Geostatistical Analysis of Settlements Induced by Groundwater Extraction

摘要

One of the most important effects induced by the over-exploitation of aquifers is the land subsidence. This dangerous situation may reduce in relatively short time the functionality and safety of structures and infrastructures present on a territory and impair their efficiency and stability. The city of Bologna is one of the most sensational cases of Italy, especially for the amount of recorded settlements and the great historical and cultural value of exposed assets. This article analyses the spatial and temporal distribution of settlements over an area of about 270 km~2 including the centre of the city. The topographical measurements, carried out starting from 1943 with a progressively increasing detail, highlight an articulated framework of settlements with maximum values exceeding 4 m. After a brief introduction of the phenomenon and its causes, a geostatistical analysis has been performed on a Geographical Information System. In order to validate the results, the potential damage on buildings present in the area has been evaluated. To this end, data were collected regarding the geometrical characteristics and the structural types of the buildings. The strain levels from the current configuration of the ground surface have been calculated for each of them. Finally, the expected damage levels have been assessed, following the classifications proposed in the literature that allow to assign a severity level for each building. These results were compared with damage observed by previous studies. This approach is a prerequisite to the planning of any vulnerability mitigation strategy.