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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #134907


item Bingner, Ronald - Ron

Submitted to: Laboratory Publication
Publication Type: Other
Publication Acceptance Date: 5/16/2002
Publication Date: 5/16/2002
Citation: Yuan, Y., Bingner, R.L. 2002. Assessment of best management practices for water quality improvement for the deep hollow watershed in the Mississippi Delta MSEA project using AGNPS 2001. USDA-ARS National Sedimentation Laboratory Research Report. No. 28, 77 pp.

Interpretive Summary: Pollution entering a water body can significantly affect the ecological balance needed in maintaining healthy recreational and municipal river or reservoir systems. Producers have to balance the effects of their farming practices on pollution with their economic benefit from those practices. A study was conducted to evaluate the capability of the USDA watershed model, AnnAGNPS, to estimate the production of runoff, sediment, and nitrogen pollutants from Mississippi Delta farms as part of the Mississippi Delta MSEA Project. Application of the USDA AnnAGNPS watershed model on the watershed produced simulation results that were similar to the long-term measured trends. A study was also performed to estimate the impact of best management practices on the watershed to reduce non-point source pollutants with impoundments providing the most pollutant reduction. By applying this watershed model to agricultural areas that may contribute to non-point source pollution problems downstream, alternative farming practices can be evaluated before their actual implementation in order to demonstrate the approach that best reduces any downstream impact on the watershed system. This technology provides a valuable tool to state or federal personnel involved in watershed management planning.

Technical Abstract: Sediment and its associated pollutants entering a water body can be very destructive to the ecological health of that system. Best Management Practices (BMPs) can be used to reduce these pollutants, but understanding the most effective practices is very difficult. Watershed models are the most cost effective tool to aid in the decision making process of selecting the BMP that is most effective in reducing the pollutant loadings. The Annualized Agricultural Non-Point Source Pollutant Loading model (AnnAGNPS) is one such tool. Objectives of this study were to assemble all necessary data from the Mississippi Delta Management System Evaluation Area (MDMSEA) Deep Hollow watershed to validate AnnAGNPS and to use the validated AnnAGNPS to evaluate the effectiveness of BMPs for water quality improvement. In this study, AnnAGNPS predictions were compared with three years of field observations from the MDMSEA Deep Hollow watershed. Using no calibrated parameters, AnnAGNPS underestimated observed runoff for extreme events, but the relationship between simulated and observed runoff on an event basis was significant. Three-year predicted total runoff was 89% of observed total runoff and three-year predicted total sediment yield was 104% of observed total sediment yield. Three-year predicted total nitrogen loading was 127% of the observed total nitrogen loading. Alternative scenario simulations showed that: for the Mississippi Delta, no-till, slotted inlet pipes, and impoundments appear to be the most promising BMPs. Information on the cost of adopting the BMPs and the impact of BMPs on water quality should both be considered in choosing the most appropriate combination of BMPs.