Date of Award

8-30-2022

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Environmental Sciences

First Advisor

Mark Borrelli

Second Advisor

Paul Kirshen

Third Advisor

Crystal Schaaf

Abstract

The Nauset barrier system is a mixed-energy tidal lagoon located on the border of Eastham and Orleans, Cape Cod, MA. The Nauset system has shown to be very dynamic over time, within the past century the barrier system has experienced changes in overall barrier volume and the tidal inlet migration rate is greater than previously observed. Historical topographic sheets dating back two centuries, high-resolution aerial imagery from 1938 to the present, and Light Detection and Ranging (LiDAR) datasets from 1998 to 2021 provide insight into barrier and inlet evolution over time. Barrier volume analysis has been conducted utilizing digital elevation models from the LiDAR datasets. Documented trends in volume change over time provide evidence of the dynamic nature of the system and possible future configurations. The increase in the rate of change of the barriers since the mid-20th century, specifically the inlet migration rate which increased from 1.46 m/yr before the mid-20th century (1844-1938) to 56.6 m/yr since the mid-20th century (1938-1997) and 68.6 m/yr from then until current positioning (1997-2021). The barrier evolution changes, and increased rate of inlet migration indicate changes in the offshore environment from rising sea levels, increased storm activity, and storm severity.

Previous work in the peer-reviewed literature has hypothesized that the tidal inlet is migrating updrift. The data analysis shows supporting evidence of a shifting nodal point causing a change in the direction of longshore transport on the Nauset barrier system, which refutes the conventional hypothesis. This study aims to identify the mechanisms responsible for inlet migration and barrier evolution within the Nauset barrier system in recent history. Understanding the past and current morphologic changes at the coast will give coastal planners, managers, and other stakeholders greater insight into potential science-based planning strategies.

Comments

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