Prosthetic Delta

[Image: 3d-printing new deltas into existence, courtesy of New Scientist].

If we could divert certain segments of the Lower Mississippi River into subsidiary canals, we'd "create up to 1000 square kilometres of new wetlands between New Orleans, Louisiana and the Gulf of Mexico, forming a vital storm surge buffer against hurricanes," New Scientist reports.
It's prosthetic deltas as the future of landscape design:
    The proposed diversion would cut breaches into a levee some 150 km south of New Orleans, Louisiana, and 30 km above where the river empties into the Gulf of Mexico. With the diversions in place, flooding would cause the river to empty into shallow saltwater bays on either side of the river, releasing sediment-rich water to produce new deltas.
As Robert Twilley of Louisiana State University phrases it: "You keep the sediment within the coastal boundary current that keeps it running along the shoreline, whereas now it gets ejected into the Gulf." This thus constructs "new delta land" instead of uselessly shooting all that sediment over the continental shelf – and that newly aggregated land, like a literal land bank, will help protect New Orleans and its surrounding parishes from future hurricane damage.

[Image: Courtesy of the Center for Land Use Interpretation].

But I'm left wondering if this might not also imply some new form of 3D printing, using river sediments as ink and machine-controlled deltas as printheads: you open certain valves, gates, and locks according to predetermined schedules, in some massive inhabitable printhead complex run by the local flood control board, and you can print deltaic land into existence, at will, moving peninsulas here and there, forming islands, atolls, archipelagos, all through the directed sediments of the Mississippi River... It'd be a kind of horizontal spray-gun, bringing terra nova into existence.
For what it's worth, meanwhile, my wife and I have co-authored a chapter in a forthcoming book called What Is A City?, published by the University of Georgia Press, in which we talk at great length about these sorts of post-Katrina hydrological projects – including the use of genetically-modified marshgrasses to anchor artificially dredged fill, in a more or less complete deterrestrialization of the earth's surface. Or, to use a bad pun, you could say that these projects are literally outlandish.
Finally, don't miss the show up now at the Center for Land Use Interpretation, Birdfoot: Where America's River Dissolves Into The Sea.
    The end of the Mississippi River Delta – the Birdfoot – is a national landscape of disintegration, a fractal labyrinth of dendritic channels, a blend of water and earth, bisected and rerouted by linear, engineered forms of pipeline canals and levees. The people who live and work here, beyond the reach of roads, do so tenuously, in a delicate, disappearing place that is battered by hurricanes, and eroding into the sea.
The closing date for the exhibition is not available.

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Anonymous Ed Richards said...

Of course, all of this ignores two points. First, the Mississippi is not very sediment rich since it has been leveed along its entire length. Second, we are losing the wetlands because of geologic subsidence of the whole of south LA, not because of erosion from the edges of a stable base. Building up the edges, even if you can, does not help with the lose of elevation in the center, i.e., the sinking away of New Orleans.

February 18, 2008 10:22 PM  
Blogger Adolph said...

By 2100 I'd hope we'd be able to come up with improvements to human activity that worked with the changing nature of the river instead of contorting it further.

February 18, 2008 10:30 PM  
Blogger Alexander Trevi said...

First, the Mississippi is not very sediment rich since it has been leveed along its entire length.

This sounds wrong to me. If you put up levees along its entire length, wouldn't this mean that the river retains all or most of its sediment? And though contained it can still receive water (and sediment!) from the entirety of its drainage basin (which of course is huge)?

If it ain' very sediment rich, what's all that thing getting dump into the gulf then?

Or am I the one who's wrong about something?

Second, we are losing the wetlands because of geologic subsidence of the whole of south LA, not because of erosion from the edges of a stable base. Building up the edges, even if you can, does not help with the lose of elevation in the center, i.e., the sinking away of New Orleans.

New Orleans needn't be saved. The center can yield to the periphery.

February 19, 2008 12:42 AM  
Blogger Geoff Manaugh said...

Ed, I totally agree that this issue is more geologically complex than our efforts to move some sediment around – but the Mississippi dumps 500 million tons of sediment into the Gulf of Mexico every year. 500 million tons. As NASA says: "The river brings enough sediment from its 3,250,000 square km (1,250,000 square mi) basin to extend the coast of Louisiana 91 m (300 ft) each year."

I have read this article – but I'm with Alex on this one.

The Mississippi is one of the most sediment-rich rivers in the world.

February 19, 2008 1:34 AM  
Blogger David said...

You could make giant fractal pictures with enough properly placed cuts.

