Establishing a record of extreme debris flow events in a high Alpine catchment since the end of the Little Ice Age using lichenometric dating
- Author:
- Rom J., Haas F., Heckmann T., Dremel F., Fleischer F., Altmann M., Stark M. & Becht M.
- Year:
- 2023
- Journal:
- Geografiska Annaler: Series A, Physical Geography
- Pages:
- 105(1): 47–63
- Url:
- https://doi.org/10.1080/04353676.2023.2187531
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.
Keywords: Debris flows; lichenometry;
central Alps; Horlachtal;
extreme events.
- Id:
- 35451
- Submitter:
- zpalice
- Post_time:
- Wednesday, 24 May 2023 11:35