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Sediment and total phosphorous contributors in Rock River watershed
Eric G Mbonimpa1, Yongping Yuan1, Maliha S Nash1
1USEPA Office of Research and Development, Landscape Ecology Branch, Las Vegas, USA.
Journal of Environmental Management
|January 4, 2014
Summary
Monoculture corn farming and urban land use increase water pollution (total suspended sediment and total phosphorous). Corn-soybean rotation and forest cover help reduce pollution in the Great Lakes region.
Area of Science:
- Environmental Science
- Water Quality Management
- Agricultural Science
Background:
- Total phosphorous (TP) and total suspended sediment (TSS) are significant pollutants in the US Midwest, particularly impacting the eutrophic Great Lakes.
- Increased monoculture corn cultivation for biofuel production may worsen water quality in these stressed ecosystems.
- Understanding landscape impacts on pollutant loading is crucial for effective watershed management.
Purpose of the Study:
- To investigate the relationship between landscape variables (land cover, soil type, slope) and TP and TSS concentrations in the Rock River watershed, Wisconsin.
- To identify specific land use practices associated with increased or decreased water pollution.
- To provide science-based recommendations for improving water quality in the Great Lakes region.
Main Methods:
- Selected eight subwatersheds in the Rock River watershed based on USGS monitoring data for flow, TSS, and TP.
- Calculated landscape metrics including land use, soil type, and terrain slope for each subwatershed.
- Employed Analysis of Variance (ANOVA) to compare TSS and TP across subwatersheds and Partial Least Square (PLS) regression to evaluate landscape-metric relationships with water quality.
Main Results:
- Urban land use and corn monoculture (rotated with non-leguminous crops) were positively associated with increased stream TSS and TP concentrations.
- Increased acreage of corn-soybean rotation was linked to a reduction in stream TSS and TP.
- Presence of forest cover and water bodies in subwatersheds correlated with decreased TSS and TP levels.
Conclusions:
- Agricultural practices like corn-soybean rotation and maintaining forest cover are beneficial for reducing water pollution.
- Urban subwatersheds could benefit from Low Impact Development (LID) strategies to mitigate runoff and pollution.
- Recommendations include promoting crop rotation, strategic corn placement on gentle slopes, and utilizing low-erodibility soils in agricultural areas.
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