HISTORICAL, EPISODIC, AND SHORT-TERM CHANGES AT LONG BEACH ISLAND, NEW JERSEY

In October 2012, Long Beach Island, NJ saw dramatic changes due to Hurricane Sandy. Episodic events such as Hurricane Sandy can cause large changes to the shoreline in very little time compared to the changes created by the typical wave conditions. Sometimes barrier islands are able to recover naturally after large erosional events like this through accretion, which typically takes place during the summer months. However, in Long Beach Island human response, such as rebuilding the dune system to provide immediate protection from a subsequent Nor’easter and localized dredging, was the main cause of recovery.

Historical shorelines were digitized from orthophotography from the New Jersey Geographic Information Network and imagery from Google Earth collected by NASA. Historical shorelines from New Jersey Department of Environmental Protection were also included in the analysis. Both long-term erosion rates and short-term changes during Hurricane Sandy were calculated using the USGS Digital Shoreline Analysis System extension for ArcGIS. The average long-term erosion rate was 1.35 m/yr over the past 176 years; whereas the average amount of shoreline lost during Hurricane Sandy was 10 meters. The shoreline change observed during Hurricane Sandy is equal to ~7 years of erosion at the long-term rate.

In addition to the historical data, four locations were chosen to measure beach profiles during the summer of 2013. The data from these stations did not follow the historical trend and show there is much short-term, spatial variability along the island. The two locations from the center of the island were fairly stable while the northern end eroded and the southern end accreted. The accretion was likely caused by nearby dredging. The morphology of the coast is the result of many processes, natural/anthropogenic, short/long-term. All of these processes need to be considered when studying these complex systems and determining the appropriate monitoring frequency.