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The challenge is that it just doesn't flood often enough to justify investing in significant defenses. If this were the type of event that occurred annually, o

The challenge is that it just doesn't flood often enough to justify investing in significant defenses. If this were the type of event that occurred annually, or multiple times a year - I'm guessing we would see investments in the sorts of thing that Tokyo builds such as https://www.bbc.com/future/article/20181129-the-underground-cathedral-protecting-tokyo-from-floods https://www.bbc.com/future/article/20181129-the-underground-...

TuringNYC 5y ago
I was disappointed to hear the term "100-yr flood" with the latest storem because I remember at least two other such floods in the area in my life -- one was in 2012 (Hurricane Sandy) And one was ~1992 (a Nor'Easter.) So that is three in thirty years. Is our distribution incorrect, or is "100-yr flood" just a media term? Or is it a way to make something sound rare so we can justify unpreparedness? Of course, all three of these were different things -- one a Nor'Easter, one a Hurricane, and the latest was the effects of a Hurricane down south.
- rtkwe 5y ago
  It's kind of an abuse of the term. The technical definition is a storm that according to historical records has a 1% chance of happening in any given year. So you'd expect to see it at least once in 100 years. As climate change increases the severity of all types of weather those level of storms will get more common than in the past in a hard to predict way. The storm percentages are also based on the historical record instead of future predictions so it will inherently lag behind the expected increasing storm frequency/intensity.
  - jensensbutton 5y ago
    I wish they'd talk about it in these terms. It's easier to think about the cost/benefit of investing in mitigations when faced with "you have an n% chance of incurring m billions in damage this year" vs "x billion dollar damage storms should only occur once every y years". We do it all the time with e.g. cloud SLAs.
  - deleted 5y ago
    [deleted]
  - phonon 5y ago
    A probability of 1% per year means 1 - .99^100 = 63.4% probability of at least 1 storm in a hundred years.
    - karatinversion 5y ago
      The expected value of how many years until such a storm occurs is 100 years.
      - phonon 5y ago
        "A common misunderstanding is that a 100-year flood is likely to occur only once in a 100-year period. In fact, there is approximately a 63.4% chance of one or more 100-year floods occurring in any 100-year period." [1] Which is different than "You'd expect to see it at least once in 100 years." However, yes, the expected value of the number of 100-year floods occurring in any 100-year period is 1. [1] https://en.wikipedia.org/wiki/100-year_flood#Probability https://en.wikipedia.org/wiki/100-year_flood#Probability
- zz865 5y ago
  I think the rain in Newark was so unprecedented it broke all expectations of what was possible. It wasn't a one-in-anything flood.
  - TuringNYC 5y ago
    I realize it was rain (and not a hurricane) but we had very similar flooding back in 2012 (just 9yrs ago) with Hurricane Sandy. https://en.wikipedia.org/wiki/Effects_of_Hurricane_Sandy_in_New_Jersey https://en.wikipedia.org/wiki/Effects_of_Hurricane_Sandy_in_... I'm not as familiar with NJ as I am with NYC -- but in NYC we had something similar in 2012 and again in ~1992 with a Nor'Easter. I'm just wondering if the risk distributions were' using are unrealistic?
    - zz865 5y ago
      The flooding from Sandy was due to extreme high tide, not due to rain. Lots of places away from the sea (like Queens) were bad this year but fine in Sandy, while places close to the sea shore (like Staten Island) were devastated with Sandy but no problem this year. So multiple threats which is bad.
goatsi 5y ago
The US has built similar systems in other places and they can't keep up with the rain. https://slate.com/business/2019/01/chicagos-deep-tunnel-is-it-the-solution-to-urban-flooding-or-a-cautionary-tale.html https://slate.com/business/2019/01/chicagos-deep-tunnel-is-i...
rytor718 5y ago
Another way of saying the same thing is enough people just havent died to justify the cost. We can't keep reasoning about how to safely build cities by how much money is justifiable. It's madness. It is a city on the ocean, surrounded by bays and lakes. The investment is justified. The political will, however, remains to be seen. EDIT: clarity
- RHSeeger 5y ago
  Why do you believe this? It seems it depends heavily on - How many people would be injured or killed by the event. - How much financial damage the event would cause. For example, if nobody ever dies, and 10 million in damage/problems occurs each time the event does, then it's almost certainly not worth spending 1 billion dollars to to fix the problem. Obviously, those numbers are ridiculous, but the point is there. The numbers need to be considered. And yes, human life is a number, too. It's just harder to quantify because there's a lot of opinion involved. But if it the expectation is that such an event will kill 1 person each time, and it would cost 1 Trillion dollars to fix/prevent... it's almost certainly not worth fixing. It's harsh, but spending a Trillion dollars for a single life would be unreasonable.
  - jacoblambda 5y ago
    Now those numbers are actually pretty reasonable. If Nobody ever dies, there's 10 million in damages each time an event like this occurs (around once every 10 years now), and with climate change we can expect the intensity + regularity to increase over time, then 1 billion is likely a good price to pay for solving the problem. Now with mitigations like those that would be used here (like the storm water systems used in Tokyo), the sooner you implement them, the easier/cheaper they'll be to implement/maintain long term. At the end of the day the best time to start adding the mitigations is now and expand later as necessary rather than wait until the cost is high enough and go into a mad dash to complete them before the next disaster. Edit: For context, the Metropolitan Area Outer Underground Discharge Channel in Tokyo cost 2 Billion USD to build and is able to easily handle this volume of floodwater.
    - 5y ago
lambdasquirrel 5y ago
When I visited home it just happened to be around the time of Sandy. It wasn’t just Sandy itself but some other tropical remnant that dumped 7 inches of rain in two or three days? I tell people in the SF Bay Area, 7 inches is about a third of what we usually get in a year. These kinds of storms seem to be happening every ten years now rather than a hundred. (Meanwhile the West is in a constant state of drought).

