Predicting the Long-Term Impact of Hurricane Sandy on Spatial Patterns of Wetland Morphology in Salt Marshes of Jamaica Bay, New York

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USGS scientists are working with collaborators to understand how Hurricane Sandy impacted wetlands in Jamaica Bay, New York. 

Figure 1. Jamaica Bay and field sampling sites
Figure 1. Jamaica Bay and field sampling sites

Science Issue and Relevance: Jamaica Bay, New York, (Figure 1) has experienced a conversion of more than 60% of the vegetated salt-marsh islands to intertidal and subtidal mudflats. Between 1951 and 2003, 647.5 hectares of salt marshes were lost. The stressors contributing to marsh loss include reduction in mineral sediment supply, sea level rise, change in tidal range, the dredging of navigation channels, and runoff of nitrogen-enriched wastewater among other factors. Hurricane Sandy (landfall along the east coast on October 30, 2012) provided an opportunity for studying the impacts of hurricanes on short-term sedimentation and erosion and long-term morphologic changes in coastal wetlands along the northeast coast, including the salt marshes of Jamaica Bay, New York.

Methodology for Addressing the Issue: In this research, USGS and collaborators are developing a high spatial resolution, process-driven, hurricane-wetland numerical modeling system for the Jamaica Bay Estuary using the Delft3D model. Hurricane-induced wind, waves, storm surge, hydrodynamics, sediment transport, wetland morphology dynamics, and interactions and associated feedback mechanisms are incorporated in the Jamaica Bay hurricane-wetland model (Figure 2). Preliminary results showed that simulated wind speed, wind direction, and water level agree reasonably well with observations. Impacts of waves and vegetation on sediment transport, deposition, and erosion were investigated using numerical experiments. We also collected soil cores (0-50 cm) at 12 salt marsh sites (Figure 1) for soil/sediment properties and surface elevation table (SET) data for model calibration and validation. Soil strength at these sites was also measured to provide information on soil/sediment critical shear stress. We will use the modeling system to assess short-term sedimentation and erosion, and to predict the long-term morphologic dynamics of Hurricane Sandy on salt marshes of Jamaica Bay, New York.

Figure 2. The hurricane-wetland numerical modeling system
Figure 2. The hurricane-wetland numerical modeling system

Future Steps: This research is a Round 1 project and is underway. This modeling approach is being used to examine future hurricane impacts on salt marsh morphology in Jamaica Bay, New York (Round 2 project).

Location of Study: 40°36’40.16’’N, 73°50’ 28.48’’W