Intercomparison of SWAT models in simulating hydrology of Cannonsville Reservoir Watershed

The Soil and Water Assessment Tool (SWAT) model is a watershed scale hydrologic model created to simulate long term runoff and nutrient losses in rural, agriculturally dominated watersheds. The important model inputs are climate, soil, elevation and land use information. In this study, three versions of SWAT models namely SWAT2005, SWAT2009 and SWAT-WB (water balance) are used to simulate hydrology of the Cannonsville Watershed. The SWAT-2005 and 2009 model hydrologic response units (HRU’s) are grouped according to soil type and plant cover while in SWAT-WB a soil topographic index is used to delineate the HRUs. Runoff for each HRU is calculated with the SCS curve number method in SWAT 2005 and 2009. In SWAT-WB the curve number routine is replaced by saturation excess runoff mechanisms where surface runoff occurs when the soils become saturated. These models are calibrated using Dynamically Dimensioned Search and Shuffled Complex Evolutionary & Uncertainty Analysis with 10 years of data for the Cannonsville Watershed and then used to predict an additional eight years of data. The models are evaluated by comparison to the discharge at the watershed outlet as well as the spatial distribution of runoff source area in selected parts of the watershed where the spatial information is available.