TuringNYC 5y ago

I was disappointed to hear the term "100-yr flood" with the latest storem because I remember at least two other such floods in the area in my life -- one was in 2012 (Hurricane Sandy) And one was ~1992 (a Nor'Easter.) So that is three in thirty years. Is our distribution incorrect, or is "100-yr flood" just a media term? Or is it a way to make something sound rare so we can justify unpreparedness? Of course, all three of these were different things -- one a Nor'Easter, one a Hurricane, and the latest was the effects of a Hurricane down south.

rtkwe 5y ago
It's kind of an abuse of the term. The technical definition is a storm that according to historical records has a 1% chance of happening in any given year. So you'd expect to see it at least once in 100 years. As climate change increases the severity of all types of weather those level of storms will get more common than in the past in a hard to predict way. The storm percentages are also based on the historical record instead of future predictions so it will inherently lag behind the expected increasing storm frequency/intensity.
- jensensbutton 5y ago
  I wish they'd talk about it in these terms. It's easier to think about the cost/benefit of investing in mitigations when faced with "you have an n% chance of incurring m billions in damage this year" vs "x billion dollar damage storms should only occur once every y years". We do it all the time with e.g. cloud SLAs.
- deleted 5y ago
  [deleted]
- phonon 5y ago
  A probability of 1% per year means 1 - .99^100 = 63.4% probability of at least 1 storm in a hundred years.
  - karatinversion 5y ago
    The expected value of how many years until such a storm occurs is 100 years.
    - phonon 5y ago
      "A common misunderstanding is that a 100-year flood is likely to occur only once in a 100-year period. In fact, there is approximately a 63.4% chance of one or more 100-year floods occurring in any 100-year period." [1] Which is different than "You'd expect to see it at least once in 100 years." However, yes, the expected value of the number of 100-year floods occurring in any 100-year period is 1. [1] https://en.wikipedia.org/wiki/100-year_flood#Probability https://en.wikipedia.org/wiki/100-year_flood#Probability
zz865 5y ago
I think the rain in Newark was so unprecedented it broke all expectations of what was possible. It wasn't a one-in-anything flood.
- TuringNYC 5y ago
  I realize it was rain (and not a hurricane) but we had very similar flooding back in 2012 (just 9yrs ago) with Hurricane Sandy. https://en.wikipedia.org/wiki/Effects_of_Hurricane_Sandy_in_New_Jersey https://en.wikipedia.org/wiki/Effects_of_Hurricane_Sandy_in_... I'm not as familiar with NJ as I am with NYC -- but in NYC we had something similar in 2012 and again in ~1992 with a Nor'Easter. I'm just wondering if the risk distributions were' using are unrealistic?
  - zz865 5y ago
    The flooding from Sandy was due to extreme high tide, not due to rain. Lots of places away from the sea (like Queens) were bad this year but fine in Sandy, while places close to the sea shore (like Staten Island) were devastated with Sandy but no problem this year. So multiple threats which is bad.

goatsi 5y ago

The US has built similar systems in other places and they can't keep up with the rain. https://slate.com/business/2019/01/chicagos-deep-tunnel-is-it-the-solution-to-urban-flooding-or-a-cautionary-tale.html https://slate.com/business/2019/01/chicagos-deep-tunnel-is-i...

rytor718 5y ago

Another way of saying the same thing is enough people just havent died to justify the cost. We can't keep reasoning about how to safely build cities by how much money is justifiable. It's madness. It is a city on the ocean, surrounded by bays and lakes. The investment is justified. The political will, however, remains to be seen. EDIT: clarity

RHSeeger 5y ago
Why do you believe this? It seems it depends heavily on - How many people would be injured or killed by the event. - How much financial damage the event would cause. For example, if nobody ever dies, and 10 million in damage/problems occurs each time the event does, then it's almost certainly not worth spending 1 billion dollars to to fix the problem. Obviously, those numbers are ridiculous, but the point is there. The numbers need to be considered. And yes, human life is a number, too. It's just harder to quantify because there's a lot of opinion involved. But if it the expectation is that such an event will kill 1 person each time, and it would cost 1 Trillion dollars to fix/prevent... it's almost certainly not worth fixing. It's harsh, but spending a Trillion dollars for a single life would be unreasonable.
- jacoblambda 5y ago
  Now those numbers are actually pretty reasonable. If Nobody ever dies, there's 10 million in damages each time an event like this occurs (around once every 10 years now), and with climate change we can expect the intensity + regularity to increase over time, then 1 billion is likely a good price to pay for solving the problem. Now with mitigations like those that would be used here (like the storm water systems used in Tokyo), the sooner you implement them, the easier/cheaper they'll be to implement/maintain long term. At the end of the day the best time to start adding the mitigations is now and expand later as necessary rather than wait until the cost is high enough and go into a mad dash to complete them before the next disaster. Edit: For context, the Metropolitan Area Outer Underground Discharge Channel in Tokyo cost 2 Billion USD to build and is able to easily handle this volume of floodwater.
  - 5y ago

lambdasquirrel 5y ago

When I visited home it just happened to be around the time of Sandy. It wasn’t just Sandy itself but some other tropical remnant that dumped 7 inches of rain in two or three days? I tell people in the SF Bay Area, 7 inches is about a third of what we usually get in a year. These kinds of storms seem to be happening every ten years now rather than a hundred. (Meanwhile the West is in a constant state of drought).