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Old 11-14-2019, 06:07 PM
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Can Venice Be Saved?


I mean in general, not just with regard to the current situation. The city is sinking, global sea levels are rising, shit's getting real. Can anything be done -- for example, somehow artificially raising it a couple of meters or something?
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Old 11-14-2019, 06:12 PM
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No.
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Old 11-14-2019, 09:28 PM
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No.
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Old 11-15-2019, 12:17 PM
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Sorry for the snarkiness. What I should have said is, Venice was a lost cause before global warming began causing catastrophic weather events. It was already subsiding to the point that flooding had become a regular feature.

Post ice-cap melt, all low-lying coastal cities are going to become unviable, and sadly Venice is going to one of them.
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Old 11-15-2019, 12:25 PM
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I was saddened to see such beautiful buildings flooded. Venice is a great city, and I’ll never forget it.

The Mose barrier is said to be able to keep out 3m tides. If it gets built. There are concerns it might hurt the water flow and local ecosystem. But it’s hard to see much alternative.

Realistically, Venice has far too many tourists and greed should not be allowed to trump local concerns for the number of cruise ships and viability. Parts of the city are very low and are going to flood, in all likelihood, regardless of barriers if world water levels continue to rise.

But this isn’t the first such event. Venice flooded 50 years ago. The icebergs and Goobal weather patterns have shown the truth of climate change for some time.
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Old 11-15-2019, 03:04 PM
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But this isn’t the first such event. Venice flooded 50 years ago. The icebergs and Goobal weather patterns have shown the truth of climate change for some time.
See my post in the other Venice thread about the several other floods since 1923. They are becoming more and more common. This is only a 50 year event in the sense of maximum severity. There have been many nearly as bad ones in between.

Last edited by ftg; 11-15-2019 at 03:04 PM.
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Old 11-14-2019, 06:30 PM
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Double post

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Old 11-14-2019, 06:31 PM
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There's the MOSE flood barrier, if it ever gets built:

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Following the worst flooding in its history in 1966, the Italian government asked engineers to draw up plans to build a barrier at sea to defend one of the world’s most picturesque yet fragile cities from the constant threat of high tides.

Fast forward to 2003 and construction finally started with completion set for 2011. But the project, known as Mose, has been plagued by the sort of problems that have come to characterize many major Italian construction programs — corruption, cost overruns and prolonged delays.

Engineers are now predicting the sea defense system will go on line at the end of 2021 at a cost of 5.5 billion euros ($6.1 billion) against an original estimate of 1.6 billion euros.
https://www.reuters.com/article/us-i...-idUSKBN1XN2EQ
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Old 11-14-2019, 06:35 PM
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the project, known as Mose, has been plagued by the sort of problems that have come to characterize many major Italian construction programs — corruption, cost overruns and prolonged delays.

Engineers are now predicting the sea defense system will go on line at the end of 2021 at a cost of 5.5 billion euros ($6.1 billion) against an original estimate of 1.6 billion euros.
That's still a helluva lot more efficient than Boston's Big Dig (originally estimated to cost $2.6 billion, final cost over $24 billion).
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Old 11-14-2019, 06:52 PM
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I'm not an engineer, but it looks like it would be feasible to block off the Venetian Lagoon. Much of the Netherlands is below sea level, and protected by dikes, dams, and floodgates.
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Old 11-15-2019, 02:26 AM
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It is possible, by blocking off the entire lagoon like Walken said and pumping water out to lower it, like in the Netherlands. But that would cause even more ecosystem damage than MOSE is already likely to.

MOSE by itself won't save Venice, only lessen the flooding.

There's also the possibility of raising the subsiding foundations by jacking up individual buildings and pumping something under them. But that's mega-engineering orders of magnitude beyond MOSE.
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Old 11-15-2019, 05:23 AM
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There is an argument that Venice has already been lost as a viable city, anyway. It's essentially just a tourist attraction these days.
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Old 11-15-2019, 08:50 AM
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Q: Can Venice be saved?

A: How much money do you have on you?

There are staggering costs involved in really doing anything significant.

