METRO - Meteorological triggers of debris flows in a future greenhouse climate

Despite very detailed studies on the occurrence of debris flows as well as on their spatial behavior on the cone, there is still a considerable lack of knowledge on the triggers of past events as well as on the spatial coherency of events. Similarly, there is much debate about changes in the frequency, magnitude and seasonality of precipitation events and related debris-flow processes as a result of projected greenhouse warming.

This research project will focus on the determination of the spatial distribution of past debris-flow events in order to reveal the temporal similarity of debris-flow occurrence in different basins. To do so, all data on past debris-flow events in the study region will be compiled in order to provide a detailed data base. Based on this data, the spatial pattern of torrents reacting simultaneously will be assessed.

Thereafter, weather situations triggering past debris-flows events will be investigated in order to identify synoptic and local atmospheric conditions responsible for the triggering of debris flows. Within the analysis of meteorological data, special focus will be addressed to the spatial distribution as well as to intensity and duration of rainfall during such events. Based on the rainfall data, the investigation aims at providing detailed information on thresholds (amount and intensity of rainfall) for the release of debris flows and analyzes extreme values recorded in the meteorological series (outlayers).


Contractors: AXA Research Fund Post-doctoral grant

Project durationr: November 2008 – October 2009

Contact: Michelle Bollschweiler


Bollschweiler, M., Stoffel, M. (2010): Tree rings and debris flows: recent developments, future directions. Progress in Physical Geography 34: 625–645. [PDF]

Bollschweiler, M., Stoffel, M. (2010): Changes and trends in debris-flow frequency since AD 1850: Results from the Swiss Alps. The Holocene 20: 907–916. [PDF]

Bollschweiler, M., Stoffel, M. (2010): Variations in debris-flow occurrence in an Alpine catchment – A reconstruction based on tree rings. Global and Planetary Change 73: 186–192. [PDF]