UNDERSTANDING AND PREDICTING THE IMPACT OF AGRICULTURE ON THE ENVIRONMENTAL INTEGRITY OF MANAGED WATERSHEDS
Location: Water Quality and Ecology Research
Title: Three Dimensional Numerical Modeling of Cohesive Sediment Transport and Wind-Wave Impact in a Shallow Oxbow Lake
| Chao, Xiaobo - UNIV. OF MISSISSIPPI |
| Jai, Yafei - UNIV. OF MISSISSIPPI |
| Shields Jr, Fletcher |
| Wang, Sam - UNIV. OF MISSISSIPPI |
Submitted to: Advances in Water Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 30, 2008
Publication Date: July 1, 2008
Citation: Chao, X., Jai, Y., Shields Jr, F.D., Wang, S.S., Cooper, C.M. 2008. Three Dimensional Numerical Modeling of Cohesive Sediment Transport and Wind-Wave Impact in a Shallow Oxbow Lake. Advances in Water Resources 31: 1004-1014.
Interpretive Summary: Lakes in agricultural watersheds sometimes experience water quality problems due to soil eroded from surrounding fields that enters the lake with runoff, and predicting water quality responses to conservation efforts is difficult due to poorly-understood processes that control sediment fate in receiving waters. An existing computer model of water movement in lakes was modified to better represent the effects of wind-driven waves and wind-induced currents on sediment resuspension, transport, and deposition. The modified model was adjusted using data from a lake in the Mississippi Delta and verified using another data set from the same lake, showing that the properties wind-driven waves are important determinants of lake water sediment concentration. Development of the capability to simulate these processes is an important step in quantifying the benefits of conservation practices applied to cultivated lands near natural lakes.
Presented are the development and application of a three-dimensional numerical model for simulating cohesive sediment transport in water bodies where wind-induced currents and waves are important. In the model, the bottom shear stresses induced by currents and waves were calculated, and the processes of resuspension (erosion), deposition, and settling were considered. This model was first verified by a simple test case consisting of the movement of a nonconservative tracer in a prismatic channel with uniform flow, and the model output agreed with the analytical solution. Then the model was applied to Deep Hollow Lake, a small oxbow lake in Mississippi. Simulated sediment concentrations were compared with available field observations, with generally good agreement. It was observed that sediment transport was primarily caused by wind-induced currents, and the sediment resuspension was primarily driven by wind-induced waves. The transport and resuspension processes of cohesive sediment due to wind induced current and wave in Deep Hollow Lake were also discussed.