Modification of SWAT for modelling streamflow from forested watersheds on the Canadian Boreal Plain

Several modifications were made to the Soil and Water Assessment Tool (SWAT) to better represent processes occurring within forested watersheds on the Boreal Plain in Canada. The modified model, called SWAT(BF), was applied to the Willow Creek watershed (15.1 km(2)) in north central Alberta. The performance of the model for the calibration period (2001-2003) was good with coefficients of efficiency of 0.89 and 0.81 being achieved for the prediction of monthly and daily runoff, respectively. However, it was found that SWATBF did not perform as well for the validation period (2004-2006) with the monthly and daily coefficients of efficiency being 0.44 and 0.27, respectively. Potential sources of error to explain the decline in model performance for the validation period are discussed. SWAT(BF) has the potential to be used as a tool by forest managers for predicting the effects of land use change on the Boreal Plain provided that it can be satisfactorily validated.