Date of Award

Spring 5-10-2019

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

Kimberly Huguenard

Second Committee Member

Lauren Ross

Third Committee Member

Kelly Cole

Abstract

Storm surges are the most destructive component of coastal storms, and climate change is predicted to enhance the frequency of intense storm events in the future. Currently, most storm surge forecasting assumes linear surges and the extent to which this assumption leads to model inaccuracies is currently unknown. The goals of this research are to characterize storm surge in estuaries and determine the contribution of nonlinear tide-surge interaction to total inland surges. A citizen science experiment was conducted in four estuaries in Maine. Results show the estuary shape influences surges through convergence, friction and man-made constrictions. These mechanisms modified total surge levels by more than 50% from estuary mouth to head. The mechanisms behind higher order tide-surge interactions were also identified for the first time. The D6 and D8 bands were recognized as the dominant frequencies in tide-surge interaction, sometimes creating a total storm surge that was more than double that of the low-frequency, linear surge. Enhancement of quadratic friction from storm-induced currents is the primary mechanism causing the D6 interaction. The D8 interaction scales with the D6 and resonates in a portion of the estuary, amplifying the total surge. Sea level rise from climate change is expected to enhance inland storm surges as higher sea levels bring the system closer to the resonant depth for the D8 tide.

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