Header

UZH-Logo

Maintenance Infos

Changing debris flow activity after sudden sediment input: a case study from the Swiss Alps


Baer, Patrick; Huggel, Christian; McArdell, Brian W; Frank, Florian (2017). Changing debris flow activity after sudden sediment input: a case study from the Swiss Alps. Geology Today, 33(6):216-223.

Abstract

On 27 December 2011, a rock avalanche in the upper Val Bondasca in the southern Swiss Alps deposited 1.5–1.7 million m3 of rock debris. The following summer, debris flow activity in Val Bondasca was unusually high with four events after a 90-year period of debris flow inactivity. This was an exceptional situation for the valley. Analysing the 2012 events, the long-term record of meteorological conditions such as rainfall intensity and duration, in comparison with debris flow activity, suggests that the meteorological conditions in summer 2012 would not have triggered the high intensity debris flow events without additional sediment input. Consequently, the suddenly increased debris availability can be considered a major factor in these events. Interestingly, rainfall events of similar magnitude in the subsequent years 2013–2015 did not trigger additional debris flow events, indicating that debris flow initiation thresholds are increasing again, back towards pre-rock avalanche levels. This study aims to help in understanding the so far poorly understood temporal evolution of debris flow triggering thresholds and the effect of sudden changes in sediment availability.

Abstract

On 27 December 2011, a rock avalanche in the upper Val Bondasca in the southern Swiss Alps deposited 1.5–1.7 million m3 of rock debris. The following summer, debris flow activity in Val Bondasca was unusually high with four events after a 90-year period of debris flow inactivity. This was an exceptional situation for the valley. Analysing the 2012 events, the long-term record of meteorological conditions such as rainfall intensity and duration, in comparison with debris flow activity, suggests that the meteorological conditions in summer 2012 would not have triggered the high intensity debris flow events without additional sediment input. Consequently, the suddenly increased debris availability can be considered a major factor in these events. Interestingly, rainfall events of similar magnitude in the subsequent years 2013–2015 did not trigger additional debris flow events, indicating that debris flow initiation thresholds are increasing again, back towards pre-rock avalanche levels. This study aims to help in understanding the so far poorly understood temporal evolution of debris flow triggering thresholds and the effect of sudden changes in sediment availability.

Statistics

Citations

Dimensions.ai Metrics

Altmetrics

Downloads

2 downloads since deposited on 23 Jan 2018
2 downloads since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Date:2017
Deposited On:23 Jan 2018 16:22
Last Modified:19 Feb 2018 10:43
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0266-6979
OA Status:Closed
Publisher DOI:https://doi.org/10.1111/gto.12211

Download