What is Soil Erosion?
Soil erosion is the removal of soil by force of nature, especially wind and water, faster than the various processes of soil formation can replace it. This may affect farmers not able to grow fertile crops, and the forest green cover may affect which indirectly change the pattern in rains we receive.
Factors Responsible For Soil Erosion
The intensity of precipitation, its duration and frequency influence the volume and rate of runoff. High-volume, high-velocity runoff is a potential factor in soil erosion.
Alternate wet and dry soil conditions result in hydration and dehydration of the thin soil layer. This leads to the expansion of soil particles resulting in cracks that fill with water during rains, resulting in the removal of the soil.
The wind is an important erosive agent, especially during summer in the regions with a monsoon climate and in the dry season in regions with a temperate climate. The wind can deflect raindrops and minimize the kinetic energy of raindrops.
2. Topographic Factors
Flow velocity and Kinetic energy of surface runoff increases in steep gradients. This accelerates soil erosion. Studies show that a longer slope causes more soil erosion than shorter slopes.
3. Lithographic Factors
Rock type and their physical and chemical properties also influence erosion.
4. Natural Vegetation
a) Vegetation intercepts rainfall and thus protects thee ground surface from the direct impact of raindrops.
b) It slows down the rate of runoff with which rainwater infiltrates through and reaches the ground surface.
c) Plant stems act as obstructions and decrease velocity of surface runoff hence reduces soil erosion,
d) Roots of plants decrease the rate of detachment and the moving of soil particles.
e) Vegetation slows down wind speed and this reduces soil erosion.
Erodibility of soil is related to its physical and chemical characteristics like particle size, distribution, humus content, structure, porosity, root content, strength, etc.
“FAO” (Food and Agricultural Organisation) listed detachability, transportability and molecular attraction of soil particles, depth and moisture retaining capacity of soil as important factors influencing soil erosion.
6. Anthropogenic Factors
a) Deforestation and removal of grassland for expansion of agricultural land, Industrialization, urbanization, mining and constructional purposes such as rail, road, dams, etc.
b) Agricultural practices – Unscientific land and water management, intensive mechanized farming leads to soil erosion.
c) Overgrazing is also major factor of soil erosion.
Types of Soil Erosion
1. Water Erosion
During heavy rains, the water removes a lot of soil. Raindrops fall at a speed of approximately 10 m/s and wash away the topsoil.
Rill erosion: Runoff water erodes the soil through surface creep, saltation, and suspension. If erosion continues uncontrolled for a long time, numerous finger-shaped groves can develop, resembling twinges, branches, and trunk of a tree.
With increased erosion, streams can deepen and widen and eventually become gullies. When the gully bed cuts into the soil with an immediate drop of 3-4 meters and gradually flattens, a ravine forms. Its depth can reach 30 m or more.
When the entire top sheet of soil is carried away by water or by wind, leaving behind the barren rock, it is called sheet erosion.
Sea erosion: In coastal areas, tidal waves clash along the coast and cause heavy damage to soil.
Glacial erosion: In higher regions of Himalayas, soil erosion on a large scale is caused by glaciers.
2. Wind Erosion
In arid and semi-arid lands with low rainfall, the wind acts as a powerful agent of soil erosion causing great loss to agricultural land. It is counted when the soil is dry, added weekly, devoid of vegetative cover with overgrazing, and strong winds.
Soil Conservation Methods
1. Afforestation – It increases the area under forest cover.
2. Checking Overgrazing – Animals freely move in fields for grazing and spoil soil by their hoofs which leads to soil erosion.
3. Construction of Dams – By constructing dams soil erosion by river floods can be avoided.
4. Changing Agricultural Practices
- Crop rotation conserve soil fertility.
- Cultivation crops on alternate strips can be a good method to conserve soil.
- Contour plowing in hill slopes also can help, this type you can see in Assam.
- Shifting cultivation practices, etc.
[ Also Checkout: Floods in India ]