Re: New Orleans Levees

it's a combination of factors.  The area around new Orleans and the gulf coast around the Mississippi delta is generally subsiding due to sediment compaction.  The weight of sediments "squeezes" out the water and affects the grain orientation in soft sediments so the porosity decreases and the general section decreases in thickness. Also, there is a component due to the sediments loading the upper lithosphere and depressing the crust (isostasy).

The sediments are probably not building upward.  The affects of levees and the dredging of the Mississippi for shipping has allowed a lot of the sediment in the river to bypass the delta and get deposited further outbound in deeper water.  This sediment starvation has allowed the barrier islands to diminish if not disappear.

Here's a starter:

http://www.lacoast.gov/news/press/2003-09-11b.htm



Glenn Otto wrote:

I think I heard that either N.O. is still sinking or the mighty River sediment is building higher.  Does anyone know? 

 

Are they rebuilding in the 9^th Ward?  As we used to say in Florida " I've got some low land for a low price!"

 

Glenn C. Otto, P.E.

A Structural Engineer, P.C.

Virginia Beach, VA 23454

www.astructuralengineeronline.com

 

"Contemplate the mangled bodies of your countrymen, and then say 'what should be the reward of such sacrifices?' ... If ye love wealth better than liberty, the tranquility of servitude than the animated contest of freedom, go from us in peace. We ask not your counsels or arms. Crouch down and lick the hands which feed you. May your chains sit lightly upon you, and may posterity forget that you were our countrymen!"

--Samuel Adams