Normal or geologic erosion
Weathering of parent rock and erosion by agencies like water and wind are natural
processes. There is always equilibrium between the removal and formation of soil,
and harm is done when this equilibrium is disturbed by an outside agency.
Accelerated soil erosion
Areas denuded of their natural protective cover, excessive grazing, land that has been ploughed excessively results in the removal of top soil and thus accelerated
Wind erosion is caused by strong wind mainly in arid and desert areas. It causes
dust storms, forms sand dunes and buries localities with deposition of sand, rendering
fertile lands unfit for cultivation. It is more common in Rajasthan.
When rain comes down in torrents there is not enough time for the water to soak
through soil and the run off causes erosion.
- Splash erosion is caused by falling torrential rain. The raindrops beat hard on the surface of the soil. The flowing mud splashes as high as 60 cm and about 150
- Sheet erosion occurs with the uniform removal of a thin layer or ‘sheet’ of soil.
Sloping land with shallow, loose topsoil overlying compact subsoil is the most susceptible.
This type of erosion continuously makes the soil shallower and decreases crop yield.
It can be detected by the muddy colour of the run-off from the fields.
- Rill erosion is an intermediary stage between sheet erosion and gully erosion. It
involves the removal of soil by rainwater run off through small finger-like channels.
- Channel or gully erosion occurs when the volume of concentrated run off increases
and attains more velocity. The rills enlarge into gullies. It often starts along
bullock cart tracks, cattle trails and burrows of animals. At an advance stage,
gullies result in ravines making the soil unfit for cultivation.
Landslide or slip erosion
The pressure caused by the moisture going deep into the soil during heavy rains
that is unable to penetrate further due to hard soil or rocky strata below, move
a large mass of overlying soil. Such landslides are more common in hill areas.
Stream bank erosion
During a flood, the river carries large masses of soil, boulders and plants and
deposits them downstream. The deposit reduces the transporting capacity of the torrent
resulting in overflows and meandering of the river, and in erosion of the riverbank.