LOUISIANA: They're trying to wash you away

News Analysis by Kip Hansen

 

Jean_Lafitte_map_420Jean Lafitte, Louisiana, is situated at two feet above sea level and about ten miles south of New Orleans.   It has the misfortune to sit just outside of the protective system dykes and levees that keep New Orleans from flooding.

John Schwartz, at the New York Times, writes about “the ecological crisis facing Louisiana’s vanishing coast” in “Left to Louisiana’s Tides, a Village Fights for Time”, a long narrative magazine piece relating the struggles of this small town to save itself from what appears to be the ultimate fate of much of the Mississippi Delta:

“Saltwater intrusion, the result of subsidence, sea-level rise and erosion, has killed off the live oaks and bald cypress. Stands of roseau cane and native grasses have been reduced to brown pulp by feral hogs, orange-fanged nutria and a voracious aphid-like invader from Asia. A relentless succession of hurricanes and tropical storms — three last season alone — has accelerated the decay. In all, more than 2,000 square miles, an expanse larger than the state of Delaware, have disappeared since 1932.”

“….Just two miles north is the jagged tip of a fortress-like levee, a primary line of defense for greater New Orleans, whose skyline looms in the distance. Everything south of that 14-foot wall of demarcation, including the gritty little town of Jean Lafitte, has effectively been left to the tides.”

The Times’ piece lays out the emotionally rending story of this small bayou fishing village’s political attempts to somehow, anyhow, get itself included inside that 14-foot tall fortress-like system of levees that protect New Orleans from the  rise and fall of the tides, storm surges and seasonal  floods that relentlessly eat away at the coasts along the Gulf of Mexico.

levees_800

FULL SIZE image

Schwartz asks:

“Jean Lafitte may be just a pinprick on the map, but it is also a harbinger of an uncertain future. As climate change contributes to rising sea levels, threatening to submerge land from Miami to Bangladesh, the question for Lafitte, as for many coastal areas across the globe, is less whether it will succumb than when — and to what degree scarce public resources should be invested in artificially extending its life.”

Isn’t it a shame, what the river has done to this poor crackers’ land?

What has happened here?   Where has all that land gone, and why?  According to the US Geological Survey:

“The swamps and marshes of coastal Louisiana are among the Nation’s most fragile and valuable wetlands, vital not only to recreational and agricultural interests but also the State’s more than $1 billion per year seafood industry. The staggering annual losses of wetlands in Louisiana are caused by human activity as well as natural processes. U.S. Geological Survey scientists are conducting important studies that are helping planners to understand the life cycle of wetlands by detailing the geologic processes that shape them and the coast, and by providing geologic input to models for mitigation strategies.”  – S. Jeffress Williams, U.S. Geological Survey

What are these forces that are causing the demise of the Mississippi Delta?

USGS and other studies indicate that major shifts in the course of the Mississippi River have contributed significantly to the demise of the wetlands.

“The 300 kilometer-wide Mississippi River delta plain and its associated wetlands and barrier shorelines are the product of the continuous accumulation of sediments deposited by the river and its distributaries during the past 7,000 years. Regular shifts in the river’s course have resulted in four ancestral and two active delta lobes, which accumulated as overlapping, stacked sequences of unconsolidated sands and muds. As each delta lobe was abandoned by the river, its main source of sediment, the deltas experienced erosion and degradation due to compaction of loose sediment, rise in relative sea level, and catastrophic storms. Marine coastal processes eroded and reworked the seaward margins of the deltas forming sandy headlands and barrier beaches. As erosion and degradation continued, segmented low-relief barrier islands formed and eventually were separated from the mainland by shallow bays and lagoons.”  —  Louisiana Coastal Wetlands: A Resource At Risk

There is a nicely done, if simplistic, animation that illustrates some of the problems with the Delta at interactive-earth.com:  How Have We Changed the Delta? (requires Flash).  Here’s a few stills from the animation so we can see the situation today:

How_We_Changed

In words, from the American Museum of Natural History in NY City,

Disappearing Delta:   Humans have upset the delicate balance of land gain and loss in the Mississippi River Delta. Dams, levees and channels along the Mississippi have prevented land-forming sediments from reaching the delta, and most of those that do are discharged deep into the Gulf of Mexico. Meanwhile, old land continues to compact and erode, a process aggravated by human activity. As a result, over the past 75 years, almost 5,200 square kilometers (2,000 square miles) of wetlands, which once sheltered coastal cities from storms, have been lost to the ocean.”

Here’s the long-term historical perspective on the Mississippi Delta:

Through-the-ages

Today’s delta comprises the darkest black portions of the image. The graphic is organized from the smallest area to the largest, dark to light.   The Delta has grown and shrunk over the last 6,000 years — and appears to have been at its historical largest limit about 3,000 years ago.  Change in the Delta seems to be the constant, the rule, and not the exception.

The Times’ article draws parallels between the Mississippi Delta and both Miami and Bangladesh.  Long-time readers here know the story with Miami, it is a disaster-in-waiting, and  Bangladesh  is the delta of a major Asian river system, diked and bermed and no longer being renewed, continually sinking below the level of the sea and rivers.

The Times’ Schwartz  comes on strong about Sea Level Rise:

“…the master plan’s authors adopted far more pessimistic forecasts of the impact of climate change. They effectively doubled their previous 50-year projections for likely sea level rise to more than two feet, the highest rate in the country, according to the National Oceanic and Atmospheric Administration.”

The link goes to NOAAs Sea Level Trends map, which shows two nearby tide gauges that show a trend of around 9 mm/yr (3  ft/century) of ….. relative sea level rise.  Yes, that it perfectly correct, USGS also blames many of the Delta’s problems on changes in relative sea level rise.

Reminder:  “The mean sea level (MSL) trends measured by tide gauges that are presented on this web site are local relative MSL trends as opposed to the global sea level trend.  Tide gauge measurements are made with respect to a local fixed reference level on land; therefore, if there is some long-term vertical land motion occurring at that location, the relative MSL trend measured there is a combination of the global sea level rate and the local vertical land motion.”

Relative sea level is the only sea level of concern to local residents and planning officials — it is where the sea meets the land at that spot.  Local relative sea level rise (or fall) is the surface of the sea getting higher (or lower) in relation to the land.

Yet the Times’ Schwartz keeps referring to sea level rise caused by climate change.  It fascinates me that Schwartz is allowed (or forced) by his editors to keep going on about climate-change-caused sea level rise yet somehow he actually never makes the distinction between changes in local sea level caused by subsidence and compaction of the land — the land sinking — and the type of sea level that can be caused by climate change — Absolute Sea Level and its rise or fall.  Schwartz does not quantify Absolute Sea Level rise at all.

So what’s the real deal here in the Mississippi Delta?  The USGS and NOAA both tell us the land is sinking — this is subsidence caused by the pumping of petroleum (and water) out from under the Delta and compaction of the sediments that make up the land.

