16 ms·

New Orleans levees passed their first major test

103 points by yread 5y ago

yread 5y ago
> Army Corps of Engineers, which rebuilt the system It's funny they don't mention the companies like Arcadis that actually designed the barrier, because they have the know-how from managing the Dutch flood barriers https://www.h2owaternetwerk.nl/h2o-actueel/beschermingssysteem-new-orleans-heeft-met-gemak-orkaan-ida-doorstaan https://www.h2owaternetwerk.nl/h2o-actueel/beschermingssyste...
- beerandt 5y ago
  With the political nature and extreme size of the project, there weren't many engineering companies with a presence in SE LA that didn't get a sizable contract out of it.
- xxpor 5y ago
  Wow, someone in a US government (at any level) actually consulted a foreign expert for something? And a non-Anglo country at that? Can whoever was responsible please take over transit funding at DOT? We need so much more of this.
  - koheripbal 5y ago
    US gov't contracts frequently go to non-US companies - and non-US gov'ts contract US companies all the time. The global economy is, wait for it, global.
    - tnel77 5y ago
      It’s more fun to complain about the USA and the military than to realize this fact.
  - bargle0 5y ago
    You’d be surprised how many weapon systems used by the US military were not developed domestically.
    - brian_herman 5y ago
      Yeah the M9 was made by the Italian company Beretta. It was the main handgun of our armed forces.
sixothree 5y ago
There is plenty of good news from Louisiana. But mostly because of the levees holding, the loss of life was low.
- dredmorbius 5y ago
  Evacuations from outlying areas also helped tremendously. Those were hammered.
selimthegrim 5y ago
I’m not sure they were really tested what with the track to the west.
- dredmorbius 5y ago
  In the northern hemisphere, the worst quarter of a cyclonic storm is to the NW. That's where winds blow in toward, driving storm surge, and it's where the warm tropical moisture tends to meet cooler northern continental airmasses, triggering rain (cold air can hold less total moisture than warm). Storms tracking east of New Orleans produce less overall damage as the primary storm surge is directed further east, and the city itself is subjected to the less-damaging, and already somewhat moisture-depleted NE and NW winds as the storm passes. Ida tracked just west of downtown New Orleans. The eyewall didn't interact with downtown proper, though it did cross the Mississippi a few miles NW of New Orleans. Storm surge was significant, though because Ida was a smaller (though intense) storm, total surge was less than for Katrina, 16 years earlier (14 ft vs. ~20). Katrina's peak surge was far closer to Lake Ponchartrain, whilst Ida's was further to the SW, being highest near Grand Isle. https://www.weather.gov/mob/katrina https://www.weather.gov/mob/katrina https://www.weather.gov/mob/ida https://www.weather.gov/mob/ida
  - 8note 5y ago
    North West? Like Portland and Seattle?
    - dredmorbius 5y ago
      No. I'm not referring to portions of the US, but to segments of any given storm. Given counterclockwise rotation in of these storms in the northern hemisphere, and a westward track of tropical storms (see for example the 2020 North Atlantic Hurricane storm tracks: https://en.wikipedia.org/wiki/2020_Atlantic_hurricane_season#/media/File%3A2020_Atlantic_hurricane_season_summary_map.png https://en.wikipedia.org/wiki/2020_Atlantic_hurricane_season...): - Hurricanes will make landfall from the east or south. - Winds will tend to approach landfall from the east or south. - Most intense rain activity tends to be to the NE of the storm. (I'd miswritten this as NW above. I've corrected that in a follow-up self-reply.) Because of the westward storm track, hurricane landfalls on the West coast are exceedingly rare. They occasionally happen on the Pacific coast of Mexico or Baja California (about 19 or 20 storms between 1950 and 2000). By the time storms reach the latitude of Los Angeles they're subtropical. https://en.wikipedia.org/wiki/List_of_Baja_California_Peninsula_hurricanes https://en.wikipedia.org/wiki/List_of_Baja_California_Penins... Most Eastern-Pacific hurricanes (that is, off the west coast of Mexico or the US) drift westward into the Pacific. Some strike Hawaii.
ahnick 5y ago
As the article rightly points out, levees will do nothing for a slow moving hurricane like Harvey that dumps tons of rain or for a large cat5 hurricane with storm level surges that are much higher than Ida. The place is sinking while sea level rise is already locked in with current levels of CO2 in the atmosphere. The only solution is relocation, but nobody wants to hear that. It is an inevitability that New Orleans will be uninhabitable. The only question is when.
