The Flood in Venice

1. The usual daily sights, with the ebb and flow of the tide.
2. A particularly high tide, such as occurs only during a full moon or new moon, and
3. A specific weather pattern over the Adriatic Sea that, combined with strong winds, pushes water into the lagoon.
4. The southerly wind, the sirocco, pushes the water into the lagoon.
5. Water level of the Adriatic Sea, which depends on the rainfall in the preceding period.

Given their positions relative to Earth, the Sun and the Moon must exert a particularly strong gravitational pull, thereby causing an exceptionally high tide.
This is only the case on the days before, during, and after the full moon and new moon.
Only on these days can the tide rise high enough to affect parts of Venice.
On the days around the half-moon, high tide is not expected. The difference in water level between high tide and low tide is far too small here.

You’ll be surprised at how unremarkable the high water is to the Venetians themselves. Only the tourists with their cameras are excited about it. If you ever visit Venice in the winter—between November and March—and see people wearing tall rubber boots, you’ll know: High water is forecast for today. Even in the media, the situation is often portrayed as much more dramatic than it really is.

The flooding does have its (small) advantages:
Being the shrewd businesspeople that Venetians are, many shops around St. Mark’s Square sell colorful „disposable“ plastic boots for just a few euros. Children, in particular, love them. As you can see in the picture, the floodwaters cover only a few Zenit meters of the alleys and squares. The water is clean and clear.

The high tide does NOT flood the entire city for days on end. The water comes in with the rising tide—lasting only a few hours—and recedes again with the next low tide. The high tide is also NOT felt equally throughout the entire city. The lower-lying areas in particular—including St. Mark’s Square and the Rialto Bridge—are the first places where the water becomes visible.

As in all coastal cities around the world, the water level rises and falls with the tides. This is also the case in Venice, an island in the northern Adriatic Sea. Without you even noticing, the water level in the numerous canals that crisscross Venice fluctuates daily. Flooding occurs only when the high tide is particularly high. The only question that remains is: When is the high tide high enough to affect the lower-lying parts of Venice?

The cobblestones in the narrow alleys and squares—such as St. Mark’s Square—are deliberately NOT laid perfectly flat (100%). A slight undulating pattern has been incorporated here, which you as a tourist may not particularly notice. This allows water to drain away during rain or thunderstorms. Similarly, the surface of the numerous alleys is intentionally slightly arched toward the center and slopes slightly toward the building walls on the sides. In addition, there are small drainage slits in the pavement along the sides, through which rainwater can flow away.

The surface of St. Mark’s Square is slightly undulating. You probably won’t even notice it here. In the slightly sunken areas, there are white marble covers with small openings through which rainwater can drain. If the high water is „only“ one meter above normal sea level, only a few—and only the lowest-lying—parts of the city are affected. 50–79 cm above sea level is normal; 80–119 is already high. Only when the water rises higher are larger areas of Venice affected.

Rainwater flows into these cracks, crevices, and openings and can then drain away through underground pipes. The water rises through the sand and seeps back down through it. There is no drainage system. Conversely, during particularly high tides, seawater enters the city through this rainwater drainage system. Even St. Mark’s Square is not completely level. There is always a small depression where the round manhole covers are located. These manhole covers are not made of cast iron, but of marble.

The city's ground has been sinking for many years due to groundwater extraction.
1. Groundwater was extracted for the industrial port of Mestre until the early 1970s, when it was discovered that the artesian wells had run dry. In Venice, this led to the city sinking, so the practice was discontinued.
2. The entire Po Plain has been subsiding at an average rate of 4 cm per century for centuries, and this process cannot be stopped.
3. Rising sea levels are also a problem for Venice. Even though the city has sunk by only about 20 centimeters over the past 100 years, the effects are noticeable. You can easily see this for yourself: Most of the staircases leading down from the alleys and houses to the canals are overgrown with green seaweed and, even at low tide, are usually still below the water’s surface.

I'm not getting involved in the argument here about

• rescue projects such as Moses,
• the influence of industry in Mestre on the mainland and
• the impact of large tankers and ships.
• The much-cited issue of climate change, with its feared rise in sea levels,
  That's not an issue here.
  By the way, the Italian name for high water is „Acqua Alta.“

The police, wearing knee-high rubber boots, seem to be enjoying the water. Anyone who lingers on the narrow walkways is asked to:

• not to hold up traffic for too long,
• take his picture and move on.

By the way:
Over the past 10 years, only one guest has canceled a hotel reservation with us, the Venice accommodation agency.
He thought that all of Venice would be flooded for several days and that he therefore wouldn't be able to go on a city tour.

The vendor stands and cafes on St. Mark's Square aren't doing any business during this time.

But as the next low tide rolls in, the water slowly recedes again, and the first vendors are already back!
The pigeons are hungry now, too, and are after their food again!

Many businesses protect themselves with special barriers (partition walls) during periods of flooding. At the rear of many buildings, doors that are rarely used are permanently locked and protected year-round. The problem with these partition walls arises only when weather forecasts are inaccurate or incorrect. If the floodwaters do end up rising higher than expected, many homes and stores get flooded. Who pays for the damage then?

If the forecast is timely and accurate, you can protect yourself by taking additional precautions (such as sandbags, etc.). The floodwater does NOT penetrate the walls of houses on a large scale; the flood is far too brief for that.

You can tell by the Venetians’ reaction. Everything proceeds very calmly, serenely, and routinely. No rush, no fear, no panic. Flooding is simply part of everyday life in winter. They usually sit in a café until the floodwaters recede, then sweep out their shops and the sidewalk, and daily life goes on as usual. Venetians who are out and about a lot wear rubber boots all day long.