Remote Sensing and GIS Application for Soil Erosion and Sediment Yield Estimation of Purna River Sub-Basin

Abstract

Apart from other significant environmental issues, one of the severe threats to the continents is soil erosion. As a result, significant cultivable land has been deteriorated. The Purna River watershed, located at south east of Gujarat, India, was selected as a study area for this research work. The rainfall, DEM, soil map, and satellite imagery were used to compute various factors of soil erosion such as rainfall erosivity, topography, conservation practise factor, soil erodibility, and cover management sequentially. NDVI which reflects the percentage of vegetation was used for the estimation of C-factor. The sediment yield was determined by using the SDR model. After spatial evaluation using RUSLE model within GIS interface, it was seen that 1131.73 × 103 t soil was lost annually at average rate, and sediment yield was 122.68 × 103 t/year. Resulted soil erosion map showed that in the Purna River basin, the steeper the slope, the more erosion occurs. That leads to conclusion that soil erosion for Purna River watershed was more correlated with the LS-factor than any other factor. Sediment yield was found out using SDR model as a fraction of soil loss. It was seen that SDR model gave closest result to observed sediment load with R2 = 0.99 for validation of model at Mahuwa station. Net sediment load at the outlet of Purna River into Arabian Sea was found out to be 112,680 t/year with sediment delivery ratio 10.84. All the statistics about soil erosion, SDR model, and sediment yield can be much resourceful for watershed management study of Purna River watershed. On a catchment scale, geospatial technologies proven to be effective tools for evaluation of soil erosion and estimating sediment output at the definite location on the streams.