Wellies out in Venice as 'acqua alta' hits

Venice - Venice residents donned their wellies Monday as the second 'acqua alta' (high water) of the autumn hit the lagoon city. The water level was measured at 102 cm above sea level, at which 7% of the city centre is flooded.

However, sirens did not blare out nor pontoons come out as the 'acqua alta' was lower than the 110 cm above sea level at which citizens are alerted to the phenomenon.

"We were expecting this. There's been a surge in tides, heavy rain, and the sirocco winds on top," said a local weatherman. The first acqua alta of the autumn was on September 25, at 105 cm.

More high water is forecast for November 1 and 7.

The high-water threat has been increasing in recent years as heavier rains have hit northern Italy due to climate change, weather experts say.

However, the record acqua alta is still the great flood of 1966, at 194cm, when flood waters caused huge damage.

Levels of 120-140 cm above sea level are quite common in the lagoon city, which is well-equipped to cope with its rafts of pontoon walkways.

But anything much higher than 150cm risks swamping the city and washing the walkways away, as happened in December 2008 (156cm), December 1986 (158cm) and December 1979 (166cm).

Scientists have conceived various ways of warding off the waters since the catastrophic 1966 flood and a system of moveable flood barriers called MOSE is being installed after years of polemics.

Experts say there are three main reasons for high water in the city: the rising floor in the lagoon caused by incoming silt; the undermining of the islands by the extraction of methane gas in the sea off Venice; and the overall increase in sea levels caused by global warming.

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