Morphologic Response and Recovery of the Beach System Related to Hurricane Sandy at Fire Island, NY

Presenter: 
Cheryl Hapke, St Petersburg Coastal and Marine Science Center, USGS
Event Location: 
BCCMWS 100
Event Date: 
Thursday, February 12, 2015 - 3:00pm
Event Type: 
SCMSS Seminar Series

Presenter: Cheryl Hapke (USGS)

Abstract: A variety of morphologic data of the Fire Island, NY barrier island system were collected prior to, and in the time period since, the landfall of Hurricane Sandy - the largest hurricane recorded in the Atlantic basin. Data include topography of the beach and dunes, bathymetry of the nearshore and sub-bottom data to map sediment thickness in the nearshore. These data are used to assess morphologic change related to storm processes from Hurricane Sandy and the winter storms that followed. In addition, we are monitoring the system to develop data-driven approaches for quantifying response, recovery, and resilience which will be incorporated into models for predicting recovery from future storms.

During Hurricane Sandy, the beaches and dunes on Fire Island were severely eroded, and the island breached in several locations on the eastern segment of the island.  The surfzone morphology was extensively impacted by Hurricane Sandy and continued to evolve during subsequent winter storms. As is typical during large storm events, the outer bar moved offshore during Sandy. Almost two years after the storm, however, the bar remains further offshore than prior to Sandy, resulting in a widened surfzone. The average volume of the shoreface seaward of the bar increased, which is attributed to the seaward translation of the outer bar and additional offshore transport and deposition of material from the inner surfzone during the storm.

The subaerial beach has experienced substantial recovery since the winter of 2012-13. A new morphometric for tracking the recovery of the upper beach at Fire Island indicates there is a temporal trend towards a wide, flat beach berm which was sustained even through a winter storm season. This trend may represent a new “recovery state” of the beach which is wider than the pre-Sandy beach, providing an increase in the fetch that favors the aeolian processes of dune reformation.