Geospatial Tools in Support of Urban Planning: A Possible Role of Historical Maps in Programming a Sustainable Future for Cities

In urban planning, a numerical and spatially based approach is expected to drive to the “best” choice. In this work a GIS-based procedure is proposed to model territorial dynamics by comparing maps of two different periods (1830 and 2000). The study area is located in the urban fringe of Torino (NW Italy) that suffered from important changes especially in the last 60 years. A workflow was defined and applied, based on a multi-criteria approach implemented by GIS. With reference to existing maps, strength and direction of forces, opposing urban to rural/semi-natural surroundings, were mapped and described operating through the following scheme: a) vectorization and qualification of both impacted (rural) and impacting (urban) landscape elements; b) implementation of spatially dependent functions representing strength and direction of urban pushes against rural; c) qualification of rural areas majorly exposed to urban growth. Accordingly, some maps, useful to read the playing urban growth dynamics, were generated and some applications proposed. Nevertheless some limitations still persist: the proposed methodology is based on simplified hypotheses, mainly related to the definition of spatial indices that somehow depend on the type of information that available maps contain. A second limitation is related to the persistence of a great component of subjectivity during the extraction of the starting information from the available maps and weights assignation.