Mapping of Soil Losses in the Gheralla Watershed (Eastern Pre-Rif Morocco) Using the RUSLE Model and GIS

Abstract

Water erosion has become one of the main natural hazards encountered in the Mediterranean mountains. Population growth, land clearing and overgrazing lead to the degradation of the vegetation cover and, consequently, to the increase of the erosive risk, which affects the soil productivity and accelerates the silting up of the dam. The Gheralla watershed is an elongated mountainous basin in the Perif region of northern Morocco and is strongly affected by soil erosion. The objective of this study is to map the erosion risk in order to help decision makers to take the necessary measures. Erosion drivers according to the RUSLE model were integrated into the GIS and combined according to the Universal Soil Loss Equation (RUSLE). The results show that the erosive risk in this basin is critical. Soil losses are estimated at 62.5 t/ha/year. The conclusions are intended for managers for a better management of natural resources, taking into account the agricultural vocation of the area and the need to preserve the hydraulic infrastructure downstream.