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The rapid and uncontrolled evolution of urban and industrial settlements often turns to be unsustainable for the natural and anthropic system. A prominent example is the subsidence induced by intensive groundwater exploitation. Assessing the risk produced on urban agglomerations by the groundwater table drawdown enables to visualize the impact and to undertake policies that protects structures, infrastructures and, more generally, the socio-historical-cultural environment of the cities. This task implies to assemble hydrological, hydrogeological and geotechnical factors into comprehensive models that lead to compute free field deformation. Interfacing this effect with the mechanical characteristics of buildings or infrastructures allows to quantify damage severity. The present paper reports a study carried out for the city of Bologna, one of the most emblematic examples in Italy, whose old town and suburbs have undergone an extensive and continuous subsidence from the early seventies. An integrated risk assessment methodology is implemented defining the paramount factors, intensity measures, engineering demand parameters, vulnerability and exposure and building an interpretative model based on observation.

Geographic information systems (GIS) are very powerful tools capable of performing spatial analyses over large amounts of the territory representing large amounts of data. They consist of hardware, software, and human activities that facilitate collection, analysis, and storage of data, in different forms, related to the features of the territory. In the present chapter, the potential of the GIS tool is explored in a study of the effects of subsidence that occurred during the previous decades in the city of Bologna, where a valuable historic and cultural heritage made up of an intricate system of old masonry buildings, churches and monuments, is exposed and at risk. Data from previous geological, hydrogeological and geotechnical studies was collected and georeferenced. Then, topographical investigations and periodic records of the groundwater level in the network wells were superposed to establish a relation between causes and effects. The analysis reveals the spatial and temporal distribution of settlements in the city center and in the surrounding area. The evolution of the subsidence phenomenon has been possible, and the use of GIS has revealed the role of different factors and their mutual correlation. By combining all information, it can be seen that the area is severely affected by the distribution of total and differential settlements and that a particularly critical situation emerges in the city center. Additionally, the causes of the phenomenon could be established with great precision, enabling the identification of appropriate countermeasures.