Identification of Sensitive Parameters for Runoff Simulation in Santrod Watershed Using QSWAT

In this study, Soil and Water Assessment Tool (SWAT) was employed in conjunction with remote sensing and geographic information system to simulate runoff in Santrod watershed, located in Mahi River basin, in the north-west region of India. The model calibration was performed on a monthly time-step for 2000-2014 period with an initial 2-year warm-up period (1998-1999). Following calibration, the model was validated using observed runoff data for 2015-2019. Model calibration and parameter sensitivity analysis were performed using automatic calibration feature available in the SWAT Calibration and Uncertainty Procedures (SWAT-CUP) software. Sensitivity analysis showed that hydrological processes of the watershed are highly influenced by soil evaporation compensation factor, threshold depth for shallow aquifer and runoff curve number factor. The model performance was found good during calibration with values of coefficient of determination (R²) as 0.91, Nash-Sutcliffe efficiency (NSE) as 0.91, percent bias (PBIAS) as 7.2 and root mean square error to standard deviation ratio (RSR) as 0.3. Similarly, the model performance was found satisfactory during validation with values of R², NSE, PBIAS and RSR as 0.86, 0.89, 8.4 and 0.24, respectively. Findings of this study provide valuable insights for policymakers, water resource managers and environmental planners. The findings can further guide in sustainable water allocation strategies and watershed conservation efforts, to ensure long-term health of Santrod watershed and support in effective water management practices in the region.