In order to understand how much the surface of the Gulf of Mexico is rising, we have to have two things: a reliable measurement of the relative change between some point of land and the surface of the Gulf, which we can get from a good Tide Gauge, and a reliable measure of how much the land at that same point is moving up or down.   The nearest Continuously Operating GPS Reference Station at a Tide Gauge (CORS) is at nearby Dauphin Island:

Lousiana_Delta_800

C. Letetrel et al. (2015) — “Estimation of vertical land movement rates along the coasts of the Gulf of Mexico over the past decades” gives us the two figures from “13 years of data from January 1995 to December 2010.”  At Dauphin Island, the relative sea level is rising about 3 mm/yr.  The land, however, is sinking at a rate of 4.2 mm/yr.  The result for rate of Absolute Sea Level Rise is minus 1.26 mm/yr — at Dauphin Island, the surface of the Gulf of Mexico is not rising at all, it is falling.  Now, if you’ve been following my series here, Sea Level: Rise and Fall,  or Dr. Curry’s series at Climate Etc., you are well aware of the fact the sea level doesn’t rise evenly everywhere — so we can’t assume that the surface of the Gulf is falling at all points along the Gulf Coast.  The same paper supplies a usable answer:

“We corrected the tide gauge records from the vertical land rates and estimated the absolute sea level rise [averaged along the US Gulf Coast]  to be of about 2.07 (± 0.4) mm/yr. This value is comparable to the global absolute sea level rise estimates over the last 50 years (Church and White,2011): 1.970.4 mm/yr over the period 1961–2009.”

That makes about 100 mm over the 50 year period, or about 4 inches (or about 8 inches per century).  There is nothing unusual about Absolute Sea Level Rise in the Gulf of Mexico — and at the Delta, the surface of the Gulf may even be falling — not rising at all.

So there may be a small contribution of the rising sea to the problems of the Delta but this is comparatively tiny when weighed against the effects of subsidence, compaction and erosion all compounded by the total lack of soil replenishment.

What has happened down here?

watershedMan is losing yet another battle against Nature.  The Mississippi River carries water from 1,245,000 square miles (3,220,000 km²) of its watershed which extends all the way up into parts of Canada  in the northwest and southern NY State in the northeast.

This river system has experienced tremendous flooding — the Great Flood of 1927 being the most recent mega-flood.   It was that flood that prompted a massive engineering project:

“Following the Great Flood of 1927, the US Army Corps of Engineers was charged with taming the Mississippi River. Under the Flood Control Act of 1928, the world’s longest system of levees was built. Floodways that diverted excessive flow from the Mississippi River were constructed.  While the levees prevented some flooding, scientists have found that they changed the flow of the Mississippi River, with the unintended consequence of increasing flooding in succeeding decades. Channeling of waters has reduced the absorption of seasonal rains by the floodplains, increasing the speed of the current and preventing the deposit of new soils along the way.” – Wiki

That project, initiated 90 years ago, is the cause of the little village of Jean Lafitte’s problems today.  The Great Mississippi is literally washing Jean Lafitte away — the river’s replenishing soil loads are being washed far out into the Gulf instead of being captured by the vegetation of the Delta.  The barrier islands that in the past have been replenished each flood season have diminished and been washed away by Gulf storms — a reiterative process of erosion, death of the swamp and  marsh, and more erosion as storms keep coming.   After Hurricane Katrina, the Delta got a ten year streak of good luck and a chance to recuperate, but the 2017 hurricane season was harsh and extremely damaging.

The Mississippi Delta has further been damaged the dredging of canals to facilitate oil drilling and oil pipelines that crisscross the delta.  Traffic on the canals causes boat wakes that eat away at the banks of the canals, widening them year after year.  Almost everything that moves in the Delta moves on boats. The wider canals are subject to more wind chop which further erodes the banks, especially when storms come.  We want the oil but it comes at a terrible cost for the Delta.

Is there a solution?  Can Jean Lafitte and the Delta be ultimately saved?  Should it be saved? If so, at what cost?  These are questions that cross the lines between science, engineering and public values — and I have no suggestions to offer.

But one thing is certain — climate change, by any name, is not responsible for the fact that the Mississippi Delta is washing way.

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Author’s Comment Policy:

 It takes a lot of time to dig up all the [alternative] facts to correct the skewed impressions that poor science writing in the media can create.  Often, the task is to supply the rest of the story, or the details in which the devil lies.

The NY Times piece is part of a long series of stories on the human interest side of ecological and environmental disasters that insist placing the blame on “climate change” and specifically “climate-change-caused-sea-level-rise”.   It appears so very easy to shift the blame for relative sea level rise to climate — which can only be responsible for absolute SLR. It is always possible that the journalists themselves actually don’t understand the point, I guess — but it stretches my imagination to think that someone could be hired as a science journalist without even basic science knowledge.

Randy Newman, one of America’s musical geniuses,  wrote the song “Louisiana: 1927” — he performs it here.  The incomparable Aaron Neville recorded the definitive version.

Address your comments to “Kip …” if you are talking to me, I’ll see it and try to answer best I can.

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markl

Yes, the sea level changes naturally.

ossqss

I have oftern wondered how much the forming of the Great Lakes added to SLR? How thick was that ice again?comment image

John Harmsworth

Yes! My sediments exactly.

Jeff Alberts

Do these people expect things to NEVER change?

Hi Kip
Sidel Global has a Carbon Capture Utilization System that we are desperatly trying to get the DOE and EPA to recognize. https://www.youtube.com/watch?v=RQRQ7S92_lo
We transform the CO2 into calcium carbonate and this calcium carbonate can and should be used over the next 30 to 50 years to build sea walls. The White Cliffs of Dover are calcium carbonate. It will stand up to the waves and the surf. It can also be used to regain lost beaches.
If you can help us with a way into Secretaries Pence and Perry, please help us out.

TonyL

@ Sid Abma
I have a few quick questions from watching your video. I hope you do not mind.
1) Your top output stream in calcium carbonate. The only source of calcium is from the plant matter in the input stream. The plant matter is from farm residue, I take it.
a: What percentage of the total CO2 winds up as CaCO3?
b: What is the expected yield of calcium from the farm residue in terms of lbs./acre?
2) The second output stream is biofuel of some description. The farm residue in the process stream is largely cellulose. Can you sketch out the chemical reactions such that cellulose + CO2 == biofuel?
The reaction pathway is not obvious to me.
Thanks in advance.

hunter

Hmmmmm….very long on wild claims of a cure to a nonproblem.

Sly Rik

Just an observation. The white ciffs of dover are eroding at a furious rate..
Also where do you get the calcium from? what is the total energy cost of processing the calcium and transpoting it to site and then transporting it to wher it will be used??

MarkW

It’s a solution that is slightly less uneconomical than all the other so called solutions.
It’s also a solution we don’t need since the problem it’s supposed to solve doesn’t exist.

Ozwitch

There was a guy who built his house on the southern English coast. He was told that in 50 years it would be gone over the edge. He built it anyway and within 20 years he had to abandon it as it was unsafe. Nature usually wins.

Tom Halla

Dubious attribution of the sinking of that delta as due to “sea level rise” caused by AGW is a standard talking point. Compared to the other influences, AGW related seal level rise is tiny. “Other than that, Mrs Lincoln, how was the play?”

Typical of the mainstream media the Times gives the distinct impression that man-made global warming is the primary reason for the threat to Jean Lafitte. Damn the science… full speed ahead.

