Hill slope runoff estimation by using curve number method

Abstract

USDA-SCS (now NRCS) Curve Number method is most widely used for runoff estimation due to its simplicity and lesser-input data. Though this method was developed for event-based rainfall, it has been widely used for predicting runoff from daily rainfall data. This method was developed for small agricultural watershed with slopes less than 5 per cent. There is necessity to estimate runoff from hill slope areas for implementing several soil and water conservation programmes, water resource assessment. development and management. In this study runoff from small hilly watersheds was estimated by using USDA-NRCS Curve Number method and estimated runoff were compared with the observed runoff. From the results of the study it was observed there are wide variations between estimated and observed runoff and variations are increasing with storm size. From the results of the study it can be concluded that curve number method for runoff estimation when applied to hilly micro watersheds would lead to underestimation of runoff.