Hazard Zoning for Landslides Connected toudTorrential Floods in the Jerte Valley (Spain) byudusing GIS Techniques

摘要

The Jerte Valley is a northeast-southwest tending graben located in the mountainousudregion of west central Spain (Spanish Central System). Mass movements have been a predominantudshaping process on the Valley slopes during the Quaternary. Present day activity is characterized asudeither ‘first-time failure’ (shallow debris slides and debris flows) or ‘reactivations’ of pre-existingudlandslides deposits.udA delineation of landslide hazard zoning within the Valley has been carried out by using the detaileduddocumentation of a particular event (a debris slide and a sequel torrential flood, which occurredudon the Jubaguerra stream gorge), and GIS techniques. The procedure has had four stages, which are:ud(1) the elaboration of a susceptibility map (spatial prediction) of landslides; (2) the elaboration of audmap of ‘restricted susceptibility’ in the particular case of slopes that are connected to streams andudtorrents (gorges); (3) the elaboration of a digital model which relates the altitude to the occurrenceudprobability of those particular precipitation conditions which characterized the Jubaguerra event andud(4) the combination of the probability model with the ‘restricted susceptibility map’, to establishud‘critical zones’ or areas which are more prone to the occurrence of phenomena that have sameudtypology as this one.