DECADAL-SCALE EVOLUTION OF BARRIER ISLAND GEOMORPHIC--ECOLOGIC SYSTEMS, NORTH CAROLINA OUTER BANKS

The evolution of geomorphic features and associated ecosystems over the past 15 decades on the NC Outer Banks is part of the ongoing USGS-ECU-NCGS cooperative research program that is being carried out in partnership with the USNPS and USFWS. The study is based on the process-response analysis of georeferenced aerial photograph sets (1932-2003) and topographic survey maps (1852-2003) of 23 sites between Kitty Hawk and Cape Lookout, NC. These sites include the “more natural” Core Banks (Cape Lookout National Seashore--CLNS) and the “severely human modified” northern Outer Banks (Cape Hatteras National Seashore--CHNS), representing different geologic frameworks, physical processes, and biological ecosystems.

The geomorphic and associated ecosystem units within each site were defined during field surveys and analysis of georeferenced materials. These units were mapped on 1998 digital orthophoto quarter quads (DOQQs) using MapInfo and ArcView and combined with modern close-up maps, sections, and photographs for each site. These modern data were integrated with the time series analysis of historical aerial photographs and topographic surveys to interpret the evolutionary responses of geomorphic--ecologic systems to storms, sea-level rise, and human modification within the different geologic frameworks through time. Sites that result from similar evolutionary processes, but occurring at different stages of development are compared. Mapping the geomorphic--ecologic system changes through time allows for differentiation of natural barrier island processes and responses from those due to anthropogenic modification. As economic growth and development escalate, the pressure for further modification increases. These scientific data will provide a framework for understanding the economic and environmental trade-offs necessary for developing long-term management strategies for North Carolina’s barrier island system.