|Shields Jr, Fletcher|
Submitted to: American Society of Civil Engineers Water Resources Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2006
Publication Date: 5/25/2006
Citation: Chao, X., Jai, Y., Shields Jr, F.D., Cooper, C.M. 2006. Three dimensional numerical modeling of cohesive sediment transport in a shallow oxbow lake. IN Randall Graham (ed.) American Society of Civil Engineers Water Resources Conference Proceedings, Reston, VA. CD-ROM. Interpretive Summary: Lakes in agricultural watersheds sometimes have 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 associated with settling and resuspension of very small soil particles. An existing computer model of water movement in lakes was modified to better represent wind-driven waves and currents and the behavior of small-grained sediments. The modified model produced extremely accurate simulations of hypothetical situations and fairly accurate simulations of observed lake conditions. These findings provide a foundation for additional lake water quality model development.
Technical Abstract: This paper presents the development and application of a three-dimensional numerical model for simulating the cohesive sediment transport in water bodies where both currents and wind-driven waves are important. The model was verified by a simple test case with an analytical solution (nonconservative tracer in a prismatic channel with uniform flow) and applied to Deep Hollow Lake, a small oxbow lake in Leflore County, Mississippi. The model produced predictions within 2% of the analytical solution. The bottom shear stresses induced by currents and waves were calculated, and the processes of resuspension, deposition and settling were considered. The primary forces associated with sediment transport were caused by wind-induced currents and waves. Simulated sediment concentrations were compared with limited field observations with generally good agreement. Simulated concentrations for a scenario with wind-driven waves were about one to three times greater than for a simulation without wind-wave processes.