Dune Retreat and Shoreline Change on the Outer Banks, North Carolina, 1997-1998

LIDAR data were collected in late September of 1997 and 1998 along a 175 km stretch of the Atlantic coast of the Outer Banks, North Carolina between Cape Lookout and Oregon Inlet. These data, available from NOAA, provide the basis for quantitative determination of the changes in beach morphology during this one-year interval. There had been no recent large storms preceding the 1997 data collection. The 1998 data were collected 4 days and 10 days after Hurricane Bonnie. Beaches east and north of Ocracoke Inlet have been stabilized and maintained since the 1930s while beaches to the south and west have been left in their natural state. We examine shoreline perpendicular profiles, taken every 20 m along the shoreline, that extend from an onshore baseline to the shoreline. Using these profiles, we determine horizontal shoreline position and, for the most seaward dune, dune height and the position and elevation of the dune base. These parameters change between 1997 and 1998 due to changes in beach morphology. For locations where the 1997 beach width was wider than approximately 20 m, there is a nonlinear relationship between the 1997 beach width and the associated maximum dune retreat. This relationship varies from south to north. Greater maximum dune retreats are found for comparable beach widths north of Ocracoke Inlet, the region where beaches have been actively maintained.