Sediment recharge of a debris flow channel: Insights from a 7-year monitoring campaign in the Northern Calcareous Alps

Debris flows in steep mountain channels are commonly triggered due to heavy precipitation events mobilising the sediment in the channel bed and from the banks. The magnitude of these events is heavily influenced by rainstorm intensity as well as the sediment availability in those channels. After a debris flow has occurred, the system recharges with material from the upstream catchment until the next event. This poses the question of how large these sediment recharge rates are and how they are connected to rainfall intensities.

Here, we present a 7-year monitoring campaign of a debris flow channel in the Northern Calcareous Alps between 2015 and 2022. Biannual measurements resulted in ten terrestrial laser scans and five UAV surveys to observe the sediment deposition and erosion magnitudes. Additionally, the local precipitation was measured in the vicinity of the channel from the second year of the campaign. We analysed how sediment recharge rates change after a debris flow event and how they are influenced by season and precipitation.