Identifier

etd-04302010-171225

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

The need to characterize offshore resources as borrow areas for beach restoration has initiated interest of the impact of storms to the inner continental shelf. While numerous studies have investigated the response of coastal systems to major storms, very little is known about the geological response of inner shelves to frequent and intense storms. This approach integrated a geological study with modeling of hydrodynamics during recent storms, in order to relate trends in the geological signature to physical forcing mechanisms during storms. First, waves and hydrodynamic conditions were modeled during two major recent storms that made landfall in the northeastern Gulf of Mexico. Results of the models were used in calculations of bottom shear stress and potential for resuspension of sediments. These results were further corroborated with satellite images of suspended particles. Second, vibracores, seismic and bathymetry data were collected to characterize the geologic history and recent changes to the geology of the inner shelf. These data were analyzed through physical interpretations, granulometric and radiocarbon analyses, and erosion/accretion calculations. The results indicate that storms have the potential to have a tremendous impact on the continental shelf, and can resuspend sediments in depths of 80 m or more, and last for several hours to a few days. A substantial offshore movement and downwelling component is also evident, with implications for a southwest moving geostrophic flow. The results of the geological analysis indicate that the stratigraphy of the inner shelf is a derivative of the last glacial to interglacial changes in sea level, with a highly modified Holocene reworked section. These modifications include winnowed sediments that coarsen to the inner shelf seafloor, the maintenance and migration of shelf shoals, and the development of numerous shelf ridges and troughs. These modifications are the direct result of frequent and intense hurricanes impacting the northeastern Gulf of Mexico. The modifications observed can be directly correlated to different phases of a storm’s impact on the shelf. From this, a conceptual model was developed that summarizes these modifications and the phases from which they formed.

Date

2010

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Stone, Gregory W.

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