Fighting Water with Water: To Lift the City, Pump the Sea beneath Venice

Article excerpt

With technology commonly used in oil fields, engineers say they could inject seawater into sandy strata deep beneath Venice, Italy, to boost the subsiding ground that now aggravates flooding there.

Venice, which is known for its architecture, bridges, and gondola-filled canals, is slowly losing ground. Over the past century, land beneath the city subsided almost 12 centimeters, and the sea level rose almost 11 cm. That net increase in water level significantly exacerbated flooding, says Giuseppe Gambolati, a hydrologist at the University of Padua in Italy.

One government-approved project to protect Venice includes inflatable barriers that will be raised when severe storms boost the water level in the surrounding lagoon more than 1.1 meters above sea level, says Gambolati. Despite its multibillion-dollar cost, that future system isn't designed to protect Venice against smaller floods. Even when waters reach only 80 cm above sea level--which they do dozens of times annually--the plaza in St. Mark's Square is submerged.

At many sites around the world, the oil-drilling industry injects large volumes of water into petroleum-bearing rocks to increase the pressure there and ease the extraction of oil. That technique often prevents ground overlying the oil from subsiding and sometimes even pushes the ground upward, says Gambolati. …