The Effects of the &quot;Ike Dike&quot; barriers on Galveston Bay

In 2008 Hurricane Ike flooded large parts of the barrier islands in front of the Galveston Bay near Houston, Texas. The storm surge also entered the bay through the inlets causing great damage along the bay and the port of Houston. Because of the high probability that a hurricane would strike again the “Ike Dike” was developed. The concept consists of heightening and extending the floodwall on Galveston Island and Bolivar Peninsula. Barriers will be placed at the San Luis Pass and Bolivar Roads inlet whereas the Rollover Pass might be closed completely. The Bolivar Roads barrier will be a combination between a floodgate and a lifting gate structure. During non-storm conditions, when the gates are open, the flow area through the inlets are expected to reduce up to 40-60% due to the barriers. The reduction of flow area can cause a decrease of the tidal prism and tidal range. Also current velocities are expected to increase near the barriers and decrease in the main bay. The residence time of fresh water in the bay is expected to increase and the salinity to decrease. The reduction of the tidal prism, tidal range and current speeds can cause a redistribution of the sediment from marshes and flats to the channels within the bay. The blocking of sediment from the Mexican Gulf by the barriers can further enhance this. Changes of the hydrodynamics, water quality and morphology in the bay could potentially result in loss of habitat and disturb the ecology. A 2D hydrodynamic model has been created in order to investigate the impact of the barriers on the tidal prism, tidal range and circulation in the bay. The morphology and water quality of the bay are investigated qualitatively using literature, reference projects and the outcomes of the 2D model. It is concluded that a 40-60% decrease of the flow area at the Bolivar Roads entrance affects the hydrodynamics of the Galveston Bay. To mitigate or prevent these effects the design could be altered such that the flow area is reduced by less 20%, because the impacts of such a barrier are relatively small. Another mitigating solution could be to build compartment dams to preserve the tidal range.

Subject

Galveston Bay
barrier
Ike Dike
hydrodynamics
morphology
water quality

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