Comparison of Single-site and Multi-site Based Calibrations of SWAT in Taleghan Watershed, Iran

Calibration of model is a critical role for hydrologic modeling in a large mountainous watershed. In this study, Soil and Water Assessment Tool (SWAT) was calibrated in single-and multi-site approaches to simulate streamflow. In single-site calibration, a streamflow measurement at outlet of watershed was used for calibration of SWAT. Whereas in multi-site calibration approach, we used streamflow measurements at three stations namly Galinak, Joestan and Dehdar stations. The results showed that the single-site calibration was able to sufficiently simulate the streamflow for Galinak, Joestan and Dehdar stations (Nash-Sutcliffe criteria (NS: 0.66–0.81). The results of multi-site calibration method also showed slight improvement in Galinak, Joestan and Dehdar stations, whereas it was improved in upper stations i.e. Joestan and Dehdar (NS: 0.70–0.82). But, in validation period, there were clearly adventage of results provided using multi-site calibration procedure (NS: 0.78, 0.63 and 0.64 for Galinak, Joestan and Dehdar stations, respectively) compared to single-site calibration method (NS: 0.74, 0.61 and 0.50 for Galinak, Joestan and Dehdar stations, respectively). The results of this study showed that the multi-site calibration method improved calibration of SWAT.