Short-Term Evolution of Cape Morphology: Cape Lookout and Cape Fear, North Carolina

Abstract

Cuspate forelands often occur as a series of seaward projecting capes and their cape-associated shoals. Capes are important physical and ecological discontinuities in a coastline, yet their dynamics are poorly understood. The barrier coastline of North Carolina, consisting of Capes Hatteras, Lookout and Fear, typifies a cuspate foreland coastline. The evolution and morphology of the subaerial cape points at Cape Lookout and Cape Fear, North Carolina were examined through a field-intensive study using Real-Time-Kinematic Global Positioning System (RTK-GPS) from September 2000 to August 2001.

Topographic surveys of the subaerial cape points were conducted to assess changes in volume and shoreline position. Direct observation of waves, currents and bathymetry on cape-associated shoals is extremely difficult and often hazardous. This field-intensive study at Cape Lookout and Cape Fear uses the changing geometry of the subaerial cape point as an easily observed proxy for complex nearshore sediment transport processes at capes. Geo-spatial analysis of topography and shoreline position was used to assess geomorphic trends in volume change and shoreline variability. These results indicate that: 1) Short-term and seasonal changes in shoreline position are a result of changes in nearshore wind and wave energy; 2) variability in shoreline position and morphology increases with distance from the landward end of the cape to the seaward tip; and 3) the seaward tip of the subaerial cape point responds uniquely to changes in the nearshore wind and wave energy, and indicates that this region of the cape point plays a key role in sediment exchange between the subaerial cape and cape-associated shoal. Given the unique behavior of the seaward portion and transitional area of these capes, a previously un-described sequence of morphologic events I call 'clipping' plays a dominant role in the transfer of sand from the tip of the subaerial cape point offshore to the adjacent shoals.