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Floodgate system to protect Venice from high water passes test

  • Floodgate system to protect Venice from high water passes test
    Acqua alta floods in Piazza San Marco. Credit: Wolfgang Moroder. Wikipedia.

The floodgate system built to protect Venice from flooding was tested last Saturday and worked as intended: water levels inside the lagoon where the city is located remained stable when the tide reached 4 feet (1.22 m), reports The New York Times.

The project to protect the city from high tides using mobile barriers, known as Mose, had been designed four decades ago, but throughout the years experienced problems including corruption, cost overruns and opposition from environmental groups.

All 78 gates closed off the lagoon from the sea by 10 a.m. Without the flood barriers, half the city’s streets would have been flooded, and St. Mark’s Square would have been in some 1.5 feet of water (45 cm), said Alvise Papa, director of the city’s department that monitors high tides. During the test “there wasn’t even a puddle in St. Mark’s Square”, he said.

In November 2019, flood levels peaked at 1.87 metres, the second highest level since records started in 1923, flooding more than 85% of the city, affecting businesses and causing damages to historical buildings. Mayor Luigi Brugnaro blamed the devastation on climate change.

Flooding in Venice is common, and residents are used to dealing with acqua alta (high water), a term used in Italy’s Veneto region for the exceptional high tides that occur in the northern Adriatic Sea mostly in the winter. While the city is practically not affected by a tide of 3 feet (90 cm) above sea level, tides reaching more than 4.5 feet (140 cm), considered exceptional, have been increasingly more common in the past 20 years. Sea level rise associated to climate change and natural and human-caused subsidence both contribute to Venice’s sinking.

Last Saturday mayor Brugnaro tweeted “Everything dry here. Pride and joy.” The floodgate system still has to become fully operational; construction companies have to finish the work by December 2021. For now, the system will function when the tide reaches 4 feet (122 cm). Once the project is completely operational, the barriers will close off the lagoon when the tide goes up to 3.5 feet (1.06 m).

Project opponents think it will not solve the threats posed by climate change, as rising sea levels could force the gates to be closed so often that ship traffic would be hindered and the lagoon could be cut off from the sea for up to 150-180 days per year. “If the lagoon is cut off from the sea for long periods, it dies, because the natural exchange of waters stops, and all of its organic life risks decaying,” said Cristiano Gasparetto, architect and former provincial official. And he added: “If the lagoon dies, Venice dies”. The costs of maintaining the system are also a concern.

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