Acqua alta is a Venetian phenomenon that has been the subject of novels, scientific papers and movies. It has captured the imagination of the world, but to the Venetians it is a threat to their homes, offices and many of the historic buildings located in their city. Not to mention wading through water 60 days a years is a nuisance at best.
What exactly is acqua alta? It is the high water that reaches to the average person’s knees around 60 times per year. The cause of the high water is the sinking of the city combined with the rising level of the Adriatic sea and higher tides.
Sandbags are placed at the doorways of buildings throughout Venice including St. Mark’s Basilica and the Doges’ Palace. Raised plank walkways are set up around the piazza in Venice so tourists and residents can walk without getting wet feet.
When Venice was founded about 1600 years ago the Adriatic’s standard sea level was almost six feet below what it is today. The problem has been getting worse. In 1900 serious flooding occurred 7 times a year. This increased to 40 times a year in 1989 to now when there have in some years been close to 60 days of flooding per year.
Now a group of Italian engineers and geologists has proposed injecting sea water under Venice to see if they can raise the city.
The sea water would be pumped into the sand deposits that are under the city of Venice. The water would be pumped into 12 holes located throughout the city. A team from the University of Padua claims they could raise the city by 12 feet (30 centimeters) in 10 years. This would improve the flooding, but not stop it entirely.
Professor Giuseppe Gambolati, explained that about 18 million cubic meters of water would have to be pumped into the ground each year for 10 years. The water would be injected into sand which would swell and lift the ground above it.
Last year Venice began work on a flood barrier project. The bottom of the Venetian lagoon’s three entrances will be lined with 79 hollow steel gates. When the tides are low and the possibility of flooding low, the gates will fill with water and lie on the bottom of the three channels at the north and south ends of the narrow island that
separates the lagoon from the sea. These barriers would be raised at the inlets into the lagoon when high water is predicted by having compressed air pumped into the gates. The air would force out the water and the gates would rise forming a barrier to the rising seas.
Professor Gambolati, believes that his project should go hand in hand with the barrier project, also called the Moses project. Professor Gambolati said “We have no dispute with the Moses project, which is both sound and necessary, but we think our idea can help too.” He added that it would cost a tenth of what the Moses plan will cost.
The team from the University of Padua would like to conduct tests to see if the idea would work. Some experts question the feasibility of the plan and worry that Venice’s fragile structure could be damaged.