occur during spring months when the soil water conditions are most conducive to the problem. Gully formations are difficult to control if corrective measures are not designed and properly constructed. Control measures must consider the cause of the increased flow of water across the landscape and be capable of directing the runoff to a proper outlet.

Gully erosion results in significant amounts of land being taken out of production and creates hazardous conditions for the operators of farm machinery. Figure 5. Gully erosion may develop in locations where rill erosion has not been managed. Natural streams and constructed drainage channels act as outlets for surface water runoff and subsurface drainage systems. Bank erosion is the progressive undercutting, scouring and slumping of these drainageways Figure 6.

Poor construction practices, inadequate maintenance, uncontrolled livestock access and cropping too close can all lead to bank erosion problems. Figure 6. Bank erosion involves the undercutting and scouring of natural stream and drainage channel banks. Poorly constructed tile outlets also contribute to bank erosion. Some do not function properly because they have no rigid outlet pipe, have an inadequate splash pad or no splash pad at all, or have outlet pipes that have been damaged by erosion, machinery or bank cave-ins.

The direct damages from bank erosion include loss of productive farmland, undermining of structures such as bridges, increased need to clean out and maintain drainage channels and washing out of lanes, roads and fence rows.

The implications of soil erosion by water extend beyond the removal of valuable topsoil. Crop emergence, growth and yield are directly affected by the loss of natural nutrients and applied fertilizers. Seeds and plants can be disturbed or completely removed by the erosion.

Organic matter from the soil, residues and any applied manure, is relatively lightweight and can be readily transported off the field, particularly during spring thaw conditions. Pesticides may also be carried off the site with the eroded soil. Soil quality, structure, stability and texture can be affected by the loss of soil.

The breakdown of aggregates and the removal of smaller particles or entire layers of soil or organic matter can weaken the structure and even change the texture. Textural changes can in turn affect the water-holding capacity of the soil, making it more susceptible to extreme conditions such as drought. The off-site impacts of soil erosion by water are not always as apparent as the on-site effects.

Eroded soil, deposited down slope, inhibits or delays the emergence of seeds, buries small seedlings and necessitates replanting in the affected areas. Also, sediment can accumulate on down-slope properties and contribute to road damage.

Sediment that reaches streams or watercourses can accelerate bank erosion, obstruct stream and drainage channels, fill in reservoirs, damage fish habitat and degrade downstream water quality. Pesticides and fertilizers, frequently transported along with the eroding soil, contaminate or pollute downstream water sources, wetlands and lakes.

Because of the potential seriousness of some of the off-site impacts, the control of "non-point" pollution from agricultural land is an important consideration. Wind erosion occurs in susceptible areas of Ontario but represents a small percentage of land — mainly sandy and organic or muck soils.

Under the right conditions it can cause major losses of soil and property Figure 7. Figure 7. Wind erosion can be severe on long, unsheltered, smooth soil surfaces.

Soil particles move in three ways, depending on soil particle size and wind strength — suspension, saltation and surface creep. The rate and magnitude of soil erosion by wind is controlled by the following factors:. Very fine soil particles are carried high into the air by the wind and transported great distances suspension.

Fine-to-medium size soil particles are lifted a short distance into the air and drop back to the soil surface, damaging crops and dislodging more soil saltation. Larger-sized soil particles that are too large to be lifted off the ground are dislodged by the wind and roll along the soil surface surface creep. The abrasion that results from windblown particles breaks down stable surface aggregates and further increases the soil erodibility.

Soil surfaces that are not rough offer little resistance to the wind. However, ridges left from tillage can dry out more quickly in a wind event, resulting in more loose, dry soil available to blow. Over time, soil surfaces become filled in, and the roughness is broken down by abrasion. This results in a smoother surface susceptible to the wind. Excess tillage can contribute to soil structure breakdown and increased erosion. The speed and duration of the wind have a direct relationship to the extent of soil erosion.

Soil moisture levels are very low at the surface of excessively drained soils or during periods of drought, thus releasing the particles for transport by wind. This effect also occurs in freeze-drying of the soil surface during winter months. Accumulation of soil on the leeward side of barriers such as fence rows, trees or buildings, or snow cover that has a brown colour during winter are indicators of wind erosion. A lack of windbreaks trees, shrubs, crop residue, etc. Knolls and hilltops are usually exposed and suffer the most.

The lack of permanent vegetative cover in certain locations results in extensive wind erosion. A key part of erosion is that it involves not only breakdown but also movement of rocks, soil, and minerals. Increase human activity can also rapidly erode a surface. Although this is not typically considered a cause of erosion, or at least it is not considered a natural cause. What are the causes of erosion? Kate M. Mar 15, Erosion is caused by wind, water, or gravity.

Explanation: Erosion, or the degradation and transport of rock or soil, can occur from wind, water, or gravity. Erosion due to water: Erosion due to gravity: A key part of erosion is that it involves not only breakdown but also movement of rocks, soil, and minerals.

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