Rethinking infrastructure in flood prone areas

[berkeman]

Fight, fight!

 

[Flyboy]

There were just floods, so we are focused on floods. (Not my favotite choice, as many people =- not here of course - adopt a quasi-pagan view of them "Gods angry with humans and technology!")

But these are not the only disasters, not are they the only geographically predictable ones. I mentioned earthquakes. What about heat waves? Wildfires? Volcanoes? Mudslides?

A lot of people want to live in places where there is risk and/or history of disasters. What do we do if, for example, Mauna Loa decides to do a Krakatoa?

Make it abundantly clear to people moving in what the risks are, and then wash your hands of it. They were warned. If they choose to ignore those warnings, then that’s between them and whatever higher power they believe in.

Re: catastrophic explosion of Mauna Loa: incredibly unlikely given our understanding of that particular volcano. Explosive eruptions can and have happened, as they have on Kiluea in documented history. But something on par with the catastrophic collapse of Krakatoa is, from what I understand, so statistically unlikely as to be a non-issue. It’s certainly possible under the most extraordinary scenario, but if that level of explosivity was present, we probably would have both oral records from the native Hawaiian people and in the geological record.

 

[Vanadium 50]

Make it abundantly clear to people moving in what the risks are, and then wash your hands of it. They were warned. If they choose to ignore those warnings, then that’s between them and whatever higher power they believe in.

The problem is when they are displaced by the mudslides or whatever, the cry goes out "how can you ignore all this suffering!"

In principle, one could require insurance. In practice, finding an underwriter may be impossible. And that provokes the complaint "It's not fair!"

I agree that the risk from Hawaii is low - that's what our best evidence says. I will not agree that it is zero. Furtner, the impact is astronomical, so the expected loss (risk * exposure) may still be substantial. But you don't like that one? Pick another one - I mentioned several.

Finally, there seems to be an idea that a storm that kills 100 people is somehow worse than 50 syorms that each kill 5 people.

 

[Astronuc]

While everybody loves trains, one issue is that the track was laid out where it made sense to when it happened. So Buffalo, NY - once one of the largest cities in ths US is well served, but Laas Vegas, presently once one of the largest cities in ths US is not.

And there is no longer a Chatanooga Choo-Choo.

Buffalo and Las Vegas have Amtrak service. Buffalo has three major Class 1 railroads, CSX, CP (now CPKC) and NS. Las Vegas is on the UP's Chicago to Los Angeles mainline (Nipton, California is a great place watch UP action ).

Chattanooga is planning for Amtrak passenger service on a CSX route between Nashville, Tennessee and Atlanta, Georgia.
https://www.timesfreepress.com/news...working-to-attract-passenger-rail/#/questions

Even with its history of rail, a passenger train hasn't departed from Chattanooga in the history of Amtrak, which started in 1971, but that may change in the coming years as the city has taken steps recently to bring passenger service back.
. . .
The rail service would connect Memphis to Atlanta by way of Nashville and Chattanooga. Smith said Mayor Tim Kelly has been working toward bringing passenger rail service to the city for years.

I assume that Amtrak service will use mostly CSX right of way from Nashville to Atlanta (280 miles). Apparently there is already Amtrak service between Memphis and Nashville.
https://www.commercialappeal.com/st...senger-railway-tennessee-atlanta/73532202007/

https://en.wikipedia.org/wiki/Nashville–Atlanta_passenger_rail

The goal is to have two round trips per day between Atlanta and Nashville. The route would connect with downtown Nashville, Nashville's airport, Chattanooga and it's airport, and downtown Atlanta.

Of course, Amtrak needs cooperation of CSX.


As for the flooding issue, coastal areas like Miami and Tampa are particularly vulnerable, and some folks who never flooded before are now experiencing flooding, which may be the new normal, even without a hurricane. Some area may see significant flooding several times per decade. Some Tampa neighborhoods that were supposedly in a low risk ('no evacuation required'), now appear to be in flood zones. Part of this is apparent climate change and part due to development such that there is less land available to take increased precipitation.

