Identifier

etd-06302009-161650

Degree

Doctor of Philosophy (PhD)

Department

Oceanography and Coastal Sciences

Document Type

Dissertation

Abstract

Storm surge is an abnormal rise of the sea surface caused by atmospheric forcing, including the wind stress and atmospheric pressure associated with extra-tropical and tropical cyclones. Hurricanes and typhoons have a great impact on coastal regions, and can cause severe loss of lives and great damages. A systematic investigation of storm surge impact to the coasts of Louisiana and Texas, where the continental shelf reaches up to 200 km in width, is conducted here using the hydrodynamics Finite-Volume Coastal Ocean Model, FVCOM (Chen et al., 2003). The model is applied to the northern Gulf of Mexico to simulate the storm surges caused by Hurricanes Rita (September 2005) and Ike (September 2008), and allows the resolution of the flooding along the Louisiana and Texas coasts. Observations of inland flooding from USGS are used to validate the model with satisfactory results. Various idealized scenarios are also simulated using FVCOM, to gain insight into specific surge mechanisms. This study focuses on the following topics: 1) The roles of shelf geometry and tides in a hurricane surge are explored in a set of experiments where the nonlinear interaction between tide and surge is investigated and found to be important, relative to the tidal amplitude; 2) The receding flow of Hurricane Rita’s surge waters back to the Gulf of Mexico and the different dynamics that produce the remarkably different flooding (~0.5 days) and return (>7 days) periods are explained; 3) The effect of the often overlooked forward speed of a hurricane, which was found to have an unexpected and significant impact on coastal surges, in that faster storms produce higher coastal peak surges but smaller overall inland flooding (vice-versa for slower storms); and 4) The importance of Galveston Bay’s barrier islands on the propagation of Hurricane Ike’s surge, where results suggested that under a realistic erosion scenario for Bolivar Peninsula’s, the bay is exposed to dangerously high water levels almost as much as if the Peninsula was leveled to about Mean Sea Level, underlining the non-linear nature of this bay-barrier system.

Date

2009

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Chunyan Li

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