Can an $8B dam save Venice?
By Trung Phan
On Monday, I was minding my own business on the internet when — BAM! — the trailer for Mission Impossible 7 (Dead Reckoning) hit the news feed.
My two initial thoughts: 1) this dude Tom Cruise is single-handedly keeping Hollywood afloat (the Top Gun sequel is out this weekend); and 2) wow, another movie that features Venice.
For real, though, Hollywood loves Venice.
Here are some action flicks set in the Italian city: The Tourist, The League of Extraordinary Gentleman, Spiderman: Far From Home, James Bond: Casino Royale and — this is not a joke — Shark in Venice.
While these films highlight the city’s iconic gondolas, canals and St. Mark’s Square, there is an equally interesting story happening in the waters of the Venetian lagoon.
Flooding is an existential threat for Venice. And the Italian government has spent the past 4 decades and more than $8B to protect the city.
Enter MOSE: the world’s largest flood prevention system.
What is MOSE?
It is a dam system composed of 78 mobile metal barriers built to block high tides from entering the shallow Venetian lagoon, which has an average depth of only 1m (or 3.3ft for my many American readers).
The English translation for the MOSE acronym is Experimental Electromechanical Model. If the thought of “Moses parting the Red Sea” comes to mind, that’s intentional.
The barriers are placed at 3 points where water from the Adriatic Sea enters the Venetian Lagoon.
Two points are on Lido Island, an 11km sandbar that has historically provided natural protection for Venice (the southern tip is Malamocco). The third point is Chioggia, a fishing town at the southern-most part of the lagoon.
Venice itself is 118 small islands linked together by bridges, walkways and canals. Dubbed “The Floating City”, the buildings sit on:
- a water-resistant layer of marble on top of…
- …wooden platforms on top of…
- …wooden stilts driven into the ground
Here’s an insane stat: there are 10 million tree trunks buried underneath Venice that support the city’s structures.
The threat of flooding has been persistent since Venice’s founding in the 5th century AD. It was built just above the waterline, which has risen 1.8m (6ft) in the past 1600 years.
To make it worse, the city is also sinking due to tectonic plate shifts, soil liquefaction and fresh water extraction.
In the early 1900s, Venice faced 10 floodings a year in its low-lying areas. The annual frequency of this type of flooding is now more than 50x a year.
A flood in November 1966 was particularly bad (a record 1.9m high) and forced Italy’s Ministry of Infrastructure to explore ways to protect the city.
Over the next 2 decades, the Italian government tried balancing its economic and environmental needs. They came up with some wild ideas that never saw the light of day:
- Raise all the buildings
- Fill the inlets with sand
The idea for a mobile dam system (which became MOSE) was floated in the mid-1980s.
After decades of red tape, construction began in 2003 with a target completion date of 2012 (at a cost of $4B). MOSE was frequently delayed and stained by corruption (to wit: Venice’s mayor was arrested in 2014 over bribes related to the project that totalled tens of millions of dollars).
MOSE only began operations in 2020 and the government has spent more than $8B).
The MOSE system operates on a simple hydraulic method:
- The metal barriers (“fins”) are hollow and submerged underwater
- To raise a fin, air is pumped into the hollow section and makes the barrier buoyant (it takes 32 minutes for the fin to float up)
- To lower it, water is pumped back in and the fin sinks (this takes 16 minutes)
The most impressive engineering feet for MOSE is the housing of the 78 fins. Each is placed inside a massive 14,000 ton cement case. These cases were made on land, then floated to the inlets and sunk into the seabed.
The seabed debris from installing the concrete cases was re-used to build a 114k square meter manmade island that sits in the Lido inlet. The island serves two purposes:
- it is the MOSE headquarters for monitoring water levels
- it splits the inlet — which is much wider than the other entry points (Malamocco, Chioggia) — into two manageable halves for the mobile fins to operate
In flooding season (October – March), the island HQ is run by 100 people and works 24/7. A warning system alerts citizens, tourists and ships to an incoming flood.
MOSE workers are able to walk around the system as the cement bed cases have underground service tunnels. Meanwhile, the metal fin barriers are raised independently so there are varying degrees of flood prevention and boats can still pass through open sections.
