4th Swiss Geoscience Meeting, Bern 2006 A warning system for natural hazards in summer at the

The Illgraben is one of the most active debris flow channel in the Alps (Rickenmann et al. 2001). Regularly recurring debris flows (~5 per year reach the Rhone River) endanger the village and infrastructure, and create a hazard for residents and tourists. To reduce the risk the Dienststelle für Strassen- und Flussbau (Road and River Engineering Service), Canton of Valais, commissioned a project to explore the hazard and propose protection measures. Besides technical measures the study proposed an alert concept for the village of Susten. One project outcome includes protection measures, including the development of the alert concept, which is realised in four phases: reconnaissance, design, implementation, and optimisation. The Swiss Federal Institute for Forest, Snow and Landscape WSL operates an automated observation station, for debris flow research, at the Illgraben (Hürlimann et al. 2003). Experience from this installation provides a sound scientific basis for the development of a warning system for Illgraben channel. The overall concept consists in a 4-stage alarm approach, including (i) permanent informational and organizational measures within the community, (ii) an instrumente