Exploring Hydrodynamic Modeling of Texas Bays With focus on Corpus Christi Bay & Lavaca Bay

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Texas Water Resources Institute

The work presented in this report is the basis for a portion of the author’s dissertation research. On a grand scheme, this research will enhance the effectiveness of hydrodynamic modeling and data development for Texas waterbodies, as well as for TMDL modeling in the United States. As of yet, this work is unfunded, which allows the author great flexibility in his choice of subject, project, and timeframe. However, the search for funding is far reaching and constant. The results presented in this report will likely serve as the basis for future funding proposals. The purpose of this project was ultimately to develop a hydrodynamic model of Corpus Christi Bay along the Gulf Coast of Texas. Field data has shown that seasonal hypoxia occurs near the benthic environment within the southern section of the bay near the interface with Laguna Madre. Previous modeling studies have not identified the causes of this hypoxia. However, the previous modeling attempts were 2D in nature and used simplified inputs and boundary conditions. A sophisticated 3D model incorporating a wide range of environmental variables will likely reveal those factors leading to the hypoxia. In order to develop such a model, much environmental and spatial data needed to be collected. This data includes information on regional wind patterns, tidal data, river inflow data, and weather data. It also was necessary to develop a methodology for bathymetry data generation using the ArcView/ArcGIS software, to develop a methodology for adjusting the bathymetry to include changes, and to develop a methodology for linking the generated bathymetry into the ELCOM hydrodynamic model. It was also necessary to develop a methodology for displaying and processing the ELCOM model results in the ArcView/ArcGIS system. Such a representation will be useful in disseminating the model results in a form that will allow a greater number of users to view, manipulate, and make decisions based on this data. Finally, the robustness of the ELCOM model needed to be ascertained. Hydrodynamic models should produce accurate results with any set of spatially consistent input data. To test the robustness of the ELCOM model, model runs were to be developed with spatial input data identical in every way, except for the data orientation with respect to the model grid. A methodology for creating, comparing, and displaying results in various spatial orientations needed to be developed and tested. For this purpose, Lavaca Bay was used as the study area. Lavaca Bay contains two approximately linear features in its bathymetry that would suggest the data orientation might affect the model results. The author hoped that working on this project would provide him with insight into all aspects of the hydrodynamic modeling process. Although modeling results were not obtained, the basis for future modeling efforts was firmly developed. This project also generated ideas for other avenues of research which might be included in the author’s dissertation. These ideas are presented in the final section of this report.