VENICE, Italy, Dec. 3 (UPI) -- The first "acqua alta" or high water of the winter swamped Venice's historic district Friday, including St. Mark's Square in the heart of the city.
The water rose to nearly 4 1/2 feet above sea level, the Italian news agency ANSA reported. More than half, 55 percent of the city, was underwater.
The city uses pontoon walkways to allow residents and visitors to stay dry during periods of high water. But those in St. Mark's Square had to be taken away Friday because of the risk they would be swept into the lagoon.
While the disastrous 1966 flood, when water levels reached 6 feet-4 inches above sea level, remains the worst in recent Venetian history, officials say high water has become more common in recent years.
They blame a build-up of silt in the lagoon, the undermining of the Venetian islands by offshore drilling for natural gas and general sea-level rise caused by global warming.
The current flooding is linked to high tides during the new moon and recent heavy rain. Experts say it would be even worse if the sirocco, high winds originating in the Sahara Desert and most common in November and March, was blowing. UPI