Soil erosion modelling using GIS-integrated RUSLE of Urpash watershed in Lesser Himalayas

The Urpash watershed located in the Lesser Himalayas (India) has experienced substantial soil erosion challenges. Therefore, the Revised Universal Soil Loss Equation (RUSLE) model, integrated within a Geographic Information System (GIS) environment, was employed to evaluate the spatial distribution of erosion within the Urpash watershed. To execute the model, inputs such as ASTER DEM, annual rainfall data for the year 2019, Land Use Land Cover (LULC) maps, and soil texture data were utilized as data sources. The average annual soil loss across the Urpash watershed ranged from 0 to 193.15 t/ha/year, with the mean annual loss estimated at 22.46 t/ha/year. Zonal statistical analysis revealed that barren land and open forests were more susceptible to erosion, with estimates of 86.22 and 68.46 t/ha/year, respectively. In contrast, waterbodies, built-up areas, and evergreen forests exhibited lower erosion susceptibility. Based on soil loss values, the watershed was categorized into six sub-watersheds. WS₆ and WS₃ were identified with severe soil erosion (40–80 t/ha/year), WS₂ with very high (20–40 t/ha/year), WS₅ with high erosion (10–20 t/ha/year) and WS₁ and WS₄ with moderate erosion. (5–10 t/ha/year). Thus, the sub-watershed priority was in the order of WS₆ > WS₃ > WS₂ > WS₅ > WS₄ > WS₁. Our findings indicated that regions with high slope gradients and barren land were hotspots for severe and very severe erosion. While acknowledging the existence of other factors such as soil type, intensity of rainfall, land cover, and land practices, the study found their impact to be comparatively less pronounced than the dominant roles played by high-slope areas and barren lands. The severity data from sub-watersheds can inform targeted conservation strategies to combat soil erosion effectively within the Urpash watershed.