APPLICATION OF THE SOIL AND WATER ASSESSMENT TOOL (SWAT) FOR SEDIMENT TRANSPORT SIMULATION AT A HEADWATER WATERSHED IN MINAS GERAIS STATE, BRAZIL

Hydrological models have been increasingly employed for evaluation of pollution caused by diffuse sources in watersheds. In this study, the Soil and Water Assessment Tool (SWAT) was used to simulate streamflow and suspended sediment concentration (SSC) at the Lavrinha Creek watershed (LCW) outlet, which is situated in the Mantiqueira Range region in Minas Gerais State, Brazil. Temporal series associated with climatic variables, streamflow, and SSC were obtained from existing hydrological monitoring that has been conducted in the LCW since January 2006. Eight months (January 2006 to August 2006) were chosen as the warm-up period for the SWAT model, while two years (September 2006 to August 2008) were considered for model calibration and two years (September 2008 to August 2010) for model validation. A statistical index, Nash-Sutcliffe efficiency (NSE), was employed to evaluate the model performance. Streamflow simulations with SWAT on a daily basis resulted in NSE values of 0.81 and 0.79 for the calibration and validation periods, respectively; when simulating sediment concentration, the model resulted in NSE values of 0.68 and 0.75 for the calibration and validation periods, respectively. The SWAT model was considered adequate to simulate streamflow and SSC at the LCW outlet, thus constituting an important tool for water resources management in the Mantiqueira Range region.