Inspired by this excerpt from a story of a future NYC flooded by rising water levels. Assuming that water floods the underground and first floors of a skyscraper, what changes (if any) are needed for it to remain functional? Does the water pose any dangers to the structure of the building?
Does having to take a ferry or kayak to work at your desk job have any importance? How about ordering lunch or stepping out for coffee?
Pretty much all the electrical supply system is in the basement. From there it’s distributed to the upper floors. That stuff won’t work so good under 20+ feet of seawater.
Likewise the pumps that push water to the upper floors are usually in the basement. You really don’t want your fresh city purified water pumps sitting underwater in a bath of seawater and city runoff filth.
The physical structure will be fine in the near term, like months. But any concrete or steel that isn’t designed to be immersed in salt water will begin deteriorating immediately and will become dangerous over extended time. I have no clue whether that’s years or decades, but it will be happening.
As an example, most anything built in WWII at waters’ edge that hasn’t been maintained has rusted or eroded or been battered apart by the sea. That’s 70ish years.
Beside just the consequences for tall building(s), if the normal ocean water level is above the current ground level in a city then 100% of the city’s underground infrastructure is underwater.
Every tunnel full of electrical cables is underwater and full of water. Every pipe and tunnel that’s supposed to carry fresh clean water is underwater and at risk of salt water intrusion. Every pipe or tunnel that’s supposed to carry away waste water and sewage will be underwater and at risk of saltwater intrusion. Any vents it may have to the outside air may now be under the sea. Any underground railroads are full of water. As are streetcar lines. All the roads and underpasses and maybe some overpasses as well. etc.
Pretty much everything is destroyed at least from an economic POV once sea water begins to wash over it in any depth more often than about once a decade. the only exception being stuff that was designed from the git-go to be immersed in sea water.
Since utilities are delivered from underground in a big city town center (i.e., to a skyscraper), you’ll have no utility service. No electricity, no running water, no environment control, and sewer service would be “stick your ass out the window.” :eek:
(As LSLGuy said.)
I doubt the building’s lower floors will tolerate wave action or salt-water corrosion very long.
I wonder if submersion would do anything to the buildings footings? If they’re piling-founded into bedrock, maybe not.
So basically a permanent flooding? I’m not a civil engineer, but after the floods we have here rather often*, I’d say it’s not good for buildings. Even if the water were stationary, the humidity seeps into the concrete or masonry, rises and weakens the stability. And I would expect that if the first floor of a Skyscraper crumbles after one or two years, the rest probably topples over, too.
Since NY is on the ocean coast, the flooding water would not be still, however, but there would be currents and maybe tides. That would cause damage to the wet, softened structure much faster - debris in the water knocks holes in walls, that Kind of Thing.
Aren’t a lot of technical Systems (HVAC and so on) in the Basement (along with parking garages), the water main, and the power cable coming from the street? So that wouldn’t work any longer.
In Addition to the structural damage, there’s also what the flood water brings along - not just debris, but sweeping up and re-depositing things like oil tanks ripped open. So poisinous substances may leak into the porous walls. (If the flood recedes, this is a Problem for clean-up, but this Scenario is a permanent flood).
Basically, if a City becomes flooded, move away?
*It takes only a few days for a flood to build, but weeks for the water to recede - and then, not only has the mud to be shoveled out and washed away before it hardens to Stone, experts have to go around and consider each house that was partly submerged whether it’s still safe to use or if the structual integrity has been damaged and it Needs to be demolished. Those are small houses compared to Skyscrapers, though.
I think after Superstorm Sandy, buildings in the New York area have been and will be built without critical infrastructure at or below ground level. Here’s an article from last month about a low-rent apartment building in Manhattan in which the boiler was relocated to the roof.
Heard part of the interview with the guy on SciFri today. Interesting. His scenario is that basically the skyscrapers, being built steel into the bedrock, would not collapse even as the facades on the lower floors do. Certain sections would be tidal zones. Major investments and technologies would be made adapting the structures for the new circumstances but, ehem, sunk costs being what they are many do not move and instead repurpose the city into a Venetian model.
He sounded like he researched it out well but I have no ability to judge.
My understanding is that some of the buildings in Venice, Italy already have their lowest floors flooded …
I’m reading the book at the moment, and thoroughly enjoying it.
He does seem to have done loads of research on New York and tidal flows, etc. but in the book he also makes use of graphene-based cladding materials which haven’t been invented yet.
Many building have collapsed, or are about to, but the north of Manhattan is high enough that the risen sea levels don’t cover some areas, even at high tide.
He’s known for the research he does for his novels, especially on climate change, so I’m willing to assume knows what he’s talking about.
[and they don’t even have a million tons of building sitting on them."]This is what wood and concrete piers look like after sitting in the Hudson River for a few decades and they don’t even have a million tons of building sitting on them.](This is what 100 year old wood and concrete piers look like (Hoboken) [/URL)
I actually studied civil engineering, so I kind of know what I’m talking about. Skyscrapers can certainly survive sitting in salt water for a few decades. They aren’t going to melt or anything. But their lifespans will be significantly shortened and actually using them would be impractical. There would be no roads or subway service (maybe New York Waterway ferries and Water Taxis). All the electrical, sewer and telecom services would be destroyed.
