METRICS OF STORM IMPACTS AND RECOVERY IN FORT TILDEN, JAMAICA BAY UNIT, GATEWAY NATIONAL RECREATION AREA

The occurrence of Hurricane Sandy in October 2012 caused major changes to the topography and infrastructure on the seaward margin of Fort Tilden, located in Gateway National Recreation Area, New York. Shore Road, which ran the length of Fort Tilden, was damaged or completely destroyed during Hurricane Sandy. A topographical monitoring program was initiated at Fort Tilden to document the extent of the storm impacts and the elements of recovery. Eleven cross-sectional profile lines were generated to depict the beach and dune features and establish the dimensions of change. Starting in December 2014, topographic surveys of the profile lines were conducted seasonally using geodetic-grade GPS units. LiDAR datasets from 2010 and 2012 were also used to establish the pre- and post-storm condition of the beach-dune system. Each profile incorporates a variety of metrics including dune crest displacement and change in cross-sectional area of geomorphological features, including beach, dune, washover, and accumulation around sand fencing.

The 2D metrics describe a loss and inland displacement of the coastal dune feature whereas there is considerable cross-sectional area gain and seaward displacement of the beach feature. It is likely that the beach nourishment project that put almost 2 million cubic yards of sediment updrift on the Rockaway and Riis Park beaches is causing the accumulation low on the profiles. In the three yeas post-Sandy, the dune system has recovered some of its eroded volume, but is being re-established inland of its previous location. This landward re-establishment of the dune system means the former location of Shore Road is located in the active beach for most of its alongshore length.