I worked on the surveys and cors equipment that directly measures subsidence in Louisiana, and have worked on many of the levees and other coastal civil works.
Relocation? For a problem that hasn't happened yet and isn't likely to happen in the foreseeable future is absurd.
New York City is at a much greater risk and will be inundated long before New Orleans.
The fastest rate of subsidence in New Orleans is/was due to organics in the soil decomposing once the groundwater table was lowered (drainage projects going back 300 yrs), allowing oxygen to infiltrate. This decomposition is mostly complete in most areas of the city.
Piles under everything from skyscrapers to personal homes penetrates the organic layers, so buildings don't subside even if the ground does.
The biggest risk to the city and state is environmental activists, the EPA & the Army Corps of Engineers, and the largely untouchable Mississippi River levee system, preventing the delta land building process that counteracts subsidence by depositing new sediment in yearly floods.
Additionally, erosion/ runoff prevention and dams through out the Mississippi, Missouri, and Ohio river watersheds have decreased the amount of sediment flowing down river, and results in less sediment available for natural land building.
The coastal barrier marshes and islands are dying because we've stopped the natural processes that sustain them. Each mile of marsh results in the natural lowering of storm surge by 1/2' to 2'.
The federal government, environmental groups and others fight the restoration of these natural processes. For example, they argue fresh water introduction will hurt dolphin populations in coastal bays, but they are only capable of being there in the first place because of man made interference: the bays were freshwater until the levees cut off their natural supply of freshwater.
As for global warming? Infrastructure, business and homes are amortized at 30yrs or less. Maybe up to 50yrs for very large civil projects.
Worst case sea level rise estimates easily gives New Orleans 300+ more yrs, likely much longer, a time frame longer than the current age of the city.
No one is going to make large capital investments in a city that gets blown away all the time. Every time New Orleans takes a big hit like this people leave, and less money is put back into the city.
The population of New Orleans was higher in 1980 than it is now. I am from New Orleans, and since Katrina the infrastructure has been getting worse, not better.
There probably isn't going to be some big dramatic event that kills New Orleans. It will just keep shrinking and pulling in towards the French Quarter as it gets hit repeatedly by extreme weather events. It will just become smaller and more impoverished over time until it is maybe abandoned at some distant point in the future.
It will be a death by inches.
But we don't discourage economic development in those places. My amortization comment was perhaps not explicit enough, but as long as people think the city will last beyond amortization periods, future abandonment/inundation/end-of-days predictions are not a rational reason to preclude investment.
Most businesses shoot for a payback period of 10 years or less.
I expect you're right about slow death, but it won't be for climatic or geologic or hydraulic reasons.
Fear of those reasons might contribute, but then we've gone full circle back to "alarmist BS".
People just aren't going to come in and build nice shopping centers in New Orleans. It isn't happening and hasn't happened. Why would it when they could build in another city where it won't get destroyed and it will be more profitable?
It is extremely stressful every year watching hurricanes and wondering if your house is going to be destroyed. Then when your house is destroyed it is no fun at all to be involved in gutting it and rebuilding it. On top of that no one is making investments in the city so it hardly has any good jobs.
It isn't alarmist to recognize what is already happening. The climate is creating more extreme weather events that are undermining New Orleans. It doesn't need to be some fake "The Day After Tomorrow" style disaster that people can easily recognize. It is an insidious, slow, hollowing out of the city.
How many water boil warnings have their been since Katrina? How often has electricity been inconsistent in the city? I can tell you it happens a lot more now than it did before Katrina, and it is going to be even worse after Ida.
It's not fear of flooding that prevents anyone from investing in, eg New Orleans East. It's two decades of zero policing.
And there's a reason Entergy continues to operate as a completely separate corporate entity in the city, and it's not because "used to be nopsi".
The water guys can't even operate a billing system, let alone engineer the distribution network. They ran through probably a dozen companies post- Katrina just to do an assessment and map and maintenance plans, and they all quit for having to deal with the city.
That's why they can't keep the water on. But an unnecessary new airport? They had no problem throwing a billion dollars at contractors for that.