You may have posted about this before, but this post reminded me of a passage from Mark Twain's Life on the Mississippi about cutting ditches across the necks of long bends in the river in order to turn your land into riverfront property. The passage can be found here: http://classiclit.about.com/library/bl-etexts/mtwain/bl-mtwain-lifemississippi-17.htm

Another passage is also relevant:
"One who knows the Mississippi will promptly aver-- not aloud, but to himself--that ten thousand River Commissions, with the mines of the world at their back, cannot tame that lawless stream, cannot curb it or confine it, cannot say to it, Go here, or Go there, and make it obey; cannot save a shore which it has sentenced; cannot bar its path with an obstruction which it will not tear down, dance over, and laugh at. But a discreet man will not put these things into spoken words; for the West Point engineers have not their superiors anywhere; they know all that can be known of their abstruse science; and so, since they conceive that they can fetter and handcuff that river and boss him, it is but wisdom for the unscientific man to keep still, lie low, and wait till they do it. Captain Eads, with his jetties, has done a work at the mouth of the Mississippi which seemed clearly impossible; so we do not feel full confidence now to prophesy against like impossibilities."
found here: http://classiclit.about.com/library/bl-etexts/mtwain/bl-mtwain-lifemississippi-28.htm

February 19, 2008 3:05 AM  
Blogger m.b. said...

i thought f*cking with the delta was what got them into this mess in the first place

February 19, 2008 5:17 AM  
Anonymous Hugh said...

geoff, cannot see how to contact you. but from reading your blog I think you might enjoy the advert for the Madrid Metro www.peliculasponder.com/2004/content/directors/gi_01.ht

February 19, 2008 8:57 AM  
Blogger Geoff Manaugh said...

Hugh, that's a cool little video! Thanks for the tip.

And, David, perhaps in the next ten years, instead of crop circles, we'll get extraordinarily complex subdeltas of deltas in vast daltaic complexes. Morning news helicopters fly over them, cameras at the ready, for stunned viewers in Baton Rouge.

February 19, 2008 9:36 AM  
Anonymous Rainier Simoneaux said...

m.b., who do you mean by "them"?

Alex, Geoff,
Thanks for letting me know that my city "needn't be saved." I guess me and the 1.4 million who live in the area can leave now. Thanks for your help.

February 19, 2008 10:44 AM  
Blogger BC Planning said...

This could work...as long as the Deltas do not affect the port. The creation of shipping cananls is a big part of the reason why the silt from the Mississippi river gets dumped into the Gulf instead of building up coastal land.

February 19, 2008 6:05 PM  
Anonymous Noah said...

The way the delta was created is that the river wants to find the path of least resistance... think an oxbow lake, which is leftover when the river meanders too far and then at some point decides its easier to just go straight through rather than the route it was taking. The same thing happens on the delta on a massive scale, the river was constantly moving back and forth depositing sediment, constantly finding an easier, lower path to go and depositing sediment there.

The problem is that if the river is constantly moving we cannot get ships up it because the channel might not be deep enough, even now they are constantly dredging sediment out of the mouth of the river to ensure a ship does not get stuck. If they could get a ship up they would bypass the main port of new orleans, where all of the "port" infrastructure, not to mention the financial gains to be had from controlling the shipping, are based.

Right now the entire mississippi river is literally cemented in place by giant concrete mats, from the outlet at the gulf through all of louisiana and beyond. This basically makes a giant funnel that shoots the sediment out into the gulf at a tremendous rate.

You guys should go see how MASSIVE the river control station at old river is. The river wants to split off and go down the atchafalaya basin, bypassing new orleans. To prevent this from happening the core had to build this:

http://www.btnep.org/minis/fieldtrip/images/trip_77.gif

It controls the flow of water and generates electricity. The power of the river is immense, you cant just cut holes in the banks of it or those holes will quickly get much much larger.

Another problem with sediment loss is that sediment is naturally deposited most during a flood... the river overflows its banks and sediment is deposited there as the water level returns to normal. This is why in new orleans the highest elevations and best soil for building foundations occur right next to the levees, not because we built them up so high, but because historically that is where sediment was deposited. Not such a nice thought for someone trying to build a house there.

February 19, 2008 9:40 PM  
Anonymous Anonymous said...

Seems to me that even if this was feasible, it would be a terrible idea. Our society must learn that we can not contain or tame Nature. How has this region not learned this lesson. This solution may solve some problmes, but it will undoubtedly create whole new problems.

also, much of the sediment and water we're talking about are heavily polluted with agricultural runoff. To push this sediment parallel to the caost (rather than straight out to see) seems to be asking for trouble.

What if we just didn't build in places Nature obviously doesn't want us to be?

February 25, 2008 5:46 PM  

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