The 100 Year Flood Is Not What You Think It Is (Maybe)

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Recommends JshWright · 2017-08 · on “Doomsday planning for less crazy folk”

Even that is a little misleading (given how bad our intuition about statistics is). A '100 year flood' is flood that has a 1% chance of occurring in any given year (it's independent of what happened 1, 5, or 50 years ago). Calling it a '100 year flood' makes people think 'oh, good, now we shouldn't have one of those for another ~100 years'. In reality, the odds of a flood of the same magnitude occurring next year are exactly the same as they were this year. Grady (of the Practical Engineering YouTube channel) has a great video on this topic: [this video] (Grady is in the Austin area, so hopefully he hasn't too much 'practical' experience from this storm...)

Recommends Balgair · 2019-05 · on “Making Nuclear Energy Smaller, Cheaper And Safer”

It's not human action that would worry me, it's nature. Freezing cycles could easily erode a pool in a few decades and make micro-cracks that fester unnoticed for years. Rust is an ever present issue for re-inforced concrete and is the cause of countless civil engineering disasters. Practical Engineering on Youtube is a great overview of the issues we humans have with water: [LINK] Of interest here are these videos: [LINK] [LINK] [this video]

Cites darkpuma · 2019-03 · on “Home of Strategic Command and Some of the USAF's Most Prized Aircraft Flooded”

> I observe no denigration in his comment. These people made a choice. It's not even my personal opinion. I am merely describing the biases of the general public that result in the discrepancy in newsworthiness. It's not due to some coastal conspiracy against inland states. Florida is viewed by many as a backwards state, a popular target for mockery and derision, so a bias against inland states does not explain why hurricanes in Florida get more news coverage than floods in inland states. To reiterate myself a third time, the discrepancy arises from a perceived , not actual difference in culpability of the victims. People who are hit by hurricanes are thought to be the victims of bad chance,

Cites LeifCarrotson · 2021-07 · on “Rainfall flooding is becoming an issue”

"Relatively easy" is brushing over an awful lot. [LINK] You can get a rough approximation, and that's been done at great effort for the entire US at the FEMA website: [LINK] . It's not a simple problem to solve. Some of the caveats are discussed in this Practical Engineering video: [this video] Volume of outflow through a stream is equal to rainfall times watershed area. Seems intuitive, right? Except what about water that gets absorbed into the ground, or captured in a temporary holding pond, slowed by vegetation, or accelerated in a storm drain...I think Grady put it well when he pointed out that the silly Imperial units of outflow in cubic feet per second, rainfall in inches per hour, and wate

Cites lsaferite · 2025-10 · on “Making Florida More Flood Resistant Is Forcing Hard Choices for Homeowners”

Just for clarity, you're claiming that there's data to support that 10-year flood plain areas should be marked as having a 100% chance of having a flood every year and you have enough data to say a 100-year flood plain should be reclassified as a 10-year flood plain? I ask this because those numbers are shorthand for event probabilities given (flawed) observation data over large time-frames. Argue all you want about climate change moving these number due to rising sea levels. I agree it's happening. That being said, hyperbolic assertions such as this don't help. The reality is that our flood plain designations are very flawed, but they are the only current metric we have to assess some of th