Tropical Cyclone Frequency and Barrier Island Erosion Rates, Cedar Island, Virginia

Nebel, S. H.; Trembanis, A.C., and Barber, D.C., 2013. Storm frequency and barrier island erosion rates, Cedar Island, Virginia. Journal of Coastal Research, 29(1), 133-144. Coconut Creek (Florida), ISSN 0749-0208. Shoreline surveys, high-resolution satellite imagery, aerial photography, and topographic maps were compiled using GIS and analyzed with the Digital Shoreline Analysis System to examine event- and decadal-scale patterns of shoreline movement related to tropical cyclone impacts on south Cedar Island, Virginia. Global Positioning System (GPS) shoreline surveys conducted on southern Cedar Island 1.5 months before and 3 weeks after Tropical Storm Ernesto in 2006 recorded shoreline movement that resulted from the storm. On average (arithmetic mean), the southern section of Cedar Island retreated 25.4 +/- 1 m as a result of the storm. The most severe erosion was documented to the south of an ephemeral inlet where the shoreline retreated 54.8 m. Shoreline recovery in the study area was determined from a February 2007 aerial photoset and a June 2007 GPS shoreline survey. Between September 2006 and February 2007, the shoreline accreted an average of 7.4 +/- 2.1 m. Between February 2007 and June 2007, the shoreline eroded an average of 0.2 +/- 2.1 m. The comparison of the July 2006 (pre-Ernesto) and June 2007 (9 months after Ernesto) data revealed that the shoreline had not recovered to its poststorm position but rather had undergone net erosion averaging 18.3 +/- 1 m. Additionally, the 155-year record (1852-2006) of Cedar Island shoreline retreat was compared with the historical record of tropical cyclones passing within 200 km of the Delmarva Peninsula. A marked acceleration in island retreat rates began in 1980 and continued until the end of the study period in 2007. This acceleration in island erosion rate coincided with an increased frequency of tropical cyclones within the studied region.