An alternate solution: making the flooding the attraction. Build up permanent raised walkways for the tourists. Have the tour guides go "Hey, you're walking 3 feet above what used to be the old sidewalk level just 50 years ago. Isn't that great?"

It'd be like Pompeii only recent water and not old ash.

Last edited by ftg; 11-15-2019 at 08:50 AM.
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Old 11-15-2019, 09:28 AM
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I saw something years ago about injecting fluids into porous sediments. I have no way of evaluating the cost or efficacy.
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Old 11-15-2019, 10:34 AM
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I saw something years ago about injecting fluids into porous sediments. I have no way of evaluating the cost or efficacy.
This was done in Long Beach - They clawed back around a foot ... from 30 ft of subsidence. That's not going to make enough of a difference to Venice even if the geology is right for it.
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Old 11-15-2019, 10:26 AM
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Over half of New Orleans is below sea level. (1-2 feet below)

So huge levies all around Venice and pumps to keep the water level from getting too deep (so canals still but the buildings would still be usable). If the USA could do it in New Orleans early in last century, Europeans can do it now.

Also, New Orleans periodically will face hurricanes that put extreme stress on the pumps and levy structure. Does Venice face any sort of comparable extreme weather?
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Old 11-15-2019, 10:36 AM
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Does Venice face any sort of comparable extreme weather?
Medicanes.
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Old 11-15-2019, 11:51 AM
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So huge levies all around Venice and pumps to keep the water level from getting too deep (so canals still but the buildings would still be usable). If the USA could do it in New Orleans early in last century, Europeans can do it now.
Capability is not the issue. Funding is. Esp. since the lagoon with all it's arms and inlets is a busy shipping channel.
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Old 11-15-2019, 12:08 PM
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The long term answer is 'no'. Just like me city of Charleston, SC the downtown is doomed barring truly Herculean engineering efforts that are not worth it in the long run.

We've made our decisions and we'll have to live with our losses. There's not a lot to be done other than to move and abandon the things that are lost. I know - we all know here - that the battery and shopping district downtown is going away. You can already see it in how builders are moving inland for commercial and industrial development instead of moving up and down the coast as they have before. Residential builders, of course, continue to sell beachfront property to suckers. That's going to continue until NFIP finally stops issuing flood insurance on the Carolina coast.
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Old 11-16-2019, 07:39 AM
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Re: Netherlands, you can raise polders through deliberate flooding into a central depression and redistribution of the sediment, but that's easier with farmland. Hard to scoop dirt under a cathedral.
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Old 11-16-2019, 09:28 AM
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Ignoring global warming and rising sea levels - the problem is pumping out the groundwater from the underlying geology. This groundwater abuse apparently has been stopped for several decades which has stopped the subsidence. Venice is no longer sinking. However, it is still down a ways from its historic point. The lowest areas, like St. Marls Square, flood pretty much every fall at high tide. It did while we were there, about 1 foot in the square. They put out raised wooden walkways for the tourists to get to the basilica. The steps at the doorway and the various buildings tend to have raised doorway, or some shops and restaurants just deal with the foot of water that is a regular feature. Further into the city, they are high enough the water is not a problem. It does come up - backward - through the storm drains, and in some places you have to walk around the water that looks like rain puddles; some of those quaint footbridges are too low for gondolas to get under during high water. (I saw one gondolier lying down and pulling himself through under a bridge. he had to tilt the gondola a bit for the bow and stern to clear the bridge)

The city was built over the centuries using large wood piles (think telephone pole sized) and pounding them into the mid for foundations. Then it was built up with stone construction. You aren't going to raise many of these buildings the way you could more modern, more solid construction. Quite a number of the older buildings (Sorry, they're all old) have steel rods running through the building and plates on each outside to stabilize the rock/brick walls, so they're already at risk. Uneven movement of the piles over the centuries also causes problems - the floor of the basilica is wavy due to ground movement.

They had imposed limits on number of boats and speed through the city due to concerns that wake from motorboats was eroding the foundations of buildings facing canals.

