Offshore Transport of Sediment During Cyclonic Storms: Hurricane Ike (2008), Texas Gulf Coast, USA

Extreme storms can have a large impact on coastal sediment budgets, and the character of strata preserved in the geologic record. Here we investigate the impact of a cyclonic storm surge flood and ebb on sediment transport in a microtidal beach barrier-shelf system. Hurricane Ike made landfall on the Texas (US) coast on September 13, 2008. The accompanying storm surge flooded Galveston Bay with up to 5 m of water above sea level. The surge flood and ebb preferentially flowed over the low-elevation, bay fronting spit Bolivar Peninsula, destroying buildings and eroding the sediments. Surge waters also flowed through Bolivar Roads tidal inlet, the main passageway between the Gulf and the Bay through the barrier system. Bathymetry, CHIRP data and samples were collected in Bolivar Roads 9-10 days after the storm, and are compared to data collected four months prior. Additional data were collected offshore of Bolivar Peninsula in October, 2008. Our results document the dominance of the storm surge ebb in forcing sediment transport through the inlet, which is not considered in models of beach barrier evolution. Shoreface sands appear to have been incised by the storm, and advected with beach barrier sediments sufficiently offshore by the storm surge ebb that they cannot be reincorporated, indicating a significant loss to the barrier system’s sediment budget as a result of a single storm.