| Title: | Assessment of total maximum daily load implementation strategies for nitrate impairment of the Raccoon River, Iowa |
| Authors: | Jha, M.K., C.F. Wolter, K.E. Schilling and P.W. Gassman |
| Year: | 2010 |
| Journal: | Journal of Environmental Quality |
| Volume (Issue): | 39(4) |
| Pages: | 1317-1327 |
| Article ID: | |
| DOI: | 10.2134/jeq2009.0392 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | hydrologic and pollutant |
| Primary Application Category: | BMP and/or cropping system assessment |
| Secondary Application Category: | Total Maximum Daily Load (TMDL) applications |
| Watershed Description: | 9,400 km^2 Raccoon River, which drains parts of 17 counties in west central Iowa, U.S. |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | The state of Iowa requires developing total maximum daily
loads (TMDLs) for over 400 water bodies that are listed on
the 303(d) list of the impaired waters. The Raccoon River
watershed, which covers approximately 9400 km^2 of prime
agriculture land and represents a typical Midwestern corn-belt
region in west-central Iowa, was found to have three stream
segments impaired by nitrate-N. The Soil and Water Assessment
Tool (SWAT) was applied to this watershed to facilitate the
development of a TMDL. The modeling framework integrates
SWAT with supporting software and databases on topography,
land use and management, soil, and weather information.
Annual and monthly simulated and measured streamflow and
nitrate loads were strongly correlated. The watershed response
was evaluated for a suite of watershed management scenarios
where land use and management changes were made uniformly
across the watershed. A scenario of changing the entire land to
row crop resulted in an increased nitrate load of about 12% over
the baseline condition at the watershed outlet. Results from the
15 nitrate load reduction strategies were found to reduce nitrate
from <1% to about 85%, with the greatest potential reduction
associated with changing the row crops to grassland. This
research demonstrated the use of a modeling system to facilitate
the analyses of TMDL implementation strategies, including
the ability to target the most efficient allocation of alternative
practices on a subwatershed basis. |
| Language: | English |
| Keywords: | |