Inventory of coastal engineering projects in Gateway National Recreation Area

Dallas, Kate; Ruggiero, Peter; Berry, Michael

This report includes information on coastal engineering projects identified in, or immediately adjacent to, Gateway National Recreation Area (GATE). The report serves as a supplement to a Geographic Information Systems (GIS) database (the GIS data are available online at http://irma.nps.gov). The natural processes of sediment transport and coastal evolution within GATE have been extensively altered by coastal engineering projects. Two hundred and fifty-four coastal structures were identified within and adjacent to the park. Together these structures span over 58 km (36 mi) and armor or stabilize 36% of the park’s shoreline. Nine beach nourishment projects (with 31 episodes) placed a minimum of 10.2 million m3 (13.3 million yd3) of sand within the park from 1915–2012, while four additional projects (with 29 episodes) placed over 36 million m3 (47 million yd3) of sand updrift of park shorelines between 1926 and 2009. Three dredging projects (with 44 episodes) removed over 5 million m3 (6.5 million yd3) of sediment from navigation channels adjacent to the Staten Island and Sandy Hook units of GATE between 1934 and 2011. Three filling projects (with 6 episodes) in the Staten Island unit placed a minimum of 12.6 million m3 (16.5 million yd3) of material from 1860–1948. Dredge and fill projects within the Jamaica Bay unit have dramatically altered the landscape. Very conservative estimates of dredging cite the removal of 71 million m3 (93 million yd3) of material from 1900–1992 (Swanson et al. 1992). Historic dredge and fill activities within Jamaica Bay have decreased the bay’s surface area and increased mean water depths. These changes have modified the bay’s hydrodynamics, negatively impacted water quality, and contributed to a large loss of wetland habitat. Dredge, fill, and stabilization efforts at Staten Island’s Great Kills Park have significantly altered the natural landscape. These projects altered longshore sediment transport pathways and filled historic wetlands, degrading natural ecosystem services. Sandy Hook’s Sea Bright seawall has stopped the natural processes of overwash and inlet formation. The seawall, coupled with groin construction, has artificially stabilized the southern end of the spit. While spit stabilization has promoted recreational access and development, it has also contributed to erosion at the northern end of the seawall. The feasibility of protecting all of the threatened buildings and roads within GATE will decrease in the future as sea level rises and the existing coastal engineering structures degrade. Understanding the implications associated with allowing some developed sites within GATE to revert to natural processes is critical.

Inventory of coastal engineering projects in Gateway National Recreation Area

Series

Collections