Coastal Erosion in South Louisiana: Lost Cause?

[Huckster]

I'm not a geologist or an expert on coastal erosion/wetlands loss, but I think it's a lost cause. There are some projects that have proven successful in restoring the marsh, but it's too little too late, in my opinion. Perhaps a good analogy would be the stereotypical cartoonish image of a guy with a bucket trying to get water out of a sinking boat. Yes, he's getting some out, but he cannot do it fast enough.

The Mississippi Delta is a very fragile and unstable area; it has always been changing. No matter what, even if man had not built levees and dug canals through the marsh, there would always be some part of the delta that was slowly dying, sinking into the Gulf. When the River changes course and begins to build a new delta, the old one begins to starve, and eventually the ocean will win. For at least the last 50 years, the land loss rate has been between 25 and 35 sq. miles per year in coastal Louisiana. Man has accelerated the natural process.

Basically everything in Louisiana south of a line from New Iberia to Slidell was built by the Mississippi over at least the last 5,000 years. I don't know for sure in square miles how big that area is, but just for the sake of argument, let's say it is 7,000 square miles. With a land loss rate of, let's say, 30 square miles per year since 1950, that means that 1,650 square miles of land may have been lost. Granted, the old deltas did extend out farther into the Gulf than the current boundary of the Louisiana coast, and I don't know what amount of land in square miles would be built per year by the River without the strictures of levees and canals, but my point is, does anyone really think that this problem is solvable in the short term? Even 50 or 100 years? Can you see why I am not optimistic about this at all? Besides, without the artificial structures in place where the Red, Atchafalaya, and Mississippi converge/split, the Mississippi would have already taken the path of least resistance down the Atchafalaya, abandoning the Plaquemines Parish delta, meaning the land around New Orleans would naturally have been doomed to succumb to subsidence and erosion.

I fear Katrina and Rita have accelerated an ongoing disaster, and I don't see any quick fix for the problem, and in some cases, no fix at all. Yes, we can build new levees and raise old ones, but eventually, the situation in south Louisiana is going to become untenable for many towns and cities, including and especially New Orleans.

[weatherwindow]

IMHO, it is likely that politics will always trump science in the wake of katrina....areas that are fated to face repeated destruction due to the factors that you mentioned will, without a doubt, be rebuilt and rebuilt without regard to the obvious risk of the location. it is doubtful that the levee system, given subsidence and coastal erosion, can ever be guaranteed to permanently withstand major surge events. we must rebuild southeast louisiana, we must attempt to restore the fabric of the neighborhoods and the continuity of parish life...that said, some difficult decisions must be made concerning the areas at greatest risk in order to mitigate future disasters. definitive moves to reduce coastal erosion and restore marshland must be undertaken. let's get on with rebuilding...however lets not sacrifice the ultimate future of new orleans in doing it..........................rich.....sorry about the off topic post but as an emergency manager, i have seen poor floodplain development decision making in action

[Wacahootaman]

All houses and dwelling in NOLA and the areas nearby subject to flooding should be built on reenforced pilings like the Hurricane house in Pensacola beach.

And a launchable boat on a balcony would help too

[Wacahootaman]

Dang!

A double post!

The agony of Old Timers Disease

[Dirteng]

Almost all the buildings in NOLA are built on pilings. I'm returning to NOLA to help design and build the levee systems next week. The economic situation of NOLA helped create the coast ersoion problem. The natural course of the Mississippi river was to change in 1976 down through the Atchafalia (sp) but there is a congressional manadate as I understand to keep 70 percent of the flow of the upper Mississippi routed through New Orleans. Morgan City would have been were the majority of the flow of water would have entered the Gulf without man's intervention.

The delta south of NO would have had sediment renourishment by the slower waters if the river would have ran its natural course in 1976, but the port of New Orleans was too important to let starve. Look up the Old River structure near Morganza to see what controls the lower Mississippi.

By the way, I'm a civil engineer with a speciality in Geotechnical Engineering or soils and foundations. Mother nature always wins, it is just a matter of time.

[Dr. Jonah Rainwater]

Well, if we were to remove the levees locking the Mississippi in its' present course away from the Atchafalia River, then nature would begin its' own rebuilding process following Hurricane Katrina, and presumably the Mississippi Delta should continue to grow in land area, even if most of it is below sea level.

But New Orleans is a city that needs to be there, and it already has the port facilities on the Mississippi River. Unless you want to dig a deep-water channel all the way to Baton Rouge, the way Houston overtook Galveston following its' catastrophe, then we're going to have to keep fighting the battle against nature to keep Louisiana where it is. Unfortunately I'm not so sure if I would be able to say the same about the surrounding marshland parishes that are home to the heart of Cajun culture.

[TSmith274]

No lost cause. Plans are already in place to bring back coastal Louisiana, with special importance on SE La. If I told you of all the plans, this board will crash. And, I don't want to do that to yall. Problem is, that, at the moment, the funds aren't all there.