Modelling stream flow using swat model: A case study of Thuthapuzha river Basin, Kerala

Land, water and vegetation are the three basic resources that support life on earth with water being the most widely distributed natural resource. The best way to address water related issues is to manage water resources in a single river basin system. Hydrological models are considered to be an important tool in the management of water resources. The Soil and Water Assessment Tool (SWAT) model was used to model streamflow in the Thuthapuzha watershed in Kerala. The simulation period for calibration was 1989 to 2009; for validation of the model, data from 2010 to 2017 were used and the simulation was done on daily basis. The initial period of three years (1989–1991) was taken as a warm-up period. Two indices viz p-factor and r-factor were considered in the SWAT-CUP uncertainty analysis. During calibration the p-factor and the r-factor were 0.77 and 0.64 and during validation the p-factor and the r-factor were 0.85 and 0.56 respectively. The performance of the model was assessed by Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R²;), and per cent bias (PBIAS). The R²;, NSE and PBIAS values were 0.88, 0.88 and -1.4 for the calibration period and 0.8, 0.8 and 5.4 for the validation period respectively. Overall model statistics have shown that streamflow simulation could be successfully performed in the Thuthapuzha watershed using the developed model.