If people were afraid of sea level rising, they wouldn't just be moving into another swamp/marsh outside of city limits or across the lake. People don't want to live at sea level without a levee on the North Shore, they just don't want to live in New Orleans, despite the +20ft msl and up levees.
Because the City Council-as-regulator can be astroturfed and snowed easily by false promises about "black-start" capability for power plants and work on distribution systems?
The fact that Entergy has to do so much to convince the city to allow a power plant to be built, should be all the proof you need, as far as why no one wants to invest in the city.
And that black start capability proved it's worth this week.
If they would have done a black start, rejoining the grid would have apparently been more complicated.
But the bigger point is: why does the city fight local investment and improvement of infrastructure? As if the city is doing everyone a favor that wants to build something.
That's what's killing the city, not fear of flooding.
[1] https://energytransition.umn.edu/modernizing-minnesotas-grid...
The amount of real estate investment in New Orleans is incredibly low compared to other cities. They build more buildings in Atlanta in one year than they have in the last 30 years in New Orleans.
I don't think anyone knows just yet. It took 4 days just to do the preliminary power outage assessment.
But "high 5 figures" would be >50k. According to this: https://www.usatoday.com/story/news/nation/2021/09/05/hurric... they are looking at 22k power poles.
Were homes twice as likely to be destroyed than power poles were to be damaged?
https://www.entergy.com/hurricaneida/damage/
And Entergy only covers a portion of the area, but includes all of New Orleans and most of Baton Rouge.
There are a lot more trees than power poles to fall. Lots of trees fell through houses, which allowed additional water and damage, and they won't know anything until insurance and possibly an engineer or contractor look at it.
FEMA just started blue roof on Tuesday I think.
But definitely over 50k damaged, if not destroyed. Just depends on where you draw the line.
I don't think OP is wrong in that a Harvey situation would be disastrous. A decent percentage of the pumps in the city are broken for most of the year, and without those pumps, a storm like Harvey would likely result in levels of flooding similar to the levees breaking.
Additionally, marsh biological productivity has been directly tied to shoreline length. So a marsh with proper salinity levels and more shoreline will actually create more food, for more wildlife.
I do believe that they ought to be held to the terms of their permits, which is typically to backfill anything not actively maintained or abandoned. And to prevent erosion beyond the limits of the permits. But it doesn't seem that's part of the negotiation.
>fresh water induction would indeed kill a large percentage of anything living in that induction area,
False- the locations already getting freshwater (not sediment) diversions and the natural breaks in the levees are the only healthy parts of the marsh right now. Go look at them on Google Earth. Mardi gras pass and the other natural breaks are the only places naturally building land outside of the Atchafalaya Delta.
For the new sediment diversions: It's not going to kill anything-it's just going to push the brackish water out and the salt water further, for a limited number of weeks per year. The wildlife will move with it, as it always has.
The commercial guys don't want to burn more gas to get to saltwater, and the oyster guys (the real money and lobby power) don't want conditions to change at their existing water bottom leases.
>and those living things are part of the ecosystem that keeps the marshlands alive.
No freshwater mixing with saltwater is the basis for the entire estuary systems. Without that, the photosynthesis doesn't happen in the freshwater flora, and the food chain starts there for the rest of the living things.
>A decent percentage of the pumps in the city are broken for most of the year,
Political problem with the city, not an environmental or engineering problem.
I especially agree that some dams on the Mississippi need to destroyed and have agriculture be moved away from the river, as the dead zone in Gulf of Mexico is caused by upstream agriculture states.
I was just wondering if you could provide a citation for this:
>>>Worst case sea level rise estimates easily gives New Orleans 300+ more yrs
I hope so. I fear not.
Talking to my friends in the city it feels like if ida had spooled up 1 day further out, it would have wiped the place off the map. I know it isn’t true, but man, the wetlands are so mostly water below town, the storm didn’t loose strength, the next time… etc. I hope ida was the second-order wake up call the city needed to survive a future cat 5 with 30+ foot storm surge.
