Metrics of resilience and recovery in Roxbury Cove, 2015-2016: Jamaica Bay Unit, Gateway National Recreation Area

Psuty, Norbert; Ames, Katherine; Habeck, Andrea; Haussner, Elizabeth; Schmelz, William; Butler, Kelly; Greenberg, Joshua

This report contains linear, elevation, and volumetric feature changes at Roxbury Cove, a bayside site near the western terminus of Breezy Point Spit, Jamaica Bay Unit of Gateway National Recreation Area. Surveys were conducted from the late winter of 2014-15 to the fall of 2016, and the analysis includes two LiDAR datasets, August 2010 and November 2012, to capture the effects of Hurricane Sandy. The focus of this report is on the resilience and recovery of the beach and dune system along Roxbury Cove. The analysis provides metrics of dune crest displacement, shoreline displacement, site elevation change, and site volumetric change. From 2010 to 2012, the foredune at Roxbury Cove was displaced inland throughout the site, and the shoreline was displaced seaward. From the 2010 to 2012 survey period, the dune crest shifted seaward throughout the site and the shoreline shifted seaward in the east associated with volumetric gain low on the beach. The topography from 2010 to 2012 showed volumetric gain in the beach feature to the east and volumetric loss in the beach and dune feature in the western portion of the site, concurrent with the linear feature displacement. The geomorphological recovery in the Post-Hurricane Sandy period recorded the dune crest position from Winter 2015 to Fall 2016 as relatively stable, with minimal change in position. Shoreline change was variable throughout the survey period. There was seaward displacement directly post-Sandy, followed by smaller landward and seaward displacements seasonally. During the survey period, there was a pattern of volumetric loss low on the beach and gain higher on the profile, with minimal change in the dune feature. The dune feature had not regained volume that was lost during the 2010 to 2012 period. Erosion low on the beach continued to narrow the margin between the beach and road inland of the site. After two major storms from 2010 through 2012, the beach feature lost volume and continued to lose volume during the survey period from 2015 to 2016. During the survey period, the dune feature lost volume and was displaced inland, but has remained relatively stable in the new inland location. The beach feature and dune feature persisted throughout the survey period, showing resilience in the topographic system. Spatial displays of dune crest displacement, shoreline displacement, elevation change, volumetric change, and associated metrics are presented in this report.

Metrics of resilience and recovery in Roxbury Cove, 2015-2016: Jamaica Bay Unit, Gateway National Recreation Area

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