BARRIER ISLAND RESPONSE TO SEA-LEVEL RISE, STORM DYNAMICS, AND HUMAN INTERVENTION BASED UPON TIME-SLICE ANALYSIS AND GEOMORPHIC MAPPING, NORTH CAROLINA OUTER BANKS

Barrier island processes were studied utilizing time-slice analysis of geo-referenced aerial photos (1932-2003) and topographic surveys (1852-2003) at selected sites from Kitty Hawk to Cape Lookout, NC. Based on the study, a model was developed for barrier island evolution in response to sea-level rise. The geomorphic evolution of barrier island features and associated ecosystems is a function of the geologic framework that includes barrier island orientation and sediment supply, and dynamics of sea-level rise, storms, and human modification.

The Outer Banks can be divided into those that are severely modified by anthropic development and those that are relatively unmodified. The northern section, from Kitty Hawk to Ocracoke is dominated by urban development, highways, and bridges and is home to Cape Hatteras National Seashore and Pea Island National Wildlife Refuge. Even though the lands of the latter are protected from urban development, they are dissected by a highway that connects eight isolated villages. Efforts to protect the buildings and highway eliminate the natural dynamics of building island width and elevation, and interfere with the basic processes necessary for barrier island evolution in response to ongoing sea-level rise. The southern section, from Ocracoke Inlet to Cape Lookout includes North and South Core Banks and is home to Cape Lookout National Seashore. These islands have no villages or paved roads, have experienced only minimal human modification, and exemplify the effect of un-impeded barrier island dynamics. Inlet and overwash dynamics actively build island width and elevation, enabling the upward and landward migration of the islands in response to ongoing sea-level rise. Comparison of 1998 ocean shoreline along the Outer Banks with that from the mid-19th Century topographic surveys demonstrate variability along the ocean shoreline. This variation combined with the model of barrier island evolution indicates the more vulnerable portions of the Outer Banks.