Soil Erosion

Soil Erosion | Factors Affecting Erosion by Water | Types of Soil Erosion Due to Water  

In this article, we will discuss soil erosion.

 

  1. Introduction  

Soil erosion is the detachment of individual soil particles from soil mass transport by erosive agents such as air, water, and deposition of transported particles after the energy for transport is insufficient.

 

Soil erosion agents

• Wind: by wind velocity

• Water

a. Rainfall

b. Surface runoff

c. Subsurface runoff

d. Glacier (causing landslides)

Gravity: Mass soil movement in forms of landslide, landfall, debris (mudflow), creep (movement of large soil particles by rolling and sliding).

 

  2. Factors Affecting Erosion by Water  

 

  a. Climatic factors  

Rainfall characteristics: major

Rainfall intensity<infiltration rate: not much erosion

The higher amount and intensity: higher erosion and higher runoff,

Frequency: frequent rainfall> maintaining soil moisture, high runoff, and erosion

Uniform rainfall throughout the year: less soil loss

Wind velocity

Atmospheric temperature

 

  b. Soil characteristics  

Infiltration rate

Infiltration rate>rainfall intensity: no runoff

Soil cover providing resistance

More moisture content: high runoff

Compacted soil: less erosion

High permeability: less runoff

Infiltration rate: depends on soil texture

Larger particle size: less erosion

 

  c. Vegetation  

Obstruction to flow reducing velocity and erosion

Thicker vegetation cover: less erosion Interception of rainfall reducing surface runoff and erosion

Roots reducing runoff and erosion

Water loss through transpiration

 

  d. Topography  

Slope: higher slope, more erosion

Slope length: increasing the velocity of flow

Slope shapes (concave slope: flatter at the bottom, steeper at top, mainly deposition and convex slope: Steepness increase towards the bottom, removal)

 

  3. Types of Soil Erosion Due to Water  

Soil Erosion

 

  a. Raindrop or Splash Erosion  

Raindrop or splash erosion is the erosion of small soil particles caused by the impact of raindrops on wet soils. Soil splash occurs in two ways: detachment of foil particles due to falling raindrops and transportation of the soil particle.

 

  b. Sheet Erosion  

Sheet erosion is defined as the removal of a thin uniform layer of topsoil by runoff water. In reality, sheet flow is carried out by a very small definable channel called inter-rills. The soil particles detached by the impact of raindrops are carried through the inter-rills by a very thin layer of overland flow.

This type of erosion occurs on smooth land surfaces and on uniform slopes. Although the total amount of soils removed in a storm by sheet erosion is small, the contribution becomes significant over a long period of time as it transports the soil detached by raindrop splash.

 

  c. Rill Erosion  

Rill erosion is the removal of soil by the concentrated sheet flow. Prolonged occurrence of soil erosion through inter-rills, leads to widening of inter-rills and formation of small channels. These rills carry both the overland flow from inter-rill areas and direct flow. The soil erosion is high from the channelized flow.

 

  d. Gully Erosion  

Gullies are relatively permanent steep-sided watercourses. Gully erosion is the advanced stage of rill erosion. Gullies are formed when there is more continuous erosion from rills and also due to the subsurface soil erosion.

 

  e. Stream Channel Erosion  

Stream erosion is the removal of stream banks soil by water. It is caused by the force of running water or by scouring (removal of sediments from a stream bed running water) or by undercutting.