REGIONAL-SCALE CONTROLS OF SEDIMENT DYNAMICS AND RESPONSE TO HUMAN-MODIFICATION, SOUTHEASTERN NORTH CAROLINA BARRIER ISLAND SYSTEM
Sediment sources available to build and maintain the modern barrier island system include: 1) shoreface and inner shelf stratigraphic units dominated by Tertiary rock units; 2) paleo-river valley fill and deltaic deposits dominated by small coastal plain streams; 3) modern inlets and their ebb-tide and flood-tide deltas; and 4) cape shoal structures (Cape Lookout and Frying Pan shoals). The first two sources are inconsequential to the regional sediment budget. Sediment dynamics of modern inlets are highly modified and controversial involving sand mining, stabilization, and channel re-alignment and enlargement. At regional scales, the cape shoal deposits were important for the initial formation and long-term maintenance of the OBCC barrier islands. Human modification of most inlets over the past century (dredging larger and deeper navigational channels, discharging dredged sediments onto the continental shelf, mining ebb-tide deltas, and stabilizing with jetties) has short-circuited the regional-scale sediment dynamics of cape shoal sands. Consequently, ocean shorelines on all OBCC barrier islands are severely receding with most island communities wanting nourishment sand to hold the line in a rising sea level. In spite of vast sand supplies in the cape shoals, they are not fully understood and probably are environmentally problematic and economically unavailable for future beach nourishment.