Quantification of soil erosion rates using the model SWAT in El-Hachef Watershed (north-western Morocco)

Abstract

Soil erosion is becoming acute in northern Morocco. It recognized as the most dangerous form of land degradation, which causes serious environmental problems, for agriculture, for road infrastructure and for dams. A quantitative identification of potentially most erodible areas, associated with a spatial and temporal distribution of erosion rates remain a necessity, to optimize the means implemented to combat this phenomenon. It is in this context that the use of mathematical models and computer systems are of growing importance. The purpose of this research was to study the capabilities of SWAT to simulate land losses in the watersheds of northwestern Morocco. The land, on which the model is implemented, is El Hachef watershed. SWAT model performance, as well as the dynamics and spatial disparities of soil losses at the watershed scale are illustrated and discussed. The simulation of the earth loss, at a daily time step, over the period from 1959 to 2011 shows that the average annual rate of soil erosion in the El Hachef watershed is 26.65 t/ha/yr. It also made it possible to describe the spatial and temporal variation of the quantities of sediments transported by runoff, at the watershed level. The highest rates exceeding 50 t/ha/yr are recorded in the sub-watersheds located in the northeast part of the watershed. This initiative makes it possible to accomplish a realistic soil loss modeling in El Hachef watershed, and highlights the performance of the tool for different processes.