- candiddevmike 5y ago
  This is my fear as well. All of these coastal cities are at risk for relocation, who's footing the bill for the government to buy the houses, relocate the people, provide them new houses, jobs, etc? There is a ton of self interest in keeping people in places like New Orleans (and even growing the population), but we need to accept the reality that these places will be uninhabitable in the near future. 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.
  - bostonsre 5y ago
    I can't imagine flood insurance is very cheap in these locations and I don't think this is an imminent domain type situation where the government would buy houses. At some point, people will be ruined financially and won't be able to rebuild. 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.
    - beerandt 5y ago
      The federal government actually does have block grant programs to buy out homeowners, or will pay to raise their house, if the cost is cheaper than building a levee or similar flood protection.
Exmoor 5y ago
Somewhat incredibly, Ida killed far more people as a weakened tropical storm in the northeast after crossing the entire US than it did as a Cat4/5 hurricane on the gulf coast. From Wikipedia: > As of September 4, a total of 70 deaths have been confirmed in relation to Ida: 27 in New Jersey, 18 in New York, 13 in Louisiana, 5 in Pennsylvania, 2 in Mississippi, 2 in Alabama, 1 in Maryland, 1 in Virginia, and 1 in Connecticut.
- dnautics 5y ago
  People forget that "superstorm sandy" wasn't even a hurricane, iirc it was a "tropical depression" by the time it got to nyc
  - beerandt 5y ago
    If you don't go through it, it must not be that bad. If you do go through it, it was worse than the category/ windspeed/ storm surge numbers convey. "You just had to be there! It was way worse than just a tropical depression!" It was the media experiencing this phenomenon that gave birth to the hyperbolic term "Superstorm Sandy". Anyone who's actually been through a hurricane saw through it right away.
  - jazzyjackson 5y ago
    IIRC what made it a superstorm was that several weather patterns combined and amplified each other. Same thing happened with Ida: there were storms already moving upwards into NYC and Ida just came through and gave it a push.
- datameta 5y ago
  I'm in NYC. Besides walking my dog briefly in the heavy rain twice I wasn't even aware of Ida until the clear morning after someone showed me flooded subway photos looking like from the end of MGS2. I'm not sure it was communicated properly save for the flash flooding broadcast that could have also come from just a lesser heavy thunderstorm.
  - dylan604 5y ago
selimthegrim 5y ago
In other interviews the engineers claim the levees were built to a 200-year level, and that a 100-year level would not have been sufficient for Ida.
- Filligree 5y ago
  If we get 100-year storms every five years, then is that really the correct description?
  - throwawaysea 5y ago
    From the USGS page on 100 year floods (https://www.usgs.gov/special-topic/water-science-school/science/100-year-flood https://www.usgs.gov/special-topic/water-science-school/scie...): > The term "100-year flood" is used in an attempt to simplify the definition of a flood that statistically has a 1-percent chance of occurring in any given year. Likewise, the term "100-year storm" is used to define a rainfall event that statistically has this same 1-percent chance of occurring. In other words, over the course of 1 million years, these events would be expected to occur 10,000 times. But, just because it rained 10 inches in one day last year doesn't mean it can't rain 10 inches in one day again this year. And it looks like these terms are based on past data not future projections: > Since the 100-year flood level is statistically computed using past, existing data, as more data comes in, the level of the 100-year flood will change (especially if a huge flood hits in the current year). As more data are collected, or when a river basin is altered in a way that affects the flow of water in the river, scientists re-evaluate the frequency of flooding.
- MisterBastahrd 5y ago
  The entire rest of the west bank parishes is still protected by the "old" definition of a 100 year storm, and they had multiple breeches this year.
ErikAugust 5y ago
http://trimread.org/articles/1154 http://trimread.org/articles/1154
bjourne 5y ago
So the taxpayer money wasn't squandered but actually put to good use. Who would have thought?

