Mechanisms of Shoreline Change on the Rhode Island South Coast: Past, Present, and Future

• Main Author: Vinhateiro, Nathan D.
• Format: Text
• Language: unknown
• Published: DigitalCommons@URI 2012
• Subjects: North Atlantic
• Online Access: https://digitalcommons.uri.edu/oa_diss/1302; https://doi.org/10.23860/diss-vinhateiro-nathan-2012; https://digitalcommons.uri.edu/context/oa_diss/article/2317/viewcontent/Thesis_Vinhateiro_Nathan_2012.pdf

The barrier-lagoon system along the Rhode Island south shore is a vital natural resource that provides critical habitat and protects the state's southern communities against storm damage. The response of this system to changes in global climate is therefore of great interest to those who live along and manage this coastline. Responsible planning and accurate assessment of coastal vulnerability will require consideration of barrier spit evolution on different time scales. Accordingly, this dissertation presents evidence from geologic and instrumental records that are used to examine how the south shore responds to changes in the extent and frequency of coastal storms, and to long-term processes such as sea level rise. Overwash layers present in a transect of sediment cores from Quonochontaug Pond, RI are used to construct a record of major hurricane landfall spanning the last 2200 years. An annual probability for intense tropical cyclone landfall in Rhode Island was calculated to be 0.45% - a value that is notably similar to other proxy-based reconstructions throughout the western North Atlantic. The record indicates that New England has experienced changes in tropical cyclone climatology during this time, with periods of increased activity during the past ~400 years, and between 1400-2150 cal. yr BP. Similarity in the timing of overwash events between Quonochontaug Pond and sites throughout the western North Atlantic suggests that millennial-scale variability may be the result of basin-wide climatic forcings. A long-term dataset of beach profiles is used to construct a high-resolution record of shoreline change at eight transects along the Rhode Island south shore. Shoreline positions were estimated by intersecting a local tidal datum with ~6000 coastal profiles collected over 49 consecutive years. When compared to digital vector shorelines coincident with the survey period, the time-series of profile-derived shorelines demonstrate how sampling frequency and the choice of time-scales for analysis can bias ...