A WebGIS for the dissemination of information on historical landslides and floods in Umbria, Italy

A web site was designed to disseminate new information on historical landslides and floods in Umbria, central Italy. The historical information was compiled through a thorough review of existing catalogues of historical landslide and flood events, supplemented by an extensive search of local historical archives and chronicles, for the period before 1900. The new catalogue lists 1983 landslide events in the period from 1139 to 2001, and 1956 flood events in the period from 860 to 2001. In the considered period, in Umbria there were at least 1,531 sites affected one or more times by landslides, and at least 1,071 sites affected one or more times by inundations. The seasonal distribution of landslides and inundations was found different before and after 1900, most probably because of incompleteness of the historical record prior to 1900. WebGIS technology was used to disseminate the geographical and thematic information on historical landslides and floods in Umbria. The GIS-based web site is aimed at a diversified audience of experts and private citizens seeking information on geo-hydrological hazards in Umbria.