One Year Use of High-Frequency RADAR Technology in Alpine Mass Movement Monitoring: Principles and Performance for Torrential Activities

Abstract

Automatic monitoring of alpine mass movement is a major challenge. The presented research project shows a new approach in alert systems by using a high-frequency RADAR. The considered alpine hazards are torrential hazards (debris flows, mud flows, debris floods), landslides and rock fall as well as snow avalanches. The detection system was implemented (spring 2012) in the integral monitoring system for the Lattenbach catchment (5.3 km²) run by the Institute of Mountain Risk Engineering (BOKU) in order to prove the applicability of the RADAR in monitoring torrential processes (e.g. debrisflows, mudflows, flash floods, etc.). The RADAR system emits short encoded pulses and detects the corresponding echo signals at particular time steps, along segmented distance intervals (range gates of 25 m). The operational detection distance in Lattenbach is about 300 m, but it could be in principal up to two kilometers with the same accuracy. Obtained insights were not only an idea about the magnitude of certain events but also the changing of water levels and the flow velocity distribution. The measurement is based on a frequency analysis of the echo signals (doppler shift), which gives information about the mean front velocity, the distance of several surges and the flow velocity of the river itself.