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Comment by mystraline | Hacker News Reader

This is simple. Dont live in flood planes. Dont buy houses in flood planes. And dont build houses in flood planes.

And also, dont count on the government, like FEMA, to help. Now with phrases like "climate change", and "green" now banned from federal discourse, we're not permitted to say the obvious.

And its safe to say that 10 year flood planes are now 1 year. 100 year is now every 10, and 1000 year is every 100.

In my part of the country, we've also moved 2 bands warmer in USDA ag bands in just 25 years. But no, according to the current idiots at the top, banned language, fake news, and not happening.

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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 these risks. Every location that receives precipitation or is near water has some risk of flooding and that risk of flooding may be hidden. The whole state of Florida is low elevation. Something like 1/3 of it is very low elevation and subject to sea-level rise causing catastrophic changes in coastline. But the other 2/3 of Florida is something like 100ft (30m) above sea level. The other issue with Florida is that it's the flattest state in the US. That flatness contributes to flooding being difficult to properly predict.

> Dont buy houses in flood planes.

I'd just like to call out this hard-line assertion as well. Have you looked at a flood plain map? They have hard borders of zones. Those zones are calling out that event probability. If I buy a house 10 ft outside that zone, do you think my event probability went to 0% in those 10ft? Maybe, if the terrain was drastic, but maybe not even then. Every place we humans build has some probability of catastrophic events. Evaluating those risks is difficult. Hedging against those events is why people buy insurance.

Edit:

Grady, from Practical Engineering, did a good video about this subject - https://www.youtube.com/watch?v=EACkiMRT0pc

> 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 never claimed to have that data.

I do not trust anything out of the US government, especially now. And for the time being EPA still has ArcGIS API to pull flood planes. But again, from my local area, Ive seen way too many "100 year floods" happening every 3-5 years.

I distrust the government numbers, and prefer to look at risk much more conservatively with respect to bloodlines and flooding.

> That being said, hyperbolic assertions such as this don't help.

This isn't hyperbolic. Climate devastation IS happening and worsening. Even if the previous charts were truthful, they are not being kept up. Thankfully I have local floodmaps for the state saved locally under Biden. And as someone who works with geospatial data, I'm interpreting to what is matching locally.

> The whole state of Florida is low elevation.

Yeah. Louisiana is similar. They are quite fucked. Storm surges can easily flood and destroy homes.

Part of my original comment is, if your house is destroyed, rebuild elsewhere. Or, I'm u sure of building construction techniques that can impede hurricanes and flooding. I'm in IT, not building construction.

Hoping and praying your house doesn't get flooded being 5 miles inland at 2 feet altitude is not a good plan.

> I'd just like to call out this hard-line assertion as well. (Dont buy houses in flood planes)

Of course, everything is probabilistic. But you can make a easier choice by looking at the current EPA floodplains, with a topographical and waterway map, and decide how much elevation you need to relatively guarantee your safety.

> I never claimed to have that data.

Sorry for my switch to 'you' on the second part there. I was more trying to call out if you were claiming there was data to support your assertions, not that you possessed the data personally.

I too do not trust anything being published by the US government at this point. I've always been leery of trusting their data around contentious topics, but that's progressed to zero trust and an expectation that the data is purposefully incorrect.

> "100 year floods" happening every 3-5 years

A 100-year flood plain is simply saying that each year has a 1% chance of a flood based on historical data. It does *not* mean there's only 1 flood every 100 years. We could have such a flood for 10 years running and the data could still work out to it being a 1% probability. That probability is not accumulated.

> This isn't hyperbolic.

A blanket statement saying that flood plains should increase their probabilities by an order of magnitude is hyperbolic. I'm not trying to argue climate change isn't happening, it is. I'm saying statements like that don't help the cause as they are disprovable on the whole and work against getting meaningful recognition and addressing of the issues.

> Part of my original comment is, if your house is destroyed, rebuild elsewhere.

The thing is, if your home was destroyed by a low-probability event, you can make an assessment of the risk and determine if you're willing to accept that risk. Moving from one location to another doesn't suddenly remove risk though. I might move from an area at risk of hurricanes to an area at risk of wildfire, mudslide, tornado, or flooding. Every location has risk. From a concrete POV, should you rebuild a home in a high-probability coastal hurricane impact zone with super-low elevation? I'd say heck no! I'm generally in the 'less government involvement' camp, but I'd also not have much issue with the government declining to provide last-resort insurance to people in super-high risk areas as an incentive to move them out. Or at the very least, make such last-resort insurance prohibitively expensive commensurate with the actual risk.

> decide how much elevation you need to relatively guarantee your safety

Elevation isn't even a guarantee (I know you said 'relatively'). Precipitation based flooding can (and does) happen away from waterways. Flood plain maps are generated based on flawed and spotty (literally) data. They fail to capture the totality of precipitation going into a flood and, as a result, leave people with a false sense of security in relation to potential flooding.

> And also, dont count on the government, like FEMA, to help. Now with phrases like "climate change", and "green" now banned from federal discourse, we're not permitted to say the obvious.

It's a cold calculus, but a government that is ideologically opposed to the science of climate change is more rather than less likely to help bail out flooded properties. With such a… fixed opinion, the hidebound government agencies can't allow themselves to think that the overall risk profile has increased, so they'll be surprised by a hundred-year flood every 10 years.

The confounding factor is that the current US political mix combines ideological opposition to climate change science with opposition to well-functioning assistance programs, so on balance there may be nobody left to write the bailout cheque.

> With such a… fixed opinion, the hidebound government agencies can't allow themselves to think that the overall risk profile has increased

This is only true if policy makers are logically consistent. If they're not then whatever they feel like at the time goes. I don't think it takes much effort to see that logical consistency is not something that is highly valued by the people currently in charge.

If moving millions of people—functionally including entire metro areas like…oh I don’t know…Miami and New Orleans and large swathes of NYC—by forcing them to abandon their homes (with no insurance they are now unsalable) and then buy/rent (using what money?) new homes far away from their communities and jobs (if they bought close, they’d still be in the flood plain!)—if that’s “simple”, I don’t want to know what policy implementations you’d call “hard”!

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