HR: 0800h
AN: H41B-0501    [Abstracts]
TI: High-resolution (spatial and temporal) Hydrodynamic Modeling in the Lower Mississippi River Delta
AU: * Karadogan, E
EM: ekarad1@lsu.edu
AF: Louisiana State University, Department of Civil and Environmental Engineering Patrick F. Taylor Hall, Baton Rouge, LA 70803, United States
AU: Danchuk, S
EM: sdanch1@lsu.edu
AF: Louisiana State University, Department of Civil and Environmental Engineering Patrick F. Taylor Hall, Baton Rouge, LA 70803, United States
AU: Berger, C
EM: Charlie.R.Berger@erdc.usace.army.mil
AF: Coastal and Hydraulics Laboratory, U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180, United States
AU: Brown, G
EM: Gary.L.Brown@erdc.usace.army.mil
AF: Coastal and Hydraulics Laboratory, U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180, United States
AU: Willson, C
EM: cwillson@lsu.edu
AF: Louisiana State University, Department of Civil and Environmental Engineering Patrick F. Taylor Hall, Baton Rouge, LA 70803, United States
AB: The lower Mississippi River is a highly engineered system existing in one of the world's largest deltas. This system is subject to a variety of spatial and temporal forcings due to its large watershed (drains about 41% of the continental U.S.) and from the Gulf of Mexico. Future perturbations on this system are anticipated due to the impacts of global climate change (e.g., rising eustatic sea level, changes in weather patterns) and from proposed modifications to the system such as diversion structures aimed at providing freshwater nutrients and sediments to the rapidly degrading coastal wetlands. Numerical modeling will play a large role in improving our understanding and management of the system and the ability to properly design future structural features. These models will need to have the necessary spatial and temporal resolution to account for the many important processes in the river, the Gulf of Mexico, and in the wetland areas where small distributary channels will form and wetting/drying must be accounted for. This paper will investigate the ability of a 2D shallow water and sediment model to reproduce the complex distributary development associated with flow diversions into quiescent bays. A reach of the Lower Mississippi River from Point a la Hache to the Gulf of Mexico was used as a test domain to evaluate the performance and capabilities of the U.S. Army Corps of Engineers ADaptive Hydraulics (ADH) model. ADH is an unstructured finite element modeling system that includes unsaturated Richards' equations for groundwater, Navier Stokes for nonhydrostatic flow calculations, and Shallow Water equations. ADH conducts automated refinement and coarsening of the mesh based upon flow characteristics. In this case the 2D shallow water model is being used. It includes coupled flow and sedimentation. An unstructured mesh was developed for the study area which includes detailed bathymetry and topography from available survey data. The mesh is fine enough to capture the changes in bathymetry and relies upon the automated refinement in ADH to capture flow details. Numerical experiments conducted include modeling 1) existing flow conditions in the river, 2) the effects of sea level rise, 3) a hypothetical diversion opening connecting the river to the adjacent wetlands. Model capabilities and limitations, such as how much variability it can simulate, were evaluated by sequentially including more complete flow and sedimentation descriptions. Investigating the sediment depositional patterns provides information useful for design and tests the capabilities of ADH in modeling variability in sediment transport and capturing some of the fine details that will have a large impact in the wetland areas. Results from these tests are being used to define further research questions and possible scenarios.
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 1824 Geomorphology: general (1625)
DE: 1862 Sediment transport (4558)
DE: 3022 Marine sediments: processes and transport
DE: 4217 Coastal processes
SC: Hydrology [H]
MN: 2007 Fall Meeting