Groundwater level evolution in the Milan area: natural and human issues

The history of groundwater level development in Milan province and in Milan city is analysed. It is very well recorded by piezometric data from a monitoring network of 284 wells, with a monthly frequency. In 1915 the water table depth, quite close to Milan city, was about 1 m below the ground surface. The groundwater table has since fallen rapidly, with an historical minimum in the 1970s, some 40 m below ground surface. However, a rapid increase is now occurring and in recent years (1993-1997) the situation in Milan is getting worse. Many areas of the town's subsurface (parking, underground, houses, hospitals) are now flooded by groundwater. A study of the Milan hydrogeological system has been carried out to analyse the natural and human causes determining the groundwater level evolution. The historical sequences of all the different factors of the mass transfer, from the beginning of the century through to 1997, have been analysed to evaluate their synergistic relationships