Chapter 3 - Storm surge modeling in the Gulf of Mexico and Houston-Galveston regions

Abstract

Two processes primarily influence the generation of hurricane-induced storm surge along the coast of the United States adjacent to the northern Gulf of Mexico. One is the surge forerunner, an Ekman wave forced by the hurricane’s far-field winds. The forerunner develops while the hurricane is offshore. The second process involves the high core winds that wrap around the eye. As the hurricane crosses the continental shelf and makes landfall, strong onshore-directed winds in the core push accumulated water on the shelf toward the coast, which leads to the generation of the peak surge. In the Houston-Galveston region, the surge forerunner and peak surge propagate through Bolivar Roads and San Luis Passes that connect the Gulf of Mexico to Galveston and West Bays. The forerunner hastens dune erosion, degradation and possible breaching of the barrier islands, inundation of the barrier islands by the peak surge, and subsequent flow of more water over Galveston Island and Bolivar Peninsula and into the shallow bays. Hurricane winds force additional wind setup inside the bays, which are swollen with water, exacerbating the storm surge. A system of coupled models that simulate hurricane winds and atmospheric pressures, storm surge and waves, is the current state of engineering practice for understanding the storm surge in a coastal setting, quantifying vulnerability to coastal flooding, designing flood risk reduction projects, and for storm surge forecasting. The Ike Dike coastal spine concept has been proposed to reduce flood risk in the Houston-Galveston region. Storm surge modeling enabled understanding of the complex dynamics of forerunner and peak surge generation in the northwestern Gulf of Mexico and Houston-Galveston region of the Texas coast; and it enabled evaluation and optimization of the performance of the Ike Dike concept to reduce the risk of flooding in this region.