USING INUNDATION DEPOSITS TO CONSTRAIN THE STORM SURGE HEIGHTS OF STORMS THAT AFFECTED NEW YORK CITY, NY: HOW DOES HURRICANE SANDY COMPARE?
Sediment cores were taken from Seguine Pond, a ~1 m deep back-barrier pond located on Staten Island’s southern coast, about one month after Hurricane Sandy impacted the area. The cores contain several coarse grained deposits most likely associated with storm surge inundation of the pond, including a surficial deposit associated with Hurricane Sandy’s surge. Age constraints on the inundation deposits are developed by using C-14, Cs-137, and Pb-210 radiometric dating methods. The grain size distribution is measured for the event deposits to help constrain flow conditions required for erosion and transport of sediment. The maximum grain size of the deposits is used to estimate their storm surge heights using an advective-settling model.
We find that 1) several deposits have a maximum grain size larger than Hurricane Sandy’s deposit, suggesting that they were created by larger storm surges, 2) sea-level rise and tides are two of the primary causes of Sandy’s very high water levels relative to these older storms, and 3) inundation deposits show decreased concentrations of heavy metals than the background sediment, suggesting that storms can sequester contaminated sediments.