The Technology That Could Save Venice From Flooding
PHOTO ILLUSTRATION: MACKENZIE COFFMAN
St. Mark’s Square, the lowest point in Venice, Italy, flooded only about 40 times a year as recently as 50 years ago. Today, it floods about 250 times a year—often in larger events that inundate much of the city.
Venice, which is also fighting to avoid drowning in tourists, spent about $6 billion on a mobile floodgate system to block high tides from causing dangerous and costly floods. But even this system, MOSE, won’t be enough, according to engineer Giovanni Cecconi.
This week, we look at technology that’s being developed to protect the “floating city” from being overrun by water.
Cecconi was one of the hydraulic engineers who designed MOSE's network of 78 inflatable gates, which can be raised in about 30 minutes and maintain a difference in water level from the sea to the Venetian lagoon of about 10 feet.
97 feet
The height of the largest MOSE barriers, which are 66 feet wide and up to 16 feet thick, making them more than half the size of the Leaning Tower of Pisa.
For now, the system is working: In 2022, it held off a 5 ½-foot tide that was forecast to have flooded 82% of pedestrian walkways in Venice. But if the sea level rises more than 2 feet from its current levels, the MOSE system will become useless, says Cecconi.
Communities across the globe are spending billions to mitigate the effects of flooding: Officials in Chicago are building a massive tunnel-reservoir system to protect the city from heavy rains, and the U.S. Army Corps of Engineers is building a system of tidal gates, pump stations and pipes to protect military installations and other properties along the Virginia coast.
But Venice faces another problem that compounds the threat of rising waters: It's sinking. In the last century, the city sank over 6 inches as water was pumped out from under it to support industrial development.
Some scientists have proposed to lift Venice back up by injecting water back underground, which could raise the city by as much as 12 inches. Similar technology has been applied successfully in Long Beach, Calif.
Critics of the plan say it would require expensive, constant pumping and could cause uneven displacement at the surface that damages Venice’s historic buildings and bridges.
There’s another, larger engineering solution: Super levees. Unlike normal levees, which can break and cause water to cascade or seep into the areas they’re meant to protect, super levees create a massive flood protection zone that’s resistant to overflow.
“The history of Venice is a 2,000 year history of adaptation, in which the solutions were found by trial and error. I am optimistic because there will be great transformation in the future.”
— Giovanni Cecconi, hydraulic engineer
In Venice, a super levee would divide the lagoon, forming a lake inside the boundary that would use pumps to mimic the natural tide. Proponents say a super levee would revitalize the city by allowing swimming, electricity generation, and the creation of more much-needed space atop the barrier to accommodate tourists and other industries.
Cecconi estimates that a super levee would cost just one-tenth as much as the MOSE system and require limited maintenance. But in order for a super levee to be built, public approval would need to coalesce and laws would need to change.
🤔 What strategies should Venice and other coastal communities adopt to prevent flooding—and how much should they spend? Send me your thoughts, questions and predictions by hitting "reply" to this email.
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