02 May 2022
02 May 2022

Brief Communication: An Autonomous UAV for Catchment-Wide Monitoring of a Debris Flow Torrent

Fabian Walter1,2, Elias Hodel2,1, Erik Mannerfelt2,1, Nicolas Ackermann3, Kristen Cook4, Michael Dietze4,5, Livia Estermann6, Daniel Farinotti2,1, Martin Fengler7, Lukas Hammerschmidt7, Flavia Hänsli6, Jacob Hirschberg1,6, Brian McArdell1, and Peter Molnar6 Fabian Walter et al.
  • 1Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
  • 2Laboratory of Hydraulics, Hydrology and Glaciology, ETH Zurich, 8093 Zurich, Switzerland
  • 3Swiss Federal Railways SBB, 3000 Bern, Switzerland
  • 4GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany
  • 5Faculty of Geosciences and Geography, Georg-August-University Göttingen, 37077 Göttingen, Germany
  • 6Institute of Environmental Engineering, ETH Zurich, 8093 Zurich, Switzerland
  • 7Meteomatics AG, 9014 St. Gallen, Switzerland

Abstract. Debris flows threaten communities in mountain regions worldwide. Combining modern photogrammetric processing with autonomous unmanned aerial vehicle (UAV) flights at sub-weekly intervals allows mapping of sediment dynamics in a debris flow catchment. This provides important information for sediment disposition that pre-conditions the catchment for debris flow occurrence. At the Illgraben debris-flow catchment in Switzerland, our autonomous UAV launched nearly 50 times in the snow-free periods in 2019–2021 with typical flight intervals of 2–4 days, producing 350–400 images every flight. The observed terrain-changes resulting from debris flows exhibit preferred locations of erosion and deposition, including memory effects as previously deposited material is preferentially removed during subsequent debris flows. Such data are critical for the validation of geomorphological process models. Given the remote terrain, the mapped short-term erosion and deposition structures are difficult to obtain with conventional measurements. The proposed method thus fills an observational gap, which ground-based monitoring and satellite based remote sensing cannot fill as a result of limited access, reaction time, spatial resolution, or involved costs.

Fabian Walter et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-156', Marcel Hürlimann, 12 May 2022
  • CC1: 'Comment on egusphere-2022-156', Alexander Raphael Groos, 02 Jul 2022
  • RC2: 'Comment on egusphere-2022-156', Velio Coviello, 07 Jul 2022

Fabian Walter et al.

Fabian Walter et al.


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Short summary
Debris flows are dangerous sediment-water mixtures in steep terrain. Their formation takes place in poorly accessible terrain, where instrumentation cannot be installed. Here we propose to monitor such source terrain with an autonomous drone for mapping sediments, which were left behind by debris flows or may contribute to future events. Short flight intervals elucidate changes of such sediments providing important information for landscape evolution and the likelihood of future debris flows.