Suitability of distributed SCS-CN model for Narmada basin: A case study of Uri river sub-basin

Abstract

Estimation of watershed runoff accurately has been a challenge for water resource managers and planner especially for large river basins. Inflow forecasting in the series of multipurpose reservoirs constructed in Narmada river basin shall be useful for maximization of hydropower generation to its optimum capacity. The accuracy in predicting the surface runoff becomes more imperative in case of large watersheds like river Narmada basin. In the present study, alternate options of spatially distributed SCS-CN model and modified SCS-CN model have been applied in the Uri river basin. The daily runoff has been computed under three conditions; (i) by considering area weighted average CN and rainfall, (ii) spatially distributed CN and rainfall with Ia/S ration as 0.2 and (iii) considering average CN and rainfall with Ia/S ratio as 0.05. The analysis shows that the computed runoff are more close to the observed runoff, if runoff is computed by considering area weighted average CN and average rainfall in lower Narmada river basin.