This paper examines the value of historical documents for the analysis of past flood events and the landscape history of the Bisagno Valley, Genoa, NW Italy. The Bisagno Valley has been historically affected by a number of flood events, which became particularly frequent in the last decade. This is mainly due to the urbanisation of the valley since the 1950s and the recent climate changes, with increased flash flood events. There is, however, evidence of the past occurrence of floods, of which the event of 1822 is well documented by letters, written reports, maps and drawings. Drawing upon a multidisciplinary methodology which involves a wide range of sources, this work seeks to investigate the dynamic and effects of the flood of 1822. These sources need to be critically examined, contextualised and compared with other contemporary documents.
The weather event and flood dynamic are described in detail by contemporary writers such as Lord Byron, who at the time was residing in Genoa, and by local newspapers. These records allow to reconstruct the rainfall event and flood dynamic. The Genoese painter Luigi Garibbo represented the effects that the flood of the Bisagno had on a bridge in Genoa. Other contemporary commentators reported the damages of the Bisagno in written descriptions and plans of the river; based on these documents, it was possible to map the flooded areas of the Bisagno Valley. In addition to the reconstruction the flood event, the historical documents help to reconstruct the landscape of the Bisagno Valley in the nineteenth century. A large corpus of topographical drawings, views and maps document the landscape the valley in the C18th and 19th, before the urbanisation of the C20th. The documents are analysed in terms of land use and management of the river bed. They provide evidence of the rural past of the valley, with extensive terraced areas which are today largely abandoned. The paper demonstrates the value of historical documents as a source to investigate past extreme weather events and to reconstruct landscape history.