ABSTRACT
The Outer Banks of North Carolina extend from the Virginia-North Carolina border south to Cape Lookout, a distance of 240 km. These islands were originally one continuous biophysical system, but the upper section has experienced three decades of dune and beach stabilization, coupled with extensive public and private development. In 1957 the stabilized islands became the Cape Hatteras National Seashore. The southern segment, which includes Core Banks, remains in a natural state and is authorized to become the new Cape Lookout National Seashore. The responses of these two different systems to the inshore processes are of special interest for both preservation and management reasons.
Natural barrier islands are much better adapted to steady-state processes and extreme events than are the man-manipulated islands. Since there is little resistance to the storm surge movement across the natural barriers, wave energy is dissipated across the wide berm, among the low dunes, and finally in the grasslands and marshes behind. These islands actually gain material from the beach as the surge moves across the islands, and such deposits serve as sources of supply for new dune growth.
Within the stabilized segment of the Outer Banks, the massive and unbroken man-made dunes act as an impenetrable obstruction to a storm surge, so the energy dissipation and sediment transfer processes are significantly different. The most important differences are associated with the restrictions of the run-up profile and the elimination of oceanic overwash. Overwash is the major means by which low barrier islands retreat before the rising sea. It is the only way massive quantities of coarse sediment can be moved inland from the beach.
