Satellite imagery shows sinking Venice

Venice, one of the most visited cities by tourists worldwide, is increasingly submerged by the waters. What scientists had already anticipated is really happening to that set of canal-cut historic buildings that form this romantic gondola destination that couples adore.

The action of the ocean on Venice was proven in a new study, which used state-of-the-art satellite data. The recorded images show how Venice is sinking to an unprecedented level of resolution. These revelations are allowing scientists to dismount the influence of the causes of Venice's “wreck”, whether due to the compacting of sediments on which the city is built or the constant restoration of structures.

Global warming

According to a report by the NGO Co + Life, based on the Intergovernmental Panel on Climate Change, sea levels are expected to rise by 0.8 to 2 meters this century. As a result, various places on the planet may disappear submerged by water in the not too distant future and Venice is one of them.

“Understanding how the earth is sinking is particularly important in the face of rising sea levels. Venice is so critical of the sea that continuous monitoring of the city's movement is of paramount importance, ”Italian researcher Pietro Teatini told Live Science.

With the data from this imaging research, scientists first recognized the problem decades ago when they noticed that the pumping of groundwater beneath Venice was causing the city to settle on land. Pumping and its effects stopped long ago, but the city continues to sink.

Measuring systems

To arrive at the survey results, Teatini and his colleagues used two sets of satellite measurements, both from the historic city center of Venice and the surrounding area. The first set of data came from first-generation satellite sensors, which have lower resolution and collect data about once a month.

The second data set comes from a newer satellite with sensors that have much better resolution and take measurements every 10 days. "The techniques are constantly evolving and improving and we are able to detect displacements with an accuracy that was unbelievable 10 or 20 years ago, " said Teatini.

The satellite beam signals down from the Earth's surface, where they reflect land and buildings. To determine how much Venice is sinking, the researchers measured the differences in city return signals from those returning from nearby areas, a method called interferometry.

With this, Teatini's team compared the short-term changes in city height measured by the new satellite with the medium and long-term movement assessed by the old satellite. They then subtracted short-term changes in ground level from long-term changes to determine the human contribution to sinking.

The results revealed that the city is naturally yielding at a rate of about 0.03 to 0.04 inches (0.8 to 1 millimeter) per year, while human activities contribute to the sinking by about 0.08 to 0.39 cm (2 to 10 mm) per year.

This threatens to increase flooding in Venice, which is already due to high tide about four times a year. And the problems are compounded by rising sea levels resulting from climate change.