Author(s)

J. Hübl & M. Moser

Abstract

The catchment area of Lattenbach in the District of Landeck, Tyrol, Austria is prone to debris flows. Large mass movements represent debris sources within the catchment. Debris flows, documented since 1907, pose a threat to buildings in the village of Pians. The construction of technical mitigation measures date back to 1908. Up to now, numerous check dams have been built. However, in the transit section of the channel, many of them are damaged or destroyed. Therefore, the former technical protection concept had to be reconsidered. A general risk management concept was conducted, including a detailed risk analysis. The risk analysis was based on a detailed analysis of former debris-flow events and field survey in order to collect input parameters for process analysis. Different scenarios were calculated, varying the input hydrograph, the volume of potential debris sources and the sediment concentration. The simulation results were used to derive intensity maps for the prone settlement area. In a subsequent step, an impact analysis resulted in the determination of areas bearing a lack of safety was carried out, and an appropriate map was generated. Risk management in the Lattenbach area was based on a protection concept that combines active and passive mitigation measures. Active measures include a temporary debris storage basin in the transit section to lower the peak discharge, and an improvement of the hydraulic transport capacity of the receiving stream to reduce backwater effects. Passive mitigation measures are based on an existing monitoring system, which was technically improved to an information system in order to provide information to local authorities if a debris flow will occur. Keywords: risk analysis, risk management, torrent control, debris flows.

Keywords

risk analysis, risk management, torrent control, debris flows.