PROCESSES AND MANAGEMENT ISSUES FOR ACCRETING BEACHES — SOUTHEAST USA

摘要

Rapid accretion is occurring along a number of southeast USA barrier islands via episodic bypassing of large sand bars released from ebb-tidal deltas. The process produces shoreline jumps before high dunes can be established. Incipient dunes are stabilized rapidly over several decades by a natural succession of dune grasses, maritime shrubs, and forest growth. This resulting landscape is low-relief and low-elevation seaward of development. Storm-surge modeling using WHAFIS (Wave Height Analysis for Flood Insurance Studies) at Sullivan’s Island, South Carolina (one such accreting barrier island), demonstrates that dense vegetation has minor impacts on surge and wave attenuation, whereas addition of a low dune above the 100-year flood level significantly increases flood protection and reduces damages in storms. Extensive accreted land seaward of development along some southeastern barrier islands provides opportunities for improved storm protection as well as habitat enhancement.