Assessment of Soil Erosion Susceptibility in Kothagiri Taluk Using Revised Universal Soil Loss Equation (RUSLE) and Geo-Spatial Technology

Soil erosion is a serious environmental problem in Kothagiri Taluk. Many studies have been carried out to map shifting cultivation and areas susceptible to soil erosion. Mostly, estimated soil loss is taken as the basis to classify the level of soil loss susceptibility of area. The Revised Universal Soil Loss Equation (RUSLE) function is a commonly used erosion model for this purpose in Kothagiri Taluk. This research integrates the RUSLE within a Geographic Information System (GIS) environment to investigate the spatial distribution of annual soil loss potential in the Kothagiri Taluk. Both magnitude and spatial distribution of potential soil erosion in the catchment is determined GIS data layers including, rainfall erosivity (R), soil erodability (K), slope length and steepness (LS), cover management (C) and conservation practice (P) factors were computed to determine their effects on average annual soil loss. The rainfall erosive factor was developed from local annual precipitation data using a modified Fournier index: The topographic factor was developed from a Digital Elevation Model (DEM); the K factor was determined from a combination of the soil map and the geological map; and the land cover factor was generated from IRS LISS III images. The resultant map of annual soil erosion shows a maximum soil loss of 27.11 t h-1 y-1 with a close relation to built-up land areas, crop land and forest plantation on the steep side-slopes (with high LS). The derived soil susceptibility map from RUSLE model is classified into five categories ranging from very low to very high risk (< 3 to > 20 t h-1 y-1) depending on the calculated soil erosion amount. The soil erosion in each cell was calculated using the revised universal soil loss equation (RUSLE) by carefully determining its various parameters and classifying the study area into different levels of soil erosion severity. The high soil erosion probability zone was observed in areas with high terrain alteration, high relief and slopes with the intensity and duration of heavy precipitation during the monsoons. The soil erosion susceptibility map is linked to elevation and slope maps to identify the area for conservation practice in order to reduce the soil loss.