Natural Issues: Understanding Acqua Alta
Making the problem worse is acqua alta, a phenomenon that causes waters to rise high during the fall and winter months. That being said, this phenomenon is not a constant. Rather, it’s a phenomenon that only happens under certain conditions.
Acqua alta is caused by the natural cycle of storms, mixed with sirocco winds and the area’s natural high tides. When these three factors come together, it unleashes a perfect storm that causes waters to rise high.
For most of modern history, Venice mitigated the water that seeped up through floors by guiding the water into underground clay tubs which would later be used as cisterns. Eventually, they created an aqueduct to help hold excess water. Nowadays, the cisterns are capped and water flows up.
Even with the aqueduct, the fact is that acqua alta still tends to flood the ground floors of many major buildings. It’s such a common occurrence, hotels often lend boots to visitors in order to prevent newcomers from ruining their shoes.