ARS | Publication request: Swat Assessment of Management Practices on Atrazine Loss in the Good Water Creek Experimental Watershed.

Submitted to: Soil and Water Conservation Society
Publication Type: Abstract
Publication Acceptance Date: February 12, 2007
Publication Date: July 21, 2007
Citation: Baffaut, C., Bockhold, A.R., Thompson, A.L., Lerch, R.N., Sadler, E.J. 2007. Swat assessment of management practices on atrazine loss in the good water creek experimental watershed [abstract]. Soil and Water Conservation Society Annual Conference, July 21-25, 2007, Tampa, Florida. 2007 CD-ROM.

Technical Abstract: The Goodwater Creek Watershed is a subwatershed of the Mark Twain Lake watershed, an ARS-CEAP benchmark watershed in Northeast Missouri. This 7,250-ha watershed was selected for initial modeling because of its smaller size and the large hydrologic and climatologic dataset available. A SWAT model of this watershed was developed and calibrated for flow and atrazine concentrations from 1993 to 2003. This paper summarizes the efforts to calibrate and validate the model, which was then utilized to analyze and explain the trends observed in the water quality data between 1993 and 2003. Several factors were considered: weather trends, change in tillage practices, implementation of structural practices (terraces and grassed waterways), and changes in crop distribution. Since several of the input parameters used to represent these changes in SWAT cannot be dynamically modified in the course of a simulation, some of these factors were analyzed by comparing two boundary conditions over a 12-year period. The results indicate that grassed waterways were effective at the watershed level even when implemented on a small fraction of the watershed. The benefits are tempered by other factors such as tillage practices and increase in corn acreage. This combination of factors may explain why the trends are not so easily observed in the measured data.