I'm trying to find the levee recommendations, but Biden's takeover seems to have broken all my bookmarks in the ACOE website.
Basically it's just the ipcc/ epa most-likely-worse case scenario with some local adjustments, combined with CPRA's master plan for surge reduction and (non-nola) coastal protection and barrier island rebuilding, combined with the Corps' recommended levee improvements.
You end up with lessened storm surges and raised levees that can match sea-level rise to whatever hight is feasible for the look levees, and back-out the years from the projected rate of sea level rise.
And if they do the wall across the Orleans land bridge (preventing storm surge at the Rigolets and chef's pass), it's actually a much higher number. But that plan is on the back burner for now.
I don’t understand this comment. I assume you’re not talking about financial amortization. Do you mean the climate impact of new construction (such as 1 ton CO2 per 1 ton concrete) has some kind of sunset period?
That must have an impact on saltwater intrusion and help facilitate coastal wetland loss.
Your argument depends on this but you give neither numbers nor citations, so it's unsubstantiated and we have no idea how true it is. Numbers I've seen, that are bad, but not worst case are 6' by the end of the century and 20'-60' over longer timescales. I seriously doubt New Orleans will be just fine through that. Many coastal cities will have to move. It's not practical to wall in all of the coast to that extent. Many cities would end up being islands.
Unsubstantiated on this thread. I mean, you can look it up and find out if it's true yourself. It's also weird that you follow it up with numbers of your own, but also no references, so you must think that's alright to do.
Without that I'd have to search projected sea level rise, then read all about the elevation, vulnerability to storm surge, levees, flood risks, etc for New Orleans. It would take hours to know if the OP has a valid point or not. You might have to do that anyway, but at least if his numbers are bad you can shortcut the process and ignore him.
Inside levee protections, as the system currently exists, it doesn't, so houses have to have sand pumped under them occasionally to fill gaps left by subsidence.
The house is on piles, so it remains in place.
The sinking building in SF would like to differ with this. If a building is not built correctly, all bets are off.
The problem strata in New Orleans is the top 10-20' of soil. Mostly whatever's above the pumped-down, controlled, water table.
Piles only need to go that deep to suffice, or more typically until they hit the first layer of sand, which is stable. Literally every slab house built in New Orleans is built in these, because before this, everything was on blocks so it could constantly be raised and leveled.
I wouldn't say better, because there are/were multiple skyscrapers with chunks of facade falling off them. At least a couple are abandoned because they were built so bad.
But they're not sinking.
I think this is the first time I have ever seen someone claim that a layer of sand is stable. But hey, NOLA is one of the craziest places, so sure, sand is stable there.
Sand underground with overburden pressure is quite stable, to the point that piles driven to it are treated as bearing piles (supported primarily on the end/tip), not friction piles (supported on sides by friction).
It's non-cohesive, so doesn't shrink or swell, and once it's compacted/consolidated, it's fixed volume and quite stable.
The biggest risk is the fact that according to our best estimates by 2050 sea level rise will be another 1.5 feet in that area. (https://sealevel.nasa.gov/ipcc-ar6-sea-level-projection-tool) For an area that is already on average 7 feet below sea level. New Orleans topography is basically a bowl between Lake Pontchartrain and the Gulf of Mexico. Couple that with stronger and more frequent hurricanes and there will be few places left to live in New Orleans and the surrounding area.
People who give other people a false sense of hope is what endangers lives and sets up future generations for devastation. If you really want to help people you need to break the cycle and subsidize relocation costs for those who currently live there that can't afford to move. All these mitigation efforts like restoring the natural coastal barriers may delay some flooding (so sure do it), but it will not prevent the inevitable and it is coming much sooner than 300+ years.
There are areas as low as -22' msl. Maybe -25'.
But that's irrelevant, because the edge of the bowl and protection is at a minimum elevation ~+20' msl and up, depending on adjustments for things like modeled wave height.
Whereas New York's highest protection is currently something like +8', and isn't a closed loop.
