Determination of reservoir inflows from river basin using Soil and Water Assessment Tool (SWAT) and SWAT-CUP: A case study

In this study, Soil and Water Assessment Tool (SWAT), a widely used semi distributed model (Arnold et al. 1998; Srinivasan et al. 2010; Saraf and Regulwar 2018) is adopted for estimating streamflow in Upper Godavari (UG) basin, a sub basin of Godavari river, India. The UG basin receives less rainfall compared to other sub basins of Godavari catchment, which is a major source of water for agricultural dominant land within the basin. Availability of large storage capacity in small groups of reservoirs in the catchment, improper measurements of runoff, gaps in runoff observations gives additional challenges to model the river system. Therefore, there is a strong need to determine exact potential of the watershed up to Jayakwadi dam located at the outlet of the UG basin. Secondly, streamflow estimations in large river catchments is becoming a serious issue in recent decades due to the obstruction of natural river flow by large storage structures constructed across the rivers. Improper estimation can lead to the false results which can further take hydrologic modellers near to the non-realistic results leading to failure of water resources management (Ikhar et al. 2018). Hence, the main objective of the present study is to estimate the streamflow in UG basin using SWAT model by considering several large reservoirs located within the catchment. Further, quantification of parameter uncertainty in hydrological modeling is necessary to obtain its sensitivity information. SWAT requires a large number of input parameters, which complicates model parameterization and calibration. SWAT-CUP provides a decision-making framework that incorporates a semi-automated approach (SUFI2, ParaSol) using both manual and automated calibration and incorporating sensitivity and uncertainty analysis especially with reservoir details.