The sinking city of Venice, Italy
Venice, the city of canals and gondolas, is one of the most breathtaking and unique places in the world. Built on 118 small islands in the Venetian Lagoon, it has long been a historical and cultural icon, attracting millions of visitors every year. However, this remarkable city is facing a growing crisis—Venice is sinking and flooding at an alarming rate. But what exactly is causing this? Here are the eight major factors responsible for the city’s gradual descent into the water.
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Natural Land Subsidence
Venice is built on soft sediment layers composed of sand, silt, clay, and organic material. Over time, these layers naturally compact due to their own weight and the pressure exerted by the city’s buildings. This process, known as land subsidence, causes Venice to sink at a rate of approximately 1 to 2 millimeters per year.
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Heavy Buildings and Infrastructure
The magnificent buildings of Venice, constructed from stone and brick, put additional strain on the city’s delicate foundations. Because Venice was built on wooden piles driven into the sediment, the uneven weight distribution leads to structural imbalances, cracks, and further subsidence. The more construction and restoration efforts take place, the more pressure is added to the city’s already fragile foundation.
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Mass Tourism and Overcrowding
Venice is one of the world’s most visited cities, receiving millions of tourists every year. The overwhelming number of visitors, combined with construction activities to support tourism, puts significant pressure on the city’s infrastructure. Bridges, public spaces, and water systems experience wear and tear, accelerating structural damage and increasing maintenance costs.
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Tectonic Movements
Venice is also affected by geological forces beneath the surface. The shifting of the Adriatic Plate and the Apennine Mountains contributes to the natural subsidence of the city. These slow-moving tectonic shifts alter the stability of the lagoon’s sediment layers, increasing the likelihood of minor tremors and structural weakening.
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Groundwater Extraction
During the early to mid-20th century, groundwater extraction was a major cause of Venice’s sinking. Industries in the nearby Marghera area, as well as the city’s growing population, demanded large amounts of water. As water was pumped out, the soil beneath Venice started to compact more rapidly, accelerating subsidence. By the late 1960s, authorities recognized the damage and significantly reduced or stopped groundwater extraction to slow down the sinking process.
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Acqua Alta – Seasonal High Tides
One of the most visible and immediate threats to Venice is Acqua Alta, the temporary flooding that occurs mainly in autumn and winter. Acqua Alta is caused by a combination of factors:
- Spring tides during full or new moons amplify gravitational forces, raising water levels.
- Strong scirocco winds from the Sahara push water northward into the Adriatic Sea and Venetian Lagoon.
- Low atmospheric pressure reduces the force pressing down on the sea, allowing water levels to rise.
When these factors align, severe flooding can inundate the city, causing disruptions and damage to historic structures.
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Extreme Weather and Climate Change
Climate change is making Venice’s flooding problems worse. More frequent and intense storms, heavy rainfall, and rising temperatures contribute to higher water levels in the lagoon. When combined with Acqua Alta and strong winds, these conditions increase the severity and frequency of floods, putting Venice at greater risk.
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Rising Global Sea Levels
Perhaps the most alarming factor in Venice’s future is global sea level rise caused by climate change. As polar ice caps melt and ocean temperatures increase, sea levels continue to rise. Higher water levels make high tides even more extreme, leading to frequent and severe flooding. If global warming continues unchecked, Venice’s future as a livable city may be in jeopardy.
Can Venice Be Saved?
With all these threats, is there a solution to save Venice? While the answer is complex, several efforts are being made to protect the city.
MOSE Flood Barrier System
The MOSE system with the city on the left and the sea on the right.
The MOSE system is Venice’s most ambitious flood protection project. This system consists of 78 mobile barriers installed at lagoon inlets to block rising tides, such as Acqua Alta, from flooding the city. Initially planned for completion in 2011, the project faced numerous delays, budget overruns, and political scandals. However, it became operational in 2020, with final completion expected soon. MOSE can protect Venice from tides up to 3 meters (10 feet), safeguarding critical areas like Piazza San Marco.
Additional Measures
Besides MOSE, Venice has implemented other flood mitigation efforts:
- Elevating infrastructure such as streets and public spaces.
- Improved drainage systems and water pumps.
- Water-resistant restoration techniques for historic buildings.
- Sediment management in the lagoon to maintain water balance.
- Regulations on large ships to prevent further erosion.
- Climate adaptation strategies to prepare for future changes.
The Future of Venice
The fight to save Venice is ongoing. While technological solutions like MOSE and improved infrastructure provide hope, the city’s survival ultimately depends on long-term strategies addressing climate change and responsible tourism. Public awareness and global efforts to combat rising sea levels are crucial to ensuring that Venice remains a cultural treasure for generations to come.
Venice’s story is a cautionary tale about the delicate balance between nature and human intervention. As we admire its beauty, we must also recognize the urgent need to protect it.
