Method
The universal soil loss equation was employed to assess the amount of soil loss existed in the
Awash basin. The universal soil loss equation is an empirical model developed by Wischmeir
and Smith (1978) to estimate soil erosion from fields. Mathematically the equation is denoted
as: A (tons/ha/year) = R * K * L * S * C * P
Where A is the mean annual soil loss, R is the rainfall erosivity factor, K is the soil erodability
factor, L is the slope length factor, S is the slope steepness factor, C is the crop management
factor and P is the erosion control practice or land management factor. The USLE was applied
in GIS based on the flow chart as shown in figure 2.