Assessment of Soil Erosion with RUSLE 3D and USPED in the Nekor Watershed (Northern Morocco)

Abstract

Over the last decades, estimation of soil erosion using empirical models has long been an active research topic, especially because they are useful to establish watershed management plans. Nevertheless, their application over large areas in a data-scarce Mediterranean region is still a challenge given the furrowed and steep nature of landscapes as well as the aggressiveness of the semi-arid climate. The main purpose of this research was to identify the spatial patterns of erosion and deposition in Nekor river basin (Northern Morocco) using two models: the Revised Universal Soil Loss Equation for Complex Terrain (RUSLE3D) and the Unit Stream Power-based Erosion Deposition (USPED). The two models were evaluated using existing annual soil loss rate measurements. As a result of the RUSLE3D application, about the 73% of the Nekor basin ranges between moderate and extreme risks of erosion, while according to USPED estimation, only 50% of the basin ranges between moderate and extreme risks of erosion. The analysis shows that the mean annual soil erosion rate for both models ranges between 60 and 65 t⋅ha−1⋅year−1 while the mean annual deposition rate is 38 t⋅ha−1⋅year−1. The current results confirmed those coming from previous soil erosion studies, which estimated annual soil loss rates in Nekor river basin between 50 and 70 t⋅ha−1⋅year−1. This study also provided valuable guidance on where to implement soil protection measures.