Found on wizbangblog.com - from "Paul". Terrifying

If you read my "Pray" post and you read my predictions about what was going to happen in the Superdome, it should be pretty clear I understand the dynamics of the situation...

Now consider this...~10 feet of water in a city for ~10 weeks.

Most homes will simply dissolve. Basically anything under 3 stories is gone...

But the big concrete buildings including the office buildings are safe right? We just replace the interior of the bottom floors right? Not so fast....

In New Orleans (and many other places) our buildings "float" via a system of modo [sic] sized pilings. The mud is too soft to actually support them but the friction holds them in place. -- Now take that same mud and let it sit underwater for 10 weeks.

The foundation of our 30 to 40+ story skyscrapers will erode. When that happens they will start to lean.... 40 story buildings don't "lean" too well.

My discipline is electrical engineering not civil- but it seems to me that there is a large chance many of the major office buildings will tumble like dominos.

Further, the roads will all buckle. They do that after a regular spring flood -- this is 10 weeks.

Lastly, all but 2 of the telephone switches are underwater (assuming 10 feet of water). The 2 standing switches probably blew down anyway, but they are most assuredly without power even if they're still standing. The copper in the ground will corrode, so we basically have no communication infrastructure. Ditto the electric (generically speaking, I have very little knowledge of the electric infrastructure so common sense applies). The cities water system is in danger of being beyond the point of repair, etc...

Not to be a fatalist, but I don't think we even understand the half of it yet...