The Hundred Year Flood

You may not be interested in math, but math is interested in you.

To determine a floodplain boundary, we first identify a “storm event” that concerns us. We use historical rainfall data and some statistical magic to calculate the worst storm event a place is likely to experience in a 100-year time span, probabilistically speaking, and we call that the “100-year storm.” There’s a push in the field to quit calling it that, because it confuses the muggles, so now we often say something like “the storm which has a 1% chance of happening in any given year.” Then we take that rainfall data, judiciously apply more math, and turn it into a flow rate in a river. Then we do hydraulics (more math) to determine how deep the river will have to be to carry that much water, and we draw a line on a map. […]
Let’s quickly walk through this. The chance of flooding, P(F), is 1%, or 0.01. The chance of not flooding, which we notate P(F’), is 100%-1%, or 99%, or 0.99. To see the chance you don’t flood two years in a row, you would have to “not-flood” the first year, and then “not-flood” the second year, so you multiply the two probabilities together, and get 0.9801. The chance of “not-flooding” 30 years in a row is calculated by multiplying the chance of not flooding with itself, over and over, 30 times, which is a power relationship. P(F’)³⁰. That’s 0.7397 chance of 30 consecutive years of no flood, which means a 26% chance of at least one flood.
And then your mortgage broker doesn’t give you your thirty-year fixed rate loan, because a 26% chance of a disaster is a big chance, when we’re talking about disasters.
Now let’s talk about a bigger, nastier disaster than a flood.

37 Replies to “The Hundred Year Flood”

  1. from the link:
    “the fight will be unpleasant, which means you dont have to fight in the first place”

    ooooooooh jeeze. my strategy has been found out.
    it is the essence of why MAD worked.
    3 prong:
    -have the necessary physical apparatus.
    -show you are also psychologically and morally prepared to use said apparatus
    -commuuuuuunicate #2 to the enemy

    put the certitude of catastrophic consequences in the collective haids of the enemy.
    they WILL be obliterated trying any ‘funny stuff’.

    the exceptionally unique irony of nuclear deterrence; the FACT one can inflict a civilization destroying level of retaliation,

    I used this same tactic at 12 yrs old without knowing it. I figured it out later.
    I beat the shyt out of a bully (who proceeded to HANG himself that nite from the humiliation)
    aaaaaand hmpf. whut gives? nevah had to deal with ANY more bullies in grade school . . . . .

    tq tq tq Kate, what a VITAL message.

  2. Canada is sliding into a recession not so much from market cyclicals but fleeing capital, an inevitable reaction to bad governance (green theocracy). Within a few years our bad governance will find it difficult to borrow more money to paper-over the decline. The resulting loss of prosperity might start registering with the 60% brain-dead component of our electorate. If not, we are well on the road to something between the Wiemar Republic and Mad Max.

    1. Just watched a few minutes(all I could stand) of Greta TorturedSoul.Thunberg on our very own Tass/CBC . Disgusting waste of our tax dollars..

    2. My capital is fleeing. I am selling off all my Canadian stocks and putting the money into mostly American stocks.

  3. OTOH … ex-felon (securities fraud) Brother-in-Law huddled in his Kalispel, MT survivalist compound … waiting for Y2K societal implosion. Cashed out for gold coins, stocked up food, multiple generators, flew all of his children and grandchildren to huddle with him, massive food stores (he weighs about tree-fiddy) … uh … and … uh …

    Nothing happened.

    But boy howdy … he was prepped!

    1. I wonder about those people who buy gold for the apocalypse and where exactly they plan on shopping … for food … and water.

      1. Yes Steve when there is nothing to buy the gold is worthless. Plus if it is known that you have any food stored away it will be taken from you, no one has the fire power to hold off hundreds or many even a thousand hungry armed people.

      2. absolutely.
        it’s biblical, there’s a scripture ref to this very scenario where the much sought gold aint worth its weight anymore.
        except I suppose to melt down into high inertia bullets. I betcha it’s been tested somewhere already.

