Hurricane Ivan could put much of New Orleans underwater.  Not just a few inches, but many feet.  In some places the water could be 20 feet deep.  How can this be?  How much rain is Ivan going to dump?  It turns out that the rain isn’t the problem.  It’s that New Orleans is below sea level.  The entire city was built on silt the Mississippi river has dumped over several thousand years.  That silt that is several miles deep.  That silt gradually compacts and “squishes out” and the surface drops.  If left on it’s own the “big muddy” would replenish the silt to above sea level every few years as it overflows it’s banks during high water times.  But levees were built to protect the city from the flooding.  Unfortunately it’s only the battles of the first couple hundred years that can be won.  Eventually the “war” against the river will be lost.  Not only does the city continue to sink but silt from the river is dumped further and further out to sea (something like a thousand tons per day is dropped).  This decreases the slope for the river from New Orleans (and upstream) to the sea.  This means the velocity of the river decreases.  As the velocity decreases the river drops more silt in it’s channel and furthermore it must be either deeper or wider to carry the same amount of water.  Everything is working against New Orleans remaining at it’s current elevation.  This is not like Holland which is also below sea level.  The soil is much different and we have a river running through the city that is raising it’s bed every day.

It will cost billions to put up a mediocre defense against the threat.  One could argue that we should just let the city deal with it on it’s own or move.  The problem is that there is a tremendous amount of shipping that goes on through the Mississippi from the heartlands of the country to the rest of the world and New Orleans is the port that makes it all happen.  If left to it’s own devices the river would have rerouted itself a hundred miles or so to the west years ago.  It’s only the Corp of Engineers that have kept it within the current channels.  Will Ivan be the last battle?  Will this week start the journey for New Orleans to become a silt covered archeological site for some graduate students 50,000 years from now?  What will be the impact on our economy?  How will this affect the election?  Will Kerry claim Bush could have prevented it (hmmm…. I wonder what a small nuke would do to a hurricane out at sea)?

My belief is that long term the people and businesses of New Orleans should close up and move out.  Barring some extraordinary technological breakthroughs in earth moving (I’m talking raising an entire city from deep down under the water soaked earth) and/or lowering the sea this battle cannot be won.  It’s better to surrender gracefully than to let the enemy annihilate you.  Spend the billions on salvage and rebuilding in another location, but surrender the current New Orleans to it’s muddy grave.