I’m guessing it would be a lot cheaper and more practical to build sea walls around lower Manhattan or put a Themes-like flood gate across the Narrows instead of trying to retroactively turn Manhattan into Venice.
The link is hosed.
The fact that problems just getting people in and out of the building would indirectly cause problems. No company would want to be in such a building. (Just rent out space further inland!)
Without tenants, maintenance of the building is pointless. So not only are the first floors being eroded away, the rest of the building will start to decay. The windows will blow out and not be replaced. The roof would leak. Birds would start to live in it (and their poop isn’t good for the structure). Etc.
Such buildings would be a hazard to the surrounding area and need to come down sooner rather than later. (The longer the decay, the riskier the demolition.) But if the surrounding area is a wasteland, maybe no one will care.
Thanks everyone for the interesting responses.
This makes me wonder how the buildings in Venice have managed to stay up through the decades (even centuries?).
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I was in Venice a few years ago. I was told that the buildings are designed to be resilient to flooding.
Power enters the building below the street level. So power would be a problem. The main switchgear is normally where power comes into a building. But water tight splices could be made and the switch gear and distribution could be moved up to an upper floor. Water pumps are on the lower levels, they could be moved up to an upper floor. Sewer lines would be a problem. any sumps sewer would no longer be useful and the buildings main sewer lines would have to be modified. All floor drains capped off and any sinks and toilets removed and capped off. Fresh water lines that end up under water would have to be protected or removed. Any faucets or outlet valves removed and capped. Any chilled water or heating water lines that are going to be under water would have to be capped off above the water level or protected. Any machine rooms would become useless. Elevators would have to be modified. Floors under water would have to be blanked off so the elevator could not go there. The end of the shaft would have to be moved up so anyone working on the elevator could stand on something solid along with moving all the equipment in the bottom of the shaft up to the new end of shaft. Any elevator wiring under water would have to be removed. Most of the machinery would already be on the roof and upper floors so that would not be a problem. But new entrance doors would have to be added along with landings for people to get off the taxi boats. And the steel supporting the building would have to be protected from corrosion.
Or you could just build a big coffer dam around the buildings and put in major pumps with emergency power supply.
Well good thing then that the hypothetical is not talking or asking about wood and concrete so much as about the steel skeleton.
The hypothetical is placed over 120 years in the future. Assuming no flooding and just the passage of time today’s skyscrapers will, with the exception of their steel skeleton’s embedded into the bedrock, be Thesueus’ ships. Heck the Empire State Building, built in 1930, already has had large amounts of its guts (elevators, electrical, heating and AC, windows, portions of facade inside and out) replaced and brought up to current requirements with more recent technologies, mostly done when it was only about half that 120 years out.
The question has to assume that that which is likely going to replaced over the next 120 years gets replaced with technologies developed over the next century in ways that adapt to a partially flooded city. It assumes that a critical mass decides to stay in buildings so modified and further that the work of adapting the spaces and the infrastructure to the flooded circumstance is a significant portion of the local economy.
Maybe it would make more economic sense to dam and dike off the area and have pumps running all the time, maybe not, but the hypothetical is that the decision to fight the tide lost to adapting to living with the tide.
But they aren’t modern skyscrapers built from concrete. These are three- or four story buildings. And Venice has a huge problem with the difference between “floods three or four times a year” to “a 100 days of each year are now flood” eroding the structures.
Yes: what’s technological possible and what makes economically sense are different. And what makes emotionally sense is not always the same as economically.
The time factor of the flooding is also a question. If you know in advance that in 1 or 5 or 10 years, everything on Manhattan will be flooded, but make the political decision to stay, the construction business would have time to adapt the buildings to withstand.
If people wake up one morning with 3 yards of water in Manhattan, it would be much more difficult to build a dam, pump the water outside, and repair the damage. Leaving it and rebuilding elsewhere might be cheaper.
The third option - if there is not enough space for rebuilding elsewhere - would be to erect stilt houses - probably not skyscrapers - where only the stilts are immersed in the water, bearing the platforms on which the houses are erected; or simply let the platforms swim (like floating houses in the netherlands Schwimmendes Bauwerk – Wikipedia who stopped building dams because climate changes makes water rise faster than they can build. So they accept flooding and build swimming structures).
From what I understand, the importance of Manhattan is not the island itself, but the fact that “everybody else important” is there. So an agreed exodus of “everybody important” to elsewhere would make just as much sense as a costly upgrade. If the upgrade/ change is spread over decades, the cost might be low enough to be bourne and not get upset, and stay. Transport - like high-rail trains instead of subways would have to be assured.
Worst case scenario … in a century, a six foot berm will provide Manhattan protection up to, but not including, remnant tropic storms like Sandy … a few centuries down the road, who knows what technologies will be available …
There’s a higher probability that before New York City gets flooded … Vancouver, Seattle and Portland will be reduced to rubble in fifteen minutes flat … so we’ll have learned how to replaced the skyscrapers in NYC by then …
To some extent, yes, but the reason that New York is located where it is is because it’s the best port on the East Coast of the US. Some infrastructure like docks and container ports depend for their utility on being right on the coast. If the coastline is continually moving inland then it will be impossible to build port facilities that will last for any length of time.