Evaluation of Different Methods for Debris Flow Velocity Measurements at the Lattenbach Creek

Johannes HÜBL, Andreas SCHIMMEL and Richard KOSCHUCH

The Lattenbach creek, District of Landeck, Tyrol, is a very active torrent located in a geologic fault zone in the western part of Austria. The channel separates the Northern Limestone Alps in the North from the Crystalline Alps in the South. Aside from the regular flood events with bedload transport, the torrent produced seven debris flows and three debris floods within recent years. Due to the frequent debris flow and debris flood events the torrent is monitored by the Institute of Mountain Risk Engineering since several years. The parameters that are currently measured during an event include meteorological data in the upper part of the catchment and run-off data from the middle and lower reach of the torrent at the villages Grins and Pians. In the last years the monitoring equipment has been constantly improved. Additional to the standard sensors like radar for water level measurements, seismic sensors for ground motion detection and infrasound sensors for acoustic wave identification, a high frequency Pulse Doppler Radar has been installed, which provides the opportunity to measure the instantaneous surface velocity of a debris flow in different range gates. Together with a recently installed 2D-Laser scanner this setup provides the possibility to determine a very precise approximation of the discharge with a high temporal resolution. On this basis different methods to determine the velocity of debris flows were applied and compared. The results show, that the applied concept to record data of debris flows in a high temporal resolution seems to be promising.

2018/1 2-8