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ChEgrad
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Member since Nov 2012
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

Yes. That’s pretty well known by everyone. That’s why they’re planning on cutting a couple of spots in the levee south of New Orleans to let the river flow into those spots again.


If done improperly, it will not help. I was friends with one of the worlds leading authorities on sediment transport (he has passed away). Many times the diversions do not work because the sediment gets dumped early due to poor design and doesn’t travel to where it needs to go.

If I recall correctly, he proposed a new lock system for ships to access the Mississippi River and diversion (several diversions - can’t remember) of flow/sediment to build/maintain land. He was not optimistic that we would actually implement the kind of solution needed.


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Barstools
Georgia Fan
Atlanta
Member since Jan 2016
7028 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
They're kind necessary when you decide to build a city below sea level.


lshuge
LSU Fan
Member since Sep 2017
526 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
Yes. It reduces sediment.


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CarRamrod
USA Fan
Spurbury, VT
Member since Dec 2006
53187 posts

re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

he OT's favorite representative (Mandy Landry) was claiming on twitter last month that the levee system exists to prevent coastal erosion.
well she is wrong.


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GREENHEAD22
LSU Fan
Member since Nov 2009
15595 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
They need to move everyone south of bellchase out except for industry and camps and blow the levees. No one should be permanently living down there.



Oh yea Admin, good example of your hypocrisy.

Not as bad as the one about the tresuary sec though.
This post was edited on 5/4 at 12:13 pm


jimbeam
US Army Fan
University of LSU
Member since Oct 2011
71439 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
Look up “Changing Course”. It was a big program/study that looked at potentially doing that, moving the ship channel up near Belle chase and dredging it straight south to the Gulf. However, diverting water from the river and Maintaining navigation without the current flow of water coming out head of passes will make deep draft nav difficult no matter how you slice it. And keeping a nav channel open outside of the river would also require constant dredging


GREENHEAD22
LSU Fan
Member since Nov 2009
15595 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
Forgive but I am not understanding something. How would we be diverting anything by doing that? The river would still be taking its same course, just be able to flow out of its banks during high water.

I will look up the study though when I get a chance.


Did you see my question on the previous page? Would the river switching help south if houma area or would the sediment be carried west?
This post was edited on 5/4 at 1:00 pm


jimbeam
US Army Fan
University of LSU
Member since Oct 2011
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
Everything south of the new shipping outlet (around say BellChase) would be non-maintained and the river would free to move into the marsh as it wanted. This would be a HUGE programatic type change, not just a single or a few high flow sediment diversions like Breton and Barataria.

Guessing, I would say stuff as far east as Decade would see positive benefit. The stuff I know most about is basically from the Atchafalaya mouth and north. Haven’t looked too much at the studies of how a new delta would form.
This post was edited on 5/4 at 1:21 pm


GREENHEAD22
LSU Fan
Member since Nov 2009
15595 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
I am guessing the rivers normal height is now higher than the land outside the levees?


Also I am getting confused since I have asked two questions. The benefits east of Decade would come from knocking down the levees south of bellchase correct?


That is not the answer to the question about the river switching at ORCS.
This post was edited on 5/4 at 1:49 pm


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soccerfüt
Location: A Series of Tubes
Member since May 2013
48316 posts

re: Question for you civil engineers. Does the levee system make coastal erosion worse?
My amateur attempt at forensic cartography:



hubertcumberdale
LSU Fan
Member since Nov 2009
2840 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

My amateur attempt at forensic cartography


Thats awesome, thanks for editing/sharing that


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FutureMikeVIII
LSU Fan
Houston
Member since Sep 2011
433 posts

re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

My amateur attempt at forensic cartography:



What's your source for this? It's awesome

Edit: Nevermind, found it on wikipedia
This post was edited on 5/4 at 4:15 pm


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CarRamrod
USA Fan
Spurbury, VT
Member since Dec 2006
53187 posts

re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

And keeping a nav channel open outside of the river would also require constant dredging
the channel requires dredging as is.


GumboPot
USA Fan
tigerdroppings.com Elite Member
Member since Mar 2009
87294 posts

re: Question for you civil engineers. Does the levee system make coastal erosion worse?
quote:

Look at a satellite map and study the area between the mouth of the MS and the Atchafalaya... west of the atchafalaya and erosion isn’t much of a problem




This is an excellent point. However it's more precise to say that west of the Atchafalaya soil deposition is happening at the same or higher rate as soil subsidence and erosion to maintain or grow land. Whereas east of the Atchafalaya soil subsidence and erosion is happening at a higher rate than soil deposition due to the levee system causing land to disappear.


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jimbeam
US Army Fan
University of LSU
Member since Oct 2011
71439 posts
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re: Question for you civil engineers. Does the levee system make coastal erosion worse?
You think I don’t know that? I’m talking about the magnitude of requisite dredging. Decrease the flow or completely move the channel and it’s a massive undertaking vs what we’re currently working with.


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