Campus Units

Natural Resource Ecology and Management

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

8-6-2020

Journal or Book Title

Earth Surface Processes and Landforms

DOI

10.1002/esp.4973

Abstract

There exists a need to advance our understanding of debris-covered glacier surfaces over relatively short timescales due to rapid, climatically induced areal expansion of debris cover at the global scale, and the impact debris has on mass balance. We applied UAV-SfM and DEM differencing with debris thickness and debris stability modelling to unravel the evolution of a 0.15 km2 region of the debris-covered Miage Glacier, Italy, between June 2015 and July 2018. DEM differencing revealed widespread surface lowering (mean 4.1 ± 1.0 m a-1; max 13.3 m a-1). We combined elevation change data with local meteorological data and a sub-debris melt model, and used these relationships to produce high resolution, spatially distributed maps of debris thickness. These maps were differenced to explore patterns and mechanisms of debris redistribution. Median debris thicknesses ranged from 0.12 – 0.17 m and were spatially variable. We observed localised debris thinning across ice cliff faces, except those which were decaying, where debris thickened. We observed pervasive debris thinning across larger, backwasting slopes, including those bordered by supraglacial streams, as well as ingestion of debris by a newly exposed englacial conduit. Debris stability mapping showed that 18.2 - 26.4% of the survey area was theoretically subject to debris remobilisation. By linking changes in stability to changes in debris thickness, we observed that slopes that remain stable, stabilise, or remain unstable between periods almost exclusively show net debris thickening (mean 0.07 m a-1) whilst those which become newly unstable exhibit both debris thinning and thickening. We observe a systematic downslope increase in the rate at which debris cover thickens which can be described as a function of the topographic position index and slope gradient. Our data provide quantifiable insights into mechanisms of debris remobilisation on glacier surfaces over sub-decadal timescales, and open avenues for future research to explore glacier-scale spatiotemporal patterns of debris remobilisation.

Comments

This is the peer reviewed version of the following article: Westoby, Matthew J., David R. Rounce, Thomas E. Shaw, Catriona L. Fyffe, Peter L. Moore, Rebecca L. Stewart, and Benjamin W. Brock. "Geomorphological evolution of a debris‐covered glacier surface." Earth Surface Processes and Landforms (2020), which has been published in final form at doi: 10.1002/esp.4973. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Copyright Owner

John Wiley & Sons, Ltd.

Language

en

Available for download on Friday, August 06, 2021

Published Version

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