26 Apr 2023
 | 26 Apr 2023
Status: a revised version of this preprint is currently under review for the journal ESurf.

Massive sediment pulses triggered by a multi-stage alpine cliff fall (Hochvogel, DE/AT)

Natalie Barbosa, Johannes Leinauer, Juilson Jubanski, Michael Dietze, Ulrich Münzer, Florian Siegert, and Michael Krautblatter

Abstract. Massive sediment pulses in catchments are a key alpine multi-risk component. Substantial sediment redistribution in alpine catchments frequently causes flooding, river erosion, and landsliding, and affects infrastructure such as dam reservoirs as well as aquatic ecosystems and water quality. While systematic rock slope failure inventories have been collected in several countries, the subsequent cascading sediment redistribution is virtually unaccessed. This contribution reports for the first time the massive sediment redistribution triggered by the multi-stage failure of more than 150,000 m3 from the Hochvogel dolomite peak during the summer of 2016. We applied change detection techniques on seven 3D-coregistered high-resolution true-orthophotos and digital surface models (DSM) obtained through digital aerial photogrammetry later optimized for precise volume calculation in steep terrain. The analysis of seismic information from surrounding stations revealed the temporal evolution of the cliff fall. We identified the proportional contribution of > 600 rockfall events (>1 m3) from 4 rock slope catchments with different aspects and their volume estimates. In a sediment cascade approach, we evaluated erosion, transport, and deposition from the rockface to the upper channelized erosive debris flow channel, then to the widened dispersive debris flow channel, and finally to the outlet into the braided sediment-supercharged Jochbach river. We observe the decadal flux of more than 400,000 m3 of sediment with massive sediment pulses that (i) respond with reaction times of 0–4 years and relaxation times beyond 10 years, (ii) with faster response times of 0–2 years in the upper catchment and more than 2 years response times in the lower catchments, (iii) the inversion of sedimentary (102–103 mm/a) to massive erosive regimes (102 mm/a) within single years and the (iv) dependency of redistribution to rainfall frequency and intensity. This study provides generic information on spatial and temporal patterns of massive sediment pulses in highly-charged alpine catchments.

Natalie Barbosa 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 esurf-2023-10', Anonymous Referee #1, 10 Jul 2023
    • AC1: 'Reply on RC1', Natalie Barbosa, 09 Aug 2023
  • RC2: 'Comment on esurf-2023-10', Georgina Bennett, 13 Jul 2023
    • AC2: 'Reply on RC2', Natalie Barbosa, 09 Aug 2023

Natalie Barbosa et al.

Natalie Barbosa et al.


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Short summary
Massive sediment pulses in catchments are a key alpine multi-risks component. Combining high-resolution aerial imagery and seismic information, we decipher a multi-stage >150.000 m3 rockfall and subsequent sediment pulses over 4 years, reflecting sediment deposition up to 10 m, redistribution in the basin, and finally debouchure to the outlet. This study provides generic information on spatial and temporal patterns of massive sediment pulses in highly-charged alpine catchments.