From: John Cuccia 

>I can't help thinking about Venice, where the "city" itself is only
>about 40,000 people (mostly catering to 20x that many tourists)...
>and for at least the last century all the growth has been in drab,
>unhistoric but bustling Mestre and Marghera on the mainland, 5 km away
>and 10 m higher.

Here's an excellent article from a 2001 issue of Scientific American.

http://www.sciam.com/article.cfm?chanID=sa006&articleID=00060286-CB58-1315-8B58
83414B7F0000
A major hurricane could swamp New Orleans under 20 feet of water, killing
thousands. Human activities along the Mississippi River have dramatically
increased the risk, and now only massive reengineering of southeastern
Louisiana can save the city

and


As if the risk to human lives weren't enough, the potential drowning of New
Orleans has serious economic and environmental consequences as well.
Louisiana's coast produces one third of the country's seafood, one fifth of
its oil and one quarter of its natural gas. It harbors 40 percent of the
nation's coastal wetlands and provides wintering grounds for 70 percent of
its migratory waterfowl. Facilities on the Mississippi River from New
Orleans to Baton Rouge constitute the nation's largest port. And the delta
fuels a unique element of America's psyche; it is the wellspring of jazz
and blues, the source of everything Cajun and Creole, and the home of Mardi
Gras.

Thus far, however, Washington has turned down appeals for substantial aid.

Fixing the delta would serve as a valuable test case for the country and
the world. Coastal marshes are disappearing along the eastern seaboard, the
other Gulf Coast states, San Francisco Bay and the Columbia River estuary
for many of the same reasons besetting Louisiana. Parts of Houston are
sinking faster than New Orleans. Major deltas around the globe--from the
Orinoco in Venezuela, to the Nile in Egypt, to the Mekong in Vietnam--are
in the same delicate state today that the Mississippi Delta was in 100 to
200 years ago. Lessons from New Orleans could help establish guidelines for
safer development in these areas, and the state could export restoration
technology worldwide. In Europe, the Rhine, Rh“ne and Po deltas are losing
land. And if sea level rises substantially because of global warming in the
next 100 years or so, numerous low-lying coastal cities such as New York
would need to take protective measures similar to those proposed for
Louisiana.

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