Back in August, the city of Tampa asked residents to report flooding and damage following rain from Hurricane Debby.
https://www.tampa.gov/news/2024-08/residents-asked-report-flooding-and-damage-properties-153776

Since then hurricanes Helene and Milton have contributed to flooding, more from inland precipitation and less from storm surge.
https://www.wsmv.com/2024/10/11/least-135-residents-rescued-flooded-assisted-living-facility-tampa/

Hurricane Debby (an erratic Cat 1) hit the 'Big Bend' area in Florida, making landfall near Steinhatchee, Florida, early on August 5. The hurricane went to tne NE, back over the Atlantic Ocean before heading up the eastern seaboard.
https://en.wikipedia.org/wiki/Hurricane_Debby_(2024)#/media/File:Debby_2024_path.png
https://en.wikipedia.org/wiki/Hurricane_Debby_(2024)

Hurricane Helene hit roughly the same area, but then turned slightly westward into western North Carolina and eastern Tennessee.
https://en.wikipedia.org/wiki/Hurricane_Helene#/media/File:Helene_2024_path.png

Late on September 26, Helene made landfall at peak intensity in the Big Bend region of Florida, near the city of Perry, with maximum sustained winds of 140 mph (220 km/h). Helene weakened as it moved quickly inland before degenerating to a post-tropical cyclone over Tennessee on September 27. The storm then stalled over the state before dissipating on September 29.

https://en.wikipedia.org/wiki/Hurricane_Helene

Both hurricanes Debby and Helene flooded the same area in Florida and parts of Georgia. The stalling over the Tennessee-North Carolina border contributed to the catastrophic flooding in that area. Both hurricanes also cause flooding around the Tampa area. In the case of Helene, more than 250 fatalities, with another 206 folks still missing.

The third hurricane, Milton, was much more significant to Tampa and central Florida. Fortunately for Tampa, the eye moved inland south of Tampa near Sarasota. That was not good for those folks around Sarasota and the barrier islands.
https://en.wikipedia.org/wiki/Hurricane_Milton#/media/File:Milton_2024_path.png
https://en.wikipedia.org/wiki/Hurricane_Milton

Milton formed from a long-tracked tropical disturbance that originated in the western Caribbean Sea and consolidated in the Bay of Campeche on October 5. Gradual intensification occurred as it slowly moved eastward, becoming a hurricane early on October 7. Later that day, Milton underwent explosive intensification and became a Category 5 hurricane with winds of 180 mph (285 km/h). At peak intensity, it had a pressure of 897 millibars (26.49 inHg), making it the fifth-most intense Atlantic hurricane on record. Milton fluctuated in intensity after an eyewall replacement cycle, re-intensifying into a Category 5 hurricane the following day. Increasing wind shear caused the hurricane to weaken as it turned northeast towards Florida, falling to Category 3 before making landfall near Siesta Key late on October 9. Afterwards, Milton rapidly weakened as it moved across the state into the Atlantic Ocean, and became extratropical on October 10 as it became embedded within a frontal zone. The remnants gradually weakened and passed near the island of Bermuda before dissipating on October 12.

Estimated cost of damage from Helene is ~>$40 billion (2024 USD).
Estimated cost of damage from Milton is ~$30 billion (2024 USD).

I have not heard how much damage from Helene was due to wind and tornado. Most damage in Tennessee and North Carolina was due to severe flooding and more than 300 landslides.

Tornados spawned by Milton and wind caused damage in central Florida, and flooding cause damage as well.

We have another 6 weeks through Nov 30 in Hurricane Season 2024.

Some major events with hurricanes and non-hurricane (tropical storm or thunderstom) flooding events.
https://www.weather.gov/mfl/events_index

Statewide, Florida receives an average (1901-2001) of 54.02 inches of rainfall a year, with the nation (as a whole) averaging 30 inches per year.
The climate of the north and central parts of Florida is humid and subtropical with south Florida being a true tropical climate. There is a defined rainy season from May through October, with Tallahassee (the state’s capital), Miami, West Palm Beach, and Pensacola being some of the rainiest cities in the state averaging 61-65 inches annually.

https://www.floridafloodinsurance.org/flood-history/

The widespread flooding in the Tampa Bay area has necessitated over 1,000 water rescues, with Hillsborough County accounting for more than 700 of these incidents, according to the sheriff's office.

