Just heard that 100% of New Orleans
will be underwater in about ten hours. The local news is now stating the flooding should level off at about 3 feet above sea level.

That would place most of NOLA under 9 feet of water.

Amazing.

On the way in to work this morning, I wondered whether they will simply rebuild on site, abandon the area, or make some changes.

My guess is that abandoning the area is unlikely except in the more remote areas. Some people will rebuild on site, and it is appropriate that they do so. My thoughts are that rebuilding is fine, but that, due to the extent of the devastation, New Orleans has a golden opportunity to completely rebuild it's geography. Instead of relying purely on levees, I would think it advisable for NOLA to backfill the lower areas with sand, rock, and debris. If NOLA could be raised even six feet (to sea level), that would significantly reduce future flood damage.

So what kind of job would that be? Well, New Orleans covers 4190 square miles (google cache of a NOLA web page). That comes out to 12,978,943,999 square yards of surface area (or 2,681,600 square acres).

To raise that area by six feet would require 25,957,887,998 cubic yards of fill. A dump truck can carry about ten cubic yards of soil/fill. So, it would take 2.6 million dump trucks of fill to raise the area.

The cost would probably run around $3 billion dollars, give or take (at about $1,000 per truck load presumed -- I am guessing there is not a large supply of fill nearby, so it would have to be hauled in from a distance).

And this doesn't even address the cost of replacing power lines, water lines, roads, and other infrastructure.

Or what would be done with surviving high rise buildings, or the French Quarter, or existing cemeteries.

Or housing for people, or . . . sigh. It looks like this solution won't quite work, will it?

So what can we do but (a) abandon or (b) rebuild?

I've seen recommendations of a thirty-five foot "wall" around the inner city. The idea is that people could go to the city center as a "haven" from hurricanes, and that the wall would protect them.

Isn't that what the levees were supposed to do? They failed -- so why would we think a wall would do any better?

Can you imagine the devastation if 250,000 people were trapped in a rapidly flooding area because a thirty foot retaining wall buckled -- and there were no land routes out of the area?

I've also heard some say this was a one in a million event (links omitted because, well, I'm at the office and need to get back to work). Well, I respectfully disagree. As more and more of the southern Louisiana coast is eroded, hurricanes will hit inland with more force than before (the outlying coastal islands used to reduce the power of hurricanes before they got as far north as New Orleans).

This hurricane has forced New Orleans to address sine very difficult questions about what to do in the future. None of the possibilities are attractive.
- posted by MrSpkr @ 10:27