Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2008
Publication Date: 12/4/2008
Citation: Yuan, Y., Locke, M.A., Bingner, R.L. 2008. Annualized Agricultural Non-Point Source Model Application for Mississippi Delta Beasley Lake Watershed Conservation Practices Assessment. Journal of Soil and Water Conservation 63(6): 542-551. Interpretive Summary: Agricultural management practices have been developed to reduce pollutants produced from agricultural fields entering stream systems for overall watershed water quality improvement. The evaluation of the effectiveness of conservation management practices is difficult because of the long-term data collection effort needed throughout a watershed system. In order to better assess conservation practices, computer simulation modeling tools have been developed to evaluate the quantity and source of pollutants. In addition, these tools serve as an aid in determining the most effective conservation practices that can be applied to minimize any downstream impacts on water quality. This study introduces the application of AnnAGNPS to Beasley Lake Watershed, one of the Conservation Effect Assessment Project (CEAP) benchmark watersheds, to assess the impact of alternative management practices on water quality. In this study, AnnAGNPS model was used to simulate the amount of water and sediment generated from each field; thus, critical source areas producing a higher level of pollutants were identified. Then, AnnAGNPS was applied to simulate the impact of implementing alternative agricultural management options on high sediment producing areas. Through AnnAGNPS simulations, the impact of alternative agricultural management options for reducing non-point source pollution can be assessed. The model demonstrated that applications of various areas of no-tillage or grassland to the watershed could reduce sediment loadings to a range of 15-69 percent of the existing condition.
Technical Abstract: The principal focus of the USDA Conservation Effect Assessment Project (CEAP) Watershed Assessment Study effort is to provide an assessment of environmental benefits derived from implementing USDA conservation programs. When determining the priority for conservation measures within a watershed for non-point source pollution control, models are valuable tools that can provide clues as to where potential sources of water pollution may be and which problems can most easily be corrected. The USDA Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model is such a model which has been developed for conservation planning and evaluation. This paper presents the study performed on a CEAP benchmark watershed located in the Mississippi Delta to identify critical areas where conservation practices need to be implemented and how their implementations could improve lake water quality. In this study, AnnAGNPS was first validated by using monitored runoff and sediment at one of the inlets to the Beasley Lake, the AnnAGNPS was then used to simulate amount of water and sediment produced from each field within the Beasley Lake watershed and amount of water and sediment reaching to the Beasley Lake. AnnAGNPS was also utilized to simulate the impact on water quality by implementing various conservation programs recommended by the NRCS. Through AnnAGNPS simulations, high sediment-producing areas were identified, and those areas were targeted for effective non-point source pollution control. The alternative agricultural management options for reducing non-point source pollution and their impacts on water quality are also presented in the paper.