Beaches are highly unstable environments. They are continually
altered by wind and waves. Substantial shoreline change is common on
seasonal and interannual time scales. Unfortunately, progressive
shoreline change has become problematic in vulnerable coastlines.
Hurricane Irene demonstrated that coastal management practices need
be informed by shoreline change science. This study represents a
segment of a broader project initiated in coordination with NASA
Wallops Flight Facility and the Chincoteague National Wildlife
Refuge to evaluate shoreline change in Wallops Island, Virginia.
Irene occurred August, 25-26, 2011 and resulted in noticeable
shoreline change. Although not as large as predicted, this category
1 hurricane still had significant impacts on shorelines along
Wallops and Assateague Islands. This study uses GIS to: 1) evaluate
longer-term rates of shoreline change at Wallops Island as recorded
by aerial photographs over 74 years, and 2) measure more precisely
shoreline change attributable to Irene from pre- and post-storm
surveys. Our preliminary results show sedimentation patterns on the
north end of Wallops have been nonuniform. The far north (aka Cow
Gut region) has shown substantial erosion and retrogradation of 10’s
of meters with erosion of the beach-dune complex through areas that
were previously salt marsh. To the south, the beach area has been
prograding oceanward. Sedimentation here is the result of erosion
even further south, in the area of launch infrastructure and hard
stabilization areas. Based on these assessments, a compartmentalized
beach sediment budget is being constructed to evaluate sediment
re-distribution patterns through time.
High resolution GIS mapping of
shoreline change at Wallops Island, Virginia: A preliminary
investigation of the impact of Hurricane Irene