At its max, MOSE protects against 3m tides (which is ~1.5x the height of the record 1966 flood). Unfortunately, it wasn’t operational by November 2019, when the city had its worst flood in 50 years.
MOSE passed its first official test a year later (October 2020), holding back a 130cm high tide. The system has successfully turned back flood waters more than 30x since its debut (however, operators underestimated a potential high tide in December 2020 and the city flooded because they didn’t turn the system on).
Moving forward, expenses will continue to be an issue: on top of the $8B that’s already been spent, it costs >$300k each time to activate MOSE and an ongoing $100m per year for maintenance (the fins are treated every 3 months with non-toxic anti-corrosive chemicals).
When the system is fully functional in 2023, MOSE will only be activated when water levels rise up 110cm. Some residents are not happy with this coverage: while that height protects more than 80% of the city, tourists hot spots like St. Mark’s Square remain vulnerable (the square floods at 90cm).
There are two other notable criticisms:
- The construction will harm the fragile ecosystem in the Venetian lagoon
- Submerging the metal fins was financially and operationally unnecessary; there are existing flood systems (UK Thames Barrier) that are cheaper but aesthetically less pleasing to the eye (aka they aren’t submerged)
The biggest question facing MOSE: can it protect against climate change and rising water levels in the long term?
When CNN asked the project’s lead Elisabetta Spitz this question, she said: “If in 100 years the barriers aren’t enough and we can’t hold off 3m tides, I can tell you the problem won’t be Venice.”
Dealing with that type of world may be the real Mission Impossible.
Sources: CNN, Ancient Origin, Science Channel, MIT, How Stuff Works, Rolling Stone, NY Mag CurbedSubscribe Here
Links + Memes
My memory of Venice: The last international trip I made before COVID was a 3-week excursion to Italy in September in 2019. Me, my wife and toddler did 3 days in Venice at the end of the trip.
Verdict: it’s absolutely one of those places that you have to “see once in your life” but the tourist overload was real. The Instagram-worthy pic of a romantic gondola ride down the canals is fake news. So many of the vessels are stacked back-to-back-to-back that the water is basically hidden.
I still loved it and ate a ludicrous amount of squid ink pasta.
One definite takeaway: if you’re travelling with kids, pay up for the water taxi instead of trying to walk to your hotel from the train station. I HATE unnecessary expenses and the 3-minute water taxi ride we took cost $150. It pained me to pay. But when I walked around the city with a stroller while eating squid ink pasta with my hands, I realized it was totally worth it.
Early Gordon Ramsay: I LOVE finding clips of successful people before they “made it”. I recently watched one of a quiet 26-year old Gordon Ramsay taking orders from Marco Pierre White, who is considered the first celebrity chef. The interesting thing is that Pierre-White is only 4 years older than Ramsay, but way more accomplished. Ramsay just pays his dues and learns how to make lobster ravioli from an experienced mentor.
After watching this video, YouTube fed me another video of Ramsay when he’s become “the most famous chef in London”. In the 2nd clip, he’s serving the late Anthony Bourdain a special meal including…lobster ravioli. It’s amazing to watch someone’s journey and also scary how good YouTube’s recommendation algo is getting. (You can watch both clips in this Twitter thread).
Some random stats: via an entertaining Reddit post “What is the most interesting statistic you know?”:
- When tested by another agency, TSA failed to detect weapons, bombs, and other destructive materials 95% of the time.
- Even in the 2022 Kentucky Derby, 19/22 entered horses can trace lineage to Secretariat.
- We collectively receive about 2.4 Billion robocalls per month
- 20% of the mammal species on our planet are different types of bats.
- 7% of all humans that ever existed are alive today.
Good tech reads: Profile of the Collison brothers and how they built Stripe into a $95B fintech monster (fun fact: the PayPal Mafia — Elon Musk, Peter Thiel, Max Levchin — all invested in the seed round). Facebook is going all in on Reels to take on TikTok (fun fact: Instagram co-founder Kevin Systrom wanted Zuck to buy Musical.ly, the short video app that Bytedance ended up acquiring and transforming into TikTok). Why Apple will win the mixed reality headset war (fun fact: this is my latest Bloomberg article).
And here are some memes: