Sensitivity analysis of SWAT model in the Yarra River\ud catchment

Catchment-scale hydrologic and diffuse source pollution models simulating a catchment are\ud useful analysis tools to understand problems and find solutions through simulation of BMPs for particular\ud catchment and agronomic settings. However, developing reliable catchment model and validating them on\ud real-world catchment with monitored data is challenging. In this regard, model calibration and uncertainty\ud analysis help to evaluate the ability of the model to sufficiently predict streamflow and constituent yields for\ud specific applications. Complex physics-based distributed models contain many parameters that can\ud complicate calibration process. In addition, the model when includes multi-variable at multi-site with multiobjective\ud functions introduces more complexity to the calibration process. Over-parameterization is a wellknown\ud problem in such distributed model. Sensitivity analysis methods reducing the number of parameters to\ud be adjusted during calibration are important for simplifying the use of these models. The objective of this\ud paper is to perform a sensitivity analysis for multiple variables (streamflow, sediment and nutrients) at three\ud sites on a SWAT model developed in the agricultural part of the Yarra River catchment, Victoria (Australia)\ud so that the model can be calibrated efficiently for water quality analysis purposes