        1. Many years ago a guy offered me more money (gold actually) than I could refuse to cast a 32 cal. bullet from his wedding ring. His exwife heared about it and left town.
          Gold melts at much higher temperature than lead. I had to use oxyacetylene and ruined the handle of my casting ladle. Gold is much harder than lead. Even though I down loaded the cartridge, the gun buzzed in my hand (he wanted the rifling on it) said he was going to hang it around his neck on a gold chain but he never came back.
          I still have the bullet (and the gold) never saw either of them again.
          It is much easier to make bullets from lead than gold. I hope never to see the day so desperate that they trade one to one.

  4. Re: Zombie apocalypse, I recall an analysis that decided the north shore of Lake Erie was one of the best spots in North America to weather such a thing. Not very many people, reasonable resources, pretty good growing season, and too far for the zombies to walk from population centers.

    Over all, Canada is a very harsh place and not very cooperative with ideological flummery. Winter always comes, and power outages are frequent enough that everyone remembers that the furnace goes off when the power goes out. Everyone who’s lived here more than ten years has -seen- the furnace go off in an ice storm.

    Although lately I’m seeing a great many woodpiles out here in the country along the north shore of Lake Erie. You can tell that people are generally thinking about their furnace and our government managed electrical system, and their lack of faith is apparent. Wood stove always works, doesn’t need a generator, you can pick up fuel off the ground.

    In fact even a suburbanite can press grass into pellets all summer and burn them all winter. When the average Joe knows what a grass-pellet machine is, that’s when you’ll know that trouble is arriving shortly.

    1. Not sure how anyone thinks the north side of Lake Erie is far enough away from population centres.

      Probably 7 million people are two days walk or less away. And there quite a few people living there already.

    2. ?
      *the* north Erie shore?
      the one being pummeled and washed into said lake by the waves?

      note how ‘lake’ is ‘spleled’ in the url.

      I once walked all the way from London to pt stanley overnite with a buddy whose mom had a cottage there back around 1968.
      spent the next day with my throbbing feet propped up on the stern of a cabin cruiser.
      the place is unrecognizable since then from erosion. the road along the top of the cliff west is LONG gone.

  5. If you live in Alberta or Saskatchewan Canada, there is absolutely no reason to worry about a potential future civil disorder event. When was the last time you heard someone here advocating a major change in government allegiance? Or someone in the government outlawing and confiscation of your major fuel and transportation supplies? Floods? How long since you had a really wet year? Fires? How long since you had a dry Summer? And thanks to Global Climate Change, you never have to worry about early winters, blizzards or freezing cold again.

    No, no reason to prep for the unexpected at all. Life will always be sunny ways. Relax, All is Well.

    All is well.

    1. Calgary did not pay attention to the fact that it is built on a floodplain and look what happened in 2013. And then the government allowed the idiots to re-build on the floodplain. House insurance went way up, but I had already sold my house (NOT on the floodplain) and had bugged out to Regina.

      1. My house is high and dry away from the floodplain. However it is right in the path of the next ice age glacier that will eventually push us all down into the Bow Valley. (if you look closely, you can still see the scrape marks from the last one)

  6. “Buy another box of ammo. Clearly.”

    Yes. Always good advice.

    “leave it in his attic with a couple of cans of ammunition”

    No. Guns and ammo should always be secured in proper storage: gun safes, etc.

    1. But then put that proper storage gun safe ammo under the insulation in the attic so the RCMP can’t find when they come to confiscate firearms and ammunition. I know some people bury them to fool the dogs but honestly, in Canada you’d be frozen solid half the year so it won’t do you much good.

      1. “So the RCMP can’t find”. You have obviously never seen a home after the RCMP have searched for a firearm.

  7. Steelman my argument in whatever way you like, and the answer will still probably scare you.

    Okay. The math is bullsh*t because it assumes that a violent nation-state transition is a statistically independent random variable. It isn’t.

    A flood isn’t either, but it depends on a system so chaotic that it may as well be, and so the mathematical approximation is good enough.

    Hari Seldon was a fictional character and there’s no such thing as sociohistory. This isn’t modelling, it’s curve fitting. And on average, empires last about 200 years.

    1. Thank you someone gets it. Someone else in the comments over there does too: “I think you’re using statistics like a drunk uses a lamp post: for support not illumination.”

      Isaac Asimov is overrated af.

  8. That Bernoulli Process– what’s that?
    Asked the richest county in the whole damn country.
    This is like a colorary to moving into a Mexican border town. PS it’s pretty obvious that there could be high water issues there, or cartel wars, or whatever.
    Not against firearm preparedness, just noting the other category.
    The prepared
    The unprepared
    The stupid and unprepared.