So you're not going to raise the city - just not practical, nor survivable. Water control? One of the big concerns was, that the lagoon was self-flushing - the tides and river flows ensured a regular turnover of water that helped with the ecosystem. Messing with the shape or volume of the lagoon, building out or building too many causeways or dikes, would completely mess up this natural flow with disastrous results. Diking off the city would basically destroy the character - unless you had a massive pump system continuously operating to maintain a water level lower than standard sea level, or trickled in water to keep the lower level and destroyed the ecology. With a lagoon where in many spots fishermen could stand less than waist-deep and dig in the mud for shellfish, etc. - how long in a closed off lagoon before erosion fills it up enough and it becomes a swamp instead of open water?

Amsterdam is often cited as the Venice of the North, but my experience was that it was built quite a few more feet above sea level = canal levels there are typically 8 to 10 feet down from street level, whereas in Venice they are only maybe 3 feet down in some places. In others, they are pretty close to ground level.

Project Moses seems to be the most practical solution - block off the worst of the high tides temporarily. The effect (so far) is tidal, meaning the high water lasts for a few hours at a time, worst case for a few days, when sun and moon coincide and storm surges line up with that phenomenon.

But then there's global warming. How much sea levels with rise is open to debate, but any rise, even a foot or two, is bad for Venice - even though that doesn't hurt generally, in the extremes of tide and weather, it does - bigly. Add in the likelihood of more frequent, more powerful storms and we will see much more of what we are seeing today. Some day, the Project Moses gates will not be enough. But if 3m storm surges become common around the world, Venice will be crowded out of the headlines by other disasters.

Can Venice be saved? Not if it is to stay the same. We can only postpone the inevitable, and hope head-in-the-sand works and that the climate deniers are right or a new ice age is coming very quickly. 150 years from now? I fear a few of the main areas will be diked off and available to tour, and the rest will be visible from boat tours through the ruins.

Meanwhile, Venice is barely a city any more. The population has dropped by half, and is getting much older as young people cannot afford to live there. Movie stars and one-percenters are buying up all the available housing. Much of the industry has left for the mainland, and it is basically a giant tourist attraction, and overwhelmed as that. The extremely old buildings often require extensive maintenance; building anything new requires reams of permits and needs to match the character of older buildings, but if too much new construction happens, then it won't be the same tourist attraction any more. For now, enjoy it if you can as an example of what life was like before wiring and automobiles invaded.
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Old 11-16-2019, 12:53 PM
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There’s a nice Scientific American article from 2002 discussing the problem and MOSE. But the walls will be obsolete if there is much ocean rise, and the engineers felt winds would not be a problem. However, wind seems to be one current cause. They made a lot of similar assumptions.
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Old 11-16-2019, 03:13 PM
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One shouldn't expect a barrier that is only used in the highest tides would be used only a few times here and there. And it will also have a short* lifespan before it has to be replaced or significantly upgraded.

The Thames Barrier was expected to be used 2-3 times a year. It was used 50 times in the 2013-14 season.

It was opened in 1982 and expected to last until 2030. It will still be useful for a while after that but they need to start seriously working on a new barrier fairly soon.

And that means even more £s.

Otherwise, they'll be experiencing the situation shown in the fine documentary Split Second.

* Compared to the lifespan of a city like Venice.
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Old 11-16-2019, 03:33 PM
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Could it be saved. I think certainly yes it could. We seemingly have the ability to do that and I don't think it's in question. There are several ways it could be done listed here. It appears feasible to close off the inlets during the highest water mark. If needed the city could also be dyked and the ability to pump out adding a second layer of protection. Parts of the city can be raised which would be a more long term evolution, and complicated by the historic way this city was built. Water exchanges and the removal of stagnant city water would need to be considered in these plans.

Will it is another question, do people have the determination and want to spend the money to build and maintain a continuous defense against the sea? But this is seemingly not your question.
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Old 11-22-2019, 11:31 AM
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Between a short news cycle/attention span, and all things Trumpian, I noticed that the Venice floods have disappeared from my local news.

But I understand the floods are still there. There were a few spiteful articles that saw humour in the fact local Venitian politicians opposed climate change. Perhaps not all politics are local, after all.

