Two-Dimensional Hydrodynamic and Water Quality Modeling for Evaluating Impacts from IH45 Galveston Causeway Construction

Su, Yu-Chun, Ph.D., Julie Morse, Martin Heaney, and Stanley Cooper
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Galveston Bay Estuary Program

The IH 45 Galveston Causeway is a major bridge connecting Galveston Island to the Texas mainland. Due to the age and condition of the bridge, the Texas Department of Transportation (TxDOT) has developed a plan to rebuild the bridge. The proposed construction included alternatives to build temporary access roads for the construction of the main bridge. These access roads would cause partial blockage of West Bay for an estimated period of four years that could result in 1) an increase in current velocity that may impact navigation; 2) a reduction in tidal flushing that may impact water quality, bay benthos, peripheral salt marshes, and other aquatic communities; and 3) an impact on salinity distribution in the area. To investigate these potential impacts, a two-dimensional (2D) hydrodynamic and water quality model was developed.... This paper will present the development and findings of this modeling effort. Conclusions of this modeling effort contributed to the change of construction method toward a more environmentally friendly approach. The paper will present the new approach and a proposed schedule to complete the construction of the Galveston Causeway Bridge.

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water quality, habitat, ecology, watershed management, interstate, galveston, causeway, construction, west bay, bay benthos, salt marshes, aquatic communities, salinity distribution, hydrodynamic models, tide, freshwater flow, bathymetry, point source, san luis pass, galveston entrance channel, chocolate bayou