Shoreline change monitoring at Gateway National Recreation Area: 2010-2011 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 short-term variation that has occurred during the period from Spring 2010 to Spring 2011 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. 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 12.7 m and +-6.83 m, and an average annual variation of 5.53 m, with considerable gain in the Gunnison Beach area. Great Kills had mean seasonal changes ranging from -0.98 m to -0.33 m, with a mean annual loss of -1.24 m, with greatest losses in the vicinity of the old bathhouse location. The west end of Great Kills Park had an annual mean change of 0.24 m, with accumulation downdrift of the jetty, erosion along the inland shoreline, and accumulation at the entrance to the marina. Miller Field had an annual change of 0.72 m, with erosion to the west and gain in the middle and eastern portion. The change at Fort Wadsworth was modest, a mean of 0.68 m, with erosion at the western portion and accumulation to the east. Plumb Beach had an annual change of 0.64 m, with erosion at the western and central portions balancing larger accumulations at the eastern end of the spit. The annual net condition at Breezy Point was a mean gain of 14.55 m; with considerable accumulation along the western half of the spit and no net change along the eastern half. The area of Breezy Point beyond the terminal jetty and along the bayside margin had a net gain of 2.37 m, with most of the gain immediately downdrift of the jetty and small changes along the reminder of the bayside shoreline. 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: 2010-2011 annual report

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