Assessment of soil erosion processes by applying IntErO model within the Mkhdach catchment (Middle Atlas of Morocco)

Water erosion processes primarily cause soil degradation and environmental issues in Morocco. The Middle Atlas Mountains have faced significant problems related to soil erosion. In addition to the actual increase of this phenomenon, this study aims to (i) evaluate soil erosion dynamics using the Intensity of Erosion and Outflow (IntErO) model, (ii) identify the main environmental factors controlling sediment generation within the Mkhdach Mediterranean headwater catchment, and (iii) validate the model outputs through field monitoring of representative gullies between January 2021 and December 2023. Some representative gullies were monitored to estimate the rate of soil loss in this headwater. To achieve this goal, the study applied the Intensity of Erosion and Outflow (IntErO) method in conjunction with the Geographic Information System (GIS) to assess the soil erosion dynamic in the study area. Field observations were used to analyze the interaction between soil properties and precipitation related to rainfall erosivity. Representative gullies were monitored between January 2021 and December 2023 to assess soil erosion dynamics under varying rainfall conditions. The studied catchment covers an area of approximately 2,537 hectares (> 25 km²) and is characterized by geological formations dominated by marls, red clay, limestone, and shale, which influence soil erodibility and sediment generation within the basin. Consequently, the obtained results indicate that rainfall is characterized by a significant variability at annual and seasonal scales. This variability is in line with the Mediterranean climate’s tendency for irregular rainfall distribution. The modeling results revealed a substantial intensity of soil erosion, with a total estimated sediment production of approximately 417,484.70 m³ yr⁻¹. Considering the catchment’s deposit retention coefficient (Ru = 0.34), only a portion of this material is expected to remain within the basin, while the remainder is effectively exported as sediment yield. Accordingly, the net or “actual” soil loss reaching the outlet was estimated at 143,368.44 m³ yr⁻¹, corresponding to approximately 51.2 Mg ha⁻¹ yr⁻¹ when normalized by basin area. A Pearson correlation matrix of key IntErO parameters revealed strong interdependencies between erosion variables and highlighted the central role of precipitation in soil erosion and sediment generation. Nevertheless, it should be noted that the IntErO model assumes simplified relationships between variables and may have several limitations that can underestimate or generalize complex erosion processes. These findings indicate a high risk of excessive soil erosion compared with other small Mediterranean mountain catchments, mainly due to the basin’s erodible lithology and limited vegetation cover, which together amplify runoff and sediment yield intensity. Gully erosion is a complex process in the studied area, indicating the high intensity of soil loss. This study offers a valuable and unique contribution by combining field data on gully erosion with the IntErO model and GIS techniques to evaluate soil erosion in a Mediterranean mountain area that hasn’t been well researched. Consequently, this study’s results offer substantial understanding of the geographical patterns and factors that influence soil erosion in Mediterranean mountain ecosystems. They will aid decision-makers to mitigate erosion risks through climate-resilient land management policies specifically designed for vulnerable headwater catchments.