And what's the elevation of the deepest basement/ subway/ tunnel in NYC? Because I bet it's a lot lower than -22' or -25' msl.
It won't, precisely because New Orleans already has many places below sea level. It's got a head start.
It's spent billions of dollars over 100+ years making the outer boundaries water tight, and building the infrastructure to support all of that, including the ability to pump 100% of rainfall out.
To New Orleans, the cost of any sea level rise has essentially already approached the marginal rate.
No where else in the world, with the exception of probably the Netherlands, is better prepared for rising waters, whether it's storm surge or sea level rise.
Everywhere else has to pretty much start from scratch.
The post-Katrina improvements have combined the patchwork systems into one.
The improvements should have been made long before Katrina, but the corps of engineers stalled most attempts, and Congress refused to let the corps do anything without direct Congressional funding, which never came. Until Katrina.
People aren't currently avoiding New York because of sea level rise. And are spending far greater amounts on business investments there.
New Orleans already has.
And the buildings are on piles already. Relatively simple to raise, if needed, compared to what other coastal cities will have to do.
With extra stress on the word relatively.
A very, very long time from now. According to the IPCC Sixth Assessment Report sea levels are projected to rise between .57 and 1.25 meters by 2120. So unless you have waves currently lapping against your back porch you, your kids, your grandkids and your great-grandkids will be OK in NO.
For context, sea levels have risen about .3 meters over the last hundred years and we have adapted without city evacuation and relocation.
https://sealevel.nasa.gov/ipcc-ar6-sea-level-projection-tool
So maybe you and your kids MIGHT be okay, but your grandkids and your great-grandkids? probably not.
No. Not sure where 1.41m is coming from. Take a closer look at the linked NASA site. You will need to click on the link labled "View global projection" (sorry, there isn't a direct link). You will see a graph labeled "Projected Sea-Level Rise Under Different SSP Scenarios". The midpoint highest rise of all seven of the scenarios for 2100 is just .88 meters and that's for the most pessimistic SSP5-8.5 Low Confidence scenario. The more likely scenarios are about 1-2 feet.
Your great-grandkids will be fine.
It looks like all model scenarios agree fairly well out to 2100 both in the global projections and in projections for Grand Isle. Thus, I’d wager good money that New Orleans will see 1-2m sea level rise by 2100 regardless of any climate mitigations we perform.
https://www.atlasobscura.com/articles/new-orleans-wood-screw...
You say that nobody want to hear your hot take on abandoning New Orleans, a city with one of the most important ports in the country, yet I hear this proposed constantly (and upvoted) by people that have almost no specialized knowledge of infrastructure. It is armchair nihilism and imo not helpful at all. The army corps of engineers thinks differently. Agencies like the CPRA are working to restore land on the coast. There are ways to mitigate the damage, to reduce the risk and protect the city. Yes it is expensive. No it is not cheaper than losing our ports, our people, our culture.
https://gnoinc.org/news/ports-of-south-louisiana-new-orleans...
Soon enough, if we don't invest in NOLA, you will likely be right, but I doubt it will be because there was no other option. It will be because we as a country made a huge mistake and failed to act.
The truth is, a lot of America does not care about people or cities in the south. New Orleans gets a bit more attention because tourists had a good time on Bourbon once, but overall it is treated as an oddity and not an essential piece of the both the economic and cultural fabric of America. There are people down here that feel the same way about California with its earthquakes and wild fires and I make similar arguments when arguing with them. Speaking of which, NYC fared far worse against the remnants of a storm we took head on. Should we abandon it or improve it? Hell no we should not give up on NYC, nor SF with it's earthquakes, or LA with it's water shortages, or Baltimore with its crime, or Detroit with its collapse of industry and definitely not New Orleans.
To clarify, those are metal pumps invented by a man named Albert Baldwin Wood, not pumps literally made out of wood.
The army corps of engineers is not given the option of not trying to save New Orleans. People in government tell them to go build levees and protect the city from flooding and they do the best job that they can, but they are fighting a losing war. The time to introduce relocation assistance programs is now, so you spread the cost and process out over many years; otherwise, you are going to just end up doing the same thing later, but it will cost more money and more lives will have been lost.
