SCI/TECH: A radical plan to save Venice

Eschewing conventional flood defences a team of geologists at Padua university hope that hydraulic forces will help them save Venice from flooding . they intend to pump millions of gallons of water under the city , forcing it to rise above the encroaching sea



Well wow . I hope it works , it sounds totally counter intuitive . pumping water into sand equates to " quick sand " in my mind

how quicksand works

I guess the geologists must be confidant that there is an impermeable layer above the zone they want to pump water into , strong enough to ` float ` the city on .

While Venice is not prone to earthquakes , the phenomenon of " liquefaction " springs to mind , given that they intend to create a low density fluid pocket under the city

how liquefaction can affect structures

The aesthetic benefits of a dyke free flood defence system are appealing , but is it worth the risk ?

While Venice is not prone to earthquakes , the phenomenon of " liquefaction " springs to mind , given that they intend to create a low density fluid pocket under the city

Italy is prone to Earthquakes, so it is a risk.... I wonder if they have thought of that?

2001 07 17 Northern Italy 4.7
Two people killed and one person missing and presumed killed by landslides near Gargazzone and Val D'Ultimo. One person died of a heart attack at Bolzano. At least 3 people injured and minor damage in the Merano area. Felt throughout northeastern Italy as far south as Venice. Also felt in Austria, Slovenia, Switzerland and southern Germany.

Source

Mexico City is sinking also, and in that case its accelerated because the underground water in the pore spaces of the sediment and rock is being pumped out for drinking water. Looks like the Venetians are trying to do the reverse. Surprising, but interesting.

This sounds interesting, but only a short term solution IMO. If they would stop pumping the water, it would probably sink again. Do they plan on doing this forever? Maybe soon they will have more than one leaning tower to draw tourists.

Italy has alot more than the Leaning Tower of Pisa to draw tourists. Plus, it isn't in Venice, it's in Pisa.

Thanks for the geography lesson, Stu, though unnecessary. That was my lame attempt at humor.

But I still say this is a futile attempt because the sea levels are going to continue to rise. Like New Orleans, they have a history of flooding and it is not a matter of if, but when. I think they should consider moving landmark buildings further inland.

They also have other plans to help prevent flooding.

Some recent studies have suggested that the city is no longer sinking, but this is not yet certain; therefore, a state of alert has not been revoked. In May 2003, Silvo Berlusconi, the Italian Prime Minister, inaugurated the “Moses” project, which will lay a series of 79 inflatable pontoons across the sea bed at the three entrances to the lagoon. When tides are predicted to rise above 110 centimeters, the pontoons will be filled with air and block the incoming water from the Adriatic sea. This challenging engineering work is due to be completed by 2011.

en.wikipedia.org...

Thanks for the geography lesson, Stu, though unnecessary. That was my lame attempt at humor.

No worries I actually taught myself something in the process. I saw your comment about the Tower and thought "is that in Venice?", so I learned something myself.

when I read the article my concern was more of how they could be sure to get the same amount of water in the different holes -- if one side were to raise quicker than another it would break buildings and bridges.

Originally posted by Hal9000
I think they should consider moving landmark buildings further inland.

And how do you propose we do this?

With a rope and tractor perhaps...


Mic

here is a bit of a dumb drawing of how it should work :



the planned " lift " is only 250mm , so even if cracks apear in the bedrock - anysort of catastrophic faiure is unlikley


as for ensuring a stable lift - they will be able to measuire the pressure at each ` well head ` and measure the flow rate of how much water is pummped in . i have some experience of using air bags and hi pressure mats for lifting - its just the same principle on a city wide scale

my concern is , how can they be sure that the areas they are pumping water into will retain the pressure they require ?

Originally posted by MickeyDee

Originally posted by Hal9000
I think they should consider moving landmark buildings further inland.

And how do you propose we do this?

With a rope and tractor perhaps...

It can be done for buildings that are worthy of the effort. This is being done in China for the Three Gorges Dam Project for ancient buildings that are below the water line.

Each brick, tile and pillar of the ancient buildings will be marked and disassembled, and then restored at the new site. Some parts of the buildings too old to be moved will be replaced by materials similar to the original ones.

english.people.com.cn...

If it was built once, surely it can be disassembled moved, and rebuilt. It is just a matter of cost. For Venice the scale would be monumental given the number of buildings. But it will have to be done eventually. Raising the entire area 30 cm will only prolong the inevitable. The lower levels of these buildings have already been abandoned, due to the area sinking and water levels rising.

en.wikipedia.org...

edit: And it is only going to get worse due to global warming. It will take 10 years to raise the area 30 cm, and sea levels could rise that much in the next 30 years. So they will be back to where they started from.

Worldwide, sea levels are expected to rise between 0.09 and 0.88 meter (0.29 and 2.88 feet) between 1990 and 2100, the report said, citing figures from the Intergovernmental Panel on Climate Change.

go.reuters.com.../scienceNews

[edit on 11/23/2005 by Hal9000]