Print PageMonitoring and modeling the impacts of implementing a Conservation Reserve Enhancement Program (CREP) in the Green River watershed of Kentucky has led us to develop a Soil and Water Assessment Tool (SWAT) model for the 400,000 ha area. The conservation program is focused on reestablishing forested riparian corridor and replanting native grasses and forbs as stream buffers. The strengths of the USDA model, which focuses on agricultural management practices and ecosystem processes using GIS data and analyses, are in representing flows and sediment in the watershed in conjunction with landuses and changes in landuse over time. A major goal of the conservation program is to improve water quality by reducing inputs of sediment, pesticides, and nutrients into the river system.
Results/Conclusions
The model we have refined for the upper Green River basin, including calibration, validation, and sensitivity analyses, is very effective at accurately representing water flows under a range of conditions. The SWAT flow model developed and optimized using a five-year calibration period showed 97% agreement with USGS measured flows, and applying the model to a subsequent 5-year time period also showed 97% agreement with measured flows. We have also identified terms for modifying model flows in order to accommodate karst drainage in the regions where they are dominant or significant. A series of simulation experiments focused on sediment reduction using subwatersheds within the basin found differences in sediment reduction effects at field, subbasin, and reach scales that depended heavily upon landuse, watershed size, and stream order. These simulated results are compared to a background of direct water quality sampling efforts.
