CS(AR)-35/96-97 : Estimation of soil erosion and sediment yield using GIS

Abstract

In the present study, a GIS based method is proposed and validated for prediction of sediment yield during isolated storm events. Data from Nagwa in Bihar (India) have been used. The ILWIS-GIS package has been used for catchment discretization into grid or cell networks and for evaluation of spatial variation in topographic characteristics and generation of travel time map and for carrying out other geographic analysis. ERDAS imagine image processing software has been used for digital analysis of IRS-1C and LANDSAT TM digital data to derive land use and soil map of the catchment. The gross soil erosion in the watershed is calculated using Universal Soil Loss Equation (USLE) by carefully assigning various USLE parameters based on soil and land use of the watershed. To arrive at the total sediment yield of the watershed from an isolated storm event, the concept of sediment delivery ratio (SDR) have been used. The SDR of a grid cell is hypothesized to be dependent on travel time to nearest stream channel for over land flow cells and equal to unity for channel cells. The proposed method is found to satisfactorily estimate the sediment yield of the watershed for isolated storm events.