RESPONSE OF WETLANDS TO RISING SEA-LEVEL IN THE LOWER COASTAL-PLAIN OF NORTH-CAROLINA

Most of the coastal wetlands of the South Atlantic region of the Unite d States are expected to diminish in size in response to the opposing forces of increasing human population growth and accelerating rates of rising sea level. We evaluated several models that project the respon se of coastal wetlands to rising sea level and concluded that current models appear unsuited for wetlands of the Albemarle-Pamlico peninsula of North Carolina. We came to this conclusion after we examined the d istribution of wetlands, elevation contours, estimates of surface slop e, soil types, and peat deposits on the peninsula. Most of the data we re obtained from U.S. Geological Survey topographic quadrangle maps, U .S. Fish and Wildlife Service National Wetlands Inventory maps, U.S. S oil Conservation Service soil surveys, and inventories of peat deposit s. Some unusual features of this peninsula are low elevation (56% of t otal area <1.5 m), extensive coverage by wetlands (53%) and hydric soi ls (90%), negligible slopes of the land surface, virtual absence of ti des, and lack of abundant sources of sediment. In the process of recon structing how past rises in sea level most likely led to present condi tions, it became apparent that vertical accretion of peat in situ is l argely responsible for landscape features in areas where elevations ar e lowest. Were it not for these deposits, the land surface area of the peninsula would be decreasing relative to sea level. This situation c ontrasts sharply with areas in the eastern United States fringed by ti dal marshes, which are undergoing overland migration at a rate dictate d by landward slope and the rate of rising sea level. If the rate of s ea level rise accelerates, it is doubtful if vertical accretion rates of peat can prevent submergence of extensive areas of wetlands in the Albemarle-Pamlico peninsula. Land use and drainage in the lowest eleva tions of the peninsula are currently being affected by sea level. Futu re land management of the peninsula will be constrained by potential l andscape changes as a result of rising sea level.