Assessment of soil erosion and sediment transport susceptibility in the Shambhavi River Basin of India’s Western Ghats using RUSLE model

Soil erosion is a critical issue, especially during the monsoon season in the Western Ghats of Karnataka, India. Consequently, estimating soil erosion is crucial for informed decision-making to prevent further land degradation. Therefore, this study focuses on estimating soil erosion and sediment transport susceptibility in the Shambhavi River Basin of Western Ghats, India, using a GIS-based approach and the Revised Universal Soil Loss Equation (RUSLE) model. The input data include rainfall records from 1990 to 2021 to derive the rainfall-runoff erosivity (R) factor map, the FAO/UNESCO soil map for the soil erodibility (K) factor map, Sentinel-2 multispectral satellite imagery for the land use land cover (LULC) (C) factor map, and the SRTM DEM (30 m spatial resolution) to create topography-related (LS and P) factor maps. Soil loss estimates derived from the RUSLE model were mapped, and two composite indices — Soil Erosion Susceptibility Index (SESI) and Sediment Transport Susceptibility Index (STSI) — were produced using the Weighted Overlay approach. The results revealed that the total soil loss was estimated to be 23,805 t yr-1 with a mean annual soil loss of 0.69 t ha-1. Compared to the maximum permissible soil loss of 11.2 t ha-1 yr-1 in India, the estimated annual loss of 0.69 t ha-1 yr-1 is relatively low. Additionally, 87.13% of the basin lies below 1 t ha-1 yr-1. SESI classifies approximately 41% of the basin as high, 39% moderate and 20% low susceptibility. While STSI indicates 34.25% high, 48.35% moderate and 17.40% low susceptibility to sediment transport. The estimates were validated and found to align with those results reported in similar studies. The novelty of this study lies in: (i) providing quantitative soil erosion estimates and sediment transport assessment for the Shambhavi River Basin; (ii) combining RUSLE model with dual susceptibility indices (SESI and STSI); and (iii) translating spatial results into actionable conservation priorities. These contributions strengthen the scientific foundation for region-specific land management in the Western Ghats. Understanding the spatial heterogeneity of soil erosion supports improved land management practices and helps mitigate downstream impacts.