The influence of frost weathering on the debris flow sediment supply in an alpine basin

Journal of Geophysical Research
By: , and 



Rocky, alpine mountains are prone to mass wasting from debris flows. The Chalk Cliffs study area (central Colorado, USA) produces debris flows annually. These debris flows are triggered when overland flow driven by intense summer convective storms mobilizes large volumes of sediment within the channel network. Understanding the debris flow hazard in this, and similar alpine settings, requires determining the magnitude of sed- iment accumulation between debris flow seasons, and identifying the control on sediment production. To address these knowledge gaps, we measured changes in sediment produc- tion using a sediment retention fence to quantify how sedimentation was influenced by temperature at the plot scale. These measurements were extrapolated to a larger area, where we extended the sediment fence results to explore how rockfall sedimentation con- tributed to channel refilling between active debris flow periods. This work shows debris flow channel refilling is correlated with low temperatures and time in the frost-cracking window, implicating frost weathering mechanisms as a key driver of sedimentation. This sediment production process resulted in a large amount of sediment accumulation dur- ing a single winter season in our study reach (up to 0.4 m in some locations). Using these observations, we develop a channel refilling model that generally describes the mass bal- ance of debris flow watersheds in alpine areas.

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Publication type Article
Publication Subtype Journal Article
Title The influence of frost weathering on the debris flow sediment supply in an alpine basin
Series title Journal of Geophysical Research
DOI 10.1029/2019JF005369
Volume 125
Issue 2
Year Published 2020
Language English
Publisher AGU
Contributing office(s) Geologic Hazards Science Center
Description e2019JF005369, 16 p.
Country United States
State Colorado
Other Geospatial Chalk Cliffs
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