Geography puts New York in ‘danger zone’ for hurricane

September 15, 2008 at 12:30 am Leave a comment

As if marking our distance from the storm-ravaged Texas coast, the New York Harbor was glassily calm Saturday morning.

But just outside this shining and tranquil expanse remains a particular configuration of coastline and seabed that led an authoritative 1995 study to mark us a “high level danger zone” for storm surges that could cause water to rise by as much as 17 feet in an hour, to as high as 30 feet.

Those numbers were the surprising results when the U.S. Army Corps of Engineers enlisted the National Hurricane Center to plug New York’s particulars into a computer model dubbed SLOSH, for Sea, Lake and Overland Surges from Hurricanes.

Among the critical factors was the same indentation in the Eastern Seaboard that always leads the eye toward New York on a map of the U.S.

This continental dent is the New York Bight. There, the Jersey shore and Long Island’s South Shore converge almost perpendicular to one another, with the mouth of New York Harbor the apex of what could prove to be the wrongest of right angles.

The computer model considered a hurricane moving northward and tracking just to the west of the city. The highest velocity winds are to the right of the eye and blow counterclockwise.

That would drive water westward along the Long Island shore until it hit the opposing Jersey shore. The Bight would become a huge funnel.

The water would then have only one place to go and it would surge through the mouth of the harbor with such volume and force as to make a curse of what had always been the city’s great blessing.

Lower Manhattan would immediately be flooded, as it was back in September of 1821, when the eye of a hurricane passed over the city, just east of what would have been the most disastrous track.

If the worst case scenario were to develop in present times, one place you would definitely not want to go would be the subways or the tunnels.

“The possibility of voluminous floodwaters rapidly filling several roadway tunnels and a larger percentage of the rail tunnel network raises the specter of catastrophe,” noted the 1995 study.

In the SLOSH model, a category 3 hurricane in New York could generate a surge of 24 feet at the Battery Tunnel, 21 feet at the Lincoln, 25 feet at JFK Airport, 16 feet at LaGuardia.

Several recent studies have suggested that global warming and an accompanying rise in ocean temperatures might increase both the strength and frequency of hurricanes. The changing climate could also result in higher sea levels.

“Adding as little as 1.5 feet of sea level rise by the 2050s to the surge for a Category 3 hurricane on a worst-case storm track as described above would cause extensive flooding in many parts of the city,” suggests Climate Systems Research at Columbia University.

“Areas potentially under water include the Rockaways, Coney Island, much of southern Brooklyn and Queens, portions of Long Island City, Astoria, Flushing Meadows-Corona Park, Queens, lower Manhattan and eastern Staten Island from Great Kills Harbor north to the Verrazano Bridge.”

The probability of such a disaster remains low, but it remains well within the bounds of possibility. Three years prior to the 1995 study, a nor’easter followed this same worst-case track, causing tides to rise as much as 6 feet above normal, flooding the tip of Coney Island and even a stretch of the FDR Drive, as well as the Hoboken PATH station.

A PATH train was stalled just outside the station, stranding 19 passengers for more than an hour before they were rescued. The Army Corps of Engineers report suggested there may have been a more disastrous outcome had the storm been even just a Category 2 hurricane.

“The rapidly rising floodwaters probably would have trapped rescuers and passengers alike,” the report noted.

Some of the PATH passengers stranded by the 1992 flooding were present at the first World Trade Center bombing just three months later. That bombing was dwarfed by the far deadlier attack, the anniversary of which we observed on Thursday.

Let us just hope we never get a hurricane that comes up the worst-case track and similarly dwarfs that nor’easter

By Michael Daly
Daily News


Entry filed under: Dive In, Public Waterfront. Tags: , , , .

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