The Effects of Geomorphic Changes during Hurricane Sandy on Water Levels in Great South Bay

Hurricane Sandy caused record coastal flooding along the south shore of Long Island, NY, and led to significant geomorphic changes. These included severe dune erosion along the length of Fire Island and the formation of the Wilderness Breach. This study attempts to use numerical models to quantify how these changes affected water levels inside Great South Bay during and after Hurricane Sandy. The results suggest that overwash along Fire Island may have locally increased peak surge levels in the bay by 20 cm during the storm. There is however large uncertainty surrounding the overwash fluxes. The model results suggest that the development of the Wilderness Breach had locally led to an increase in peak water levels of approximately 7 percent at Lindenhurst by mid-2014, and an increase in tidal amplitudes here of 15 percent. The models predict that the largest changes have occurred in the central part of Great South Bay