Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

The Soil and Water Assessment Tool (SWAT) model was the primary model selected for use in the Conservation Effects Assessment Project-Watershed Assessment Study (CEAP-WAS). In this paper, the performance of SWAT in simulating streamflow, sediment yield, and atrazine loss from Goodwater Creek, a 72 km2 watershed located in the claypan soil region of north-central Missouri, was evaluated. When the model was run using default parameters, it overestimated average annual streamflow by 32%, underestimated average annual sediment yield by 23%, and overestimated average annual atrazine loss by 8%. The Nash-Sutctliff coefficient (ENS) values were < 0.35 when annual estimated and measured values were compared. The model was calibrated for streamflow using data collected from 1992 through 1996. After calibration, the difference between measured and estimated average annual flow was < 5%, and the ENS values for annual and monthly simulation results were 0.90 and 0.85, respectively. After calibration, the model did not perform well in estimating streamflow on a daily basis (ENS=0.3). The calibrated model was also validated using data collected from 1997 through 2002 from the Goodwater Creek watershed and the performance of the model was good with ENS=0.88 for annual streamflow and ENS=0.68 for monthly streamflow. Overall, the annual and monthly streamflow predictions of the model were good. Future plans include (1) improving streamflow estimation on a daily basis, and (2) calibrating the sediment and pesticide components of the model.