A RECONNAISSANCE STUDY OF SHOREFACE SAND RESOURCES OFF A STORM IMPACTED BARRIER: SURF CITY, NORTH CAROLINA

Surf City is a 17 km long transgressive barrier segment located along the central portion of 45 km Topsail Beach. It is one of eight coastal communities in southeastern North Carolina that have requested assistance to mitigate chronic erosion and the impact of recent storms. Development along this reach is sited on historic flood tidal delta deposits of Stump Inlet. Prior to the onset of the recent hurricane activity in 1996, long term average erosion rates indicate that much of the area was either stable or was characterized by erosion rates of less than 0.75 m/y. Since 1996 major segments of the fronting dunes were eroded and much of the area was overtopped, resulting in development of extensive washover deposits. Destruction of many of the oceanfront homes and the lack of significant post-storm shoreline recovery has prompted an exploration of the shoreface as a potential borrow source for beachfill material.

A preliminary assessment of the resource potential of a 75 km² area of the shoreface was based on side-scan sonar and diver-retrieved vibracores, surface samples and rock samples. Compilation of the data indicates that much of the offshore area within the state's jurisdictional limits is dominated by Oligocene limestones and siltstones mantled with a patchy, thin veneer of interbedded muddy sands and shell units.

The lack of a significant volume of sand in the offshore area precludes the use of the shoreface as a viable borrow site. As a result it is unlikely the community will satisfy its need for the initial nourishment that exceeds 3.5 million m³ of material. Its central location along Topsail Beach and the use of the relatively small bordering ebb deltas further minimizes future nourishment. Consequently additional development should be discouraged.