Cover management factor in RUSLE model (C-factor)

Cover management factor in RUSLE model (C factor)

What is C-factor?

C factor is cover management factor and it reflect by its name that it is soothing like the management of cover types.

C-factor depend on land surface cover types like barren land, waterbody, urban, vegetation types and stage of vegetation growth. 

C-factor is simply the ratio of soil loss from land surface when management practices are involved and soil loss without management practices.

Soil erosion can be assess using c-factor and it helps to analyze the roll of cropping and management practices on erosion rates. 

📥📥Download Global soil erosion data

How C-factor is helpful assessment of soil erosion??

C-factor commonly used to assess annual soil erosion in revised universal soil loss (RUSLE) equation which is as follows:-

A=R*K*LS*C*P

Where A = annual soil loss, R = rainfall erosivity factor, K = soil erodibility factor, 

LS = slope length and steepness factor, C = cover management factor, and 

P = conservation practice factor.

Its value ranges from 0 to 1 where c-factor close to 0 represent low erosion due to  surface cover like built-up, snow, water body etc. Whereas c-factor close to 1 indicates higher soil loss due to the cover like waste land, barren land or something like that which cannot cover the soil surface to reduce the soil erosion.

The crop or tress which are enough dense to cover whole soil surface will protect the soil from erosion and nutrient loss. These dense crop will reduce the intensity of rainfall drop to erode them quickly and also reduce the velocity of water flowing over soil cover.

Beside the crop or vegetation cover, some other management practices which are able to cover the soil surface from soil loss can be utilized. This means as soil surface is covered with some management practices, soil erosion will close to zero.

Therefore impact of best management practices on soil loss can be seen using c-factor as c-factor show the effect of land use change on soil erosion.

Method to calculate C-factor

There are 2 methods which are most popular to calculate c-factor  which are as follows:-

1: Literature survey method: Also known as traditional approach and here with the help of land use land cover (LULC) map, the value of c-factor is selected for each land cover types based on the previous literatures.

2: Remote sensing approach: This method is applied using the normalized difference vegetation index (NDVI) and some special formula to calculate the c-factor using NDVI.

There are two formulas used under remote sensing approach;

(a) C-factor = 0.1[-NDVI+1]/2 given by Durigon et. al. (2014)

(b) C-factor =exp [-m*NDVI/ (n-NDVI)] given by knijff et al. (1999)

Here m=2, n= 1 and both determine shape of curve relating to NDVI and C-factor.