A City at Sea
By MALCOLM J. BOWMAN
As we read about the effects of Hurricanes
Katrina and Rita on the Gulf states,
we have to wonder if the same thing could happen to the metropolitan region.
Scarily, it could.
New York City is not as low-lying as New
Orleans, but much of it is less than 10 feet above sea level, including the
perimeter of Manhattan's business district; the Lower East and West Sides;
parts of the F.D.R. Drive; Bellevue hospital; coastal Queens and Brooklyn,
including Coney Island, Rockaway, Jamaica Bay and La Guardia Airport; and the
shores of the upper East River.
Across the Hudson River
in New Jersey, Hoboken,
and Hackensack Meadows are particularly susceptible to flooding. During the
December 1992 northeaster, ocean water flooded the Hoboken
train station, short-circuiting the entire New York City
subway system. PATH trains were stranded beneath the Hudson River.
It was 10 days before the transportation system was brought back into full
operation. The F.D.R. Drive
was flooded. Sewers backed up. And this was not even a full-blown hurricane
like the one in 1938 that devastated much of southern Long Island
and the coast of New England.
Unfortunately, the 1992 storm is probably only a
warning of worse to come. The scientific consensus had been that sea level is
rising along the Eastern Seaboard at about one foot per century, but more
recent predictions by NASA scientists at the Goddard Institute for Space Studies
in New York City say that with climate change and global warming, sea level
will rise as much as an additional one and a half feet by 2050.
What this means for New Yorkers is that in the
future, relatively modest storms riding on an ever-increasing sea level will do
as much damage as rare, once-in-a-century storms do now. New
York City, New Jersey and Long
Island, particularly the low-lying south shore, are at great risk.
So what can be done? European nations with
low-lying coastal communities have grappled with this problem for years, but
they have usually taken concrete steps only after serious, prolonged floods
that caused catastrophic loss of life and property. Several countries have
constructed storm surge barriers that can be raised to block off the ocean
until the threat passes.
Storm surge barriers are giant floodgates that
lie flat on the sea floor or retracted at harbor entrances, river mouths or
coastal inlets. When an emergency is declared and before the storm surge hits,
the barriers are rotated or slid into position and locked, acting as temporary
The Thames Barrier near London
has been used effectively more than 80 times since 1982 to hold back North
Sea storm surges. And the Dutch are the masters of coastal
engineering, dyke construction, reclamation of land and flood protection
measures using surge barriers (half of the Netherlands,
including Amsterdam and Rotterdam,
lies below sea level). After debating the issue for
more than 20 years, the Venetians are finally building inflatable barriers to
close off the Venice lagoon, which
opens into the surge-prone Adriatic Sea. And Russia
is completing an extensive system of barriers to protect St.
Petersburg from storm surges arising in the eastern Baltic
There are already some modest storm surge
barriers in the northeastern United States
in places like Stamford, Conn.;
and New Bedford, Mass.
And a storm surge barrier could work for New York City,
Three barriers would be needed to protect the
city since storm surges can penetrate New York
Harbor directly from the ocean,
from behind Staten Island and from Long Island Sound.
Barriers should be built across the Narrows, which is
about one mile wide, under or near the Verrazano-Narrows Bridge;
west of Staten Island near Perth
Amboy, N.J.; and across the
upper East River near the Throgs Neck
Bridge where the river is about
two-thirds of a mile in width. These three barriers, high
enough (not less than 25 feet above sea level) to withstand any conceivable
storm surge, closed before a major storm would provide a ring of shelter around
But many questions remain. Such barriers would
represent an engineering project of a scale rarely contemplated in the United
States. The cost would be in the billions of
dollars. Communities outside the barriers would remain exposed and unprotected,
including Kennedy International
Airport and Long Island's
south shore. Wind, rain and upland flooding damage would still have to be
Professional scientific and engineering
societies, environmental groups and the City of New York
should take advantage of the shocking images of the destruction of New
Orleans and the Gulf
Coast to start planning protection
for citizens and services in a climate-changed future. The question is not if a
catastrophic hurricane or northeaster will hit New York,
Malcolm Bowman is professor of oceanography
at the State University of New York at Stony Brook and head of the Stony Brook
Storm Surge Research Group.