Comparison of Damage Mechanisms to Oceanfront Structures Protected by a Beach and Dune System with vs. without a Rock Seawall during Hurricane Sandy

This paper investigates the damage caused by three different mechanisms-wave impact, scour/high velocity flow (HVF), and debris impact-to the oceanfront structures of two New Jersey coastal communities during Hurricane Sandy. The two neighboring communities, Bay Head and Mantoloking had similar dune sizes and beach profiles before the storm, with one major difference: buried within the dune line along most of the length of Bay Head, was a relic rock seawall. The research compares the effects of the two different shoreline protection systems employed by each town, and finds that: (1) areas with the rock seawall experienced less erosion behind it but more erosion seaward of it, when compared to sections of shoreline without the rock seawall; (2) for structures with the rock seawall protection, wave impact and scour/HVF predominantly resulted in minor damage, whereas for structures without the rock seawall protection, wave impact and scour/HVF predominantly resulted in severe damage; and (3) the variation in distance to the 0 ft NAVD88 contour caused greater variance in damage levels of wave impact and scour/HVF than the variance in beach protection type.