HURICANE IMPACT AND STORM SURGE EBB DEPOSITION IN EAST GALVESTON BAY DUE TO HURRICANE IKE (SEPTEMBER 13, 2008)

Hurricane Ike made landfall on the Bolivar Peninsula barrier spit on September 13, 2008, as a Saffir-Simpson Hurricane Category 2 storm, producing a storm surge in excess of 5 meters across the barrier spit and into the East Galveston Bay. The storm surge flooded over 900 km² of mainland proximal to East Galveston Bay. Geophysical and core surveys began less than 1 year after storm, initially investigating the impact of the storm on the oyster reef communities in the bay, subsequent surveys focused on sediment transport and deposition within the bay as a whole. Results show that sediment was not deposited in a homogeneous layer throughout the bay, but rather sediment accumulated on the flanks of reefs and other areas where accommodation space was maximized. In some areas deposits exceeded 2 m in thickness, although on average the deposit was approximately 1 m thick. In general the thickest deposits were observed in center of East Galveston Bay as a lobe extending southward from the north shore of the bay. Grain size analyses of the storm deposit reveal an increase in the sand content of the deposit in the southern portion of the bay proximal to the Bolivar Peninsula barrier spit. Stable carbon isotope analysis show a more clearly defined terrestrial signature in the deposit with increased distance from Bolivar Peninsula. Based on these results, it appears that the initial surge from the storm transported sand dominated sediment into East Galveston Bay as the waters inundated Bolivar Peninsula and subsequently vast areas of land to the north and east of the bay. During the storm surge ebb, retreating waters drained these inundated lands through East Galveston Bay depositing muddy sediment into the bay as the waters retreated to the Gulf of Mexico. This data provides critical information as to susceptibility of estuarine environments to storm derived deposition as a result of both storm surge flood and ebb flows.