The white Bandama watershed in its upstream part is strongly anthrophised. Its position in a semi-arid zone gives it a high vulnerability to water erosion. However, water erosion of soils is at the root of many environmental and socio-economic problems. It therefore appears necessary to evaluate soil losses due to water erosion. To do this, the Wischmeier and Smith equation, or Universal Sol Loss Equation: USLE, is therefore a tool of choice for the modeling of the erosive process. This model works with the multiplication of six erosion factors namely the erosivity of the rain, the erodibility of the soil, the inclination and the slope length, the vegetation cover and the anti-erosion practices, in an Geographical Information System. The results obtained are at the scale of the watershed and in spatial unit (pixel of the DTM). Thus, the value of the average losses in 1986 is 42.87 t / ha / year, this value drops to 25.98 t / ha / year in 2001 and stands at 36.53 t / ha / year in 2016. In addition, vegetation cover, erodibility and erosivity of rainfall are the factors that most modulate erosion in this basin.