  9. Good article – and from April 2018 … so it predates current events.

    Hello — Hong Kong today.


    “Pretend you’re someone with your eyes on the horizon. What would you be looking for, exactly? . . . . . . . . . .

    Any one of those might not necessarily be the canary in the coal mine, but all of them in aggregate might be alarming to someone with their eyes on the horizon. Someone with disproportionate faith in the state is naturally inclined to disregard these sorts of events as a cognitive bias, while someone with little faith in the state might take these signs to mean they should buy a few more boxes of ammunition.”

  10. A failure to plan is a plan to fail. What’s your Plan B?

    “The government should do something!”
    They are, asshole, they’re saving themselves. If you think Mayor Quimby or Premier Fatass or PM Two-faced are going to save you then you don’t deserve to be saved.

  11. There is a TV show called preppers. Some of these people live in built-up areas but have a bat-cave in the country with lots of dried food (little to no water). When the day comes (most seem to stick to nuclear war) they plan on hopping into their SUVs (with upgraded tires) and driving through the city out to their bat-cave to await a new dawn. Totally Bat-S-Crazy.

    The purpose of the show is to determine how prepped these people really are, using prep-experts. Very little is made of the fact that if there is a nuclear war … how do you get out of the city in the first place?

    One guy blew his hand off teaching his kids how to fire a weapon. That was a nice touch.

    1. The antithesis is a neighbour of mine shining his van lights into his house because he has no flashlights or candles in ’03 with the big eastern power outage.
      Last year when tornadoes put power out in Ottawa a sister-in-law drove around for hours looking to get coffee. Sounds funny except that it was super dangerous as super assholes were blasting through intersections like maniacs.
      I started up my genny, made a pot of coffee, ran my fridge and freezer and worked the saw as I continued building a new deck. Had tunes going as well.

  12. *
    don’t need a nuclear war, smelly, hippie dudes.

    the power goes off in toronto for a week
    the food is gonna run out and the less
    inhibited among us will be looking for
    a haunch of, well… you, for instance.

    try making jokes about my guns, at that
    juncture in time.

    there’s tons of shit that can hit the
    proverbial fan.

    swine flu, EMP… or a terrorist attack.
    just don’t show up at my door looking
    for sympathy.


  13. Summer of 2018 we had the Alonsa F4 tornado knock out power for 36 hours. Last October’s winter storm knocked out power for 47 hours for us. We were lucky as some places lost power for two weeks. It was interesting. I thought I was prepped but I discovered some holes in my plans. I was easily able to adjust but there were holes that needed plugging. And in both instances there were looters slinking about looking for stuff to steal including at my place. Of course being a good Canadian I would never do anything like threaten looters with a gun or sic my dog on them or anything else. I would call the police and quietly let them steal whatever they like and assault me and mine however they wish, while I wait the minimum of 90 minutes they take to get to my remote area. Oh and my truck has a problem making it backfire a lot. Need to get that fixed.

  14. Hard times always come.
    Can-Ahh_Duh is determined to make them come early,by destroying the social contract that enables civil society and by shutting down the energy sources that allow a technological civilization.
    Most people alive today refuse to acknowledge how fragile our way of life is.
    One man can cut power to an entire city.
    Think about that.
    Cheap reliable energy is the life blood,lose that your known world is gone.
    When we built the distribution grids,we knew the weaknesses,for electrical power we, used to, stock on site spare transformers.
    The reasons being they are very heavy and the whole transport system can fail without that power.So a replacement 1000s of miles away,yet to be manufactured is utterly useless.
    But thanks to Government control of Electrical Utilities,systemic theft from the consumers and inventory utility can afford to have such expensive plant sitting idle.
    It is entirely due to government action and regulation that our systems are gutted to the point that even a simple event like an ice storm can cut power for weeks..
    Just wait for a real disaster.

    That said we almost always prep for the wrong emergency.
    But preparedness is a state of mind which is greatly enhanced by access to tools and material.
    Having real skills and skilled neighbours can go an awful long way toward adverting personal discomfort and danger to your loved ones.
    There is no such thing;” As too much ammo.”