EVOLUTION OF THE NORTH CAROLINA BARRIER ISLAND SYSTEM IN RESPONSE TO RISING SEA LEVEL: A VISION FOR THE FUTURE

North Carolina accepted a sea-level rise document, produced by the NC scientific community and based upon existing NC data, that projects a 1 m (possibly 1.4 m) rise in regional sea level by 2100. The forecast for barrier island evolution in response to this amount of sea-level rise could be economically catastrophic if we maintain our current coastal management policies. During the last glacial maximum (LGM) the NC shoreline was ~125 m below present sea level and ~25 to ~110 km seaward of the present shoreline. This resilient coastal system migrated upward and landward in response to sea-level rise since the LGM and is expected to continue.

NC is dominated by 3 types of coastal shorelines (complex-barrier islands, simple-barrier islands, and headland strandplains) and 3 types of back-barrier estuaries (drowned-river, open-embayed, and tributary-strip estuaries). As sea level rises, each system evolves depending upon a set of variables and processes including the underlying geologic framework, flooding surface topography, sediment supply, and storm dynamics. These variables dictate the evolutionary succession of each coastal segment which must be incorporated into local coastal management strategies to cope with rising sea level. The evolutionary response of the NE NC barrier islands (Outer Banks), will be substantially different from that of highly urbanized barriers in SE NC, requiring different management strategies. The Outer Banks will likely become increasingly dynamic and segmented, whereas the SE NC barriers will continue a typical treadmill-style transgression

Today, the natural migration of most barrier islands and estuarine ecosystems is severely jeopardized by human developments as once resilient, dynamic coastal systems are increasingly “locked in place” to maintain status quo policies of unlimited growth and development. The result is escalating cost with increased dependence upon engineered solutions to protect economic investments. It is essential that coastal policies be developed to facilitate adaptations to ongoing coastal changes in order to maintain a viable coastal economy and preserve the natural resources upon which that economy is based. A vision for the future of NC’s coastal systems represents a case study, applicable to similar barrier systems around the world.