The role of thermokarst evolution in debris flow initiation (Hüttekar Rock Glacier, Austrian Alps)
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Published:2023-07-20
Issue:7
Volume:23
Page:2547-2568
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ISSN:1684-9981
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Container-title:Natural Hazards and Earth System Sciences
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language:en
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Short-container-title:Nat. Hazards Earth Syst. Sci.
Author:
Seelig SimonORCID, Wagner Thomas, Krainer Karl, Avian Michael, Olefs Marc, Haslinger KlausORCID, Winkler GerfriedORCID
Abstract
Abstract. A rapid sequence of cascading events involving thermokarst lake outburst, local rock glacier front failure, debris flow development, and river blockage hit Radurschl Valley (Ötztal Alps, Tyrol) on 13 August 2019. Compounding effects from permafrost degradation and drainage network development within the rock glacier initiated the complex process chain. The debris flow dammed the main river of the valley, impounding a water volume of 120 000 m3 that was partly drained by excavation to prevent a potentially catastrophic outburst flood. We present a systematic analysis of destabilizing factors to deduce the failure mechanism. The identification and evaluation of individual factors reveals a critical combination of topographical and sedimentological disposition, climate, and weather patterns driving the evolution of a thermokarst drainage network. Progressively changing groundwater flow and storage patterns within the frozen sediment accumulation governed the slope stability of the rock glacier front. Our results demonstrate the hazard potential of active rock glaciers due to their large amount of mobilizable sediment, dynamically changing internal structure, thermokarst lake development, and substantial water flow along a rapidly evolving channel network.
Funder
Bundesministerium für Land- und Forstwirtschaft, Umwelt und Wasserwirtschaft Karl-Franzens-Universität Graz Amt der Steiermärkischen Landesregierung Amt der Kärntner Landesregierung Salzburger Landesregierung Landes Tirols Amt der Vorarlberger Landesregierung
Publisher
Copernicus GmbH
Subject
General Earth and Planetary Sciences
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