Schattenbachlawine Walenstadt – Modernization of the existing avalanche protection system

The Schattenbach avalanche near Walenstadt in the canton of St. Gallen (Switzerland) is a notorious avalanche that moves down into the valley as a large powder snow avalanche. The avalanche path descends steeply from “Chäserrugg” (2,300 m above sea level) to Walenstadt‘s residential area (430 m above sea level). Under dry snow conditions, the steep fall over the 200m high Schattenbach wall leads to the formation of a powder-snow avalanche that can cause serious damage to residential buildings. The municipality of Walenstadt has already sought to counteract the threat of the Schattenbach avalanche with various measures. In addition to the construction of a catchment basin around 1980 and a tunnel to Walenstadtberg constructed in 2006, various structural measures were also implemented within the avalanche starting area. The snow drift barrier on the Hinterrugg was built in 1989 and has since prevented large amounts of snow from being transferred into the avalanche starting area. In addition, a mine thrower was deployed in cooperation with the Swiss army and used for precautionary avalanche mitigation since 1970. With the prohibition of the use of army artillery for the artificial triggering of avalanches, an alternative was now sought for protecting against the Schattenbach avalanche.