Debris flows in the Alps pose a considerable hazard. The initiation mechanisms and flow behavior are complex because the debris-flow process .is a mixture of flood runoff, landslides and rockfalls. Interest in debrisflow research in European countries has increased since the 1980's. The most important methods for· debris-flow investigations are documentation of past events, geomorphologic interpretation of features created by debris flows, measurements of initiation and flow behavior both in i:he field and in experiments and the use of numerical simulation models. At present, the evaluation of potential hazards relies essentially on analogies to past events, geomorphologic assessment of the catchment area and empirical relationships to estimate the most important debris-flow parameters. Simulation models are only occasionally used. The key parameter is an appropriate estimation of the potential debris flow magnitude and in association the probability of a flow event.