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United States Department of Agriculture

Agricultural Research Service


Location: Grassland, Soil and Water Research Laboratory

2013 Annual Report

1a.Objectives (from AD-416):
The overall objective of this project is to develop a national water quality modeling system that would provide input data for applications of multiple water quality models for EPA's Office of Water. The system will consist of input data organized around the National Hydrography Dataset (NHD) stream reaches and catchments, and input file configuration subroutines to support applications of both USDA's Soil and Water Assessment Tool (SWAT) and USGS's Spatially Referenced Regressions on Watershed Attributes (SPARROW). Phase II will include finer spatial resolution down to 4 square kilometer grid cells which allows local assessment. Phase II will also include simulation of the fate and transport of selected heavy metals and pharmaceuticals.

1b.Approach (from AD-416):
The Hydrologic and Water Quality System will be an extension of the Hydrologic Unit Model of the United States (HUMUS), which has recently been upgraded for USDA's Conservation Effects Assessment Project (CEAP). The system developed in this project will extend CEAP-HUMUS by upgrading modeling capabilities and improving the quality of input data. Specifically, input data will be re-formatted or replaced with data organized around NHD stream segments and catchment delineations.

3.Progress Report:

United States Environmental Protection Agency (EPA) needs a national water quality system to determine the impacts of their environmental programs and for assessing impaired water bodies across the U.S. To meet these needs, a web-based interface was developed that utilizes the SWAT model developed by ARS. For this project, SWAT was parameterized for the Upper Mississippi, Missouri, Ohio, and Tennessee river basins using the USGS 12-digit subwatersheds as subbasins (approximately 100 Km**2). Data input files for the USGS SPARROW regression model, including connectivity, point sources, and reservoir data, were assembled for input to SWAT. Output from SPARROW was assembled to validate total annual sediment, nitrogen, and phosphorus loads at most 12-digit outlets. SWAT is currently being parameterized for all watersheds defined by the National Hydrology Dataset (approximately 3 Km**2) in the Western Lake Erie Basin. A calibration methodology has been developed to efficiently calibrate both the 12-digit and National Hydrology Dataset configurations. A web-based interface for extracting 12-digit SWAT model runs and for running SWAT on a remote server was developed. The system provides EPA and its contractors a powerful and simple tool for running national land use and climate scenarios for policy planning. A conceptual model for fate and transport of pharmaceuticals (hormones and antibiotics) across the landscape was continued and refined. Experts in fate and transport of pharmaceuticals from Louisiana State University, Texas A&M University, and Baylor University were consulted to refine the conceptual model. The results will be used by ARS scientists to develop and parameterize the emerging contaminant module within SWAT.

Last Modified: 7/31/2014
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