Establishing a record of extreme debris flow events in a high Alpine catchment since the end of the Little Ice Age using lichenometric dating

Jakob Rom*, Florian Haas, Tobias Heckmann, Fabian Christopher Dremel, Fabian Fleischer, Moritz Altmann, Manuel Stark, Michael Becht

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Establishing a record of large debris flow events in high Alpine areas prior to the availability of high resolution remote sensing data can be very challenging. In this study, we investigate the debris flow activity in two tributary valleys of the Horlachtal catchment in Tyrol, Austria between the end of the Little Ice Age at about 1850 and the first available area wide aerial images from 1947. To accomplish this, we calculated a local lichenometric calibration curve using the long axis diameters of the five largest Rhizocarpon lichen thalli at 51 different reference locations. Because of the interval-censored dating of most of the reference sites, we established a bootstrapping approach within the calibration curve calculation process. With the help of the lichenometric calibration data, we were able to date 47 old debris flow deposits in the study area. The results indicate no increasing or decreasing trends in frequencies of extreme debris flow events. In addition, the results point to a very local character of debris flow triggering precipitation events, as we can detect major differences in neighbouring valleys. Lichenometric derived datings also provide temporal informations about the end of debris flow activity at some sites in the study area and thus can contribute to a better understanding of debris flow systems.

Original languageEnglish
Pages (from-to)47-63
Number of pages17
JournalGeografiska Annaler, Series A: Physical Geography
Volume105
Issue number1
DOIs
Publication statusPublished - 13 Mar 2023

Bibliographical note

Publisher Copyright:
© 2023 Swedish Society for Anthropology and Geography.

Keywords

  • Debris flows
  • Horlachtal
  • central Alps
  • extreme events
  • lichenometry

Fields of Science and Technology Classification 2012

  • 105 Geosciences

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