| 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 |
| Year: | 2014 |
| Journal: | Journal of Environmental Quality |
| Volume (Issue): | 43(1) |
| Pages: | 177-198 |
| Article ID: | |
| DOI: | 10.2134/jeq2011.0460 |
| URL (non-DOI journals): | |
| Model: | APEX & SWAT |
| Broad Application Category: | hydrologic and 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. |
| Language: | English |
| Keywords: | |