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Image: BRETT DUKE © 2005 THE
TIMES-PICAYUNE PUBLISHING CO., ALL RIGHTS RESERVED |
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HIGH WATER pours
through a burst flood wall along New Orleans's 17th Street
Canal. | Immediately after Hurricane Katrina
pummeled New Orleans last August, President George W. Bush and the
U.S. Department of Homeland Security declared that no one could have
predicted such devastation. Yet scientists, engineers and Louisiana
state politicians had warned for years that a Category 4 or 5 storm
crossing the Gulf of Mexico from a certain direction would drown the
region. In 1998 computer models at Louisiana State University
simulated such a terrible inundation. That same year the state
proposed a $14-billion plan to restore the delta's natural
wetlands--which, by absorbing water, can help protect inland areas
from sea surges. But Congress turned it down.
What is more, engineering firms, as well as the U.S. Army Corps
of Engineers, which is largely responsible for flood protection, had
proposed constructing higher earthen levees as well as huge gates
that could have prevented storm surges from pouring into inner-city
canals and bursting their concrete flood walls. Indeed, documents
show that various gates had been recommended as far back as 1968 and
in each decade since. |
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| None of these designs has ever been funded. The
reason, for the most part, is turf battles among the Corps, local
and state politicians, and Congress. In the meantime, countries such
as the Netherlands and the U.K. have erected effective surge
barriers that the U.S. has ignored. In Katrina's wake, the
blueprints for all these structures are rapidly being dusted off,
augmented and integrated into several grand plans by L.S.U., big
engineering companies, and the Corps that could safeguard New
Orleans and southeastern Louisiana. Similar measures could save
populated coastal communities around the Gulf, the U.S. and the
globe.
Poster Child
The Mississippi River Delta is not alone
in being endangered. Deltas worldwide are in trouble because human
development is causing the land to sink. The soft delta earth
compacts naturally, but annual river floods top-coat the slumping
ground with new sediment. Yet man-made levees built to prevent
floods in many of these regions also cut off the sediment supply. At
the same time, underground extraction of oil, natural gas and
freshwater deflates the land's support structure. As the surface
subsides, saltwater from the ocean streams in, poisoning the usually
thick expanses of wetland mangroves, trees and grasses. Without
these lush buffers, even moderate storms can push sea surges far
inland.
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The earth's oceans are
also rising, compounding the problem. At current rates, sea level
will be one to three feet higher in 100 years. Low-lying cities from
New York to Shanghai may have to armor themselves with walls and
pumps and add revetments (waterproof masonry) to the bottom few feet
of every building in town, measures already under way in Venice.
One third of the world's people live in coastal zones,
particularly the deltas. Rich in farmland, seafood and underground
resources, these areas are also key exit and entry points for
armadas of ships carrying piles of goods. Cairo, at the tip of the
Nile River, is home to 16 million people. The Red River and Mekong
deltas in Vietnam each support 15 million inhabitants, yet both are
eroding. Shanghai has 13.5 million, the Ganges in Bangladesh, 10
million. Other threatened deltas include the Orinoco in Venezuela
and the Rhine, Rhône and Po in Europe.
The Mississippi Delta, home to 2.2 million, represents the
worst-case scenario. It is sinking and losing wetlands faster than
almost any place on earth and faces the most hurricanes annually.
The record sea surge that prompted the Netherlands and Britain to
erect barriers was 15 feet; Katrina's peaked at 28 feet.
Fundamental to the trouble is that for the past century the
Corps, with the blessing of Congress, leveed the Mississippi River
to prevent its annual floods so that farms and industries could
expand along its banks. Yet the levees have starved the region of
enormous quantities of sediment, nutrients and freshwater. Natural
flooding at the river's mouth had also sent volumes of sediment west
and east to a string of barrier islands that cut down surges and
waves, rebuilding each year what regular ocean erosion had stolen.
But because the mouth is now dredged for shipping lanes, the
sediment simply streams out into the deep ocean, leaving the
delta--and New Orleans within it--naked against the sea. |
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Winner Takes All 
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