Hydrologic Modeling of the Tuckahoe River Basin in Maryland's Coastal Plain.

The Choptank River watershed, located on the eastern shore of Maryland, is one of the major river basins within the larger Chesapeake Bay watershed.  This watershed is nearly 60% agriculture and contains heavily scattered poultry operations.  According to the USEPA, nearly 63% of the nutrient loads to the Choptank River come from agricultural sources and therefore, this river is considered as one of the major contributor of nutrients into the Chesapeake Bay watershed.  There is an increasing demand for a well-tested water quality watershed model that can be used as a reliable management tool to help assess the effectiveness of different BMPs and management options for more sustainable farming practices and safer environment.  As part of the Conservation Effect Assessment Project (CEAP), we successfully applied SWAT model to a small subbasin within the Choptank watershed for the purpose of model calibration. Model prediction of streamflow was good with Nash-Sutcliffe efficiency coefficients of 0.46 to 0.58 during calibration and from 0.68 to 0.76 during validation. In this work, we are applying the SWAT model to a much larger basin, the Tuckahoe River Basin, which is the upper branch of the Choptank River in Maryland.  The specific aim is to have a reliable management tool to assess the impact of cover crops, wetlands conservation and restoration, and development of management strategies in reducing nutrient loads within this river basin.  The Tuckahoe River has an extensive and long-term USGS monitoring station at the watershed outlet that will be used for model calibration and validation.  Model simulation results on water balance components as well as some of the known cropping systems rotations and cover crops with regards to nutrient loads reductions will be presented.