Using Event and Minimum Age Dating for the Assessment of Hazards on a Debris-Flow Cone

Abstract

Debris flows are common mass-movement processes in most mountainous regions of the world, where their unpredictable and sudden occurrence represents a major threat to transportation corridors and settlements. Increased anthropogenic activity in regions exposed to debris-flow risk renders a detailed hazard assessment inevitable. As a consequence, the understanding of the debris-flow process as well as the behavior of events in space and time is crucial for the mitigation of hazards and risks (e.g. Cardinali et al. 2002; Pasuto and Soldati 2004). For many torrents in Alpine regions, however, systematic acquisition of data on past debris flows only started after the series of catastrophic events in 1987 and 1993 (Haeberli et al. 1990; Rickenmann and Zimmermann 1993; Zimmermann et al. 1997); there is still a considerable lack of knowledge about earlier events for many regions. Thus the reconstruction of past activity is essential for the understanding of current debris-flow dynamics in mountain torrents, possible future developments due to potential climatic change (Goudie 2006) and a realistic assessment of the hazards.