8 Main Types of Water Erosion

This article throws light upon the eight main types of water erosion. The types are: 1. Splash Erosion 2. Rill Erosion 3. Gully Erosion 4. Slip Erosion 5. Stream Bank Erosion 6. Sea-Shore Erosion.

Water Erosion: Type # 1. Splash Erosion:

Falling raindrops splash soil. Raindrops fall at a speed of about 20 miles per hour. The raindrop splash beats the bare soil into flowing mud. A single raindrop may splash wet soil as much as two feet high five feet away.

The splash erosion process produces three different types of erosional damage:

(a) Puddle erosion,

(b) Fertility erosion, and

(c) Sheet Erosion

(a) Puddle Erosion:

The raindrops beat on the naked earth surface, shatters the clods and soil crumbs and break down the soil structure into puddle condition. The beating and churning action of raindrops make the soil into an impervious layer of surface mud.

The soil surface layer is made dense and compact. Eventually, porosity of this surface layer is reduced by the infiltration of muddy surface materials. Then the important entrance channels to deep soil are closed. The soil profile material can no longer absorb air freely nor can it receive and store abundant supplies of rainfall. A single storm leaves visible effects of this puddling only on the surface of the soil.

Control of Puddle Erosion:

The secret of controlling this erosion is to prevent and reduce the force of raindrops on the surface of the soil. The puddle erosion may be controlled by growing cover crops and grasses; and by the use of organic matter and stubble mulch.

(b) Fertility Erosion:

When raindrops, loosen the soil and splash it into the air, nearly all of the particles that are dislodged seem to be 2 mm or less in diameter. They also splash some particles larger than this. As these splashes fall back into the surface water, many of the finer particles are carries away and the coarser material settle out after being moved a short distance downhill. This produces what is known as fertility erosion.

It results in the accumulation of excessive coarse material on the surface within a short time after the beginning of rainfall. Even though the land is practically level, much of the organic matter and fertility bearing elements of the soil may be floated away.

Control of Fertility Erosion:

It may be controlled by the following conservation methods:

(1) Mulching

(2) Vegetative cover

(3) Strip-cropping

(4) Organic matter

(5) Tillage

(6) Bunding

(7) Terracing

(8) Outlet channel.

(c) Sheet Erosion:

By this erosion, soil is removed uniformly in thin layer from the entire surface area. Movement of soil by splash erosion is the primary cause of sheet erosion.

Water Erosion: Type # 2. Rill Erosion:

It takes place when run-off water laden with soil flowing along the slopes forming small finger-like channels. Rill erosion is an intermediary stage between sheet erosion and gully erosion.

Water Erosion: Type # 3. Gully Erosion:

As the volume of concentrated run-off increase and attains more velocity on slopes, it enlarges the rill into gullies. Gullies often starts along bullock cart tracks or burrows of animals (Fig. 23.1).

At an advanced stage, gullies result in ravines which are sometimes 50 to 10 feet deep. In India, ravines cover about 6 million acres.

Water Erosion: Type # 4. Slip Erosion:

Landslides cause slip erosion, big masses of soil and rock bodily slip down damaging the field. The effects of slip erosion are localized.

Water Erosion: Type # 5. Stream Bank Erosion:

Streams and rivers change their course by cutting one bank and depositing silt loads on the others. During flash floods, the damage is very much accelerated. The Kosi river in Bihar is reported to have changed its course westward by 65 miles within the last 100 years.

Water Erosion: Type # 6. Sea-Shore Erosion:

Sea-shore erosion is caused by the striking action of strong waves.