High-resolution satellite monitoring of Venice’s historical city centre provides estimates of the relative contributions of natural subsidence and human activities to land movements in the city over the past 20 years. The findings are published in Scientific Reports this week.
Luigi Tosi, Pietro Teatini and Tazio Strozzi devised a study to distinguish between natural land subsidence and movements induced by anthropogenic activities in Venice. The effects of pumping groundwater (which contributed to land subsidence historically) ended a few decades ago. However, reliable and detailed knowledge of land subsidence affecting Venice’s city centre is still crucial, due to recent sea-level changes that have increased the city’s vulnerability. The authors examined long- and short-term displacements of the city centre using two different types of high-resolution satellite monitoring, which can reveal the tiny movements of individual buildings.
The study indicates that natural subsidence is occurring in Venice at a rate of about 0.8-1 mm per year, while human activities are contributing to land movements of about 2-10 mm per year, but only on a very localized scale and over short time-scales. The anthropogenic changes are mainly caused by conservation and reconstruction processes to preserve the building heritage, as well as urban maintenance works, including efforts to stabilize the canal walls, the authors say.