If the storm were strong enough, Ivan could drive water over the
tops of the levees that protect the city from the Mississippi River
and vast Lake Pontchartrain. And with the city sitting in a
saucer-shaped depression that dips as much as 9 feet below sea
level, there would be nowhere for all that water to drain.
Even in the best of times, New Orleans depends on a network of
canals and huge pumps to keep water from accumulating inside the
basin.
"Those folks who remain, should the city flood, would be exposed
to all kinds of nightmares from buildings falling apart to floating
in the water having nowhere to go," Ivor van Heerden, director of
Louisiana State University's Hurricane Public Health Center, said
Tuesday.
LSU's hurricane experts have spent years developing computer
models and taking surveys to predict what might happen.
The surveys predict that about 300,000 of the 1.6 million people
living in the metropolitan area would risk staying.
The computer models show a hurricane with a wind speed of around
120 mph or more — hitting just west of New Orleans so its
counterclockwise rotation could hurl the strongest surf and wind
directly into the city — would push a storm surge from the Gulf of
Mexico and Lake Pontchartrain over the city's levees. Ivan had
sustained wind of 140 mph Tuesday.
New Orleans would be under about 20 feet of water, higher than
the roofs of many of the city's homes.
Besides collecting standard household and business garbage and
chemicals, the flood would flow through chemical plants in the area,
"so there's the potential of pretty severe contamination," van
Heerden said.
Severe flooding in area bayous also forces out wildlife,
including poisonous snakes and stinging fire ants, which sometimes
gather in floating balls carried by the current.
A rescue of people who stayed behind would be among the world's
biggest since 1940, when Allied forces and civilian volunteers
during World War II rescued mostly British soldiers from Dunkirk,
France, and carried them across the English Channel, van Heerden
predicted.
Much of the city would be under water for weeks. And even after
the river and Lake Pontchartrain receded, the levees could trap
water above sea level, meaning the Army Corps of Engineers would
have to cut the levees to let the water out.
"The real big problem is the water from sea level on down because
it will have to be pumped and restoring the pumps and getting them
back into action could take a considerable amount of time," said
John Hall, the Corps' spokesman in New Orleans.
Hall spoke from his home — 6 feet below sea level — as he
prepared to flee the city himself. The Corps' local staff was being
relocated 166 miles north to Vicksburg, Miss.
New Orleans was on the far western edge of the Gulf Coast region
threatened by Ivan, and forecasters said Tuesday that the hurricane
appeared to moving toward a track farther east, along the
Mississippi coast.
If the eye came ashore east of the city, van Heerden said, New
Orleans would be on the low side of the storm surge and would not
likely have catastrophic flooding.
The worst storm in recent decades to hit New Orleans was
Hurricane Betsy in 1965, which submerged parts of the city in water
7-feet deep and was blamed for 74 deaths in Louisiana, Mississippi
and Florida. That storm was a Category 3, weaker than Ivan is
expected to be.
Even if New Orleans escapes this time, van Heerden said, it will
remain vulnerable until the federal and state governments act to
restore the coastal wetlands that should act as a buffer against
storms coming in from the Gulf.
Louisiana has lost about a half million acres of coast to erosion
since 1930 because the Mississippi River is so corralled by levees
that it can dump sediment only at its mouth, and that allows waves
from the Gulf to chop away at the rest of the coastline.
"My fear is, if this storm passes (without a major disaster),
everybody forgets about it until next year, when it could be even
worse because we'll have even less wetlands," van Heerden said.
