Mapping and predicting of water erosion using RUSLE in Mediterranean context: Case of El Kharroub watershed (Western Rif, Northern Morocco)

Abstract

Worldwide, soil erosion is one of the hazards posing a serious threat to soil and water resources, especially in the Mediterranean context. In Morocco, this phenomenon is a major problem in the natural territory, especially in the Rif Mountains in the north of the country, where fragile rocks dominate on steep slopes. Thus, this work aims to assess the soil erosion in the El Kharroub River watershed over the baseline period 2000-2020 and two future periods 2021-2030 and 2031-2050, using the Revised Universal Soil Loss Equation (RUSLE). For the future climate periods (2021-2030 and 2031-2050), precipitations were produced using a classical statistical downscaling model (SDSM). Over the current period, the results showed that the annual rainfall erosivity and the vegetation cover decreased from 2002 to 2020 by 34.3% and 28.6% respectively. The annual soil loss maps showed a decline of about 54.8% during the baseline period. The changes in rainfall and vegetation cover are largely due to climate changes effect and the deforestation/reforestation that the region has experienced, which subsequently leads to changes in soil erosion due to the important function of these two factors. Furthermore, projected scenarios revealed that the average annual erosivity could decrease to 268.4 and 267.1 for 2031-2050 and 2031-2050 scenarios compared with the current period. As a result, the average annual soil losses could decrease by 21.3 and 21.8% for the projected scenarios.