Shoreline change monitoring at Gateway National Recreation Area: 2008-2009 Annual Report

Psuty, Norbert; Silveira, Tanya; Soda, Daniel; Spahn, Andrea; Zarella, Paul; McDermott, Jacob; Hudacek, William; Gagnon, John

This annual report documents the collection of shoreline position data and describes the shortterm variation that has occurred during the period from Spring 2008 to Spring 2009 in the Gateway National Recreation Area, as called for in the Northeast Coastal and Barrier Network’s protocol on shoreline monitoring (Psuty, et al., 2010). The changes in shoreline position are generally descriptive of the seasonal contrasts (lower energetics in the summer period versus higher energetics in the winter period) that support sediment accumulation during summer and erosion during the winter. However, there are many natural variables and cultural events that affect the gains and losses of sediment and the displacements of the beach, especially along a coastal setting where sediment input and shoreline exposure are as varied as they are at Gateway National Recreation Area. In this survey period, the storm season was exceptionally mild and most areas and there was little seasonal or annual inland displacement of the shoreline. Further, sediment input from outside of Gateway probably influenced the dimension and direction of shoreline displacement. This short-term annual report is just the first step in characterizing the Park’s ocean shoreline by establishing a baseline of information for subsequent descriptions and analyses. The ocean shoreline of the Sandy Hook Unit had an average seasonal variation of -5.58 m and +6.71 m, and an average annual variation of +1.19 m, although with considerable loss as well as gain in the northern portion of the Hook. Great Kills had a mean annual gain of +1.30 m. Plumb Beach has seasonal gains of +2.26 m and +1.03 m, with a mean annual gain of +3.14 m. The Breezy Point ocean shoreline had the greatest variation with a mean seasonal range extending from +19.54 m to +0.95 m, and a mean annual displacement of +20.50 m. This annual report on shoreline position change of the Gateway ocean shoreline does offer some insight into the areas of coastal dynamics and sediment budget. However, it is a report on only one year of observations and does not establish a trend. The protocols for shoreline monitoring created a comparable geodatabase that will lead to efficiencies in data assembly and analysis.

Shoreline change monitoring at Gateway National Recreation Area: 2008-2009 Annual Report

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