Water Resources Research Act Program

Details for Project ID 2017MS207B

Study of Sediment and Nutrients in Pelahatchie Bay and Upland Mill-Pelahatchie Creek Watershed

Institute: Mississippi
Year Established: 2017 Start Date: 2017-03-01 End Date: 2019-02-28
Total Federal Funds: $21,534 Total Non-Federal Funds: $43,208

Principal Investigators: Xiaobo Chao

Project Summary: Fresh water is one of the most important natural resources on earth. However, deterioration of water quality has been frequently observed in many rivers, lakes and coastal waters, which greatly affects human lives and economic development. Water quality is generally the result of the physical, chemical and bio-chemical processes in water bodies; and is also strongly influenced by human and natural activities in the surrounding watersheds that produce a significant amount of sediment, nutrients, pathogen and other pollutants. Best Management Practices (BMPs), such as constructed-wetlands, establishment of grassed buffers, sediment erosion control, reduced-tillage, no-tillage, etc., have been applied to reduce the loads of sediment and nutrients in watersheds, resulting in the improvement of water quality in surface water bodies. However, these measures often have limitations and the water quality of the downstream waterbody may still have problems. Evaluating the effectiveness of these practices by analyzing the response of water quality in surface waters to the BMPs implemented in the upland watersheds is critical to the success of watershed management and restoration plans. This project studies the response of water quality in a Mississippi reservoir to incoming sediment and pollutant loads from upland watersheds. The hydrodynamics, sediment transport, and water quality processes will be studied using numerical simulations. The effectiveness of implemented BMPs in the upland watershed on the reservoir water quality will be evaluated. The Mill-Pelahatchie Creek Watershed (MCW) in Rankin County, Mississippi, is selected as the study site due to high sediment yield production there. The water, sediment and nutrients in this watershed flow into Pelahatchie Bay (PB) of the Ross Barnett Reservoir (RBR), the largest drinking water source in the state of Mississippi. The Annualized Agricultural Non-Point Source (AnnAGNPS) pollutant loading watershed management model, developed at the USDA ARS, National Sedimentation Laboratory (NSL), will be applied to simulate the loads of runoff, sediment and nutrients from the upland watershed. The simulated results will be used as boundary conditions for CCHE, a free surface flow, sediment and water quality model developed at the National Center for Computational Hydroscience and Engineering (NCCHE), to simulate flow, sediment transport and water quality processes in the Pelahatchie Bay. The concentration distributions of sediment and nutrients (nitrogen and phosphorus), and their variations in time due to the influence of loading, wind, and the operation of the Ross Barnett Reservoir will be simulated. Several tasks are proposed, including (1) Application of the AnnAGNPS watershed model to simulate runoff, sediment and nutrient loads in the upland watershed MCW; (2) Modeling flow, sediment and nutrient concentrations in PB; (3) Analyzing the response of sediment and nutrient concentrations in PB to alternative BMPs implemented within MCW. A team particularly strong in water quality modeling is to be formed: NSL has led the development of AnnAGNPS; NCCHE has developed the surface waterbody numerical model CCHE, which has been successfully applied to water quality studies in natural water bodies. In addition, the Mississippi Department of Environmental Quality (MDEQ) has abundant field measurements for model calibration and validation. The proposed research is anticipated to help understand the water quality process affected by many human and natural factors in the Pelahatchie Bay, to evaluate the implemented/planned BMPs, and to provide information for improving the water quality and recreation of the Pelahatchie Bay.