Integrating RUSLE, GIS, and Remote Sensing for Soil Erosion Assessment in Morocco's Raouz Watershed

Abstract

Soil erosion threatens sustainable development in Morocco's Rif Mountains, causing severe land degradation and reservoir sedimentation. This study quantifies erosion rates in the Raouz watershed (46.89 km 2 ) using the Revised Universal Soil Loss Equation (RUSLE) integrated with GIS and remote sensing. We analyzed five erosion factors: rainfall erosivity (R), soil erodibility (K), topography (LS), cover management (C), and conservation practices (P). Results reveal a mean annual soil loss of 16.53 t ha -1 yr -1 , with severe erosion (>20 t ha -1 yr -1 ) affecting 26.4% of the watershed. Critical hotspots (7.3% of area) contribute 35-40% of total sediment yield. Validation against Caesium-137 measurements shows strong agreement (R 2 =0.76). Topography (52% variance) and vegetation cover (31% variance) emerge as dominant erosion controls. The Moulay El Hassan Ben Mehdi Dam faces annual sedimentation of 23-31 t yr -1 , threatening water security for 500,000 inhabitants. Findings support targeted conservation strategies prioritizing steep, sparsely vegetated upper watershed areas.