Adaptation of the revised universal soil loss equation (RUSLE) to soil loss modeling in a semi-arid watershed: a case study from western high atlas, Morocco

Abstract

Soil loss called also soil erosion is one of the most irreversible natural phenomena that affect the topsoil of Earth’s surface worldwide, as it causes soil fertility reduction, water availability decrease, and initiation of geo-hazards, which leads to negative repercussions on agricultural production, considered the main source of income for most of the autochthonous in the moroccan High Atlas. Due to its climatic and anthropogenic conditions, this region is considered one of the most vulnerable areas to soil erosion in Morocco, with consequential environmental and socioeconomic concerns. This study assesses soil loss in the upstream part of the High Souss watershed in the moroccan western High Atlas, using an integrated analysis of Remote Sensing, GIS, and the Revised Universal Soil Loss Equation (RUSLE). This assessment is based on the integration of different influencing factors: climate, soil erodibility, topography, vegetation cover, and soil conservation practices. Results reveal that the High Souss watershed is exposed to significant erosion, with an average soil loss of 57.27 t/ha/year and an annual erosion amount of 7.3 million tons. This rate is considered to be intensively high in the moroccan context. Moreover, areas subjected to intensive erosion risk are mainly located in the upstream part of the basin, where moderate to steep slope lands are concentrated. The used methodology and results have been compounded to facilitate the analysis of this risk, providing an important basis for government decision-makers, helping the design of meaningful conservation planning programs to reduce soil erosion and conserve natural resources, thus supporting regional development.