MORPHOLOGY OF THE SUBAERIAL CAPE POINT AT CAPE LOOKOUT NATIONAL SEASHORE, NORTH CAROLINA

Capes and their associated shoals are part of several national parks and seashores on the North American coast. Capes often form important physical and ecological discontinuities in the coastline, yet their dynamics are poorly understood. Processes controlling the morphology of Capes Hatteras, Lookout and Fear along the coast of North Carolina involve both the submerged, cape-associated shoals and the subaerial cape headland. Direct observation of waves, currents and bathymetry on associated shoals is extremely difficult and often hazardous. Our field-intensive study at the Cape Lookout National Seashore uses the changing geometry of the subaerial point as an easily observed proxy for complex nearshore sediment transport processes at capes. Real-time-kinematic GPS mounted on an all-terrain vehicle was used to generate high-spatial and temporal resolution maps of Cape Lookout. The cape point responds rapidly to changes in nearshore wind and wave energy and direction. During southerly swell conditions the seaward-most tip of the subaerial cape point may extend ephemerally to the southeast by as much as 150 m from the cape baseline. In contrast, during significant northeaster events the seaward-most tip can be eroded by as much as 60 m. As the seaward-most tip of the cape point is eroded during these events, its volume may decrease by approximately 3900 cubic meters or 40% , while the entire cape point has increased in volume by as much as 5200 cubic meters. These changes in the morphology of the seaward-most tip of the cape point are highly contrasting to changes in the entire cape. Our long-term study objective is to relate these changes in morphology to nearshore wind and wave energy and direction, and infer sediment transport pathways between the subaerial cape and cape-associated shoals. Findings collected through this study can be conveyed to national seashore and coastal-zone managers and may be extremely relevant to possible beach nourishment projects on adjacent shorelines.