Statistical Evaluation of Shoreline Change: A Case Study from Seabrook Island, SC

Abstract

Seabrook Island is a barrier island located approximately 28 km south of Charleston, South Carolina. As a residential and resort area, Seabrook Island is important to the economic health of the Charleston, SC, region. Portions of Seabrook Island are impacted by accelerated erosion, which has been combated with engineered stabilization methods, inlet relocation, and beach nourishment. Despite stabilization attempts, localized shoreline erosion is continuing, leading to potential economic and ecological loss. We used the Digital Shoreline Analysis System (DSAS) to determine long- and short-term erosion rates on the island, focusing on natural and anthropogenic changes to the beach. Our results assessed beach change by comparing historical aerial photographs and satellite imagery. The use of digital imagery allows for rapid assessment of the shoreline to highlight areas experiencing shoreline change, to monitor the impacts of structural controls, and to focus site-specific field investigations. Our results show that since 1939, Seabrook has experienced erosion up to 52.4 m/yr at the northern end of the island near Captain Sams Inlet that is likely related to relocations of the inlet, accretion of up to 9.0 m/yr on Seabrook Beach due to nourishment of the beach, and relatively stable conditions near the southern end of the island as a result of structural control and nourishments. This method of analysis is useful to support urban planning consistent with preservation of natural resources; and thus may be suitable for application and testing elsewhere.