A GIS spatial analysis model for landslide hazard mapping application in Alpine Area

This research describes an application of an existing method for evaluating landslide susceptibility in alpine contest that may be considered a useful support in better land-use planning and risk management. In order to perform the method and improve it creating landslide maps of probability, we investigated the several conditioning factors that in general affected these morphological processes. Firstly, a landslide inventory was prepared using both in-depth analysis of historical records and aero-photos (or orthophotos) investigation. Secondarily, a set of conditioning factors which may affect slope movement and failure (particularly lithology, geomorphology, land use, slope angle and aspect) was considered. Then, the method involved the application of GIS techniques, specifically, spatial Data Analysis application. The thematic maps of conditioning factors overlapping together with the support of the raster calculator allowed the susceptibility map creation. The method was applied to the Germanasca Valley, a small basin in the Italian Western Alps. This easy to use method allows one to individuate various classes of susceptibility and to identify slope, lithology and geomorphology, driven by old landslide events as the main conditioning factors. Furthermore, the individuation of area susceptible to landslides verification is strictly related to risk and, as a consequence, this method permits specific zone to be selected for detailed engineering geology studies in land-use planning.