103 points by yread 5y ago

> Army Corps of Engineers, which rebuilt the system It's funny they don't mention the companies like Arcadis that actually designed the barrier, because they have the know-how from managing the Dutch flood barriers https://www.h2owaternetwerk.nl/h2o-actueel/beschermingssysteem-new-orleans-heeft-met-gemak-orkaan-ida-doorstaan https://www.h2owaternetwerk.nl/h2o-actueel/beschermingssyste...

beerandt 5y ago
With the political nature and extreme size of the project, there weren't many engineering companies with a presence in SE LA that didn't get a sizable contract out of it.
xxpor 5y ago
Wow, someone in a US government (at any level) actually consulted a foreign expert for something? And a non-Anglo country at that? Can whoever was responsible please take over transit funding at DOT? We need so much more of this.
- koheripbal 5y ago
  US gov't contracts frequently go to non-US companies - and non-US gov'ts contract US companies all the time. The global economy is, wait for it, global.
  - tnel77 5y ago
    It’s more fun to complain about the USA and the military than to realize this fact.
- bargle0 5y ago
  You’d be surprised how many weapon systems used by the US military were not developed domestically.
  - brian_herman 5y ago
    Yeah the M9 was made by the Italian company Beretta. It was the main handgun of our armed forces.

sixothree 5y ago

There is plenty of good news from Louisiana. But mostly because of the levees holding, the loss of life was low.

dredmorbius 5y ago
Evacuations from outlying areas also helped tremendously. Those were hammered.

selimthegrim 5y ago

I’m not sure they were really tested what with the track to the west.

dredmorbius 5y ago
In the northern hemisphere, the worst quarter of a cyclonic storm is to the NW. That's where winds blow in toward, driving storm surge, and it's where the warm tropical moisture tends to meet cooler northern continental airmasses, triggering rain (cold air can hold less total moisture than warm). Storms tracking east of New Orleans produce less overall damage as the primary storm surge is directed further east, and the city itself is subjected to the less-damaging, and already somewhat moisture-depleted NE and NW winds as the storm passes. Ida tracked just west of downtown New Orleans. The eyewall didn't interact with downtown proper, though it did cross the Mississippi a few miles NW of New Orleans. Storm surge was significant, though because Ida was a smaller (though intense) storm, total surge was less than for Katrina, 16 years earlier (14 ft vs. ~20). Katrina's peak surge was far closer to Lake Ponchartrain, whilst Ida's was further to the SW, being highest near Grand Isle. https://www.weather.gov/mob/katrina https://www.weather.gov/mob/katrina https://www.weather.gov/mob/ida https://www.weather.gov/mob/ida
- 8note 5y ago
  North West? Like Portland and Seattle?
  - dredmorbius 5y ago
    No. I'm not referring to portions of the US, but to segments of any given storm. Given counterclockwise rotation in of these storms in the northern hemisphere, and a westward track of tropical storms (see for example the 2020 North Atlantic Hurricane storm tracks: https://en.wikipedia.org/wiki/2020_Atlantic_hurricane_season#/media/File%3A2020_Atlantic_hurricane_season_summary_map.png https://en.wikipedia.org/wiki/2020_Atlantic_hurricane_season...): - Hurricanes will make landfall from the east or south. - Winds will tend to approach landfall from the east or south. - Most intense rain activity tends to be to the NE of the storm. (I'd miswritten this as NW above. I've corrected that in a follow-up self-reply.) Because of the westward storm track, hurricane landfalls on the West coast are exceedingly rare. They occasionally happen on the Pacific coast of Mexico or Baja California (about 19 or 20 storms between 1950 and 2000). By the time storms reach the latitude of Los Angeles they're subtropical. https://en.wikipedia.org/wiki/List_of_Baja_California_Peninsula_hurricanes https://en.wikipedia.org/wiki/List_of_Baja_California_Penins... Most Eastern-Pacific hurricanes (that is, off the west coast of Mexico or the US) drift westward into the Pacific. Some strike Hawaii.

