Modeling Daily Streamflow from Idamalayar Catchment Using SWAT

SWAT, a semi-distributed, continuous, and process-based hydrologic model, is used for many applications such as streamflow simulations, water quality modeling, sediment yield modeling, etc. It requires spatial as well as temporal data as input. The present study examines the application of SWAT in simulating the daily streamflow from the Idamalayar catchment, Kerala. The model was simulated from 1987 through 2017 using daily meteorological data keeping three years as a warm-up. To calibrate and validate the model, a stand-alone tool, SWAT-CUP, is used. The model's capability to reproduce daily streamflow was assessed by means of the four performance- measures, which are R2, NSE, PBIAS, and RSR. The values of these indicators turned out to be 0.64, 0.61, 22.5, and 0.63, respectively, in calibration, and while validating, these values were found to be 0.75, 0.67, 36.9, and 0.58, respectively. These values show that the model reasonably simulated the streamflow, especially at a daily time scale. Global sensitivity analyses showed that the effective hydraulic conductivity in main channel alluvium is the most sensitive parameter, followed by the SCS runoff curve number.