Susceptibility and Triggers for Debris Flows: Emergence, Loading, Release and Entrainment

Evidence for enhanced debris-flow activity in the Northern Calcareous Alps since the 1980s (Plansee, Austria)

“…Debris flows are often triggered by intensive rainfalls within a few minutes to a few hours (Caine, 1980;Johnson and Rodine, 1984;Guzzetti et al, 2008;Kaitna et al, 2013). However, most intense summer precipitation in the last decades has often coincided with certain weather patterns and storm trajectories like the Vb (according to the van Bebber classification) bringing wet air from the Mediterranean Sea to the Northern Alps causing some of the most intense debris-flow seasons such as in 2002and 2005(Krautblatter and Moser, 2009Morche and Schmidt, 2012).…”

Can bed-load help to validate hydrology studies in mountainous catchment? The case study of the Roize (Voreppe, France)

“…The active bed width (~5 m) varies with the gorge width: Several wider areas (up to 20 mwide) seem to be natural solid-transport regulating areas since evidences of debris flows deposits are numerous along these specific gorge reaches and the solid transport processes slightly shift from mainly debris flows to mainly bedload. This analysis is based on a detailed catchment field survey with a special attention to natural traces of sediment transport processes, the so-call "silent witnesses" (lateral levees, old boulder fronts, deposit patterns, bed morphology - Kaitna and Hübl 2013).…”

Periglacial Preconditioning of Debris Flows in the Southern Alps, New Zealand

“…The 'concept of disposition' for debris flow formation (cf. Kienholz, 1995;Zimmermann et al, 1997a, b;Kaitna et al, 2013) allows the classification of the numerous controlling factors according to their temporal efficacy into basic susceptibility, variable susceptibility, and triggering events.…”

“…Event records may be extended into the pre-aerial survey times by absolute and relative dating of debris flow scars or deposits at selected sites (e.g. radiocarbon dating, lichenometry, schmidt hammer exposureage dating, cosmogenic nuclides dating, or optically stimulated luminescence (OSL) dating; see Lang et al, 1999, Goudie, 2006, or Schneuwly-Bollschweiler et al, 2013, for details on the individual methods). However, large populations of debris flow systems, necessary for statistical evaluation of preconditioning factors, are hardly realisable when using direct dating methods for debris flow event identification (cf.…”