Latitude

“prevented land-forming sediments from reaching the delta, and most of those that do are discharged deep into the Gulf of Mexico— the river’s replenishing soil loads are being washed far out into the Gulf”…
..and we were told that all this dirt has very little effect on sea level rise
but one good rain in Australia can make it drop

Don K

AFAICS, much of the Mississippi Delta is doomed. Even if sea level rise could be stopped (Good luck with that), the combination of substrate compaction and lack of land replenishment from upstream erosion is going to be lethal. The only salvation I could conceive of would be to pump vast amounts of water (probably salt) into the strata below the region. Frankly I think that would likely turn out to be too costly to contemplate even if it is technically feasible.

Louis Hooffstetter

“Can Jean Lafitte and the Delta be ultimately saved? Should it be saved?” The answer is No.
The area of the Mississippi delta where Jean Lafitte is located is subsiding at a rate of between 1/4″ to 1/2″ per year. All deltas subside as their sediments compact and dewater under their own weight. It’s a natural process and nothing will stop it.
The National Flood Insurance Program should be re-tooled to take situations like this into account. Home and business owners should be bought out, the buildings and infrastructure should be removed, and nature should be allowed to take its course.

Louis Hooffstetter

Here’s an interesting and relevant Power Point presentation on this subject:
https://biotech.law.lsu.edu/climate/docs/2006_october_RDokka.pdf

commieBob

One thing they can do cheaply is to introduce salt tolerant plants. link

Gunga Din

Generally, what happens upstream effects what happens downstream in regards to flooding.
TWC got all excited about the flooding in Cincinnati, the Ohio River recently crested about 20 feet lower than in 1937.
Why wasn’t Jean Lafitte, Louisiana wiped out back then? Or New Orleans, for that matter?
Hmmm…How does the Katrina flooding in NO compare to the flooding in 1937?
(I don’t know. I’m asking.)

Gunga:
The Mississippi River varies in depth. Above Memphis, the river becomes shallower.
From Memphis south to Baton Rouge and New Orleans the river is deep and widens as it descends to the Gulf.
Normally, destructive floods along the upper Mississippi and it’s tributaries are only a concern, not a problem to the lower Mississippi.
Floods along the entire Mississippi River are not common and are very worrying.
That you are just talking is, unfortunately obvious.
The flooding that occurred during Katrina came about when several dikes ruptured as Katrina passed nearby. Ruptures caused by storm surge and winds.
Many areas immediately adjacent to flooded areas did not have any problems.
Gulfport, was flooded by Katrina’s storm surge,
Floods along the Mississippi River, or any river, are not uncommon.

Boris

I was in Galveston a number of years ago and happened upon the 1900 The Great Storm Museum on pier 21. The presentation was a telling of the hurricane that struck the city in 1900 and wiped it out causing more than 6000 to 12000 lost lives. After the storm the city rebuilt but included a sea wall that raised the city by 17 feet. The city of Galveston also added fill to bring the level of the city to its present height. With the amount of silt the Army Corp of engineers remove every year from the water ways of the delta instead of dumping it in the gulf it could be used to raise Jean Lafitte. Though this maybe a solution for Jean Lafitte I doubt that with the environs-natzies out there it would never be viable. Like most of the land use doctrine of agenda 21 man is supposed to abandon land to return it to nature rather than Terra-form it to support man.

As rivers slow near the sea they tend to deposit their sediment on the river bed, until the river bed gets to be higher than the flood plain it runs through. As water doesn’t like to move up hill, it then changes course, moving down into the lower flood plain. At times it will chose a new route that reaches the sea far from the original delta. There was one flood in China where a major river chose a new route that reached the sea hundreds of miles to the north. Thousands upon thousands died.
The Mississippi, left to its own devises, would chose a new route and make a new delta over towards Texas. It wants to shift into the channel of the Atchafalaya River, but the Army Corp of Engineers has built an impressive system of power-generating dams to restrict that flow, and keep water heading to the old delta.
The tree-huggers oppose any and all interference with nature, (at least until their own city is threatened). However people have to make a choice: To battle the floods or to move away. The history of the expansion of the English Channel and North Sea after the last ice age involved peoples with a rising sea. It is fascinating to read of their battles. The Frisian people were beaten back in many ways, but the Dutch made fighting the rising sea into an art.
New Orleans needs to decide if they plan to stay and fight, and then perhaps hire some Dutch consultants.

Caleb:
New Orleans made that decision over a century ago.
Most New Orleanians are downright proud that parts of the city are up to 10 feet below sea level.
By the same token, New Orleanians also know which roads not to take home during occasional severe downpours. Some underpasses can fill with many feet of water.
Most of the New Orleans areas that are sinking are areas of fill.
Fill, that occurred long before people figured out that fill with high levels of decomposing matter continually lose that volume.
The oldest portions of the city, e.g. French Quarter, are built upon original land forms; many of which contain middens. These areas are not sinking anywhere near as fast as areas built upon swamp bottom and trash fill.

Michael Jankowski

Nothing but disdain for southerners from the bleeding hearts…unless they can be used as a poster child for political gain.
Just like how Native Americans are all but ignored by the same unless there’s an oil pipeline to protest.

this screwing around with Nature and the crappy results are not any different than the Gov’t fucking with the Economy as much as it does… there are consequences for all actions… then there is the Chaos Theory, ” A very small change may make the system behave completely differently. ” Further explanation can be found in Jurassic Park- M Crichton … but I don’t have to tell ya’ll

John F. Hultquist

Kip,
Just did a quick read — very busy today.
Did you mention the depth of the sediments near NO?
I think I recall seeing it is about 50,000 feet.
20-25 years ago, NOVA or ?, had a good video about this.
I do not know if those are available on the web

Louis Hooffstetter

John, you are correct. The sediment thickness in the area of New Orleans is estimated to be approximately 15 km (or 50,000′) thick.

Martin457

I keep thinking about all the farmers upstream that do everything they can to keep their fields from getting washed away.

scraft1

For the most part they’re not being washed away – they’re being flooded like in the old days, which is good for farmland but not for the permanent structures palced there.

“Kip Hansen February 27, 2018 at 6:47 pm
scraft1 ==> Depends on where you are — the Gulf side of everything has been washed away, in many cases, whole islands have disappeared. Banks of canals get eroded and canals widen.
The farmers upstream though, get their fields replenished, but sometimes by nothing but sand.”

Not quite Kip.
Outside of tidal movement, there is very little water movement. With a typically small tidal change; e.g. Jefferson Parish’s tides for Jean Lafitte have a water hight total change of 0.41m (16.14 inches).
The current in the Mississippi River is swift enough to wash away stuff, but the river is channeled from well above New Orleans until the river exits into the Gulf of Mexico.
Decomposing vegetable matter eventually lowers islands until the grasses and reeds drown, or the floating plants (hollow stems) float off with the tide.
One can find rafts of these floating plants out in the Gulf.
Storms can and do exacerbate this loss, but the action is more similar to shaking a glass of muddy water. When it settles, lumps tend to be flattened.
Most of the bayous along the Gulf coast are brackish and salt water bayous. Except when planting salt loving plants, flooding does not improve farmland.

“Kip Hansen February 28, 2018 at 6:48 am
Theo ==> I think we’ve got two subject conflated here. The farming bit refers to upriver flooding.
The historical map shows where the River delta has been washed away.
Canal bank erosion is a long-term problem, see the animation linked in the essay.”

