1a. Objectives (from AD-416)
The objectives of this study are to: 1) Compile environmental, water quality, and agronomic data from the Leon River and Riesel watersheds and deliver to the STEWARDS data system in a compatible format; 2) Measure and quantify hydrologic and water quality effects of conservation practices and management at the field, farm, and sub-watershed scale within the Leon River and Riesel watersheds; 3) Validate, quantify uncertainties in model output, and conduct land use and climate analyses with the SWAT and ALMANAC models at field, farm, and watershed scales; 4) Provide proper output and linkages from SWAT to economic models to ensure appropriate environmental and crop yield output at spatial scales compatible with selected economic models; and 5) Extract relevant components from the ALMANAC and SWAT models for integration into the Object Modeling System (OMS) and assist in the verification of the ALMANAC and SWAT models for major agricultural regions.
1b. Approach (from AD-416)
For Objective 1 we will provide data to the STEWARDS data system from the Leon River and Riesel watersheds. Data will include environmental and agronomic data, measured water quality data, and SWAT output. Socio-economic data will not be collected. Our role in Objective 2 involves quantifying the effects of conservation practices (with emphasis on nutrient and manure management) in the Leon River and Riesel watersheds. It also involves quantifying nutrient and manure management of grasses and pastures for bio-fuels at three field sites in Texas. Although several models are considered in the overall CEAP Objective 3, our focus is solely on the SWAT and ALMANAC models. SWAT will be evaluated and uncertainty analysis will be performed on varying spatial scales in the Leon and Riesel watersheds. Model development will include: 1) river basin scale processes in SWAT, 2) plant growth and land management processes in ALMANAC, and 3) linkage with remotely sensed data. Our role in Objective 4 is to provide proper output and linkages from the SWAT model to economic models. We will ensure appropriate environmental and crop yield output from SWAT at spatial scales that are compatible with the selected economic models. For Objective 5, we will extract relevant components from SWAT and ALMANAC model for integration into the Object Modeling System (OMS).
3. Progress Report
Data collection and public outreach have substantially advanced for two projects investigating application of poultry litter and proper fertilizer management. Experimental results on effects of conservation practices in the Leon River and Riesel watersheds have been analyzed. The compartmentalized version of the ALMANAC model was incorporated into the SWAT model to improve SWAT's plant simulation components. The ALMANAC model was extensively tested against NRCS Ecological Site Descriptions in the Intermountain West. Work is continuing with the SWAT and ALMANAC models, to provide linkages to models with different application and scales.
1. Improved model to simulate water quality in large river basins. The U.S. Environmental Protection Agency (US EPA) and state environmental agencies have identified approximately 15,000 water quality-impaired water bodies in the U.S. At the same time, USDA is mandated to conduct a thorough analysis of the risks and benefits of USDA's conservation programs to human health, safety, and environment; determine alternative ways of reducing risk; and conduct cost-benefit assessments. New algorithms were developed for a river basin scale model called SWAT (Soil and Water Assessment Tool) to simulate on-site septic systems, stream sediment routing, urban management practices, improved phosphorus fate and transport, and stream health. As part of the CEAP (Conservation Effects Assessment Project) National Cropland Assessment, SWAT was validated at more than 70 USGS stream gauges across the country to assure realistic simulation of stream flow, sediment, nutrient and pesticide (atrazine)loads. Final SWAT validation and scenario analysis was completed on the Upper Mississippi river basin, the Chesapeake Bay watershed, the Ohio-Tennessee river basin, and the Great Lakes watersheds; the final draft reports are under review by USDA-NRCS and are available on the CEAP website. Validation and scenario analysis has been completed for the Missouri, Arkansas-Red, and Lower Mississippi river basins, and reports are being developed. The scenario runs from this model are being used by USDA-NRCS to identify places where conservation practices such as conservation tillage, terraces, and CRP (Conservation Reserve Program) will be most efficient and provide the greatest benefits. This will help guide USDA conservation policy and Farm Bill debate. The model is also being used in more than 30 states by US EPA and is impacting the selection of land management alternatives to resolve water quality concerns.
White, M.J., Storm, D.E., Busteed, P.R., Smolen, M.D., Zhang, H., Fox, G.A. 2010. A quantitative phosphorus loss assessment tool for agricultural fields. Environmental Modeling & Software. 25(10):1121-1129.