SWAT Literature Database for Peer-Reviewed Journal Articles

Title:Long-Term Agroecosystem Research in the Central Mississippi River Basin: SWAT Simulation of Flow and Water Quality in the Goodwater Creek Experimental Watershed 
Authors:Baffaut, C., E. J. Sadler, F. Ghidey and S. H. Anderson 
Journal:Journal of Environmental Quality 
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Model:SWAT (modified) 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:baseflow and other hydrologic component analysis 
Secondary Application Category:pesticide fate and transport 
Watershed Description:The Goodwater Creek Experimental Watershed (GCEW)covers 73 km^2 of relatively flat row crop fields, along with pastures and some woodland, about 45 km north of Columbia, Missouri. Goodwater Creek drains to Young’s Creek, which drains to Long Branch and ultimately to Mark Twain Lake, an artificial lake used for recreational purposes and drinking water supply. The GCEW lies within the Central Claypan Areas, which cover nearly 30,000 km2 in northeastern Missouri and southern Illinois and are characterized by claypan soils. In the GCEW, erosion has resulted in cultivated slopes being degraded: overall, the depth to claypan varies from the surface to 60 cm. 
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Abstract:Starting in 1971, stream flow and climatologic data have been collected in the Goodwater Creek Experimental Watershed, which is part of the Central Mississippi River Basin Long-Term Agricultural Research site. Since 1992, water quality and socio-economic data have complemented these data sets. Previous modeling efforts highlighted the challenges brought by the presence of a claypan. Specific changes were introduced in the Soil and Water Assessment Tool to: 1) better simulate percolation through and saturation above the claypan, and 2) simulate the spatial and temporal distributions of the timing of field operations throughout the watershed. The objectives of this paper were to document the changes introduced into the code, demonstrate that these changes improved simulation results, describe the model’s parameterization, calibration and validation, and assess atrazine management practices in the hydrologic context of claypan soils. Model calibration was achieved over 1993-2010 at the daily time step for flow and at a monthly time step for water quality constituents. The new percolation routines ensured correct balance between surface runoff and groundwater. The temporal heterogeneity of atrazine application ensured correct frequency of daily atrazine loads. Atrazine incorporation by field cultivation resulted in a 17% simulated reduction in atrazine load, without a significant increase in sediment yields. Reduced atrazine rates produced proportional reductions in simulated atrazine transport. The model can be used to estimate the impact of other drivers, e.g., changing aspects of climate, land use, cropping systems, tillage, or management practices in this context 
Keywords:restrictive layer, atrazine, operation timing, percolation, saturation