We research debris flows at various levels: we observe their behaviour via automatic monitoring stations, trigger experimental debris flows in the laboratory, and simulate their courses and spread using a computer. Our research focuses on the following areas.
The Illgraben - the gorge of the Illbach - sees several debris flows per year. This makes researchers interested in this valley. The WSL has installed technical instruments all over the gorge and implemented an alarm system.
Understanding processes through field observation
We have set up multiple automatic debris flow monitoring stations in the Swiss Alps which provide us with important data sets for describing flow processes and for developing and calibrating numerical simulation programmes. Various measuring systems are used and tested at the stations.
Two automatic debris flow monitoring stations (Illgraben, Dorfbach) are currently in operation. Other stations were installed in previous years and have also provided key data sets: Schipfenbach, Preonzo, Riascio.
Application and development of numerical simulation programmes
Developing numerical simulation programmes enables us to make reliable calculations of the flow behaviour of debris flows in the torrent on a debris-flow fan, which but also to identify critical conditions for overloading the torrent and indicate possible flow paths and at-risk areas outside of the torrent channel. We show the limitationss and possibilities of numerical simulation programmes based on exemplary ample applications and devise recommendations and guidelines for their use in hazard analysis. This work is carried out within the RAMMS Rapid Mass Movements programme.
At WSL's large-scale laboratory we can study the trigger, transit and deposition behaviour of debris flows can be studied on a smaller scale. In a debris flow channel, the flow behaviour of different debris flow mixtures can be analysed and measuring instruments can be tested before they are used in the field. The debris flow channel can also be used to demonstrate the characteristic features of debris flows to visiting groups.
Based on findings from new field data, laboratory experiments and calculations using numerical simulation programmes, we can continue to improve our knowledge of debris flows, a complex phenomenon that we still know do not know enough about. All of these findings contribute to the improvement of practical methods and tools for evaluating and mapping natural hazards.
The WSL observes debris flows in Valais. To this end we have installed technical instruments in the Illgraben (the trench of the Illbach). François Dufour explains both projects, research and protection (French with German subtitles) (Video: WSL)