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[Phys-L] Re: New Orleans




It was the ideal site for a port; all sites farther downriver
were too swampy, and sites slightly farther upriver were no better,
and therefore the site closest to the mouth was the winner. In
the days before railroads and highways, water transportation was
predominant, and New Orleans was the gateway to most of an entire
continent.

While this is a fair description, there is a site not far upriver which is
also a good port and is actually quite high, Baton Rouge. It sits on high
bluffs above the river, but there are accessible areas to the river. At
present the Mississippi is tending to take a straighter route to the ocean
than its current path and bypass New Orleans, but it is being stopped by
manmade dykes or levees. Baton Rouge is a port and also has a fair number
of refineries across the river from it.

It is quite possible that the hurricane will accelerate the process of
moving the port facilities inland. This happened to Houston and Galveston.
Houston enlarged a bayou (large stream or small river) and developed inland
port facilities. Meanwhile Galveston, a sandbar devastated by the turn of
the century hurricane, decreased in significance as a major port.
Galveston, in a similar fashion to New Orleans, is sinking. They raised the
ground 10 ft after the devastating hurricane, and put in an 18 ft seawall.
But due to subsidence they are again in danger from large hurricanes. There
is only one road to the mainland and it can flood in places so residents are
quite aware that they must get out. This plus the fact that it is a smaller
city allowed almost total evacuation before Rita. Every year there are
pictures on TV showing the total devastation after the 1900 hurricane, so
people are continually being shown how dangerous it can be.

The Galveston hurricane still qualifies as the deadliest disaster in
American history. "On September 8, the hurricane slammed into Galveston
almost head on. Waves were higher than 15 feet and winds howled at 130 miles
per hour. By the time the storm passed, more than 8,000 people were dead,
countless were injured and half of the island's homes had been swept away."
According to: http://www.noaa.gov/galveston1900/ . Katrina may be worse in
dollars adjusted for inflation, but the evacuation plus rescue made it
milder in terms of deaths.

Houston had a number of voluntary evacuees because of the problem of high
winds and rain. While the winds are decreased by the 60 mile distance from
the shore, they can still gust to high enough levels to rip off roofs of
older homes. Newer homes are built to slightly higher standards which
include better anchoring of the roofs. There are also low areas which can
experience flooding and were under mandatory evacuation rules. However
unlike New Orleans, the water will drain off. It takes a while because the
grade is about 40ft/60miles. The low areas are all over the city and one
end of a block can be high, while the other end can flood. The water can
literally shoot up out of a storm sewer and flood an area. Again the
problem is increased by "modern" building practices. The slab homes are
lower than the older "pier and beam" homes which are typically raised 3 or
more feet off the ground.

John M. Clement
Houston, TX
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