Nadia Bernardi Bonumá,C. G. Rossi,J. M. Reichert, University of Santa Maria, , nadiabonuma@gmail.com
ABSTRACT
In Southern Brazil, native forests are being replaced by tobacco crops. These changes are negatively impacting the region’s water balance and resource quality. Accurately representing the region’s hydrologic processes is essential to obtaining meaningful water and contaminant transport results. The Soil and Water Assessment Tool (SWAT) model was used to evaluate the hydrology of the Arroio Lino watershed, located in Southern Brazil. Measured streamflow data was used in model streamflow parameter sensitivity analysis, calibration and validation. Sensitivity analyses were performed on 27 input variables. Model calibration was performed with a Shuffled Complex Evolution Algorithm (SCE-UA). The parameters that had the most responsive model outputs were: runoff were curve number (CN2), soil evaporation compensation factor (ESCO), and baseflow alpha factor (ALPHA_BF). The predicted monthly streamflow matched well with the observed values, with a Nash–Sutcliffe coefficient of 0.87 and 0.76 for calibration and validation, respectively. Daily simulations were less accurate than monthly predictions. Results indicate that the model is a promising tool to evaluate small watershed hydrology in subtropical areas for long time periods. This model will continue to be used for climate and land use change analyses and to assess the impact of various management scenarios on stream water quality.
Keywords: SWAT model; Hydrologic processes; Agricultural watersheds