Evaluating Best Management Practices For Minimized Pesticides Transport With The Wepp-Ui Model

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Best management practice (BMP) tools that provide site-specific water quality suggestions with limited input data are needed to assist consultants and farm advisors as they work to target BMP placement and reduce dissolved and sediment bound pesticide loads from agricultural landscapes. BMP effectiveness largely depends on accurate characterization of dominant regional hydrologic processes. However, most BMP tools capture either infiltration excess runoff or saturation excess runoff but cannot predict a combination of the two. The objective is therefore to develop an easyto-use BMP tool capable of (1) accurately characterizing the dominant hydrological processes in a region of interest and (2) evaluating the selection and placement of various BMPs for reductions in pesticide loss. In this study we show that the Watershed Erosion Prediction Project University of Idaho (WEPP-UI) model with coupled pesticide module can realistically simulate both types of runoff processes as well as dissolved pesticide loss. Simulated runoff and dissolved atrazine concentrations were compared to observed data from mulch till (MT) and no till (NT) plots in the Goodwater Creek Experimental Watershed (GCEW) of northeastern Missouri. The timing of runoff predictions by WEPP-UI coincided well with observed events and flow magnitudes were between minimum and maximum observations for the two replicate plots. Nash-Sutcliffe efficiencies (NSEs) were 0.84 and 0.79 for MT and NT runoff simulations, respectively. Both simulations and observations showed little difference in total growing season (planting to harvest) runoff between MT and NT. Dissolved atrazine loads were well predicted for MT and NT plots with NSEs of 0.59 and 0.71, respectively. Consistent with observations, seasonal NT atrazine losses were higher than losses from MT plots. Lastly, we also use the WEPP-UI pesticides module to simulate the impact of precision application on dissolved pesticide loss. While this study only focuses on dissolved pesticide transport at the bottom of a 3 hillslope, the WEPP-UI pesticide transport module can predict loads for a variety of pesticide types from each section of the hillslope (i.e. top-slope, mid-slope, and toe-slope), including sediment bound pesticide loads. Vegetated buffer strip routines are also available but more extensive field monitoring is needed to validate these aspects of the model. 4
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water quality; atrazine; runoff
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Steenhuis, Tammo S
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Walter, Michael Todd
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Agricultural and Biological Engineering
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M.S., Agricultural and Biological Engineering
Degree Level
Master of Science
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Government Document
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dissertation or thesis
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