ABSTRACT
Land subsidence is a gradual lowering of the ground surface that occurs in shallow and deep subsoils due to natural soil compaction and man-induced processes. These processes may develop over thousands and thousands of years, as in the case of natural subsidence, or over several decades, as in the case of man-induced subsidence.
The increasing number of high tides in Venice, described in Chapter 1, is caused by the natural eustatic sea level rise, by natural subsidence, and, more particularly, by regional man-induced subsidence, particularly prominent between 1946 and 1970. The man-induced subsidence was caused by intensive water exploitation for industrial purposes on the closest mainland, which had an impact even on the historic city and the surrounding islands. This type of subsidence has ceased, but the significant sinkage that occurred in the 20th century has not been entirely regained; thus, the margin of safety of the whole lagoon has diminished.