There's many billions of dollars of port and plant infrastructure there.
Its way cheaper and easier just to rebuild the city every few years and pay to buffer it against disaster than to relocate all of that.
Just like it's easier to keep a legacy code base that's working and making money than fully rebuild it.
Nola's not going anywhere anytime soon.
They just don't have the Alcoholism.
Also, if the Old River control system ever fails Morgan City will be the next New Orleans.
"America has only three cities: New York, San Francisco, and New Orleans. Everywhere else is Cleveland" - Tennessee Williams
Am currently evacuated from Ida, and drove all the way to Kentucky from Nola and from what I'm seeing so far, can confirm that quote is depressingly accurate.
Why does the rest of the country look like one giant strip mall from coast to coast? What happened to America?
Glad we're safe, the levies held, and the city appears to be coming back faster than expected.
Have a fried Orphan and catfish basket.
Nobody wants to lose New Orleans. It's a great city. But the problem is accurately summed up by the OP: "How much can places where millions of people live be fortified? At what cost? And who pays for it?"
The only good news is that the Port of South Louisiana is the biggest and arguably most important port in the Western Hemisphere (and that's without even taking into account the Port of New Orleans or the Port of Baton Rouge, both in the top 10). There is enormous nationwide economic and geopolitical incentive to protect the city. The bad news is that New Orleans would be sinking even without rising sea levels.
[1] https://www.logisticsmgmt.com/article/top_30_u.s._ports_big_...
Total Tonnage US:2 South Louisiana, LA, Port of 238.0
3 New York, NY and NJ 136.6
4 Corpus Christi, TX 111.2
5 Beaumont, TX 101.1
6 New Orleans, LA 92.
7 Long Beach, CA 80.7
8 Baton Rouge, LA 73.4
9 Los Angeles, CA 63.0
10 Virginia, VA, Port of 61.7
11 Lake Charles, LA 58.0
13 Mobile, AL 56.9
14 Plaquemines, LA, Port of 52.8
15 Baltimore, MD 44.2
16 Savannah, GA 41.9
17 Texas City, TX 41.3
18 Huntington - Tristate 36.8
https://www.bts.gov/content/tonnage-top-50-us-water-ports-ra...
Biggest airport in The Netherlands is 3 meters below the sea level, but at least we don't have hurricanes here, just North Sea
I already foresee a bunch of folks getting tons of money for Hurricane Ida claims only to rebuild houses in the same exact spot. We should encourage them to take the money and move away, not stick around.
The only big river delta in the US is the Mississippi. East Asia has far worse problems. Most of China's port cities are on river deltas. Tapei is on a river delta. Ho Chi Min City is on a river delta. Singapore is on a river delta. These are all areas where the land to water slope is very low.
The western US is mountainous enough that there's more than enough land rise to prevent flooding more than a short distance inland. Even in places that look flat, like LA near Venice, go three blocks inland and you're tens of feet higher. Places that built on fill, such as San Francisco and Foster City, do exist, but are small enough for barriers and not fed by upstream rivers.
Other wealthier places may be able to use municipal bonds to fight sea level rise. In the valley in Foster City, the choice was between pricey flood insurance and a cheaper municipal bond to construct a robust levee and the latter was chosen. The city is small enough and the residents were wealthy enough to do it.
I'm kind of curious if anyone will attempt to damn up or construct locks under the golden gate bridge. I think the valley could be wealthy enough to do it.
Plus those grants are kinda complex to navigate, and you can't do it as an individual. It has to be part of a local communities overall flood mitigation / risk-reduction plan.
Assuming flood insurance prices are realistic (not propped up by government), eventually no new construction will happen because no one will approve/afford insurance.
Existing places will get cheaper / hell hole as rates keep going up.
Federal flood insurance has distorted market prices drastically in many places
Of course they will. Over-topping of a levee is a MUCH LESS SEVERE outcome than a levee breach.