Assessment and mapping of water erosion by the integration of the Gavrilovic “EPM” model in the Inaouene watershed, Morocco

Abstract

Water erosion is one of the main causes of soil degradation around the world. In M orocco, In M orocco, the watersheds have very significant soil wastes, related to various physical and anthropic factors. The Oued Inaouene watershed is concerned because of its location in the eastern part of the Saïss basin, between the Middle Atlas and the Pre-Rif, where water erosion is more accentuated. This basin covers a total area of 3597.13 Km2 and it is marked by a semi-arid climate with relatively abundant (989.68 mm), irregular rainfall and strong anthropic pressure. This will have an impact of overexploiting natural resources in general and soils in particular. The excessive use of agricultural land has led to their fragility and aggravation of their susceptibility to erosion. These conditions, both natural and anthropic, have induced a rather intense erosive dynamic, which can be visible in its various forms, including gullying and landslides. The erosive dynamics leads progressively and certainly to impoverish the soils of the watershed and the silting of the dam Idris 1st located downstream of the Oued Inaouene, hence the interest of this study. The use of the “EPM” model for the estimation of soil losses approaches the severity of the erosive phenomenon. The average soil loss due to water erosion according to the model used is estimated at 53.34 t/ha/year. The maximum losses are about 597.642 t/ha/yr per plot. Total annual losses for the watershed are approximately 211084195 t/yr. Furthermore, the analysis of these results allowed, with the help of GIS, to determine the factors that control water erosion and which are, in order of importance: rainfall, slope, and soil sensitivity Soil protection. If anti-erosion measures aren’t adopted in the threatened parts of the watershed, this will have serious consequences for the dam and water quality .