Assessment of soil erosion risk severity using GIS, remote sensing and RUSLE model in Oued Laou Basin (north Morocco)

Abstract

Soil loss by lateral flow is a critical bother in the Oued Laou basin due to the steepness of its landscape relief and the considerable deference altitudinal between the upstream and downstream area. Those predispositions highly increase soil vulnerability to the risk of erosion indeed; tones of sediment are transported each year, causing significant damages regarding structures and waterworks such as siltation. For this reason, this work focus on the merging of remote sensing techniques, GIS, and the Revised Universal Soil Loss (RUSLE) Equation to quantitatively evaluate soil erosion severity as well as highlight the most erosion-prone areas in the Oued Laou basin, Northwestern Morocco. Accordingly, the study site area was arranged into six soil erosion risk categories: very slight (25.3%), slight (12.4%), moderate (40.5 %), intense (12.2%), very intense, (5%) and severe (4.6%). Moderate to severe soil loss rates that are correlated to abrupt slopes defined most of the basin area. In addition to the spatial distribution of soil severity classes over the study area, the average annual soil erosion rate was estimated to be 31.5 t ha–1 year–1 in the Oued Laou watershed. The latter amount was compared to many previous studies that have been carried out in the surrounding basins based on RUSLE or other techniques to validate the model accuracy.