CLASSIFICATION AND DECADAL-SCALE EVOLUTION OF GEOMORPHIC-ECOLOGIC FEATURES ON NORTH CAROLINA'S OUTER BANKS

An understanding of the large-scale geomorphic framework, associated ecosystems, and detailed process-response dynamics on the NC Outer Banks is being developed through analysis of aerial photographs and field mapping of 18 sites between Kitty Hawk and Cape Lookout, NC. These sites, differing in geologic framework, physical processes, and biological ecosystems, represent both the “human-modified” northern Outer Banks and “more natural” Core Banks.

Scanned, geo-referenced aerial photographs (1932-2005) and topographic surveys (1849-1917) were utilized to identify geomorphic units and associated ecosystems and to map their changes through time. Definition of geomorphic units is based on the concept that the fundamental barrier island structure is a sand ramp that evolved in response to storm-generated inlet and overwash dynamics during rising sea level. Superimposed on the barrier-island ramp are smaller-scale geomorphic units that vary due to differences in sand supply, island orientation and location, age of formation, underlying geology, and degree and type of artificial modification. Interpretation of the modern geomorphic systems is based upon the integration of field maps and process-response studies for each site with the analysis of aerial photographs and topographic surveys. The geomorphic and ecologic units are mapped on 1998 color infrared digital ortho-photograph quarter quadrangles (CIR DOQQs).

Each site has a detailed series of maps, sketches, photographs, and aerial photograph time-slices that demonstrate storm responses and evolution of geomorphic-ecologic features. Several sites that appear very different today were similar in the past and are now simply at different stages of evolutionary development. Furthermore, comparison of the evolutionary changes of these geomorphic-ecologic systems through time elucidates the various processes and responses on natural versus human-modified barrier islands. As pressure for artificial modification and intervention of barrier islands increases, understanding the geomorphic-ecologic evolution of barrier island systems provides a critical scientific framework for improving long-term management strategies for barrier island systems in North Carolina and beyond.