To Keep Venice From Going Underwater, Researchers Say, Pump Water Under Venice

By Valerie Ross | December 29, 2011 2:19 pm

Flooding in Piazza San Marco, Venice

Venice is sinking, and the nearby Adriatic sea—like the global sea level—is rising. The city could, some estimates suggest, be underwater by the end of the century. Much of the trouble is due to Venice’s precarious, low-lying position in the middle of a lagoon, but human activity in the area has played a role in the city’s subsidence, as well. As Scott K. Johnson explains at Ars Technica:

The pumping of shallow groundwater in the mid-1900s also contributed to the problem. Water in the pores between grains of sediment provides pressure that bears some of the load. When pore pressure decreases, or water is removed completely, grains can be packed together more tightly by collapsing the pore spaces. As sediment is compacted, the land surface drops. While the effect was small (less than 15cm), Venice doesn’t have much wiggle room.

One possible solution to the problem may be, in essence, reversing what was done last century: rather than pumping groundwater out from under Venice, some scientists suggest, it’s time to pump it back in. While injecting water won’t undo all the damage, it can stop subsidence—and even slightly lift an area. The technique has worked before; it halted the downward creep of Long Beach, California, half a century ago, as nearby oil extraction caused the city to sink.

In the current study, Italian researchers modeled how groundwater injection would work in Venice and found, happily, that the technique would likely be a success:

The group simulated the effects of 12 injection wells in a ring around the city. The results showed that, after 10 years of continuous seawater injection (a total of almost 150 million cubic meters of water), the city could be lifted 25-30 centimeters.

What’s more, the researchers modeled how carefully calibrated pumping rates could keep Venice level as it rose, safeguarding the city’s venerable architecture and historical landmarks.

Read more at Ars Technica.

Image courtesy of Rene Cunningham / Flickr

  • MikeG

    Why don’t they investigate the use of Dutch type dykes?

  • OliverJ

    Because it would ruin the beautiful view around Venice. Also, the city needs to have easy access to the sea, as the city depends on boats.

  • Bruce Golden

    very low probability of any rebound, these aquifers have the same plate-like sands as the Houston/Baytown Texas area. When these aquifers are pumped, the sand slides and slips so that the plate surfaces collapse together. Once this occurs, no rebound is possible unless water and air is pumped in with sufficient pressure(turbulence/velocity) to “fluff” the grains and re-establish some edge of plate to center of the next plate contact and the resulting larger “void” zone. Practically speaking, is uneconomic and with the very shallow Venice aquifers, substantial probablilty of breakthrough to the surface and complete de-pressurization of the aquifer.

    would have some success if use mud-jacking or the equivalent.

  • Victor Grauer

    Why not simply repave it, or at least repave the peripheries, adding a layer of roughly 1 foot of concrete? Also, if Global Warming is causing the sea to rise by the dangerous margins now being predicted, why isn’t Venice in a lot more trouble than it is? As I understand it, the sea has been rising around it for centuries.

  • Mike

    How can 15 cm be considered “small” in light of the global sea level rising being a problem? Drop 15 cm of water out of that picture and would it be close to dry? Surely would make the tidal effect a much shorter period each day.

  • http://n/a m

    Better to spend that money on building another layer. Raise the buildings (you wish to save) up by putting an EXTENSIBLE LAYER in at the base, which in 50-100 years can be increased again easily.

  • http://none Bill Carruth

    Gotta idea. How about pumping water into the pie holes of the GOP candidates for president. With luck they – one at a time- would be ‘lifted’ and eventually float away never-ever to be heard from again.

    Meanwhile, let’s save Venice and all the history surrounding. Good luck!

  • Geack

    @ 3. Bruce,
    Your argument is based on what, exactly? I suspect that the people who studied the area geology and concluded there was a good chance of success have at least as good a grasp of the local sediment structure as you do.

    @1. Venice isn’t built on a low spot next to the ocean – it’s mostly built on piers, IN the lagoon. Isolating it from the ocean would be very difficult, aesthetically unacceptable, and more expensive than the pumping concept, plus it would introduce a whole bunch of unpredictable new conditions.

    @6. Another layer of what, built where? Most of the city is built on tens of thousands of wooden piers driven into the mud bottom of the lagoon. No good place to slip in another layer of some magical extensible material.


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