SWAT Literature Database for Peer-Reviewed Journal Articles

Title:An integrated modeling approach for estimating the water quality benefits of conservation practices at river basin scale 
Authors:Santhi, C. N. Kannan, M. White, M. Di Luzio, J.G. Arnold, X. Wang and J.R. Williams 
Journal:Journal of Environmental Quality 
Volume (Issue):43(1) 
Article ID: 
URL (non-DOI journals): 
Broad Application Category:hydrologic & pollutant 
Primary Application Category:Hyrologic Unit Model of the U.S. (HUMUS) application 
Secondary Application Category:Conservation Effects Assessment Project (CEAP) based study 
Watershed Description:552,770 km^2 Ohio River, which drains portions of several states in the east central U.S. 
Calibration Summary: 
Validation Summary: 
General Comments:This paper is part of a JEQ special SWAT section. 
Abstract:The USDA has initiated the Conservation Effects Assessment Project (CEAP) to quantify the environmental benefits of conservation practices at regional/national scales. For this assessment, a sampling and modeling approach is used. This paper provides a technical overview of the modeling approach used in CEAP cropland assessment to estimate the off-site water quality benefits of conservation practices using the Ohio River Basin (ORB) as an example. The modeling approach uses a farm-scale model, Agricultural Policy Environmental Extender (APEX), and a watershed scale model, Soil and Water Assessment Tool (SWAT), and databases in the Hydrologic Unit Modeling for the United States (HUMUS) system. Databases of landuse, soils, landuse management, topography, weather, point sources and atmospheric depositions were developed to derive model inputs. APEX simulates the cultivated cropland, Conserve Reserve Program land, and the practices implemented on them, while SWAT simulates the non13 cultivated land such as pasture, range, urban, forest, and others, and point sources. Simulation results from APEX are input into SWAT. SWAT routes all sources including APEX’s to the basin outlet through each 8-digit watershed. Each basin is calibrated for stream flow, sediment and nutrient loads at multiple gaging sites and turned in for simulating the effects of conservation practice scenarios on water quality. Results indicate that sediment, nitrogen and phosphorus loads delivered to the Mississippi River from ORB could be reduced by 16, 15 and 23%, respectively due to current conservation practices. Modeling tools are useful to provide science based information for assessing existing conservation programs, developing future programs, and developing insights on load reductions necessary for Hypoxia in the Mexico Gulf.