Perhaps.
The Mississippi River is long and involves major tributaries over a substantial portion of the USA.
General discussions lose precision and accuracy when discussing specific river sections.
I am at a loss to know which map you consider historical. But the term “washed away” is still incorrect.
As decomposing matter degrades and is consumed, the land sinks. It is true for portions of New Orleans and surrounding areas, and it is true for the swamps bereft of fresh sediment.
Without fresh deposits, the land submerges. Plants on top expire or float away.
It isn’t erosion, it is loss of material! It is subsidence.
The Canal bank erosion animation is cool looking, but not accurate.
Such an assumption would mean that the banks erode bit by bit over years. Which takes substantial water movement.
Bayous do not have substantial water movement. It is one of the reasons bayous are called bayous, swamps are named swamps and rivers are rivers; water movement!
Artificial canals could erode, except that dredging spoils are used to refresh banks and dikes regularly.
Because a large majority of those canals were cut through the swamps for specific reasons, many of which still exist; e.g. maintenance.
Dikes that keep in salt water as well as allow passageways through the swamps. i.e. when a storm surge or wind blown tides push slugs of salt water over a low dike, it is retained and kills the low salt tolerant plants.
New canals cut through the delta allowed salt water influx; but the majority of the bayous and swamps under discussion were brackish to some level. It takes a continuous flow of fresh water to keep portions of coastal swamps, fresh water.
When one passes stands of dead trees in Barataria, one can stop and inquire of locals. Many of the locals know the history.
The erosion story fails to explain why there are stands of dead trees between stands of live trees. Or why the stands of dead trees are few in number while the stands of live trees are extensive.
It is a 76 mile drive from New Orleans to Venice, LA. With trees common along the route.
Though, if one wants to see dead stands of trees, drive through Chalmette, LA towards Delacroix, LA. Where the canals are cut, south of Meraux are where one sees the most stands of dead trees. Down near Delacroix, where few canals are cut, trees are alive and healthy.
I kept a boat in Delacroix, and tried to fish in many other areas right down to and including the Gulf of Mexico. Occasional stands of dead trees puzzled me, so I asked, locally.
You include a link to American Museum of Natural History. AMNH presents a picture allegedly of “dead water” showing a clear divide.
As one who has fished in the Gulf of Mexico around New Orleans, it is very easy to see where green water, dirty river water and the Gulf’s beautiful blue water meet on the surface.
Though, normally one only sees green water meeting blue water, as the river’s fresh water tends to flow under the green water as it exits the river’s various passes.
It is also normal for border waters to have debris lines. Fisherpeople search for both water borders and debris lines as either are indications of fish holding water. It’s a jackpot to find both together as pelagic species feast on foods brought by the green or dirty water.
In other words, I’d need to see sensor readings before I believe someone’s picture.
That dirty water hugs along the coast well into Mississippi and part of Alabama. Which is why Gulfport purchases sand to create a sandy beach where people can swim.
The Chandeleur Islands are best described at sand dune pinnacles barely breaking the water’s surfaces. Most of the Chandeleurs are greatly reduced in size versus what is pictured. Plus, the Chandeleurs have moved, sometimes substantially.
https://www.dropbox.com/s/2li60s01ufr8efa/Chandeleur%20Islands.geprint?dl=0
No, I am not harassing you Kip. I greatly respect your article and summaries.
I lived in New Orleans for a number of years and loved the people, city, surrounds, swamps and fishing.
Keep in mind, that it takes water movement to erode land. The river water is channeled, often between rock barriers and does not affect swamps and bayous. The tidal movement is small, e.g. 16 inches height differences between high and low tides. Neither the swamps or bayous have sufficient water movement to erode land, especially plant overgrown land.

“Kip Hansen March 1, 2018 at 6:44 am
Theo => Erosion of canal banks is a major issue — at least according to the USGA — storms from the Gulf provide the water movement to eat away at the land, as you can see in the 6,000 year historical map.
I do not mean “washed away by the passing of the river water”, which I think is what you are saying isn’t so — and I agree on that — with the odd caveat that the soil that should be building the delta is flowing far out into the Gulf.”

USGA?
No idea.
Did you intend USGS?
Kip, you do really good research and write excellent articles; but, in this case you are reliant upon other sources entirely and getting led astray.
A) The government agency that is responsible for and handles everything about the Mississippi River and Mississippi River Delta is the Army Corps of Engineers.
– i) Not USGS, Not NOAA, Not NASA
– ii) USGS used to be reliable, until they got orders to recognize anthropogenic climate change and that fracking causes quakes. Unfortunately, USGS is far down the list of agencies getting fixed soon.
B) The Mississippi River is bounded by dikes and levees.
– i) All dikes and levees get regular maintenance; i.e. when the Army Corps dredge channels, the dredge spoils are used to repair dikes and levees.
– ii) Substantial portions of the lower Mississippi River are bounded by rock levees. They ain’t eroding!
– iii) http://www.usace.army.mil/Portals/2/docs/recovery/MRTApr10RIOOMBupdatedv1.pdf, http://www.usace.army.mil/Portals/2/docs/civilworks/annual_report/fy07/MVD_fy07.pdf
C) Canals are cut for purpose.
– i) Canals that are still utilized get repaired via dredge spoils. Regularly.
– – a) This is the case whether the canals are for drainage or rig/well maintenance or resupply. – – b) Much of New Orleans, Metairie, Kenner, La Place, West Bank, Barataria are crisscrossed with drainage canals.
– – c) Water runoff drains into a canal, somewhere along that canal there are massive pumps that pump runoff into canals connected to sea level water exits; e.g. Lake Pontchartrain, Lake Borgne, Intracoastal Canal, etc.
– ii) Unused canals are slowly reverting to swamp land. I emphasize slowly.
D) As pointed out upthread, boat traffic is a problem for canal banks.
– i) Waves caused by boats travelling too fast slap the canal banks just as breakers slap a beach.
– ii) That causes banks to slump and fill channels
– iii) Or it causes gaps where high waters can flow out of the canal.
– iiii) If it’s an in use canal, it will still get repaired.
– l) Where somebody might have assumed storms cause canal bank erosion would be from the canal bank failure caused by a combination of hurricane Katrina’s storm surge, hurricane winds, and a long storm reach over Lake Pontchartrain that piled water into a drainage canal that bordered New Orleans and Metairie.
– ll) The section that failed had just undergone a multi-year improvement by the Army Corps of Engineers; including driving steel I-beams deep as support. Only the sheer height and weight of water pushed the canal bank, beams and wall into the local residential area.
– m) There was another bank ‘failure’; i.e. the Intracoastal Canal bank was overtopped by high waters that flooded another New Orleans District.
– mm After overtopping the bank, the water eroded a larger exit.
Unless, someone is actually out in the swamps following canals, channels, bayous, researching, talking to residents/fisherpersons/shrimpers verifying and validating findings they are ignorant of the situation!
It is not in USGS, NOAA, NASA remits and authorizations to go researching Mississippi River Delta. The Army Corps of Engineers is rather intolerant of fiefdom intrusions.
“I do not mean “washed away by the passing of the river water”, which I think is what you are saying isn’t so”
I did not use those words, Kip. Nor is your interpretation anywhere close.
Rapid erosion is caused by water movement. Period.
i) Water in the swamps or bayous is moved by inflowing river water; which the River dikes prevent. Too slow for erosion.
ii) Water is moved by tidal movement.! Only tidal movement in the Gulf of Mexico is minimal; maybe a maximum of 2 feet total over 12 hours and usually much less. Too little movement and too slow for erosion.
iii) Wind might cause some water movement. But this requires a constant wind from one direction for long periods of time. This rarely happens. Rare events where there is some erosion.
If a storm is large enough to cause a significant storm surge, then a storm will cause water movement. New Orleans and the Mississippi Delta, like so many other places go years without serious hurricane strikes.
Even if the New Orleans had several hurricanes every year, they are unable to cause significant water movement.
Except for the river and a few canals, all Mississippi Delta water must traverse crisscrossed bayou mazes. No sane fisherperson goes fishing in the Mississippi River bayous without a detailed map; and the latest satellite imagery was very popular. A longtime resident who traversed many bayous every day might be all right without a map, but they’re taking risks.
It is not hard at all to get lost in the bayous. Those islands that recently sank are just below the surface.
What looks like any other bayou water traps boaters. My buddy and I got caught following a map when we came to a large open water area that was supposed to be bayous and islands. He started circling while I tried to find where on the map we were.
We got stuck, and it was my turn to get in the water to clear the motor intake and try to push the boat off; all while wondering when my a$$ would get bit by a gator.
We exited the open area, where we came in and followed another route. The open water was too dangerous to try and cross.
New Orleans is 76 miles from Venice, LA. Venice is a substantial distance yet from the Gulf Of Mexico. Essentially, there are dozens of miles of swamp, bayous and islands that hinder and slow any storm surge.
Every day, the Mississippi Delta loses land. Every day, week, month and year, land is lost and the total cumulation of lost land is staggering.
I repeat.
Mississippi Delta land is lost through subsidence!
Just as, and for the exact same reasons, the land is sinking in New Orleans, it is sinking throughout the delta.
When land subsides below water, surface plants are killed, or they float away.
Yes, everyone agrees that the Mississippi river is channeling silt out into the Gulf of Mexico; and that is the actual cause of Mississippi Delta loss.
Only, no one is willing to remove all Mississippi River dikes and levees below New Orleans.
Mississippi River water would normally filter through the swamps, where slowed by the masses of swamp water, convoluted paths and islands, sediment drops from the water column or is caught by roots and plant growth.
When floods would bring larger masses of water coupled with a heavy silt load, the entire Mississippi River Delta would benefit. Muddy water that enters the swamp eventually exits into the Gulf of Mexico rather clean looking.
The moment someone starts claiming canal erosion by storms, kick em!

