Estimation of surface runoff for sub-watershed of Rajkot District, Gujarat, India using SCS – Curve number with integrated geo-spatial technique

Abstract

Catchment area of Rajkot District has described as a "water Scares" area, with constrained new water supplies, and is relied upon to be under water stress constantly. Along these lines, it is critical to building up any available means to supply water to maintain human life, for example, overflow gathering approach. The present paper carries the study of SCS CN methods of runoff estimation. Runoff is estimated for the 20 years for Sub-basin of Rajkot district. The Sub-basin and slope are delineated with the help of ASTER DEM in ArcGIS. The Sub-basin is selected which has maximum rain gauge stations. The Curve Number (CN) is a hydrologic parameter used to depict the stormwater flood potential for Drainage territory, and it is a component of land use, soil type, and soil Moisture. With the use of GIS integration and different thematic maps (Land use/Land cover, soil map, and slope map) Runoff volume can be found out. Landsat picture was converged with land cover data to make land use and land spread (LULC) depict. Yearly overflow quantity is gathered subject to the yearly precipitation surplus and spillover coefficient per pixel using a raster calculator in ArcGIS. Weighted curve number has been resolved so as to locate a representative curve number by incorporating attributes of different topical maps like LULC and Soil in ArcGIS using the area of LULC and soil types as weighted factors. Again the result by SCS CN method is compared with the rational formula and runoff coefficient method.