HAZARD PREVENTION USING FLEXIBLE MULTI-LEVEL DEBRIS FLOW BARRIERS PROTECTION AGAINST DEBRIS FLOWS BY INSTALLATION OF 13 FLEXIBLE BARRIERS IN THE MILIBACH RIVER (CANTON BERNE, SWITZERLAND)

The villages Hasliberg, Reuti and Meiringen in Canton Berne, Switzerland, were affected by flood and debris flow events resulting from unusually large rainfall in August 2005. The damage potential is large, necessitating immediate action. Access problems and environmental concerns in the debris flow source area were not possible for a variety of reasons. A promising solution consisting of multiple ring-net barriers was proposed as a potentially viable mitigation measure. Because experience with such nets for debris flows is limited, laboratory tests were performed. The results of the laboratory tests provided insight on the proper design and support the general concept. Close co-operation between the scientific team of the WSL, an industrial partner and cantonal authorities during the investigations led to a consistent and technically plausible solution within a relatively short time. These multiple barrier system will be realised in 2007.