Assessment of Soil Erosion in Siruvani Watersheds Based on USLE and Hypsometric Curve Methods

Abstract

Soil erosion poses a serious threat over the maintenance activities of a reservoir and its watershed. This study has been taken us to assess the extent of soil erosion in the watersheds of the Siruvani Reservoir located in the district of Kerala. Two methods namely, Universal Soil Loss equation (USLE) and Hypsometric curve methods are adapted in this study. Hypsometry of watersheds (area-elevation analysis) has generally been used to reveal the stages of geomorphic development (stabilized, mature and young). The watersheds of Siruvani Reservoir were delineated from the generated Digital Elevation Model (DEM) using Geographic Information System (GIS). Various set of data like land use map, rainfall and soil map have been used for this analysis to generate five factors namely finally, the soil erosion risk map was created to identify the regions which are susceptible to erosion. Hypsometric analysis deals with measurement of the interrelationships between basin area and altitude of basin which has been used to understand the influence of various factors such as climate, geology and tectonic changes. GIS provides advanced tools to obtain hypsometric information and also helps to estimate the associated parameters of landforms. The entire study area has been sub-divided into 5 watersheds for hypsometric analysis and their area ranges from 1.77 to 6.94 km2. The hypsometric curve of the whole the watersheds reflects the mature geomorphic terrain whereas hypsometric integral indicates that the drainage basin has already eroded per cent of land masses. These findings would emphasize the importance of soil and water conservation measures to be taken up in the Siruvani watersheds for controlling further erosion, reducing the sediment outflows and conserve water.