The rescues ranged from assisting a 91-year-old woman trapped in her flooded home near the Alafia River to a large-scale operation involving over 500 residents trapped in their flooded apartment complex in Clearwater.

https://www.foxweather.com/extreme-weather/video-valrico-florida-flood-alafia-river-hurricane-milton

Some folks who had flooding during Milton had not yet recovered from flooding from Helene. Piles of debris were still waiting collection and disposal when Milton crossed through Florida.
https://www.cnn.com/2024/10/11/us/florida-residents-home-hurricane-milton/index.html

 

[Vanadium 50]

You can get an Amtrak ticket to Vegas. But i's a bus. :(

 

[Vanadium 50]

Just like United Airlines used to sell tickets from SJC to SFO. It was a bus.
SFO to OAK was a plane. 11 miles. Yahoo!

 

[russ_watters]

SFO to OAK was a plane. 11 miles. Yahoo!

But oh my god, the traffic.

Different times though. My dad used to take a 20 mile flight from a tiny airport in suburban Philly to PHL. The upside was skipping all the big airport BS by checking his bag at a "terminal" the size of (though it was probably a long way between terminal).

 

[Astronuc]

You can get an Amtrak ticket to Vegas. But i's a bus. :(

I missed the part about a bus connection.
https://amtrakguide.com/directions/amtrak-to-las-vegas/

Las Vegas is a popular travel destination in Nevada. Unfortunately, the city does not have an Amtrak station. The Kingman Amtrak Station in Arizona is the closest to Las Vegas, but you’ll need to rent a car there and drive about 1.5 hours.

The Kingman Station is on the Southwest Chief route that travels between Los Angeles and Chicago.

Southwest Chief would be the old ATSF (Santa Fe) mainline from Chicago to Los Angeles. This is part of BNSF. UP is the other mainline from Chicago to Los Angeles.

Also from Amtrak

There’s also a Las Vegas, New Mexico Amtrak station, just don’t get off the train there if you are trying to reach Las Vegas, NV.

Amtrak does have a route through Nevada, but up north, which serves Reno.
https://amtrakguide.com/routes/california-zephyr/
https://en.wikipedia.org/wiki/California_Zephyr#/media/File:Amtrak_California_Zephyr.jpg
The California Zephyr route is on part of the former Western Pacific (WP) Feather River Route line, which met up with Denver, Rio Grande & Western (DRGW) in Salt Lake City, which met the CB&Q (Burlington Route) in Denver for the trip to Chicago. WP and DRGW are now part of UP and CB&Q is part of BNSF.

https://en.wikipedia.org/wiki/California_Zephyr

Not a lot of good options for Las Vegas, NV.
https://www.up.com/aboutup/reference/maps/system_map/index.htm

The UP's South Central Route from Denver to Los Angeles would be possible route to Las Vegas, assuming one wants to pass through Denver. From Los Angeles to Las Vegas, UP might make sense.

https://www.dot.nv.gov/home/showpublisheddocument/18710/637480313156570000

 

[Rive]

But this was a 1000 or 2000 year event in the worst hit areas.

With- or without climate change/ocean level rise factored in?

A lot of old infrastructure is expected to change in the next few decades around the shores. I won't say that this particular event was already 'that', but you can't prove that it isn't either.

The work will need to be done anyway.

 

[Astronuc]

At 8:30 p.m. Oct. 9, 2024, Hurricane Milton made landfall in Sarasota County near Siesta Key, Florida, as a Category 3 storm. Siesta Key is a barrier island off the coast of Sarasota, about 30 miles from Anna Maria Island. Another well-known area on Anna Maria Island is Bradenton Beach, Florida. After Hurricane Milton hit land, the tropical system then wreaked havoc across Central Florida before exiting out of Cape Canaveral a day later.

