Open Ocean/Marine - Coastal System Change at Fire Island, New York

Science Center Objects

Geophysical mapping and research have demonstrated that the seabed on the inner continental shelf has a variety of shapes which are linked to long-term evolution of the barrier island. Regional-scale modeling forecasts how atmospheric forcing and oceanographic circulation case sand, gravel, and other materials to be transported by tides, winds, waves, fresh water fluxes, and density variations.

The inner shelf adjacent to Fire Island is where geologic and oceanographic processes interact to influence the long-term behavior of the island and shoreline. First, mapping the geology of the inner shelf allows us to identify the sources of sediment that have contributed to the formation of Fire Island over the last several thousand years. Next, studying patterns of sediment distribution influence how much sand is transported along and across the shelf during stormy and fair-weather periods, contributing to our understanding of the historical behavior of the island. Finally, changes in inner shelf shape and slo pe alter waves as they approach the coast which can lead to spatial variability in coastal response to storms. All of this information helps coastal managers understand the sediment budget of the island so they can make sound sediment management decisions. 

Coastal Change Processes

The USGS has been actively studying sediment distribution, morphology, and sub-seafloor structure of the inner shelf off of Fire Island for more than 20 years. As instrumentation has improved and as data resolution has increased, we have been able to build upon previous work to augment and refine our understanding of the geological processes that shaped the coastal landscape in the past and will continue to influence coastal behavior in the future.

Tides, winds, and waves drive currents offshore that erode and deposit sediment and change offshore morphology. Using a combination of oceanographic observations and modeling, the USGS is quantifying the processes that drive the connections between shelf geology and modern coastal behavior.