Alternative Land-Use Method for Spatially Informed Watershed Management Decision Making Using SWAT

In this study, a modification is proposed to the Soil and Water Assessment Tool (SWAT) to enable identification of areas where the implementation of best management practices would likely result in the most significant improvement in downstream water quality. To geospatially link potential locations to individual land owners, a land-use layer that incorporated specific crops and crop rotations needed to be developed. Model results obtained using the new land-use layer are compared to those obtained using a more conventional land-use layer. Results indicate that water flow and nutrient loadings are similar at the basin outlet, confirming the overall consistency of the approach. Water flow results at upland subbasin outlets appear similar; however, nutrient loadings are different since the crop distributions in the alternative approach are more representative of actual practice in the basin. These results suggest that the alternative, crop-rotation-specific method can be used to provide additional information for spatially resolved decision making regarding nutrient loading and downstream nutrient concentrations.