“Italian experts are proposing a dramatic new solution to the watery threat facing the city of Venice,” the BBC reports.
“Rather than battling to keep the sea out – they want to use it to help raise the sinking island-city. The scheme would involve pumping huge quantities of sea water into the ground beneath Venice down 12 pipes each of which would be 700m (765 yards) long. The sea water would make the sand beneath the city expand lifting Venice by 30cm (11.8 inches) in 10 years.”
This, of course, comes after the so-called “Moses Project,” which, as the BBC describes it, is “a series of 78 mobile steel barriers to be activated during exceptionally high tides. The barriers, due to be in place by 2011, will lie on the seabed most of the time, but will be filled with air to create a dam when Venice is threatened.”
Of course, soon they’ll just put the whole city atop a mechanized webwork of spindly little hydraulic legs that will stand up and walk inland – taking the Bridge of Sighs with it. The fully automated Robo-Venice of the future.
Meanwhile, for comparison, there’s always the Thames Barrier –
– but everyone knows that won’t save us…
fascinating.
Then there’s this from the New Scientist:
“Venice’s problem is largely one of subsidence, both natural and man-made. From the 1930s to the 1970s, fresh water was pumped out of underground reservoirs beneath the city to supply surrounding factories. As the water was pumped out of these aquifers – which are rather like rocky sponges – their water-filled pores compressed and the ground sank. Combined with sea-level changes, this has produced an effective rise in sea level of 23 centimetres over the past 100 years. Water is no longer being extracted but natural subsidence, probably caused by plate tectonics, is continuing to drag the city down by 0.5 millimetres a year. Add to that the problem of rising sea level and it is clear that Venice’s predicament is getting steadily worse.
“Numerous plans have been proposed to prevent Venice succumbing to the floodwaters, many of them controversial. But if the latest idea gets the go-ahead it will raise more than a few eyebrows. Rather than trying to control the rising water level by keeping the sea out, engineers at the nearby University of Padua want to lift the entire city out of harm’s way by raising the ground upon which it sits.”
The plan is good but leaves out an additional step once the aquifer is expanded to pump sand in to make the rise more permanent. Over time (years) the cycle of pumping could be repeated expanding the aquifer beds and pumping more sand in.
This approach could possibly be modified by pumping concrete down to the edges of city aquifer beds to create a barrier to prevent migration of water out from beneath the city. I doubt feasibility of these methods have been pursued to any great extent to date but its time we do!