Hurricane Milton brought 8-10 feet of storm surge to Sarasota, destroying more than 100 homes in the area, downing trees and power lines. More than 227,000 customers in Sarasota County were without power the next day – about 76% of the county.

https://news.yahoo.com/news/heartbreaking-hurricane-milton-damage-photos-205557158.html

 

[Vanadium 50]

With- or without climate change/ocean level rise factored in?

This is exactly what I mean by "The gods ba angry".

This is a counterfactual. No way to tell. Taking it to its (ill)logical conclusion, if we all drove Priuses and voted the right way, there would never be another hurricane.

Predicting the severity of storm seasons is hard. I can show you two equally reasonable models that make very different predictions. A more productive approach than blaming storms on Bad People is to plan for them.

 

[jtbell]

Apparently there is already Amtrak service between Memphis and Nashville.

Not as of 2022:

https://www.amtrak.com/content/dam/...c/documents/Maps/Amtrak-System-Map-020923.pdf

 

[Vanadium 50]

"Amtrak service" can be "the bus" anyway. And given that they are usually more expensive than flying, I expect this is not so popular.

 

[ohwilleke]

While everybody loves trains, one issue is that the track was laid out where it made sense to when it happened. So Buffalo, NY - once one of the largest cities in ths US is well served, but Laas Vegas, presently once one of the largest cities in ths US is not.

And there is no longer a Chatanooga Choo-Choo.

Las Vegas will have high speed passenger rail to Los Angeles in a year or two.

 

[sophiecentaur]

You are fearmongering.

The problem with 'the general public' is that they are far more interested in low taxes and cheap fuel etc. than in possible disaster events which may or may not happen 'here'. If only they would 'fear' a bit more about the risks to their homes. God knows how any government would get away with spending a lot on a proper prevention and rescue scheme.

The UK government talks the talk about encouraging home owners to use porous ground surfaces where possible but I can safely say that I have never seen a contractor laying a suburban drive way with anything other than hard covering. Not a single advert on a van, driving around with an advert for driveway improvements. There just isn't enough fear around yet. And that's despite the fact that so many people can get their houses insured against flood. That's a truly awful predicament to be in and that's

 

[Baluncore]

And that's despite the fact that so many people can get their houses insured against flood.

You need to verify your country's interpretation of the strict insurance term "flood".

If the roof or pipes leak, or the bath overflows and the house floods, that may be covered as the water comes from above.

You may find that if the river rises, or there is a storm surge, that is inundation. With rising-water, overland-water, it is then not a flood, so may not be covered by insurance.

 

[Baluncore]

Nothing is new.
https://en.wikipedia.org/wiki/North_Sea_flood_of_1953#United_Kingdom
https://en.wikipedia.org/wiki/Storm_tides_of_the_North_Sea

The Goon Show. Insurance – the White Man’s Burden.
Neddie Seagoon tries to set fire to the English Channel to claim the insurance. Starring: Harry Secombe, Peter Sellers and Spike Milligan
First broadcast: 28 February 1957. BBC Home Service.
https://www.bbc.co.uk/sounds/play/b007jtth

 

[sophiecentaur]

so may not be covered by insurance

Loopholes have always be a favourite with insurance companies but the present situation has left many home owners unable to take out insurance at all. That must be hellish and there's nothing they can do about it; they can't move because no one will buy and mortgage companies won't lend.

Developers will build anywhere and, insult to injury, they give roads with names like 'Spring Lane', 'River Way' yet customers queue up.

Nothing is new.

It's just worse now. I'm paranoid about the topic and would never ever buy a house that looked even a tiny bit vulnerable. Many of those 'peripheral' factors don't even seem to be reflected in the asking price.

 

[Dale]

this was a 1000 or 2000 year event in the worst hit areas

A similar flood happened in 1916.

