Modeling and Mapping Water Erosion Risk via GIS, Remote Sensing, and the PAP/RAC Model - Case of Tamdrost Watershed, Morocco

Abstract

Water erosion remains the main form of land degradation globally, with a particularly high sensitivity in Morocco. This study aims to assess and map areas at risk of water erosion in the Tamdroust watershed (Settat Plateau, Morocco) using the PAP/RAC model combined with Geographic Information Systems (GIS) and remote sensing. This comprehensive approach integrates several factors influencing erosion, such as topography, lithology, vegetation density, and land use, to identify erosion-prone areas. The methodology comprises three phases.The first, "predictive" phase generates a synthesized map illustrating the distribution of erosion states. The second phase spatializes different forms of erosion. Finally, the third phase integrates the results of the first two phases. The first phase reveals an abundance of moderate erosion covering 52% of the area, with significant erosion observed in about 7% of the watershed, indicating a trend towards increased erosion without intervention. The subsequent phases identified several forms of erosion such as sheet erosion, gully erosion, solifluction, and Badlands, mainly in areas with steep slopes and low vegetation cover. These results underline the need for interventions to prevent further deterioration of the Tamdroust watershed, highlighting the importance of sustainable land and water resource management in the region.