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

Calibration of model is a critical role for hydrologic modeling in a large mountainous watershed. Inthis study, Soil and Water Assessment Tool (SWAT) was calibrated in single-and multi-siteapproaches to simulate streamflow. In single-site calibration, a streamflow measurement at outlet ofwatershed was used for calibration of SWAT. Whereas in multi-site calibration approach, we usedstreamflow measurements at three stations namly Galinak, Joestan and Dehdar stations. The resultsshowed 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-sitecalibration method also showed slight improvement in Galinak, Joestan and Dehdar stations, whereas itwas 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, 0.63and 0.64 for Galinak, Joestan and Dehdar stations, respectively) compared to single-site calibrationmethod (NS: 0.74, 0.61 and 0.50 for Galinak, Joestan and Dehdar stations, respectively). The results ofthis study showed that the multi-site calibration method improved calibration of SWAT.