Comparative Effects of Sea Level Rise Versus Hurricane Event on Coastal Erosion

Abstract

Rising sea level from global warming raises concerns about coastal erosion. While gradual erosion from sea level rise may go almost unnoticed, combined effects of sea level rise and hurricanes can be devastating. For this reason, historical shoreline changes provide planners valuable tools to forecast and lessen impacts. Sakonnet Point, RI, USA, suffered the dramatic ‘one-two punch’ of a major hurricane and rising sea level and offers such a case history. This peninsular headland is the most seaward extension of RI near the Massachusetts border. The seaward extension of Sakonnet Point was historically a 300 m long peninsula of glacial till with large dunes. My study utilized a nearly 100-year photographic time-series and on-site observations to evaluate this dune system’s disappearance. Since 1938, this peninsula was altered from a system of nearly fifteen-foot (4.6 m) high dunes to nearly complete submergence at high tide. Sea level rise along this New England coast was 0.25–0.3 m over the last century. Superimposed upon sea level rise was the catastrophic 1938 hurricane surge. Our results show that major storm damage to barrier dunes sets the stage for sea level rise to produce rapid beach disappearance. With accelerated sea level rise from global warming, Sakonnet Point serves as a valuable tool for coastal planners.