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[Phys-L] Re: New Orleans



Is a river delta swampy??? Of course! Actually most of Louisiana is a
swamp, or at least appears to be a swamp. There is a 10 mile stretch of I10
which is on piers over a huge swamp.

New Orleans suffers from the same problems as Amsterdam, London, Bangala
Desh, and Venice. As it is one of the earliest settlements in the US it
grew and as the natural forces that change river deltas happened, the
residents fought them. Over time between subsidence and the prevention of
natural silting, New Orleans has become progressively more endangered. At
present the Mississippi would tend to go down the old channel which would
leave New Orleans low and dry with no port. This tendency was fought by
forcing it to stay in the current channel, but the result is no flooding to
build up the land.

Parts of Amsterdam are also underground, and London has problems during
spring tides combined with storms. Venice has also sunk and they are
building flood gates to prevent very high tides from flooding the lagoon.

NY does not have this problem as it is built on rock rather than muck, and
as I recall may be undergoing isostatic rebound from the last glacier.

There was a good Nova about the Mississippi delta and man's futile attempts
to control nature. In this case nature will eventually win. The big
attraction is the culture which is still heavily French influenced. The
long time residents have a great cultural attachment to the area. A French
dialect is still spoken in places, and the cuisine is essentially French
adapted to local circumstances. Louisiana also was a refuge to the French
speakers who were expelled by English speakers, so it has a great amount of
sentimental attachment. A fun movie which give a glimpse of the culture is
Belezaire the Cajun.

As to living below sea level, the earliest settlements in the French Quarter
are barely above sea level. According to the Wikipedia the original
settlements were in a crescent on barely high ground. But then

" In the 1910s engineer and inventor A. Baldwin Wood enacted his ambitious
plan to drain the city, including large pumps of his own design which are
still used. All rain water must be pumped up to the canals which drain into
Lake Pontchartrain. Wood's pumps and drainage allowed the city to expand
greatly in area. However, pumping of groundwater from underneath the city
has resulted in subsidence. The subsidence greatly increased the flood risk,
should the levees be breached or precipitation be in excess of pumping
capacity (as was the case in 2005 in the aftermath of Hurricane Katrina).
There were many warnings in the late 20th century that a major hurricane or
a Mississippi flood could create a lake in the central city as much as 9 m
(30 ft) deep, which could take months to pump dry."

I think we can blame this on 20th century hubris. But let us not forget
that the Dutch have been living below sea level for centuries.

See:
http://en.wikipedia.org/wiki/New_Orleans#Geography_and_climate
for more information about the history of the area.

As to danger we now know that the Pacific NW does have humongous earth
quakes which are only every few hundred years. Will we abandon Seattle?
What about the volcanos which will eventually destroy major cities there?
What about all Southern coastal settlements which will eventually be knocked
down by hurricanes. We all pick our own level of danger.

John M. Clement
Houston, TX


Ever since Katrina devastated New Orleans, I have been wondering about
this city. Do any of you know about how this place was settled?
Specifically, when the city was founded, was it a "swampy" area? What made
people settle there? When hurricanes/storms/floods came, didn't it take a
very long time for this city to dry out? How were the levees developed
over time? I am trying to understand the history and development of this
city, of which I have never visited. I personally could never live in a
place that is below sea level.
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