From: David A Gabel, ENN
Published March 23, 2012 09:21 AM

Venice Getting that Sinking Feeling

Venice, the northeastern Italian city along the Adriatic Sea, is a marvel of man-made construction. Its beautiful buildings and structures built along the myriad of canals have made it what some consider to be the most romantic city in Europe. The city is actually made up of over 100 small islands within the Venetian Lagoon between the Po and Piave Rivers. For years, the city was thought to be subsiding into the lagoon, but recent studies had shown that it had in fact stabilized. The newest research, unfortunately, shows different. It has not only found that the water level is rising every year, but the city itself is tilting.


The lead researcher, geodesist Yehuda Bock from Scripps Institution of Oceanography at the University of California (UC) San Diego, worked with colleagues from around the world to analyze data using GPS and satellite instruments, measuring Venice in relation to the lagoon. They found that the city was subsiding on average 1-2 millimeters per year (0.04-0.08 inches).

The rate seems small, but it is important, explains Bock. At the current rate, in 20 years, the land would sink up to 80 millimeters (3.2 inches). Again, this may seem small, but it spells doom for Venice's long-term aspects.

Bock's research also uncovered another interesting phenomenon affecting Venice. The city is actually tilting. The western section of the city is actually higher than the eastern section. The tilt has been going on at an average of 1-2 millimeters per year.

When Venice was first discovered to be sinking several decades ago, scientists realized that pumping out the groundwater was a major cause. Officials put a stop to this, and for a while, the city was believed to have fully settled.

Now that new research has shown the subsiding to continue, officials have to look for new ways to save the city. Unfortunately, the cause may not be something that man has any control over.

One cause identified is plate tectonics. Venice sits upon the Adriatic plate which subducts underneath the continental plate to form the Apennines Mountains. Also, the compaction of the earth from the weight of the buildings continues to push down.

Flood protection walls are being erected around the city to stop incoming high tides and storm surges. However, these are also built on land that is sinking. Builders must take this into account as well.

The barrier islands and spits of land protecting the Venetian Lagoon from the Adriatic Sea are also expected to sink considerably in the coming decades. These will also have to be reinforced. Keeping Venice afloat is sure to be a monumental task for many generations to come.

This study has been published in the journal Geochemistry, Geophysics, Geosystems which is a journal of the American Geophysical Union.

Venice canal image via Shutterstock

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