Application of Soil and Water Assessment Tool for Runoff Simulation in a Data Scarce Himalayan Watershed

Abstract

The present study was conducted to simulate runoff in the watershed of Dal (188.72 km2 ) located in the temperate region of Kashmir using Soil and Water Assessment Tool (SWAT). The study watershed is characterized by significant climatic contrast, abrupt topography, and soil fragility, thereby resulting in flash floods and water erosion. Such situation requires interventions to preserve soil and water resources, and a decision tool for integrated watershed management. The SWAT was calibrated for the year 2010, and validated for the year 2011, based on a comparison of simulated and observed monthly runoff at the watershed outlet. The model performance was evaluated using coefficient of determination (R2 ), Nash-Sutcliffe efficiency (ENS), relative root means square error (RRMSE) and percent bias (PBIAS). During the calibration period, R2 , ENS, RRMSE and PBIAS were 0.98, 0.87, 1.3 and (-) 26, respectively. During the validation period, the values of R2 , ENS, RRMSE and PBIAS were 0.97, 0.84. 1.1 and (-) 26.0, respectively. The modelled values showed reasonably good agreement with the observed values of runoff, both during calibration and validation periods. The runoff in the watershed was quantified under the prevailing land use conditions. The study demonstrated a satisfactory application of the SWAT model for quantification of hydrological processes in a watershed under data scarce condition.