Gums

No time for long reply until home, but good stuff out there regarding the south Louisiana loss of land, and it is likely mostly due to man! Not climate change or even a few storms.
Born and raised in NOLA and even in the early 50’s the changes were evident and the land was sinking. So go back and look at:
– levee construction since 1927
– the Old River diversion project
– thousands of miles of canals dug for petroleum exploitation
– the MRGO project in more recent times
and I could on, but have to drive home manana and there’s no lack of info about the loss of wetlands down there and plenty of orgs associated with it. So start with LSU and then just surf.
Gums…
P.S. My classmate in Jean Laffite came thru Katrina just fine and our class had its reunion crawfish boil there in 2010. NOLA flooding was mostly bad engineering and a big storm.

Bad engineering indeed, if this area is worth saving perhaps the Dutch engineers should be invited to participate. These areas are sediment, protected and drained properly you can grow anything.

Germinio

Kip,
It would appear that you are deliberately mis-stating what the article states. Every contributor to land
loss that you mention is mentioned in the article. Climate change is only every listed as one of the causes.
The article states that:
“Rapid subsidence and associated wetland loss were largely induced by extraction of hydrocarbons,” concluded a 2005 study of the Mississippi Delta plain by the Geological Survey.
or
Scientists and conservationists have sounded alarms since the 1920s about the loss of land
to oil exploration.
or
the land sinks, canals widen and sea levels rise because of climate change.
which I at least understand to mean that only sea level rises due to climate change. And again note
the qualifier “As climate change contributes to rising sea levels”. So the article is not stating that
climate change is the only cause of rising sea level as you would appear to believe.

Windsong

Kip, have you seen this information previously? The nola.com article is based on a paper/poster presented at the 2017 AGU meeting in NO about the upriver silt buildup and potential for the Mississippi River to return to the Atchafalaya River basin. I wandered through Louisiana in 2016, stopping in a number of museums and historical parks. I think it was at one of the Jean Lafitte NHP locations (but I can’t recall which one) where a display implied it is just a matter of time before the Mississippi deserted its present channel and took a more direct route south along the Atchafalaya.
http://www.nola.com/environment/index.ssf/2017/12/rising_river_bottom_could_swit.html

Windsong:
You are more correct than one likes.
Right now, the Army Corps of Engineers are very proud that their chaining the Mississippi to it’s current exit to the Gulf of Mexico is successful.
And they celebrate every time a near disaster passes close.
A major flood event throughout the upper Mississippi River strains the flood control system at at Atchafalaya.
When both the upper river and the lower river systems are seriously flooded, the Engineers divert water from the MIssissippi through the Atchafalaya basin. Each time, the Engineers worry that water will wash out some critical component with the resulting flood then carves a new Mississippi River channel to the Gulf. Much like the dam failure in California, but much bigger.
The truth of the matter is that it is not natural for a river to only flow in one channel forever.
Using Google Earth, one can locate oxbows along the Mississippi River and along many other large rivers. Oxbows are one result when a river cuts a new channel.
It is also the Army Corps of Engineers responsibility to dredge excess silt out of the river.

Walter Sobchak

“the Mississippi Delta is washing way.”
Common Yankee error:
The Mississippi Delta is not to be confused with the Mississippi River Delta.
“The Mississippi Delta, also known as the Yazoo-Mississippi Delta, is the distinctive northwest section of the U.S. state of Mississippi (and small portions of Arkansas and Louisiana) which lies between the Mississippi and Yazoo Rivers.”
https://en.wikipedia.org/wiki/Mississippi_Delta

Walter Sobchak

“… [R]ead John McPhee’s “Atchafalaya.” https://www.newyorker.com/magazine/1987/02/23/atchafalaya It was published in February, 1987, and it’s about the Herculean effort of the U.S. Army Corps of Engineers to control the flow of the Mississippi River, the fourth-longest river in the world. “Atchafalaya” is the name of the “distributary waterscape” that threatens to capture and redirect the flow of the Mississippi. If that happens, the cities and industrial centers of Southern Louisiana could find themselves sitting, uselessly, next to a “tidal creek,” and economic ruin would be the inevitable result. To prevent that, the Corps of Engineers embarks on a vast project to artificially freeze the naturally shifting landscape. McPhee meets the engineers and explores the structures they’ve built to “preserve 1950 … in perpetuity.”
* * *
In 1989, McPhee incorporated “Atchafalaya” into a book called “The Control of Nature.” http://www.amazon.com/dp/0374522596/ (He’d been passing by the engineering building at the University of Wyoming, and had been struck by its inscription: “STRIVE ON—THE CONTROL OF NATURE IS WON, NOT GIVEN.”) Like the Mississippi, “Atchafalaya” is long—around twenty-seven thousand words. But it’s all available online, and it gives you a real sense of what it’s like not just to live and work beside one of the world’s great rivers but actually to struggle with it.”
https://www.newyorker.com/books/page-turner/letter-from-the-archive-john-mcphee-on-the-control-of-nature

Walter Sobchak

The Mississippi River Problem is complex and mufti-faceted. Solutions will be complex and expensive. i would urge one and all to start with the John McPhee essay I linked above.
The Mississippi River should be allowed to go where it wants to go: the watercourse of the Atchafalaya river. The river should be replaced as a transportation artery by canals — big ones at that from Cape Girardeau south. The canal system should allow river traffic to be trans-shipped to ocean ships at Mobile Bay which is a superior natural harbor.
None of this can happen until the last lawyer is strangled with the entrails of the last environmentalist.

barryjo

When the Corps of Engineers built the main stem dams on the Mississippi and Missouri, and the locks below, they effectively stopped the deposit of soil in the delta region. Now the reservoirs are silting in and things will only get worse. IIRC, Lake Sakakwea (the reservoir in North Dakota) was predicted to be usable for 600 years. Not going to happen. Downstream from Pierre,SD, the pass-thru lakes are becoming very silted. Mother Nature will prevail.

