An Integrated Modeling Approach for Estimating the Water Quality Benefits of Conservation Practices at the River Basin Scale

摘要: The USDA initiated the Conservation Effects Assessment Project (CEAP) to quantify environmental benefits of conservation practices at regional and national scales. For this assessment, a sampling modeling approach is used. This paper provides technical overview used in CEAP cropland assessment estimate off-site water quality using Ohio River Basin (ORB) as an example. uses farm-scale model, Agricultural Policy Environmental Extender (APEX), watershed scale model (the Soil Water Tool [SWAT]) databases Hydrologic Unit Modeling for United States system. Databases land use, soils, use management, topography, weather, point sources, atmospheric depositions were developed derive inputs. APEX simulates cultivated cropland, Conserve Reserve Program land, implemented on them, whereas SWAT noncultivated (e.g., pasture, range, urban, forest) sources. Simulation results from are input into SWAT. routes all including APEX's, basin outlet through each eight-digit watershed. Each calibrated stream flow, sediment, nutrient loads multiple gaging sites turned simulating effects practice scenarios quality. Results indicate that nitrogen, phosphorus delivered Mississippi ORB could be reduced by 16, 15, 23%, respectively, due current practices. tools useful provide science-based information assessing existing programs, developing future insights load reductions necessary hypoxia Gulf Mexico.