Hydrological Simulation in a Forest Dominated Watershed in Himalayan Region using SWAT Model

The present study is taken up to test the suitability of SWAT (Soil and Water Assessment Tool) model for estimation of runoff and to understand sensitiveness of model input parameters in a predominantly forested watershed in Kumaun region of Himalaya. The study area Dabka is a small watershed (69.41 km<Superscript>2</Superscript>) lies in North West of Nainital in Uttarakhand. The SWAT is calibrated at an upstream intermediate gauging site Bagjhala draining approximately an area of 65.78 km<Superscript>2</Superscript> on monthly basis due to non-availability of observed data at main outlet. A local sensitivity analysis is performed on 13 input variables in terms of model outputs such as water yield, surface runoff and baseflow to gain in depth understanding of the role of different model parameters for their proper selection. The study concluded that model performed well with Root Mean Square Error (RMSE) value 0.242 for calibration and 0.81 for validation. Nash Sutcliffe Efficiency (NSE) for calibration and validation period is obtained as 0.77 and 0.73 respectively whereas Coefficient of determination (R<Superscript>2</Superscript>) for calibration and validation period is 0.86 and 0.90 indicating good model performance. The most sensitive model parameters affecting water yield are CN2, GWQMN and SOL_Z. On the basis of sensitiveness of model parameters, the ranking of most sensitive parameters from highest sensitive to relatively lesser sensitiveness on stream flow are CN2, SOL_K and SOL_AWC whereas for base flow SOL_AWC, SOL_Z and GWQMN are found to be more sensitive followed by CN2, ESCO and SOL_K. Copyright Springer Science+Business Media Dordrecht 2013