Water erosion assessment in watersheds of the Tunisian semi-arid area with RUSLE and MUSLE models coupled with a Geographic Information System

Abstract

Water erosion is an important agronomic, economic and environmental concern in the semi-arid Mediterranean environment. Characterization of the process and choice of a method for estimating it depends on available data and characteristics of the study area. This article aims at quantifying and spatializing water erosion using the Modified (MUSLE) and Revised (RUSLE) Universal Soil Loss Equation coupled with a Geographic Information System (GIS): MUSLE-SIG and RUSLE-SIG. Erosion was modeled in two watersheds located in central Tunisia, Fidh Ali and Fidh Ben Naceur. Field data from 1994 to 2000 were used to calibrate RUSLE-GIS and MUSLE-GIS. Results showed a faithful modeling of reality in terms of landscape degradation. Both models gave relatively similar results. While RUSLE-GIS, more recent, is widely used by researchers in Tunisia, the calibrated version of MUSLE-GIS also gave satisfaction in simulating water erosion. Consequently, both models could be used in Tunisia by development agencies aiming at reducing soil erosion, the choice of one or the other depending on the available data.