ahnick 5y ago

As the article rightly points out, levees will do nothing for a slow moving hurricane like Harvey that dumps tons of rain or for a large cat5 hurricane with storm level surges that are much higher than Ida. The place is sinking while sea level rise is already locked in with current levels of CO2 in the atmosphere. The only solution is relocation, but nobody wants to hear that. It is an inevitability that New Orleans will be uninhabitable. The only question is when.

candiddevmike 5y ago
This is my fear as well. All of these coastal cities are at risk for relocation, who's footing the bill for the government to buy the houses, relocate the people, provide them new houses, jobs, etc? There is a ton of self interest in keeping people in places like New Orleans (and even growing the population), but we need to accept the reality that these places will be uninhabitable in the near future. 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.
- bostonsre 5y ago
  I can't imagine flood insurance is very cheap in these locations and I don't think this is an imminent domain type situation where the government would buy houses. At some point, people will be ruined financially and won't be able to rebuild. 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.
  - beerandt 5y ago
    The federal government actually does have block grant programs to buy out homeowners, or will pay to raise their house, if the cost is cheaper than building a levee or similar flood protection.

Exmoor 5y ago

Somewhat incredibly, Ida killed far more people as a weakened tropical storm in the northeast after crossing the entire US than it did as a Cat4/5 hurricane on the gulf coast. From Wikipedia: > As of September 4, a total of 70 deaths have been confirmed in relation to Ida: 27 in New Jersey, 18 in New York, 13 in Louisiana, 5 in Pennsylvania, 2 in Mississippi, 2 in Alabama, 1 in Maryland, 1 in Virginia, and 1 in Connecticut.

dnautics 5y ago
People forget that "superstorm sandy" wasn't even a hurricane, iirc it was a "tropical depression" by the time it got to nyc
- beerandt 5y ago
  If you don't go through it, it must not be that bad. If you do go through it, it was worse than the category/ windspeed/ storm surge numbers convey. "You just had to be there! It was way worse than just a tropical depression!" It was the media experiencing this phenomenon that gave birth to the hyperbolic term "Superstorm Sandy". Anyone who's actually been through a hurricane saw through it right away.
- jazzyjackson 5y ago
  IIRC what made it a superstorm was that several weather patterns combined and amplified each other. Same thing happened with Ida: there were storms already moving upwards into NYC and Ida just came through and gave it a push.
datameta 5y ago
I'm in NYC. Besides walking my dog briefly in the heavy rain twice I wasn't even aware of Ida until the clear morning after someone showed me flooded subway photos looking like from the end of MGS2. I'm not sure it was communicated properly save for the flash flooding broadcast that could have also come from just a lesser heavy thunderstorm.
- dylan604 5y ago

selimthegrim 5y ago

In other interviews the engineers claim the levees were built to a 200-year level, and that a 100-year level would not have been sufficient for Ida.

Filligree 5y ago
If we get 100-year storms every five years, then is that really the correct description?
- throwawaysea 5y ago
  From the USGS page on 100 year floods (https://www.usgs.gov/special-topic/water-science-school/science/100-year-flood https://www.usgs.gov/special-topic/water-science-school/scie...): > The term "100-year flood" is used in an attempt to simplify the definition of a flood that statistically has a 1-percent chance of occurring in any given year. Likewise, the term "100-year storm" is used to define a rainfall event that statistically has this same 1-percent chance of occurring. In other words, over the course of 1 million years, these events would be expected to occur 10,000 times. But, just because it rained 10 inches in one day last year doesn't mean it can't rain 10 inches in one day again this year. And it looks like these terms are based on past data not future projections: > Since the 100-year flood level is statistically computed using past, existing data, as more data comes in, the level of the 100-year flood will change (especially if a huge flood hits in the current year). As more data are collected, or when a river basin is altered in a way that affects the flow of water in the river, scientists re-evaluate the frequency of flooding.
MisterBastahrd 5y ago
The entire rest of the west bank parishes is still protected by the "old" definition of a 100 year storm, and they had multiple breeches this year.

ErikAugust 5y ago

http://trimread.org/articles/1154 http://trimread.org/articles/1154

bjourne 5y ago

So the taxpayer money wasn't squandered but actually put to good use. Who would have thought?