Italian authorities say half of Venice is set to be flooded after high tides and heavy rains combined in a phenomenon known as the ' acqua alta '.
A third of the lagoon city is already under water as waters passed the 125-centimeter mark amid an unrelenting wave of rain across Italy. The 'acqua alta' or high water covers low-lying areas like St Mark's Square, forcing tourists to wade across the landmark piazza. While many are having fun with the pleasant scenery caused by the acqua alta, some are worried that the floods that have swamped Venice could threaten the treasures of Western art and undermine the very fabric of the city. Water routinely spills over Venice’s banks all through the high-tide season, which lasts from autumn to spring, flooding the city’s streets and squares. The highest-ever acqua alta took place during the great flood of 1966, when high water went over the 194-cm level and caused major damage. Acqua alta is triggered by both natural and man-made causes. Italian authorities started pumping groundwater for industrial uses in the 1930s, causing the city to settle into the earth and causing significant damage to
the delicate foundation. By the 1970s Venice started sinking, prompting officials to call off the practice. Weather experts say the high-water threat to Venice has been increasing in recent years as heavier rains have lashed northern Italy. Other possible explanations for the phenomenon include the sea floor rising as a result of incoming sludge and gas extraction in the sea off Venice.