Walter Sobchak

“Mother Nature will prevail.”
Amen.

An article from Sept 2005, but still on target
https://pesn.com/archive/2005/09/23/9600175_Rebuild_Energy_Systems_Not_NewOrleans/index.html

Infeasibility of Rebuilding New Orleans
The river is moving away from the city. The city is sinking because of ts weight, because no upbuilding by new muck for many decades, because of being cut off from the fresh water, because it is sliding off a cliff (the Continental Shelf), and because the Oil and Gas Industry is extracting oil out from under it. It is a city that for all intents and purposes is now Sea domain. Spend the money on developing alternative energy solutions instead.

And near the end, a pragmatic recommendation to accept defeat. New Orleans and surroundings have been sinking for the past several thousand years. There are better things to spend trillions on, than to reverse the inexorable course of nature.

The City of New Orleans should be abandoned to the sea that is going to take it anyway. The dikes on the river and throughout the city should be deliberately and completely destroyed to allow buildup of whatever wetlands we can keep for as long as possible.
The persons displaced should be assimilated into the rest of the USA. This should be made as painless as possible for all concerned. Give the displaced people vouchers that are payable for building at any location at least 30 feet above sea level. Let them find their own locations. This will be far less complex than the current system of keeping them penned in large buildings, and much less expensive.

One item that no one else wants to talk about, but I will. Once you put an entire sinking city at/below sea level, with over 1/3rd of a million inhabitants behind a 14-foot seawall, it becomes a very tempting terrorist target. A couple of airplanes or explosive-laden trucks flown/driven by suicidal terrorists, breaching the sea wall at strategic locations in the middle of a storm (let alone a hurricane) will cause major flooding if not loss of life. Every anti-American nutcase will be targetting it. Don’t do it.

Ennis Bruce

Kip,
Great story. Thanks. BTW, where did you get that fine diagram of Mississippi watershed? I want to have one.
BLE

Leo Smith

In a sufficiently complex system any attempt to change it will almost certainly result in unintended consequences.
Life is hard, isn’t it?

Edwin

During the 1980s I often attended Gulf States Marine Fisheries Commission meetings. During much of the 1990s I was one of our states representatives on the commission. Reading this essay is deja vu all over again. Once a year the Corps of Army Engineers give us a detailed briefing on the Mississippi Delta. While they mentioned the possibility of rising sea level due to global warming they were quite clear about the problems the Delta and the communities, especially New Orleans faced. Basically the Mississippi was dike and the mouth controlled for shipping, not just oil and gas. The sediment that once came down the Mississippi and made the Delta now flows well offshore, sinks and creates an oxygen zero area on the bottom of the Gulf. It has gotten worse over time as the Delta has continued to subside. Remember the massive flood in 1993 when many of the dikes failed upstream.

AZ1971

I blame the Mississippi River delta issues on the US Corps of Unintentional Consequences.

Paul Marchand

How about having a time set to take the levees of the Mississippi River down, say in 50 years, and in the interim build high (both buildings and roads)?
Thereafter siltation is back.

HDHoese

Nearly 25 years ago I was a consultant to one of the earlier Mississippi River diversion projects, almost a half century ago I was on the committee that started the Louisiana Coastal Zone Management Program, and a lot in between. There is still mud in my pores and concern that so many still do not understand that “Land.-1a: The solid part of the surface of the earth” is a standard dictionary definition and a small portion of the delta. Most of the “wetland” loss is actually marsh conversion to shallow water to a meter plus or minus, even wetter. Two geologists remarked that the marsh is only a speed bump for storms, still better than open water. There is some land at Lafitte and closure of Bayou Lafourche at Donaldsonville was also part of the problem. It is also not “fragile” or “delicate” and is nothing like Miami, more like other deltas, which are all different. Neither are the people to have survived and prospered there.
Most of those writing about it, including too many scientists and journalists sitting behind computer screens, have little insight or experience with the problem. Long deceased old school geologists were convinced that the river could not be stopped from going down the Atchafalaya and they may be right as it almost went in 1973. It is the biggest and perhaps most misunderstood environmental problem in the United States, maybe North America. Little known, for example, some sediment is added in places from hurricanes and there is less coming down the river. There is also faulting and other natural processes. Some places with oil operations have little erosion. It is an amazing and very complicated place, but is, and will remain no matter what, one of the most productive places on earth. As noted, climate change is the least of their problems and the people deserve better analyses. They certainly did not get it with the oil spill.
I like this quote from geologists studying the Gulf as a largely closed system as the result of collection of “…organic and inorganic debris…” who stated crudely but accurately — “In terms of geologic pollution the Mississippi River was, and is, North America’s largest sewer system. It collects and dumps waste into the Gulf cesspool, where oil and gas forming processes start immediately.” (Clark, R. H. and J. T. Rouse. 1971. A closed system for generation and entrapment of hydrocarbons in Cenozoic deltas, Louisiana. Bulletin of the American Association of Petroleum Geologists. 55(8):1170-1178.)
There are no satisfactory answers, but there is a plan if anyone has brilliant ideas to compare.
http://coastal.la.gov/wp-content/uploads/2016/08/2017-MP-Book_2-page-spread_Combined_01.05.2017.pdf

Kip: The Randy Newman version of the song is the definitive version. Neville is good, but not that good. Great article. Very informative.

sophocles

Kip Hansen said:

it stretches my imagination to think that someone could be hired as a science journalist without even basic science knowledge.

Think about how dangerous they would be to the propaganda if they (the journalists) actually did have some science education; they wouldn’t do as well at supporting the desired pseudo-science as they do.
That wouldn’t sell as many papers.

John F. Hultquist

Kip & others, [Hope this is late enough that it is not intrusive.]
If you have an interest in music history there is an interesting analogy to explore.
It is that of Steve Goodman and the song “City of New Orleans.”
Riding on the City of New Orleans
Illinois Central Monday morning rail
Fifteen cars and fifteen restless riders
Three conductors and 25 sacks of mail…
Good morning America, how are you?
Say, don’t you know me? I’m your native son.

