SAND RESOURCES FOR SHORELINE RESTORATION ALONG A HURRICANE IMPACTED COASTLINE: OAK ISLAND, BRUNSWICK COUNTY, NORTH CAROLINA

The Brunswick County coastline in southeastern North Carolina continues to be major tourist destination that is experiencing sustained development despite the devastating impact of recent hurricanes. A primary concern of local government is the environmentally sensitive issue of beach nourishment for this chronically eroding reach where most developed shorelines have planned nourishment projects. Costs and environmental restrictions limit the utilization of the mainland as a borrow source. Stringent regulations involving mining of sand within estuaries also pose serious obstacles for dredging within flood tidal deltas and interior channels for beachfill. Consequently, the shoreface seawards to the 5.0km state's jurisdictional limit as well as ebb-tidal deltas have been targeted.

South facing Oak Island is one of five municipalities slated for nourishment. Located immediately west of the entrance to the Cape Fear River Estuary this 22km long reach is composed of a Pleistocene subaerial headland flanked by transgressive barrier spits. Beachfill needs are conservatively estimated to range up 6.0 million m3. Approximately 2.6 million m3 of material has already been excavated from an AIWW dredge disposal site and placed along a portion of the shoreline. Additional sand from Lockwoods Folly Inlet’s small ebb-tidal delta to the west will provide only short-term relief. Dredging of the entrance to the Cape Fear River estuary will play a major role in the initial construction and maintenance of the project. Activities include deepening and realignment of the ship channel that will yield 6.6 million m3 of material for placement on this and adjacent beaches. Contrary to conventional wisdom the shoreface, which is characterized by hardbottoms of Cretaceous-Eocene age sandstones and limestones, is an unlikely borrow source. The sediment cover when present, is thin, mobile, and consists of 10-200cm units of muddy sands and gravelly, muddy sands. The distribution of hardbottoms and the muddy nature of the sediments indicate the shoreface has a very low potential for providing significant volumes of beachfill quality sand. Long-term solutions have focused on sand management of the western Jay Bird shoal segment of the Cape Fear River ebb-tidal delta.