 

[Dale]

I do think there is a lot to be said for rethinking what is where if you have to replace it.

I agree. And perhaps what we replace is less convenient for places that are at high risk of catastrophic damage. How much does it make sense to rebuild in a place that got destroyed? Such areas probably should target reduced population and infrastructure density anyway.

Insurers are going to have to adjust premiums to reflect better understanding of actual risks. This will not be appreciated by people currently choosing to live in disaster-prone areas.

 

[sophiecentaur]

Insurers are going to have to adjust premiums to reflect better understanding of actual risks.

They have a much more powerful way of reducing their risk because they can just refuse to sell insurance in high risk areas. They realise that weather is not a memoryless process, meaning that. flood today can be followed by another flood next week. It's just not worth their while to insure bad risks.

So then the government has to support the unfortunate uninsured victims. The recent US and UK elections were won with 'manifestos' which promise low / no taxes.

 

[Flyboy]

A similar flood happened in 1916.

A "1000 year storm" is one that has a 1 in 1000 chance of happening any given year, not one that can only happen every thousand years or so. Meaning you could, in theory, get two thousand year storms in under a month. Highly unlikely, but not impossible.

 

[sophiecentaur]

Highly unlikely, but not impossible.

If only people appreciated what statistics really tells them, they would never play the lottery or roulette. Poker, on the other hand allows good players to make a fortune; they rely on the first sentence of this post. Open season.

 

[Dale]

A "1000 year storm" is one that has a 1 in 1000 chance of happening any given year, not one that can only happen every thousand years or so. Meaning you could, in theory, get two thousand year storms in under a month. Highly unlikely, but not impossible.

I understand. But the fact that such a storm happened in 1916 and 2024 indicates that the hypothesis that it is a 1000 year storm is probably not correct.

In fact, with 173 years on record and with two such observations, the probability that it was a 1000 year (or more) event is only 0.00076. The 95% credible interval is a 24 to 280 year storm. (Bernoulli likelihood with a uniform prior)

 

[gmax137]

In fact, with 173 years on record and with two such observations, the probability that it was a 1000 year (or more) event is only 0.00076. The 95% credible interval is a 24 to 280 year storm. (Bernoulli likelihood with a uniform prior)

Hi @Dale can you outline the method for making such determinations? Thanks.

 

[Flyboy]

I understand. But the fact that such a storm happened in 1916 and 2024 indicates that the hypothesis that it is a 1000 year storm is probably not correct.

In fact, with 173 years on record and with two such observations, the probability that it was a 1000 year (or more) event is only 0.00076. The 95% credible interval is a 24 to 280 year storm. (Bernoulli likelihood with a uniform prior)

A valid point, and one I'm sure that the people who make those assessments are looking into as we discuss this.

Most of those assessments of storm frequency are model-based, not empirically based over a representative timespan. But for the purposes of planning, they have been largely sufficient.

 

[Dale]

Hi @Dale can you outline the method for making such determinations? Thanks.

This is a Bayesian method using the simplest model that the likelihood of such a storm occurring in a given year is Bernoulli distributed with some probability $\lambda$ (independent fixed probability). A 1000 year storm is one where the annual probability is $\lambda=0.001$.

In Bayesian methods, you start with a model and some prior belief, and then Bayes' theorem tells you how to update your belief based on the data you observe. Bernoulli models are particularly convenient because if the prior is beta distributed $\lambda \sim \beta(a,b)$ then the posterior is also beta distributed $\lambda \sim \beta(a+m,b+n)$ after observing $m$ "successes" and $n$ "failures".

So here, if we start with a uniform prior that is $\lambda \sim \beta(1,1)$. Then we observe 171 years without such a strong storm and 2 years with such a strong storm. Applying Bayes' theorem then says our updated belief is $\lambda \sim \beta(3,172)$.

With this we can simply evaluate the PDF and the CDF to get probabilities of interest. For example $P(\lambda < \frac{1}{1000}) = 0.00076$ and $P(\frac{1}{280}<\lambda<\frac{1}{24})=0.95$