 – Steve Goodman, “City of New Orleans”, 1970
Steve had leukemia and also road the Illinois Central Railroad.
Realizing that such passenger trains and he were slowly dying, the song is an analogy one for the other.
It could just as well be for the Delta of which you write, but I’ve not found that such was in his mind 50 years ago.
Here he is:
Steve’s live version
He had to buy Arlo Guthrie a beer to get Arlo to listen to it.
I guess, as they say, the rest is history.
{Arlo changed a few words.}
Arlo’s City of New Orleans

icisil

“Now, if you’ve been following my series here, Sea Level: Rise and Fall, or Dr. Curry’s series at Climate Etc., you are well aware of the fact the sea level doesn’t rise evenly everywhere — so we can’t assume that the surface of the Gulf is falling at all points along the Gulf Coast”
I haven’t been keeping up with the series, but this makes no sense to me that water rise/fall in a regional area like the Gulf of Mexico isn’t consistent, after filtering out influences like storm-surge river drainage, changes to salinity and temperature, etc. Assuming, of course, that there is no land rising/falling.

knr

Such deltas have come and gone through-out history , even major rivers can and have changed their course with significant effects down stream with no help from man .

Joe Wagner

Wait- if Man is such the problem, why aren’t they fighting to remove the levees and go back to nature???
Nothing will help the AGW “problem” like a Major city being washed into the Gulf (we’ll just ignore the pollution for now- no more CO2 from NO!)

beng135

John Schwartz is an idjit. Those areas are subsiding because of the channelization of the Mississippi. Nothing to do w/”sea-level rise”.

ResourceGuy

Give them their share or river mud in place of NYT word count.

michael hart

It’s not difficult. If you buy a house down there, know what you are doing. If you build a house down there, you might want to consider building it a couple of feet higher off the ground than your neighbors.
It is probably as true today as it was a century ago, except that today you have no excuse for ignorance. The people writing for the NYT are anyway probably too afraid to go anywhere near a place with the word Mississippi attached to it, in case they met a Trump supporter. So it shouldn’t trouble them unduly.

PRDJ

Kip, once again you have provided me with a starting platform to teach my science classes complete with references. You publish it a day after I introduced my Environmental Science class to the paddlefish, and now we have a starting point to discuss anthropogenic changes to riverine systems and those affects to the species adapted to them. Since we are in a school in Louisiana, we have the additional requirement to bring those topics to a more localized point of view, which you provide here. Thank you.
There are many programs you don’t mention specifically which are designed to both build awareness and actually do something constructive to marsh restoration. One of these is known as “Marsh Maneuvers”, a 4-H program which educated children in how marsh/wetland ecosystems function, the threats to them, and how restoration efforts are conducted. MM takes it a step further and provides these students with an opportunity to participate in the planting of wetland plants in areas where freshwater inputs have been restored and a brackish water environment is established. Particularly planting Spartina sp. is conducted in wetlands. This program has been in place for at least 20 years.
If you wish to educate yourselves (speaking more broadly than just Mr. Hansen) on wetland science, I recommend the text, “Wetlands” written by Mitch and Gosselink, used broadly in graduate level studies. My edition is getting outdated, but I believe there are more current versions. These guys are a little on the liberal side, but the basic science is sound and well founded.

HDHoese

Gosselink is a very good scientist, part of the long legacy from the realists dealing with the problem. Marsh (and other) restoration is sometimes a pork barrel project, too often fails. This is a good summary useful for students, possibly available on line.
Gosselink, J. G. 1984. The ecology of delta marshes of coastal Louisiana: a community profile. U. S. Fish Wildl. Serv. FWS/OBS-84/09:134.
While there is a younger group that seems to be more realistic, there are still otherwise good scientists bought into it. This work while having some good information is an example, and the chapter on Louisiana is inadequate. Day, J. W. Jr. (Ed.) 2013b. Gulf of Mexico, Origin, Waters, and Biota. Ecosystem-Based Management. Vol. 4. Texas A & M. Univ. Press.
Gulf of Mexico sea levels are a mess. Seasonal levels vary more than daily, and in the early 90s there was a long period when Louisiana marshes were never covered. Not considering possible cooling and even sea level falling, even as a mental exercise, is a scientific failure..

Bruce C. Atwood

Kip, I agree with Germinio’s post above, and have have read your entire essay, which ends with,
“But one thing is certain — climate change, by any name, is not responsible for the fact that the Mississippi Delta is washing way.”
You are building a straw man. The Times article clearly comments on the natural part of the subsidence, and gives several column inches to the fact that one partial cause, petroleum extraction, has been known for half a century. The Times discusses the effects of levees in detail. The article is 9000 words long, and does mention climate change as contributing to the problem, but makes clear that climate change is not the main cause of the present problems.
Your calling the writer of a well written comment a “Troll” perhaps exposes your real intent.

Richard

There are many who fancy themselves as “science journalists” but who don’t know beans about science. But then, what is “science”? The definition is changing.
Back when I was a science student at a state university, the profs and textbooks all had a unanimous definition of “science”. It was defined as a methodology, and a “scientist” was anyone who practiced that methodology. But even then there were “scientists” teaching at universities who claimed that certain beliefs, certain teachings, were “science” even though those beliefs could not be demonstrated using the scientific method.
Today it appears that the main definition of a “scientist” is one who has papers from a university saying that he is a scientist, that he works at a university or “scientific think tank” or something similar, and that he gets his ideas published in a “peer reviewed journal”. Once he gets his papers, he gets to define what is “science”. However, if he doesn’t go along with the consensus, he can lose his status as a “scientist”.
In short, when I studied at the university, it was the science that defined the scientist. Today, it’s the “scientist” who defines the “science”.
Now take the average journalist, who has never studied any science course other than maybe an introduction for non-science majors, whose main training has been on how to do interviews and report on them, among which is to focus on the human interest side of the story as well as the eye-catching “disaster”—how is he to deal with a “science” story? If not to interview “scientists” who make headline worthy statements? Is it any wonder that science reporting is so atrocious? How does this description not fit most “science journalists”?

ResourceGuy

I’m sure New Yorkers will gladly exchange Manhattan bedrock for Mississippi delta bedrock one for one since they don’t know the difference. /sarc

CVP

I am an owner of some of the wetlands that are disappearing in South Louisiana. The State has attempted to make a dynamic system static, succeeding in some ways, but failing miserably overall.
There are many causes of the degradation of the Louisiana’s wetlands but the most dominant causes are as follows:
• Louisiana has chosen commerce over conservation. Funneling the sediment and nutrient filled water of the Mississippi River onto the outer continental shelf to inexpensively maintain the river channel deprives the coastal marshes of needed sediment and nutrients. Coastal marshes are similar to cropland (managed forests included) in that they need an input of fresh water and nutrients to thrive. The levees along the Mississippi prevent this. (See also the Dead Zone in the Gulf)
• The bureaucracy, both state and federal have, since the 1970 have increased the costs to private landowners of doing anything to maintain their properties. Regulatory hurdles and Permitting costs often exceed the costs of the projects. And high cost projects are favored over low solutions as the bureaucrats seek security over solutions at every turn.
• The crisscrossing canals dredged for oil explorations in an abundant freshwater environment could be used as a conduit to channel freshwater to places of need. In a brackish or salt water system they channel vegetation killing salt water into now fragile marshes.
• Modern sport fishing boats have more power and less draft that ever before allowing the public to cause untold damage to formerly inaccessible areas. Prop washing by these vessels cuts root systems, destroys submerged aquatic vegetation and deepens channels increasing the salt water invasion.
Until Louisiana replenishes its marshes with sediment and fresh water the losses will continue

