Spatial Assessment of Soil Erosion in the Chitar River Basin through RUSLE–GIS Approach

Abstract. Soil erosion is a major problem, which has had adverse effects on the productivity of agriculture, the quality of water, and the sustainability of land in the long term, especially in semi-arid states of southern India. This paper examines the spatial and intensity of soil erosion in the Chitar River Basin, Tamil Nadu, through the usage of the Revised Universal Soil Loss Equation (RUSLE), the Geographic Information System (GIS) techniques and remote-sensing techniques. RUSLE components, such as rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover management (C), and support practices (P), were calculated based on the Indian Meteorological Department rainfall data, FAO soil data, a digital elevation model and Landsat-based land-use/land-cover data. Annual soil loss deposition ranges from negligible to over 100 t/ha/yr, confirming the basin's high spatial variability. Findings indicate that most of the basin is very low to minimal erosion (0–10 t ha⁻¹ yr⁻¹), and moderate erosion (10–25 t ha⁻¹ yr⁻¹) occurs sporadically. Spatial areas are limited to high and very severe erosion zones (25-100 t ha⁻¹ yr⁻¹) and extreme erosion areas (100 t ha⁻¹ yr⁻¹), which are mainly found in steep slopes, upper catchments and drainage networks, where high values of R, LS and C are also accompanied by relative high values of P-factor. These focal areas of erosion are a disproportionate contributor to sediment yield and thus require immediate Erosion conservation measures, including contour bunding, terraces, afforestation, and check dams. The study revealed that the RUSLE and GIS method is a highly effective instrument of defining erosion susceptible areas and the basis of managing the watersheds on a sustainable and targeted basis in the Chitar River Basin.