Streamflow estimation using SWAT model including large storage reservoirs in Godavari River Basin, India

The present study reports the impact of multiple large storage reservoirs while estimating streamflow using the SWAT model in Godavari River Basin (GRB), India. The SWAT model used gridded precipitation data with observed large reservoir inflow and outflow. Twelve large reservoir data are used to study their impact on streamflow estimation in GRB. The streamflow has been simulated at 15 gauging stations for two scenarios, with and without large storage reservoirs. The model is validated by comparing the simulated streamflow with the observed streamflow during the period 2006–2013, after calibrating the model from 1965 to 2005. The performance indicators, namely RMSE , P bias , R 2 , and NSE have been used to evaluate the model. The sensitivity analysis revealed that out of several parameters, 16 model parameters and four reservoir parameters were the most influencing parameters. The SWAT model results revealed an underestimation of evapotranspiration (ET) and an overestimation of water yield when simulated without reservoirs. During calibration of the model, an R 2 and NSE of 0.95 and 0.94, respectively, are achieved at the Polavaram gauge station, the outlet of GRB. Overall, the SWAT model performance on streamflow estimation improved by up to 21% (at Polavaram station) during the validation period after considering large reservoirs in GRB. Research highlights Studied the impact of multiple large storage reservoirs in estimating streamflow using the SWAT model. A large Indian River Basin is studied for the first time. The results revealed the under-estimation of ET and over-estimation of the water yield in the SWAT model without reservoirs scenario. The streamflow simulation performance of the SWAT model is improved by 21% with reservoirs.