Gums

I feel that ATheoK and CVP have really nailed the situation.
I also feel that Stephen Skinner and MattS should apply the same logic of abandonment to Miami Beach, the New Jersey /New York shoreline and rivers, Charleston, Savannah, Galveston and especially Los Angeles, San Francisco, Portland and Seattle. Seems to me that years ago folks moved when things got tough, like the Okies did during the Dust Bowl, and others did years before. Mitigate or migrate or endure.
With that outta the way ( /rant), you will find those “dumb, backward” Coonass folks ( well understood term of endrearment down there, just ask) understand the problem, and they have moved and adapted and mitigated for years when they can’t fight Mother Nature or urban development or the Corps of Engineers anymore. They are not like the clueless folks in New York that experienced the “superstorm Sandy” when the water went up a few feet and the wind may not have reached 90 mph. Tidal surge? BEAM ME UP!!
THIS IS WHAT SURGE LOOKS LIKE!comment image
Thousands of folks along the Gulf Coast from Galveston to Mobile took their lumps and moved or came back. Crazy? Prolly, but as long as the NWS provides great warnings and they have been there “before”, no big deal.
+++++++++++++++++
The channeling of Big Muddy has made delta restoration almost inpossible without some sacrifice by some folks south of New Orleans. There are a few diversion structures, but there are ecological and other considerations that many do not wish to endure – the commercial oyster and shellfish and sport fishing industries have adapted over the last 50 or 60 years to less brackish water than what existed when I was ten years old.
Storms do a bit of damage, but most of the wetland loss and subsidence has been to channeling the MIss and the many canals dug and exploited since the 1940’s. I can’t name any geologists that can make a case for subsidence due to taking out all the oil and gas from uner New Orleans or LaFitte.. And if so, then compare with the basic understanding and observations of delta formation and maintenance without flooding.
Coastal and wetland restoration in South Louisiana is not a straightforward endeavor. And the economic effects of abandoning the Mississippi from the Gulf to Nathez or Vicksburg would be immense to the nation and not the fishermen and folks growing sugarcane. I hope all that think those ports and refineries and such should be abandoned have many solar panels and windmills and furniture made outta wood.
Gums rants…

PRDJ

That is Holly/Dung Beach in La. correct?

Great comments CVP and Gums!
I forgot about the powerboat wave impacts. Though, I can clearly remember getting chided in Delacroix for going just a shade fast.
Kip:
The canals were cut for exploration and maintenance. Boats used by the riggers, supply and maintenance crews are not shallow draft for inshore vessels.
So, those canals are shallow when compared to the local Mississippi’s 200 ft depths and some of the deeper bayous.

Stephen Skinner

Not lecturing but just stating. A river delta is created by a river depositing silt at the outlet into the sea. Deltas that are losing land (Mississippi, Nile Ganges-Brahmaputra) do so because the supply of silt has been disrupted or severely reduced. Sea level rise is incidental and ‘fixing’ that, even if we could, will not stop the current loss of land in all three deltas because if any delta is allowed to follow it’s nature the land would adjust upwards with new deposition if the sea level rises. Equally, if sea level dropped to what it was during that last or previous glacial maximums then surely a delta river would cut downwards through the silt as you can’t have a waterfall over silt?

MattS

“Is there a solution?”
Free the river. Let it loose from it’s man made chains and let it go back to replenishing the soils of the delta lands.

Eventually, in spite of man, the river will break free and carve a new path to the Gulf of Mexico.
What Kip asks is true, multiply.
Well, except for the oil fields and fisheries. Fisheries recover, oil fields don’t move.
That is, the Mississippi River changed course regularly. The Mississippi River will change course every time conditions allow. Each time leaving towns high and dry while flooding towns and localities in the path.
Perhaps worse, is finding oneself on the wrong side of a new river course.

John F. Hultquist

I suppose the term “delta” (shape of the Nile one, I think) is meant to refer to land that can be seen above the water.
One of the USA’s big rivers, the Columbia, has amassed tremendous deposits of sediments — out from and well under the surface of the Pacific Ocean.
Next, search for ” North Cove, WA ” using Google Earth . This will take you to Washaway Beach, not named on the image, but you can search the internet for it. None know why North Cove is washing away.
Houses are cheap there.
Dynamic Earth. Fascinating.
Thanks again, Kip and all. Nice info here.

Paul

Here is a quote from the book “Louisiana a guide to the state. “ Compiled by the workers of the writers program of the work projects administration in the state of Louisiana.
This book was published in 1941. This is before global warming, before any offshore drilling, or drilling at all in the marsh with canals.
“In Louisiana, except for the alluvial deposits at the mouth of the Mississippi, The shore line is receding at the rate of 6 to 125 feet a year, irrespective of hurricanes, which can cause a retreat of several hundred feet in a few hours. Two factors cause this recession 😦 1) The regional tilting bought on by the weight of the growing Mississippi Delta, which causes the lands about it to dip more sharply and become submerged; (2) the ease with which the low-lying shore line is erodedi, as is shown by the greater depth of the recession on those portions of the shoreline which are more exposed to the prevailing winds and waves. Indeed, so noticeable and rapid has been the subsidence of the mainland, that many of the old plantations have become a region fit only for trapping,hunting and fishing. “
This is from page 19
Amazing what we have forgot

Brad

Building and rebuilding a city on land that is sinking into a swamp is daft. Sounds just like a Monty Python comedy routine they did about 40 years ago. This is geology, nothing to do with man-made global warming.

Gums

I see:
“Building and rebuilding a city on land that is sinking into a swamp is daft. ”
PLZ explain that to the Dutch. And maybe lecture the New Jersey folks and Long Island folks and others in the northeast about building right on the water and then getting subsidized flood insurance to rebuild.
You are correct, Brad, about global warming and climate change not making things tough in south Louisiana, They do not apply and won’t.
OTOH we humans have done much in the last 100 years ago that nature might have taken hundreds of years or just one big flood to do. We also exacerbated things by building thousands of miles of canals and such to make things profitable for the petro industry and basic shipping. If the Miss stopped flowing today we could use the riverbed and get ships up to the Old River project and thence upriver to the rest of the United States. The Atchafalaya River could use some help for infrastructure, but it would offer good access to the Gulf and vice versa.
And while we wonder about New Orleans, what about the folks building on landfill in San Francisco and waiting for the “big one”. New Orleans will do just fine as those folks have more control about the effects of nature than the California folks living on active geologic faults.
Rant off…….
Gums sends…

Michael J. Fitzgerald

“In the space of one hundred and seventy-six years the Lower Mississippi has shortened itself two hundred and forty-two miles. That is an average of a trifle over one mile and a third per year. Therefore, any calm person, who is not blind or idiotic, can see that in the Old Oolitic Silurian Period, just a million years ago next November, the Lower Mississippi River was upwards of one million three hundred thousand miles long, and stuck out over the Gulf of Mexico like a fishing-rod. And by the same token any person can see that seven hundred and forty-two years from now the Lower Mississippi will be only a mile and three-quarters long, and Cairo and New Orleans will have joined their streets together, and be plodding comfortably along under a single mayor and a mutual board of aldermen. There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of fact.”
— Mark Twain, Life on the Mississippi (1883)