Spatial estimation of land loss in Zou catchment area at Atchérigbé outlet (Benin center)

Abstract. Soil degradation constitutes a major constraint for sustainable agricultural development, particularly in extension zones where land resources are under increasing pressure. This study evaluates soil loss and erosion sensitivity within the Zou watershed at the Atchérigbé outlet. The analysis integrated SRTM Digital Elevation Models (30 m, 2023), Landsat OLI TIRS 09 imagery (scenes 192-054 and 191-055, from 2018 to 2023), rainfall data from 1986 to 2021 provided by METEO BENIN, and FAO soil data. Soil loss was quantified using the Universal Soil Loss Equation (USLE), which combines rainfall erosivity (R), soil erodibility (K), the topographic factor (LS), and the vegetation cover factor (C) derived from supervised land cover classification. Five classes of erosion sensitivity were identified with in average 54 t ha−1 yr−1. Very low and low sensitivity zones dominate the watershed, covering 97 % and 2 % of the area, respectively. Medium-sensitivity areas (0.21 %) form a longitudinal band across the basin, while high-sensitivity areas (0.29 %) occur mainly in the western sector. Very high sensitivity zones (0.013 %) are localized in slope failure sites. These spatial patterns underscore the heterogeneous nature of erosion processes and their potential impacts on agricultural productivity, biodiversity, and ecosystem stability. While the USLE provides a robust framework for large-scale erosion assessment, its application remains constrained by sensitivity to input data accuracy and limited suitability under extreme conditions. Nevertheless, the results offer critical insights for watershed management. To mitigate ongoing land degradation, the study emphasizes the necessity of compensatory reforestation and the adoption of sustainable land management practices.