TerraSAR-X reveals the impact of the mobile barrier works on Venice coastland stability

Land subsidence and eustacy concurred to make the relative sea level in Venice (Italy) 23 cm higher over the last century. In order to protect the city and its lagoon environment from increased flooding, a series of mobile barriers are under construction at the three inlets of Lido, Malamocco, and Chioggia connecting the Adriatic Sea to the inner water body. Since 2003 work has been proceeding with the reinforcement and extension of the existing jetties and the construction of breakwaters, harbors, and a small island within the Lido inlet. We detected significant local settlements of a few centimeters between March 2008 and January 2009 at the three inlets induced by the construction works through an interferometric analysis of 30 satellite radar images acquired by the new German TerraSAR-X mission. On a more regional scale we observe that the city of Venice and the other major urban settlements on the lagoon littorals are not impacted by subsidence during this period. The very high spatial resolution of 3 m and the short repeat-time interval of 11 days of TerraSAR-X enable the investigation of displacements with an unprecedented observed level of details, opening new perspectives to geodynamic's research and civil engineering sectors for the monitoring of large infrastructures with potential vulnerability to terrain motion.