2007 GSA Denver Annual Meeting (28–31 October 2007)
Paper No. 33-5
Presentation Time: 2:50 PM-3:10 PM


PILKEY, Orrin H., Division of Earth & Ocean Sciences, Duke University, Box 90228, 321 Old Chemistry Bldg, Durham, NC 27708, opilkey@duke.edu and NEAL, William J., Department of Geology, Grand Valley State University, Allendale, MI 49401

Three communities are found on 35.8 km long Topsail Island on the central North Carolina coast. From north to south are North Topsail Beach, Surf City and Topsail Beach. Our subjective view is that North Topsail Beach is the most unsafe barrier island community for development south of Long Island, NY; exceeded in the degree of hazards only by West Dauphin Island, AL on the Gulf Coast. In a 1998 study we classified the community as 85% high-to-extreme risk for development. Most of North Topsail is less than 1.5 m in elevation and large portions of the island are only 50 to 200 m wide. The narrow predevelopment dune line was mostly less than 5 m in elevation, and broken by overwash passes. Past storms and development both contributed to dune loss. Little or no natural dune remains along most of the island, although a single, repeatedly repaired, bulldozed sand ridge is present. Erosion rates are between 0.6 and 1.5 m per year. All development is post-WWII and most is post-1970. Hurricane Hazel (1954) completely submerged the site (before buildings) and Hurricane Fran (1996) did the same, but with hundreds of buildings present, so property losses were extensive. Hurricane Bonnie (1998) destroyed post-Fran artificial dunes and caused extensive overwash. Most buildings are large single-family rental houses and duplexes, but several medium-rise hotel/condos are located at the north end of the island. The single road available for evacuation was threatened by erosion, and the state forced the developer to move the road back. The new road is now at a lower and more flood-prone elevation, and the site of the old road next to the beach was soon filled with houses. Seven small bridges span marsh fingers that intrude into the island, two of which became shallow inlets during hurricanes Fran and Betsy (1996). These past and likely future inlet sites are now occupied by houses. Hundreds of buildings were damaged or destroyed in Hurricane Fran, and in spite of the COBRA designation (no federal support allowed), much of the infrastructure was replaced with federal funding. The vulnerability of this island community to storm surges, continued erosion, and sea-level rise impacts is extreme. In addition, the community probably can't be evacuated safely on the single low escape road.

2007 GSA Denver Annual Meeting (28–31 October 2007)
General Information for this Meeting
Session No. 33
Identifying America’s Most Vulnerable Oceanfront Communities: A Geological Perspective
Colorado Convention Center: 708/710/712
1:30 PM-5:30 PM, Sunday, 28 October 2007

Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 95

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