re: Mid-Barataria Diversion

Posted by Tiger Prawn

Member since Dec 2016

22001 posts

Posted on 5/11/21 at 8:43 am to Junky

quote:
Guess what assholes, no diversion means no more land. They need to face the reality that the wetlands they love to fish are disappearing and we cannot manhandle nature.

I don't get how some of them get so up in arms about wanting to close Mardi Gras Pass. MGP is a blessing. Didn't cost the state anything to build it and its already been building new land in only a few years of existence.

Posted by lotik

Member since Jul 2018

323 posts

Posted on 5/11/21 at 9:31 am to EveryoneGetsATrophy

I'm not saying I disagree with you, but can you cite anything to back this up?

I wasn't able to find much, but I did find these soil cores.

Caernarvon Freshwater Diversion and Delta

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 9:51 am to lotik

Proof like that gives me hope. I just wish we could somehow get diversion flow like that to Terrebonne

Posted by jimbeam

University of LSU

Member since Oct 2011

75703 posts

Posted on 5/11/21 at 10:02 am to lotik

Now imagine what would happen if the sill was designed at an optimal level for sediment capture, and the location was in even a better spot along the river, what kind of good sand that would spew into the marsh.

Y’all want proof? Go look at West Bay on the right descending side of the river south of Venice.

This post was edited on 5/11/21 at 10:04 am

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 10:11 am to jimbeam

I am assuming optimizing it would mean basically rebuilding it?

Also I am assuming the sediment carry if limited by the length of the run, the further from the river the slower the water will flow causing the sediment to drop out?

This post was edited on 5/11/21 at 10:28 am

Posted by jimbeam

University of LSU

Member since Oct 2011

75703 posts

Posted on 5/11/21 at 10:26 am to GREENHEAD22

Ah I’m just talking about Mid Bar and Mid Bret

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 10:29 am to jimbeam

Copy, I was thinking Caernarvon.

My added question above is basically asking a sediment diversion has to be close to the river to work?

Posted by EveryoneGetsATrophy

Member since Nov 2017

2907 posts

Posted on 5/11/21 at 10:37 am to GREENHEAD22

Wasn't West Bay dredged?

Posted by jimbeam

University of LSU

Member since Oct 2011

75703 posts

Posted on 5/11/21 at 10:40 am to EveryoneGetsATrophy

The West Bay opening was man-made, and it widened substantially. Some wanted to close it once they saw it widening; fortunately it hasn’t been. Those “islands” that you see in west Bay were constructed via dredged fill and act as speed bumps to assist with sediment capture.

Posted by lotik

Member since Jul 2018

323 posts

Posted on 5/11/21 at 10:43 am to GREENHEAD22

Their theory is that they can control it with flow rate. Slower rate, sediment is deposited closer. Higher rate, sediment is deposited further.

Posted by lotik

Member since Jul 2018

323 posts

Posted on 5/11/21 at 10:54 am to EveryoneGetsATrophy

Dredging is expensive. Especially went its not a competitively priced market. You can thank the Jones Act and the Foreign Dredge Act.

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 11:32 am to lotik

I understand that but I would think there is a limit to the distance in which it will work.

Unfortunately you can't run from the MS river south through Larose down to south houma.

Posted by jimbeam

University of LSU

Member since Oct 2011

75703 posts

Posted on 5/11/21 at 11:39 am to GREENHEAD22

Oh. No way. There was a study done about building a long distance pipeline (like 10-20 miles or something) from basically Morgan city (atachafalaya river) east to facilitate dredging in those areas, but a large diversion down off the river would be a huge undertaking.

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 11:53 am to jimbeam

Have they done a study to see what is the furthest you could run it before the sediment falls out? I know it would depend some on the rate the river is flowing but an average.

Posted by lotik

Member since Jul 2018

323 posts

Posted on 5/11/21 at 12:28 pm to GREENHEAD22

Wouldn't it continue to expand further out? That is where the rate of flow would come into play. I wouldn't think it would build new land higher than what it is at the current highest point.

I'm sure there is a point of diminishing return.

This post was edited on 5/11/21 at 12:29 pm

Posted by Icansee4miles

Trolling the Tickfaw

Member since Jan 2007

29310 posts

Posted on 5/11/21 at 12:39 pm to EveryoneGetsATrophy

You do realize floating marsh itself captures more sediment and eventually builds land? I watched Spanish Pass fill up with water lillys and become solid ground in only 2-3 years in the 1980’s as they captured and held sediment

Posted by GREENHEAD22

Member since Nov 2009

19652 posts

Posted on 5/11/21 at 12:55 pm to lotik

I think we are talking about two different things.

If you dug a canal off of the river with a structure in place, there is only so far the sediment would carry down the canal until the flow slowed and it would fall out.

Terrebonne is in no mans land between the MS and Atch rivers with no way to get sediment to it.

Posted by Tiger 79

The Original Tiger 79

Member since Nov 2007

38074 posts

Posted on 5/11/21 at 12:57 pm to GREENHEAD22

quote:
Have they done a study to see what is the furthest you could run it before the sediment falls out? I know it would depend some on the rate the river is flowing but an average.

The sand will fall out first and the clay last. During natural flooding, the river built ridges of sand along its banks that's why its highest next to the river. As the flow continued the sandy and silty loam fell out next and then the clay particles.