Date of Award
2026
Degree Type
Thesis
Degree Name
Master of Science in Oceanography
Specialization
Geological Oceanography
Department
Oceanography
First Advisor
John P. Walsh
Abstract
Barrier-beach and estuarine areas are important ecologically and economically, and the inlets connecting them are critical for ocean exchange and greatly dynamic. Man-made jetties are often installed to maintain the connection between ocean and estuary for navigation and water quality benefits. With storms and sea-level rise, coastal systems are changing over days to decades, affecting communities in New England and around the globe. This study utilized remotely sensed data (i.e., aerial imagery, lidar, and sonar) to examine the dynamics of the Charlestown Breachway and its flood-tide delta in southern Rhode Island, USA over varying times scales. The specific research objectives of this thesis were to (1) analyze the century-scale geo-morphological evolution of a jettied flood-tide delta system, the Charlestown Breachway on Ninigret Pond; (2) investigate how this system responded to a series of powerful winter storms in recent years, and (3) examine how the system was affected by management interventions including reconstruction, dredging and nourishment since 2024.
Centennial-scale changes included oceanfront erosion (~50 m) and tidal-delta expansion (>350 m) from 1939 to 2024. Since 2003, shoreline-change rates in the flood-tide delta system varied from -1.5 to 1 m/yr with 18% of the analyzed transects displaying erosion which was locally related to channel migration. Drone-mapping showed that significant beach and dune erosion occurred since 2022 due to winter storms, emphasizing how successive storms can transform a coastal system. Drastic beach and dune erosion was mapped along the western wall of the Breachway, and a 40-m-wide tributary inlet channel was documented along the western jetty. Additionally, a large shoal complex accreted in the proximal flood-tide delta. After an emergency jetty repair in Fall 2024, rapid re-accretion was observed on the barrier beach, but high wave run-up due to Hurricane Erin in August 2025 caused more erosion and vulnerability. Following a full reconstruction of the Breachway and beach nourishment in Spring 2026, beach elevations were raised significantly (>2 m) -- to a level above those experienced during the 2022-2024 storms. The short- and long-term fate of the reconstructed system will depend on human and natural events including storms and sea-level rise. This case study provides insight into how the evolution of a flood-tide delta system is influenced by its geologic setting, history of storms, and modern-day management, allowing coastal communities to learn from the past to prepare for the future.
Recommended Citation
Levitan, Zachary Justin, "EVOLUTION OF A MANAGED FLOOD-TIDE DELTA AND BARRIER-BEACH SYSTEM, CHARLESTOWN, RHODE ISLAND" (2026). Open Access Master's Theses. Paper 2749.
https://digitalcommons.uri.edu/theses/2749