Climate Change Impacts on Sediment Yield and Debris‐Flow Activity in an Alpine Catchment

Hirschberg, J.; Fatichi, S.; Bennett, G.L.; McArdell, B.W.; Peleg, N.; Lane, S.N.; Schlunegger, F.; Molnar, P. (2021). Climate Change Impacts on Sediment Yield and Debris‐Flow Activity in an Alpine Catchment. Journal of Geophysical Research: Earth Surface, 126(1) AGU Publications 10.1029/2020JF005739

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Climate change impacts on sediment production and transfer processes on hillslopes and through channels are governed by possible changes in precipitation, runoff and air temperature. These hydrological and geomorphological impacts are difficult to predict in temperature‐sensitive Alpine environments. In this work, we combined a stochastic weather generator model with the most current climate change projections to feed a hillslope‐channel sediment cascade model for a major debris‐flow system in the Swiss Alps (the Illgraben). This allowed us to quantify climate change impacts and their uncertainties on sediment yield and the number of debris flows at hourly temporal resolution. We show that projected changes in precipitation and air temperature lead to a reduction in both sediment yield (‐48%) and debris‐flow occurrence (‐23%). This change is caused by a decrease in sediment supply from the hillslope, which is driven by frost‐weathering. Additionally, we conduct model experiments that show the sensitivity of projected changes in sediment yield and debris‐flow hazard to basin elevation, with important implications for assessing natural hazards and risks in mountain environments. Future changes in hydrological and sediment fluxes are characterized by high uncertainty, mainly due to irreducible internal climate variability. Therefore, this stochastic uncertainty needs to be considered in climate change impact assessments for geomorphic systems.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Schlunegger, Fritz

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

2169-9003

Publisher:

AGU Publications

Language:

English

Submitter:

Fritz Schlunegger

Date Deposited:

14 Jan 2021 11:51

Last Modified:

24 Jan 2021 01:35

Publisher DOI:

10.1029/2020JF005739

BORIS DOI:

10.48350/149624

URI:

https://boris.unibe.ch/id/eprint/149624

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