Spatial Mapping of Runoff from a Watershed Using SCS-CN Method with Remote Sensing and GIS

Abstract

This study aims to simulate runoff depth using the Soil Conservation Service–curve number (SCS-CN) method with remote sensing and geographic information system (GIS) techniques. In this study, the SCS-CN technique adapted for Indian conditions has been used for the generation of CNs for an ungauged watershed. The USDA SCS-CN method is used for estimating the runoff depth in the Manimuktha subwatershed. Monthly and annual runoff values have been obtained from the daily runoff values of the watershed. A base map, soil map, and land use map of the study area have been prepared using remote sensing data and Survey of India (SOI) toposheets. The vector layers have been generated in GIS software. The SCS model is then applied to estimate the daily runoff from the watershed and validated, comparing it with the observed runoff of a few selected events of the monsoon periods of 1980–2009. The statistical analysis indicates that the SCS-CN method can be applied to predict runoff depths of an ungauged watershed. The present study reveals that the remote sensing and GIS-based SCS-CN model can be used effectively to estimate the runoff from the ungauged Indian watersheds of similar geohydrological characteristics.