A HGIS for the study of waterways: the case of Bologna as ancient city of waters

Historical cartography, as a fundamental part of Cultural Heritage, constitutes a precious asset, not only to be safeguarded, but also to be used to study the evolution of the territory over time. In this perspective, regeneration of ancient cartography in digital represents an interesting way to allow new chances of using its historic and geographic information, by modalities that cannot apply to analogue supports. In particular, the creation of HGIS (Historical Geographic Information System) is a way to integrate historical cartography with historical data of various kinds and compare them with the current reality, thus constituting an aid instrument for the study of the historical landscape. The present study investigates the possibility of studying the city of Bologna, in particular its ancient waterways, using some 18th and 19th century maps – georeferenced on the current cartography – together with other archive data (drawings and news taken from an ancient gazette). All these data have been merged in one GIS, this way offering a new look at the ancient city of waters, characterized by a grandiose hydraulic system, with the Savena and the Reno artificial channels and the Aposa natural channel, several silk mills, sewer systems, water wheels and a port.