The sensitivity analysis and performance of SWAT+ in simulation of stream flow in a mountainous catchment

In the context of floods, water stress or crises, climate change planning, and human activities, the application of ecological models for environmental management is critical. In this study, we used the Soil and Water Assessment Tool Plus (SWAT+), an upgraded version of SWAT, to route runoff in a mountainous catchment, Bostanabad, which is one of the headwaters of Ajichay (connected to the Urmia Lake basin), at monthly scale. At first the most sensitive parameters were selected by sensitivity analysis, and then the model was calibrated and validated during different periodss of time. We employed gridded temperature and precipitation produced based on elevation and data from existing gauges to overcome the model calibration tool's (SWAT+ toolbox) limitations in mountainous areas. The results indicated that the model is sensitive to the parameters of snowmelt-min, CN2 and CN3-swf, snomeltmin (table of hru), revap-min, bf-max and alpha, flomin (table of aqu), bd and awc (table of soil) and bd (table of rte). The gridded approach for simulation of discharge resulted in calibration performance based on R2, NSE, BAIS of 0.71, 0.68 and −2.81, respectively. This approach can be used to simulate discharge in mountainous catchments.