**2.5 RUSLE-Model**

RUSLE- model proposes the same formula as the USLE [12] but several improvements were carried out for the determination of the various erosive factors. This included an approach different from the erodibility of the soil K-factor, a new equation for topographic LS-factor, and a new value for the crop management C-factor and the practices of conservation P-factor. The application of RUSLE model requires the calculation of the various factors intervening on the erosive processes and their spatialization in the form of the thematical maps. The integration of these data in the GIS makes it possible to superimpose them and evaluate the rate of water erosion by applying the formula of: A = R\*K\*LS\*C\*P.

Where: A: is the soil loss per unit of area (t/ha/yr). The R-factor is rainfall and runoff erosivity factor (MJ mm/ha h yr). K (t h/MJ mm) is soil erodibility factor, LS (unit-less) is a topographic factor, C (unit-less) is a crop management factor and P (unit-less) is a conservation practice factor.
