Graduation Year

2021

Document Type

Thesis

Degree

M.S.

Degree Name

Master of Science (M.S.)

Degree Granting Department

Geology

Major Professor

Shawn Landry, Ph.D.

Co-Major Professor

Ping Wang, Ph.D.

Committee Member

Jun Cheng, Ph.D.

Committee Member

He Jin, Ph.D.

Keywords

Hurricane coastal erosion, Numerical modeling, Risk assessment, St. Joseph Peninsula, Wave height

Abstract

Barrier islands shield the mainland coast from the effects of extreme storms such as increased wave energy and storm surge. During these events, however, barrier morphology can be altered by erosive forces. Thus, compromising the protection offered and leading to increased impact on the mainland. The St. Joseph Peninsula, located in the Northwest of the Gulf of Mexico, is one such barrier at threat from storm-induced erosion. Presented here is an assessment of morphology change induced by two major storms to impact the peninsula, Hurricanes Dennis 2005 and Michael 2018. These changes characterize the erosive/depositional patterns that can be expected from future major storms. Utilizing a numerical wave model, present-day and future simulated erosive scenarios are modeled to investigate the protection offered by the barrier under varying wave conditions. Significant wave height returns along the mainland coast are used to assess the effects of barrier erosion on the mainland. A risk assessment for the coastal communities is carried out using a weighted overlay analysis to rank and map vulnerable areas. The morphological impact from the two hurricanes is found to be considerable, with Hurricane Michael causing dune height reduction of up to ~6 m, over a million cubic meters of sediment eroded, and barrier breaching. In comparison, Hurricane Dennis’s impacts were less severe and focused on the protruding headland. Removing the barrier yielded increases in significant wave height, with a minimum percent increase of 300% when testing complete removal of the barrier under maximum wave conditions. The risk assessment identifies the communities on the mainland directly behind the barrier to be at the highest risk, especially under simulated erosive conditions.

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