We know the Mose system is a day late, a dollar short and may only last a few decades at best if it works. Venice is an irreplaceable treasure. London and the Netherlands have had some success in large scale hydro engineering, but apart from Italian problems, Venice seems more difficult still (being more than a hundred islands). So if money were no object, what should Venice do?
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Old 11-22-2019, 12:15 PM
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So if money were no object, what should Venice do?
The short list should include consulting the Dutch. If they haven't already, anyway.
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Old 11-22-2019, 12:20 PM
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So you're not going to raise the city - just not practical, nor survivable. Water control? One of the big concerns was, that the lagoon was self-flushing - the tides and river flows ensured a regular turnover of water that helped with the ecosystem. Messing with the shape or volume of the lagoon, building out or building too many causeways or dikes, would completely mess up this natural flow with disastrous results. Diking off the city would basically destroy the character - unless you had a massive pump system continuously operating to maintain a water level lower than standard sea level, or trickled in water to keep the lower level and destroyed the ecology. With a lagoon where in many spots fishermen could stand less than waist-deep and dig in the mud for shellfish, etc. - how long in a closed off lagoon before erosion fills it up enough and it becomes a swamp instead of open water?
This actually seems to me to be the most practical solution, short of dismantling the entire city and rebuilding it elsewhere. Cofferdam the whole thing and control the water going in and out. Perpetually keep it at a reasonable level and protected from outside floods and tides (those cofferdam walls will need to be high).

Rebuild the sewer system -- or build one in the first place -- so that you don't have to rely on the tides flushing out the sewage from your canals. The city will be a lot cleaner and the odor (which apparently tourists complain about quite a bity) will be gone. You can also build a more reliable fresh water supply.

This way you keep the city's canal -based character, you clean up a mess of many century's standing, you keep the city in a water-filled environment so that you don't have problems with pilings shrinking or whatever. You keep the ecology of the Venetian Lagoon intact (except for where the city is).

The only problem is that it will be EXTREMELY expensive and take a long time. But it's the only thing I can see -- outside of completely moving the city -- that will preserve it in the face of global warming and rising sea levels.
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Old 11-23-2019, 06:59 AM
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... Rebuild the sewer system -- or build one in the first place -- so that you don't have to rely on the tides flushing out the sewage from your canals. The city will be a lot cleaner and the odor (which apparently tourists complain about quite a bity) will be gone. You can also build a more reliable fresh water supply. ...
BBC has a program Italy's invisible cities, where they build 3D reprsentations of different Italian cities. As part of this, they did some diving in one of the canals. I had had no idea how hazardous it is to fall into the canal water. Swimming in the canals
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Old 11-23-2019, 01:36 PM
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Well, I suppose at least with flooding the canals will be flushed better. I assume the canals further away from the main body of water never flush properly in normal tides. One thing I noted was that some areas of some canals also accumulated floating garbage (like discarded water bottles) and that tended to build up in certain locales - probably again due to flow patterns and incomplete flushing.

When I was last there, way back in 2001, I noticed several smaller canals "under construction". They had coffer-dammed the ends and drained them to fix eroding sides and remove some of the accumulated sludge - and repair any piping in there. After all, even if they don't have sewer pipes, there is still water supply, plus cabling for assorted services. Another thing you would see was extensive areas of walkway lifted and massive electrical cables snaked under the cobblestones, being repaired. Keeping the city modern yet antique is an art.
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Old 11-24-2019, 04:28 AM
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Rather than fighting the rising sea levels, perhaps the opposite approach should be taken, by reinforcing and waterproofing the first floors of all the buildings. Raised walkways would allow tourists to get around, and outside stairways would allow access to second floors. Buildings of major historical value could be made watertight. so that bottom floors will not flood.
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Old 11-24-2019, 06:51 AM
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Rather than fighting the rising sea levels, perhaps the opposite approach should be taken, by reinforcing and waterproofing the first floors of all the buildings. Raised walkways would allow tourists to get around, and outside stairways would allow access to second floors. Buildings of major historical value could be made watertight. so that bottom floors will not flood.
A lot of current first floors were actually second floors when the constant flooding made the first floors unusable.

So, you're really talking about waterproofing, etc. the 2nd floors.
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