Venice’s Eternal Struggle: Acqua Alta and the Floating City’s Flooding Woes
Venice, Italy, 12 January 2026 – Venice, the city of canals and romance, faces a perennial challenge with acqua alta, the seasonal flooding that has shaped its history and continues to threaten its future. As the Adriatic Sea pushes water into the lagoon, residents and visitors navigate elevated walkways and rubber boots, while engineers battle with innovative solutions like the MOSE project.
The Phenomenon of Acqua Alta
Acqua alta, meaning “high water” in Italian, is a natural phenomenon caused by a combination of high tides, strong winds, low atmospheric pressure, and the gravitational pull of the sun and moon. This flooding has been a part of Venetian life for centuries, with records dating back to the eighth century. During high tides, water levels can rise significantly, affecting the city’s low-lying areas, particularly Piazza San Marco and the Rialto Bridge.
Typically, these events last less than an hour and a half, but they can disrupt daily life. Public transport services operate according to schedule, except during exceptional tides, and temporary elevated platforms help pedestrians move around. Real-time flood information is available via websites and apps, with forecasts provided by the city’s tide monitoring centre.
Historical Flooding and Impacts
Venice has experienced devastating floods throughout history. Notable events include the 1966 flood, which submerged much of the city, and more recent occurrences in 2019 and 2020, where water levels reached over 1.8 metres, flooding 80 per cent of the historic centre. These floods have damaged priceless art, buildings, and infrastructure, costing billions in euros.
The city’s sinking ground, exacerbated by groundwater extraction in the 20th century, compounds the issue. Sea levels have risen by about 23 centimetres since 1897, with climate change accelerating this trend. Exceptional tides above 140 centimetres are rare but can flood 59 per cent of the city, as seen in events where water reached 156 centimetres in 2008.
The MOSE Project: Venice’s Flood Defence
To combat flooding, Italy has invested in the MOSE (Modulo Sperimentale Elettromeccanico) project, a system of 78 inflatable gates at the lagoon’s inlets. Designed to block surges exceeding 110 centimetres, the gates can handle tides up to 200 centimetres. Deployed for the first time in 2020, MOSE has faced delays and controversies but offers hope for protecting Venice’s heritage.
However, MOSE is not a complete solution, as it does not address more frequent, lower-level floods. Environmental concerns about the gates’ impact on the lagoon’s ecosystem persist, prompting calls for complementary measures like wetland restoration and sustainable tourism initiatives.
Key Facts on Venice Flooding
| Aspect | Details |
|---|---|
| Reference Level | Mareographic zero established in 1897 at Punta della Salute. |
| Perceptible Flooding | Water noticeable when tide exceeds 82 cm in Piazza San Marco; 105 cm at Rialto Bridge; 135 cm at railway station square. |
| Exceptional Tides | Above 140 cm; occur infrequently, affecting 59% of the city. |
| Frequency | Average of six times per year exceeding 110 cm in recent decades. |
| Historical Record | Highest: 194 cm in 1966; 166 cm in 1979; 158 cm in 1986. |
Frequently Asked Questions
What should I do if acqua alta occurs during my visit?
Wear rubber boots or use elevated walkways. Check tide forecasts via the city’s monitoring centre and avoid low-lying areas like Piazza San Marco during high tides.
Is Venice sinking?
Yes, due to natural subsidence, human activities like groundwater extraction, and sea level rise from climate change. The average water height has increased by 23 cm since 1897.
How does MOSE work?
The system uses inflatable gates that rise from the seafloor to block lagoon inlets during high tides, preventing water ingress for up to 30 minutes.