SHORELINE ANALYSIS: DECADAL SCALE PATTERNS (1852-2007) FROM CEDAR ISLAND, VIRGINIA

Shoreline data from Cedar Island, Virginia derived from aerial photographs, NOS topographic sheets, high-resolution satellite imagery and GPS surveys have been compiled and analyzed using GIS and the digital shoreline analysis system. These shorelines, dating from 1852 to 2007, record the rapid retreat of this barrier island on decadal time scales.

Shoreline retreat rates for Cedar Island were found to have an alongshore average of -4.1 m/yr based on simple end-point analysis (1852-2007). The short-term (1994-2007) retreat rates on Cedar Island tripled and were calculated to be an average -12.6 m/yr. An increase of the short-tem erosion rates on Parramore Island, the barrier located just to the south of Cedar, was noted by Richardson and McBride (2007).

Retreat statistics were further calculated for the time intervals 1852-1910 (-5.1 m/yr), 1910-1962 (-3.5 m/yr), 1962-1980 (-3.9 m/yr), 1980-1994 (-6.5 m/yr), 1994-2002 (-12.4 m/yr), and 2002-2006 (-13.8 m/yr). This analysis indicates that retreat of the Cedar Island shoreline has been accelerating, with a notable increase in rate between 1980 and 1994.

The shoreline retreat patterns observed on Cedar Island are compared to the historical Atlantic hurricane tracks that have affected the Eastern Shore. The comparison of this storm frequency data with Cedar Island retreat rates showed that the acceleration in shoreline erosion that began in the 1980s occurs contemporaneously with an increase in tropical storm and hurricane frequency.