Hydro-meteorological trigger conditions of debris flows in Austria

Roland Kaitna*, David Prenner, Martin Braun, Markus Hrachowitz

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

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Abstract

Different factors influence the disposition of a watershed for initiation of debris flows, including meteorological trigger conditions as well as the hydrologic and geomorphic disposition. The latter includes slowly changing factors like relief energy or sediment availability, whereas the hydrologic state of a watershed may vary over short time scales. This contribution summarizes the outcomes of a long term project to quantify meteorological and hydrological trigger conditions leading to debris flows at different temporal and spatial scales in the Austrian Alps. The analysis employs a database of more than 4,500 debris flows over the last 100+ years, which is the period for which systematic rainfall data is available. A Bayesian analysis was carried out for determining occurrence probabilities for all Austria. For selected regions, hydrological trigger conditions were assessed using a semi-distributed, conceptual rainfall-runoff model, which was calibrated to measured runoff data. As expected we find increasing trigger probabilities with increasing rainfall amounts and intensities. However, the additional information of regional hydrological parameters as well as their temporal evolution over days prior to a debris-flow event, enables to capture different trigger conditions, including short duration rainstorms, long lasting rainfall events, and snow melt. We also find that a trigger-type resolved prediction of debris-flow susceptibility based on the hydro-meteorological catchment information is superior to simple rainfall-only approaches. The results of this analysis shall improve our understanding of long-term trigger conditions and trends of extreme mass wasting processes in the Alps and aim to become a valuable tool in engineering hazard assessment.

Original languageEnglish
Title of host publicationDebris-Flow Hazards Mitigation
Subtitle of host publicationMechanics, Monitoring, Modeling, and Assessment - Proceedings of the 7th International Conference on Debris-Flow Hazards Mitigation
EditorsJason W. Kean, Jeffrey A. Coe, Paul M. Santi, Becca K. Guillen
PublisherAssociation of Environmental and Engineering Geologists
Pages732-739
Number of pages8
ISBN (Electronic)9780578510828
Publication statusPublished - 2019
Event7th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Monitoring, Modeling, and Assessment - Golden, United States
Duration: 10 Jun 201913 Jun 2019

Conference

Conference7th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Monitoring, Modeling, and Assessment
Country/TerritoryUnited States
CityGolden
Period10/06/1913/06/19

Bibliographical note

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Keywords

  • Hydrologic modeling
  • Initiation conditions
  • Probabilitic thresholds
  • Susceptibility

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