# Why were the tides in Venice the highest in 50 years? **URL:** \ **Category:** Factual Questions\ **Created:** [November 14, 2019, 8:27pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440 "2019-11-14T20:27:57Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [November 14, 2019, 8:27pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/1 "2019-11-14T20:27:57Z")
Yesterday (Nov, 13) was of course full moon, but there are 12 or 13 of them every year. It was nowhere near perigee (Nov. 23), in fact a bit closer to apogee (Nov. 7). So why were the tides so high in Venice? And why only Venice or was this a world wide phenomenon? ---
**Author:** ![XT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xt/32/456_2.png) [@XT](https://boards.straightdope.com/u/XT)\ **Post date:** [November 14, 2019, 9:18pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/2 "2019-11-14T21:18:53Z")
> [@Hari\_Seldon](#): > > Yesterday (Nov, 13) was of course full moon, but there are 12 or 13 of them every year. It was nowhere near perigee (Nov. 23), in fact a bit closer to apogee (Nov. 7). So why were the tides so high in Venice? And why only Venice or was this a world wide phenomenon? Perfect storm, so to speak, is what I read. Basically, high spring tide as you indicated, plus a storm surge caused by a north-east storm in the Adriatic and high winds. Just bad luck. Plus global sea levels are rising, but this was mainly just a combination of factors due to weather and tide. Oh, and Venice is sinking as well, which probably contributed some… ---
**Author:** ![mjmlabs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mjmlabs/32/69_2.png) [@mjmlabs](https://boards.straightdope.com/u/mjmlabs)\ **Post date:** [November 14, 2019, 9:20pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/3 "2019-11-14T21:20:53Z")
It appears that [the core issue is storm surge](https://www.npr.org/2019/11/13/778812333/venice-is-on-its-knees-mayor-blames-worst-tides-in-50-years-on-climate-change), exacerbated by the high tide: > [@](#): > > “Venice is on its knees,” Mayor Luigi Brugnaro says as the lagoon city suffers through some of the worst flooding in its history. The highest tide in 50 years has brought seawater that is threatening monuments and works of art in the historic city. > > With more than 85 percent of the city flooded, Brugnaro says the city is in a state of emergency and that he has asked Italy’s government for help. > > **Water driven by strong winds and storms** overwhelmed seawalls and smashed brick docks, shoving boats into streets and leaving parts of landmarks such as St. Mark’s Basilica and La Fenice Opera House underwater. > > … ( **bolding** mine) …Curses! Ninja’d again! ---
**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\ **Post date:** [November 14, 2019, 9:22pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/4 "2019-11-14T21:22:59Z")
Sea height is influenced by a lot of things. The tidal influence of the moon and sun are clearly important, but so are things like wind direction and speed, and resonance effects / sloshing modes of nearby water bodies. Extreme weather (_e.g._, a hurricane) can increase sea height on the US coast by 15+ feet, so a few extra inches isn’t a stretch under more normal conditions. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [November 14, 2019, 10:49pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/5 "2019-11-14T22:49:52Z")
Here’s a [list](https://en.wikipedia.org/wiki/Acqua_alta#Exceptional_high_waters_since_1923) of the highest tides in Venice since 1923. So not quite a hundred years ago. 3 of those occured before 1966 (the previous record holder and close-ish to the midpoint of the time span). 16 afterwards with 11 since 2000. (I guess the 1968 one is closer to the midpoint. So like a 5-15 split.) The banning of artesian wells in the 60s helped slow down subsidence. But still a lot more recent peaks than before. Sea level rise in general isn’t helping. Note that some years appear more than once. Like 2019 and 1979. That suggests overall persistent weather patterns play a role. A high or low gets stuck somewhere and winds start to push water for a long period of time. Sort of like _El Nino_. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [November 15, 2019, 10:29am UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/6 "2019-11-15T10:29:37Z")
A look at a map shows you part of the problem. Venice is located near the end of the Adriatic Sea, which is a long narrow inlet of the Mediterranean aligned roughly SE-NW. If you get strong winds from the southeast, they push a load of extra water up the Adriatic right towards Venice. The same effect, but with winds from the opposite quarter, can lead to disastrous storm surges on the North Sea coasts of the UK and Netherlands, [as in 1953](https://en.wikipedia.org/wiki/North_Sea_flood_of_1953). Low pressure exacerbates the problem, as lower atmospheric pressure raises the local sea level slightly too. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [November 15, 2019, 7:31pm UTC](https://boards.straightdope.com/t/why-were-the-tides-in-venice-the-highest-in-50-years/843440/7 "2019-11-15T19:31:35Z")
The news reports (NPR has one) relate that the houses were shaking and shutters slamming, so this was an excessively high wind - so as mentioned above, the “perfect” storm. the Adriatic is long and narrow, so it magnifies the effect of a wind from the south. Another point was that the wooden bench walkways they usually put out so people could walk above the tide in St Mark’s Square - most washed away. To restate - the problem was that starting around 1900, mainland Mestre began sucking a lot of groundwater out of wells near Venice. This had the effect of causing the ground to subside and Venice to sink. The problem is not so much climate change, as poor control of groundwater use. Since they stopped this practice (170’s) Venice has stopped sinking - but not necessarily rebounding.