RAINFALL RUNOFF MODELLING IN EPHEMERAL RIVER BASIN USING SWAT

Abstract

Ephemeral river is surface drainage network, normally stays dry and that occasionally may drain related discharge due to rainfall events. Present study focus on Sarada river; ephemeral river where flow occurs mostly during monsoon season, located in Andhra Pradesh, India. In this study SWAT model was used to study hydrological behaviour of the river. The sarada river watershed was split into 26 sub-watersheds; land use & land cover consists mainly of five Landuse classes (with an agricultural land covering more than 62%); the slope ranges mostly 0-10 m (more than 62%). The model was calibrated (1999 to 2005) and validated (2006 to 2008) with 1996 to 1998 as warm-up period at time scale of monthly at Anakapalle gauging station. Monthly calibration and validation shows significant matching between observed and simulated values when evaluated with statistical parameters like coefficient of determination (R2), Nash Sutcliffe Efficiency (NSE) and Root Mean Square Error (RMSE) fit of 0.83 & 0.85, 0.83 & 0.67, 9.8 & 15.9 respectively. The graphical representation also shows close match with observed and simulated values. Overall, efficiency of the SWAT model generating stream flow at Anakapalle gauge station has been classified as reasonably good. Optimized SWAT model can be implemented in watershed dominating with agriculture for runoff modelling. The model is demonstrated good execution on Ephemeral River and it will be help for the other rivers also.