Date of Award

Summer 8-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Ocean Science and Engineering

Committee Chair

Dr. Davin Wallace

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Stephan Howden

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Leonardo Macelloni

Committee Member 3 School

Ocean Science and Engineering

Committee Member 4

Dr. Michael Miner

Committee Member 5

Dr. Jessica Pilarczyk

Abstract

Sea-level rise and tropical cyclone activity are threatening coastlines around the world. Past geologic coastal responses can be used to inform future scenarios. This three-part study examines the response of coastal systems to sea-level rise, storms, sediment supply, and antecedent geology over the past ~ 140 ka.

The first study is of the Bay St. Louis, Mississippi, coastal system along the northern Gulf of Mexico incorporating sediment supply, subsidence, and antecedent topography paired with an examination of geologic response to sea-level fall and rise. I used core and geophysical data that resolve incised valleys and other subsurface deposits from ~ 140 ka to the modern to understand the sequence stratigraphy and extent of geomorphologic change. The response of this previously understudied system can be considered relevant for other Gulf of Mexico systems. I conclude that an eroding bay line is on a trajectory to migrate to a landward Pliocene scarp in ~ 400 years. Infrastructure designed without consideration of this migration may be threatened.

The second study is of sedimentological effects of Hurricane Nate, a Category 1 hurricane, on Ship Island, Mississippi. While major hurricanes receive considerable attention, researchers have not extensively studied and understood the effects of minor hurricanes on barrier islands, and field data are needed to determine the precise role they play. An analysis of trench sediments in overwash fans deposited from Hurricane Nate on Ship Island led to the conclusion that minor hurricanes (categories 1 and 2) can be constructive to barrier islands. The results of this study indicate that minor hurricanes can enhance barrier protection of mainland coastlines on a decadal time scale.

The third study was a database compilation of legacy sediment cores and geophysics created along the Mississippi-Alabama Shelf. These data may be used by researchers to evaluate sediment resource availability for future nourishment projects.

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