Hal Needham, SCIPP Research Associate at Louisiana State University
Hurricane Sandy devastated much of the Mid-Atlantic Coast this week with ferocious winds, record-setting storm surge and destructive waves. While the economic toll from this disaster could total up to $50 billion (Huffington Post, November 2, 2012), the staggering human loss has made this storm a catastrophe. The latest death toll has risen to 80 fatalities in the U.S., including 38 victims in New York City (New York Times, November 2, 2012.)
The record-breaking storm surge, which smashed ashore most viciously in New Jersey and New York, caused many of these fatalities and much of the damage. On Staten Island, for example, a two-year-old boy drowned when the surge swept him from his mother’s arms (New York Times, November 1, 2012). Photos of the surge damage depict homes which were either smashed to pieces or floated off their foundations, as well as debris-covered streets, which were also buried under feet of sand.
Preliminary surge observations have provided a maximum surge level of 14.6 feet at Bergen Point, NJ (www.abcnews.go.com.) However, surge levels were devastatingly high all along the New Jersey Coast, in the metropolitan New York City area, on Long Island, and even in coastal New England.
Battery Park, NY, located at the southern tip of Manhattan Island, set a new record high water level of 17.33 feet above the station datum, a vertical reference line for measuring water heights. This water level was reached through a combination of high astronomical tides and a 9.23-foot storm surge, which is the storm-driven water height above normal tide levels. Such high water levels enabled salt water to pour over sea walls in Lower Manhattan and inundate the subway system under many feet of water.
Sandy’s water level at Battery Park broke Hurricane Donna’s (1960) previous high-water record by more than four feet. It is also interesting to note that Hurricane Sandy’s massive surge comes just 14 months after Hurricane Irene inundated much of the coastline, producing the fourth highest water level of all time at Battery Park.
These surge observations will be incorporated into SURGEDAT, the world’s most comprehensive storm surge archive. This dataset has been developed through funding made possible by NOAA-funded SCIPP, the Southern Climate Impact Planning Program. SURGEDAT has identified the peak storm surge level in more than 450 global surge events since 1880, including more than 300 events in the United States. Recently this dataset was expanded to include the entire inundation footprint for more than 240 U.S. surge events. These footprints contain more than 6,100 historic storm surge observations in the United States.
These data are useful for coastal decision makers, emergency management professionals, insurance professionals, as well as coastal scientists and storm surge modelers. For example, such data are very useful for risk-assessment studies, which identify critical inundation thresholds, such as the 100-year storm surge level for a given location. These data are also useful to validate storm surge models, which often need actual observed data to validate model runs.
Prior to Sandy’s landfall, SCIPP mapped out hurricane paths and inundation envelopes for five previous hurricanes that generated storm surges in the New York City area. These maps provided historical context as Sandy approached. One of the key messages of these historical maps is that Sandy’s storm track was unprecedented along the Mid-Atlantic Coast. These maps also provided evidence that the area of coastline near New York City is very effective at funneling in storm surge, presumably because water gets trapped in this area. Storm surge levels during the 1944 Hurricane and Hurricane Donna (1960) were higher in this region than other areas along the coast- a realization that hopefully encouraged many people in the metro New York area to evacuate Sandy’s devastating storm surge.