Title: Swat Development for Simulating Flow and Pesticide Movement in a Large Claypan Watershed Authors
Submitted to: Annual International SWAT Conference
Publication Type: Abstract Only
Publication Acceptance Date: August 5, 2009
Publication Date: August 5, 2009
Citation: Baffaut, C., Sadler, E.J., Lerch, R.N., Kitchen, N.R., Sudduth, K.A. 2009. SWAT Development for Simulating Flow and Pesticide Movement in a Large Claypan Watershed [abstract]. In: 5th Annual International Soil and Water Assessment Tool Conference, August 5-7, 2009, Boulder, Colorado. p. 123. Technical Abstract: The Mark Twain Lake/Salt River Basin is located in northeastern Missouri and is the source of water to Mark Twain Lake (MTL), a public water supply that serves 40,000 people. At the outlet of MTL, the basin drains 6417 km2, including 10 major watersheds that range in area from 271 to 1579 km2. The basin is characterized by flat to gently rolling topography with a predominance of claypan soils that result in high runoff potential. The claypan soils are especially vulnerable to soil erosion, which has degraded soil and water quality throughout the basin, and to surface transport of herbicides. SWAT modeling efforts started with the intensely studied and monitored Goodwater Creek Experimental Watershed, a 73-km2 watershed in MTL. Modifications of the code were needed to improve the simulation of saturated conditions above the claypan, which cause excess runoff and subsurface lateral flow. The ability to use planting records was added, allowing specification of planting and herbicide application dates that matched real ones over a large area and long period. Results showed improvement of calibration and validation results for flow and atrazine. The model was used to estimate the effectiveness of several practices that impact herbicide transport including incorporation, filter strips, and reduction of application rates. Further work includes the application of the model to the whole MTL watershed, the simulation of nutrient and sediment transport, and the estimation of the impact of land use changes brought about by biofuel production.