Brief communication: An autonomous UAV for catchment-wide monitoring of a debris flow torrent

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