Date of Award

2024

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

John Walsh

Abstract

Sandy barrier systems are highly dynamic, with the most significant natural morphological changes to these systems occurring during the high energy conditions present during storms. These systems provide a range of economic and ecosystem benefits and protect inland areas from flooding and storm impacts, but the persistence of many coastal barriers is threatened by storms and sea-level rise (SLR). This study employs observations and modeling to examine recent and potential future influence of storms on a sandy coastal barrier system in Nauset Beach, MA. Drone-derived imagery and digital elevation models (DEMs) of the study area collected throughout the 2023-2024 winter revealed significant alongshore variability in the geomorphic response to storms. Severe, highly localized erosion (i.e., an erosional “hotspot”) occurred immediately south of the Nauset Bay spit as the result of a group of storms in December and January. Modeling results indicate that the location of the hotspot was largely controlled by the location of a break in a nearshore sandbar, which allowed higher waves and current to affect the shoreline. Additionally, models of the December and January storms under 1 ft of SLR showed the system to be relatively resistant to major geomorphic changes in response to an isolated storm event, but susceptible to significant overwash and breaching in response to consecutive storms. This research suggests that very strong and sequential moderate storms pose an enhanced risk of major overwash, breaching, and possibly inlet formation. This research was conducted as part of a NOAA project focused on the effects of storms and sea level rise in National Parks in coastal New England and will contribute to the project’s effort to inform an array of stakeholders.

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