Quantitative Mapping of Soil Erosion Using GIS/RUSLE Approach in the Falémé Sub-Watershed (Senegal/Kédougou)

The Faleme sub-watershed is influenced by several environmental factors. Located at the convergence of the Sudano-Guinean, Sudanian, and Sahelian climatic zones, the region is subject to diverse rainfall regimes. It is also an area of intense economic activity, notably mining and agriculture, both of which significantly contribute to land degradation. This degradation, primarily associated with rainfall variability and the shifting course of the Falémé River, results from a combination of natural and anthropogenic factors that shape the landscape. Key influencing variables include topography, pedology, rainfall, vegetation cover, and human-induced pressure. These elements collectively exacerbate the sub-watershed’s vulnerability to water-induced soil erosion, which manifests in three main forms: sheet erosion, rill erosion, and bank undercutting. The integration of remote sensing and Geographic Information Systems (GIS), combined with empirical modeling tools like RUSLE (Revised Universal Soil Loss Equation), enabled the quantification of annual soil losses. Spatial analysis and mapping revealed the most erosion-prone areas, particularly in the southern section, where moderate to severe losses represent approximately 14% of the basin’s surface area. A classification of annual soil loss levels indicated that 80.12% of the sub-watershed area falls within a tolerable range, whereas about 5% of the area experiences low losses.