Computation of Runoff by SCS-CN Method from micro watersheds of Urmodi basin in Maharashtra state using RS and GIS

Abstract

Flood is a natural or manmade phenomenon and timely and accurate forecasting of flood is very important. However forecasting of flood is a difficult task due to influence of rainfall-runoff process which depends on various factors. Estimation of surface runoff in a watershed is based on the rate of precipitation and discharge at the outlet. In this study, runoff from micro watersheds of Urmodi basin in Maharashtra state was computed by Soil Conservation Service-Curve Number method using remote sensing and Geographic Information System (GIS) techniques. Various thematic maps such as soil map, land use/land cover, stream order, slope etc. were prepared using remote sensing and GIS. Daily rainfall data was used for determining runoff. Antecedent moisture conditions were determined from daily rainfall data and for different CNs with the help of combined land use land cover and hydrologic soil group map in GIS environment. Results showed that the highest runoff for Bharatgaon and Nagthane micro watersheds was 46.20 mm and 54 mm respectively. Total runoff depth for the year 2014 was computed as 215.05 mm for Bharatgaon micro watershed and 277.68 mm for Nagthane micro watershed. Different soil and water conservation measures and water harvesting structures were recommended to control soil erosion and to harness the surface runoff.