Venice underwater

Focus Information Agency: More than half of Venice was under water Wednesday as two days of driving rain helped push the acqua alta (high water) to 143 cm above sea level, a record for the year and the 11th-biggest since records began, Rai Radio 1 reported.

Venetians were getting about on pontoon walkways in the estimated 56% of the city that was flooded, including St Mark's Square and the historic centre. "As well as the rain, which played a big part, strong sirocco winds swelled the flood tide, combining to bring one of the biggest recent events", experts said. The first big tide of the year was on November 30 when the water rose 131cm above normal. When the waters get that high some 43% of the city surface is under water.

Next month, experts say, forecast bouts of more heavy rain could push the sea level to 150cm above normal, the highest acqua alta since 156cm last December, 158cm in December 1986 and 166cm in December 1979. The record acqua alta was in 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. The high-water threat has been increasing in recent years as heavier rains have hit northern Italy due to climate change, weather experts say. 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….

High tide in Venice, shot by Paolo da Reggio, who has generously released the image into the public domain