This happened again: Marea eccezionale

The hefty storm came as a surprise, following sunny and rather mild autumn days. And months of siccità – during which it was raining very little. The day before, 21 November when Venice celebrated La Festa della Madonna della Salute, the air felt almost spring-like, one of those days you’d love to begin with breakfast on the altana.

But again, there was that heavy smell of humid sea tang as the sky was slowly turning leaden in the late afternoon. And by the morning, it was raining heavily, accompanied by unusually hefty gusts of wind while the first messages arrived in Venice via Comune di Venezia’s Telegram Channel. Avviso Maree is where we check for the tides, especially in November, and especially during the days before and after New Moon.

It took an hour or so to grasp what was going on: At 2 am, the engineers had activated the 78 mobile barriers of the MoSE plus the Mini Mose at Chioggia, to totally lock out the fury of the sea from the Lagoon. Outside,

It sunk in that Venice had just been spared a disaster. 22 November 2022 would otherwise have been the most critical day: Without those 78 MoSE barriers, the city would have been seriously damaged.

Thankfully, the city wasn’t flooded but still, the waves went high in the Lagoon due to the storm. Trees were uprooted, and there was more damage done behind the scenes.

Leaden skies and dripping fog. What Venice looks like on such a day. Image by Jacopo de Michelis on Instagram.

Venice was in danger as the weather conditions were almost identical to those we witnessed three years ago: The southerly scirocco wind pressing the tides towards the Lagoon. The northerly bora chasing the water surplus out of the Lagoon. And another disturbing factor, the south-westerly Libeccio, bringing in tornadoes and heavy gusts of rain. Those three winds combined always wreak havoc on the sensitive system of tides.

It happened on 12 November 2019. And again, on 22 November 2021. It used to happen about once every 150 – 200 years, but climate patterns are obviously changing, Venice being no exception.

What makes me really thoughtful is that a situation like this, which used to happen every 150 – 200 years, has repeated itself after three years. That’s the underlying problem, threatening the physical experience of Venice: The Lagoon has been altered by eep water channels which means that currently about two parts of the Lagoon are not fit for long-time survival. MoSE’s just its first line of defense.

Why does acqua alta “always” happen in November?

Tides are more pronounced now than in early autumn and late summer, changing twice a day instead of once in summer and spring. Yes, there are seasonal differences, especially during Full and New Moon in autumn and early winter.

Lessons learned?

By now, it looks like the Lagoon is dependent on the functioning of the MoSE mobile barriers installed at the three inlets. But which steps need to be taken next, to tackle the real issue we have: The physical survival of the Lagoon in which Venice sits.

  • With climate patterns changing, we can learn from the various parts of the Lagoon less exposed, and learn that shallow areas, surrounded by barene and velme (marshlands), are able to soak or mitigate excess water. The southern Lagoon, criss-crossed by deep water lanes is so exposed to tidal peaks and changes in tides.
  • With the MoSE representing the first line of defense, there must a second and a third: This was the main tenet of the Venetian engineers of the Republic of Venice, mentioning shallow and narrow canals as “second line of defense”, and barene (marshlands) that soak up excess water, as “third line of defense”.

As of today, I’d add another line of defense: A solution for the deep water lanes in the Lagoon. That won’t the high tides from coming in, but four lines of defense will make the Lagoon much more robust. Click here to read more about the MoSE and long-term solutions to safeguard the Lagoon.

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