Assessment of soil erosion by the USLE model and geospatial analysis in the watershed of the Ben Abdelkrim El Khattabi dam (Northern Morocco)

Abstract

Soil erosion is a major environmental threat in the Rif region of northern Morocco, where steep slopes, fragile lithology, and anthropogenic pressures accelerate land degradation. This study applied the Universal Soil Loss Equation (USLE) combined with geospatial analysis to estimate and map soil loss in the Nekor watershed, upstream of the Mohamed Ben Abdelkrim El Khattabi dam. The results indicate a high spatial variability, with soil losses ranging from zero to more than 40 t·ha -1 ·year -1 . Low to moderate erosion (< 20 t·ha -1 ·year -1 ) dominates approximately 81% of the watershed, while severe to very severe erosion (> 20 t·ha -1 ·year -1 ) affects nearly 6.4%, mainly on steep and degraded land. These critical areas are primarily responsible for the rapid siltation of the dam. The findings emphasize the urgent need for effective soil and water conservation measures to ensure the sustainable management of land and water resources in the region.