Location: Watershed Physical Processes ResearchTitle: Numerical modeling of flow and sediment transport in Lake Pontchartrain due to flood release from Bonnet Carré Spillway Author
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 12/5/2012
Publication Date: 3/13/2013
Citation: Chao, X., Jia, Y., Hossain, A.A. 2013. Numerical modeling of flow and sediment transport in Lake Pontchartrain due to flood release from Bonnet Carré Spillway. In: Sediment Transport Processes and Their Modeling Application, Andrew J. Manning (Ed.). ISBN 978-953-51-1039-2, InTech, 14:357-380, DOI: 10.5772/54435. Interpretive Summary: The CCHE2D model was applied to simulate the flow circulations and suspended sediment transport in Lake Pontchartrain during the Bonnet Carré Spillway (BCS) opening for flood release. In this event, a vast amount of fresh water, sediment and nutrients were discharged into Lake Pontchartrain. The dispersion and transport processes of the suspended sediment in the lake were simulated successfully using the numerical model. The simulated SS concentrations are generally in good agreement with satellite imageries provided by NOAA. The differences of flow circulation and sediment transport in the lake under normal condition and BCS opening event were discussed. The simulated results and satellite imageries show that after the BCS opening, a large amount of sediment discharged into the lake, moved eastward and gradually expanded northward, eventually affecting the entire lake. After the BCS closure, the sediment derived from the Mississippi River gradually deposited to the lake bed and it took two to three months for the SS concentration in the lake recovered to the seasonal average level. This study demonstrates that the CCHE2D model is capable of predicting free surface flow and sediment transport in Lake Pontchartrain during BCS opening for flood release. It is a useful tool for providing information on hydrodynamics and sediment transport in such a big lake where the field measurements may not be sufficient. The information obtained from the numerical model is important for environmental assessment and restoration of lake water quality.
Technical Abstract: In this study, the flow fields and sediment transport in Lake Pontchartrain during a flood release from Bonnet Carré Spillway (BCS) was simulated using the computational model CCHE2D developed at the National Center for Computational Hydroscience and Engineering (NCCHE), the University of Mississippi. This model can be used to simulate free surface flows and sediment transport, and the capabilities were later extended to simulate the water quality, pollutant transport and contaminated sediment. CCHE2D is an integrated numerical package for 2D-depth averaged simulation and analysis of flows, non-uniform sediment transport, morphologic processes, water quality and pollutant transport. There are several turbulence closure schemes available within the model for different purposes, including the parabolic eddy viscosity, mixing length, k-epsilon and nonlinear k–epsilon models. A friendly Graphic User Interface (GUI) is available to help users to setup parameters, run the simulation and visualize the computational results. In addition to general data format, CCHE2D has capabilities to produce the simulation results in ArcGIS and Google Earth data formats. Those capabilities greatly improve the model’s applications. The simulated flow and sediment distribution during the BCS opening were compared with satellite imagery and field measured data provided by the United States Geological Survey (USGS) and the United States Army Corps of Engineers (USACE). Good agreements were obtained from the numerical model.