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United States Department of Agriculture

Agricultural Research Service

Research Project: Conservation Effects Assessment Project (Ceap) 2013 - Agricultural Research Service Benchmark Watershed Assessment Studies (On Croplands)

Location: Hydrology and Remote Sensing Laboratory

Project Number: 8042-13610-028-64
Project Type: Interagency Reimbursable Agreement

Start Date: Jun 01, 2013
End Date: Sep 30, 2015

Objective:
The Hydrology and Remote Sensing Laboratory (HRSL) plans to develop a reliable management tool for quantifying the water quality impacts of cover crops using validation data from the Choptank Watershed. In FY12, HRSL successfully applied the SWAT model with adjustments to the NEXRAD precipitation input data (Sexton et al, 2010; Beeson et al., 2011), both at the German Branch (a 48 km2 sub-watershed above the tidal line in the Choptank watershed) and the South Fork watershed in Iowa. HRSL is now extending the application of the SWAT model to a significantly larger river basin, the Tuckahoe River watershed (228 km2), which is the upper branch of the Choptank River. The goal is to have a refined model to accurately assess the impacts of cover crops over a much larger region, containing a majority of the farmland supported by Maryland Department of Agriculture’s $18M cost-share cover crop program.

Approach:
Model simulations under current planting and cover crop conditions establish a baseline of nutrient load reduction effectiveness at a large scale that will be compared to an extensive and long-term USGS monitoring station and newly installed nutrient sensor at the outlet of the Tuckahoe river. In addition, an eddy covariance flux tower for measuring evapotranspiration has been installed in the Choptank, and will be used to evaluate and improve SWAT model water balance and soil moisture estimates. The HRSL will also continue similar SWAT modeling work by leveraging our NASA/NRCS project to develop a decision support system (DSS) to assess the impacts of shifting crop rotations as a result of biofuel demand for the CEAP Southfork Watershed and conduct preliminary testing on whether it is transferrable to the Choptank Watershed.

Last Modified: 12/21/2014
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