Thursday, March 22, 2012

Venice hasn't stopped sinking after all

Terra Daily via SPX: The water flowing through Venice's famous canals laps at buildings a little higher every year - and not only because of a rising sea level. Although previous studies had found that Venice has stabilized, new measurements indicate that the historic city continues to slowly sink, and even to tilt slightly to the east.

"Venice appears to be continuing to subside, at a rate of about 2 millimeters a year," said Yehuda Bock, a research geodesist with Scripps Institution of Oceanography at the University of California, San Diego, in La Jolla, Calif., and the lead author of the new article on the city's downward drift. "It's a small effect, but it's important," he added.

Given that sea level is rising in the Venetian lagoon, also at 2mm per year, the slight subsidence doubles the rate at which the heights of surrounding waters are increasing relative to the elevation of the city, he noted. In the next 20 years, if Venice and its immediate surroundings subsided steadily at the current rate, researchers would expect the land to sink up to 80 mm (3.2 inches) in that period of time, relative to the sea.

Venice's subsidence was recognized as a major issue decades ago, he noted, when scientists realized that pumping groundwater from beneath the city, combined with the ground's compaction from centuries of building, was causing the city to settle. But officials put a stop to the groundwater pumping, and subsequent studies in the 2000s indicated that the subsidence had stopped, he said....

Some flooding in Venice, shot by Xell, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 2.0 Austria license

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