Preprints
https://doi.org/10.5194/esurf-2021-18
https://doi.org/10.5194/esurf-2021-18

  29 Mar 2021

29 Mar 2021

Review status: this preprint is currently under review for the journal ESurf.

Intensified paraglacial slope failures due to accelerating downwasting of a temperate glacier in Mt. Gongga, Southeastern Tibet Plateau

Yan Zhong1,2, Qiao Liu1, Matthew Westoby3, Yong Nie1, Francesca Pellicciotti4, Bo Zhang5, Jialun Cai5, Guoxiang Liu5, Haijun Liao1,2, and Xuyang Lu1 Yan Zhong et al.
  • 1Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
  • 2College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Department of Geography and Environmental Sciences, Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, UK
  • 4Swiss Federal Institute for Forest, Snow and Landscape Research WSL, 8903 Birmensdorf, Switzerland
  • 5Department of Surveying and Geo-Informatics, Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China

Abstract. Topographic development via paraglacial slope failure (PSF) represents a complex interplay between geological structure, climate, and glacial denudation. Where debris generated by PSFs is deposited on the surface of a glacier, this debris can increase the extent or thickness of a supraglacial debris-cover, in turn modifying glacier ablation and affecting meltwater generation. To date, little attention has been paid to intensity and frequency of PSFs in glacierised, monsoon temperate regions of Southeast Tibet. We mapped PSFs along the 5 km-long, west-east trending ice tongue of Hailuogou Glacier (HLG), Mt. Gongga, using repeat satellite- and UAV-derived imagery between 1990 and 2020. Three types of PSF were identified: (A) rock fall, (B) sediment-mantled slopes slide and collapse, and (C) gully headwards erosion. We analyzed the formation, evolution and current state of these PSFs and discuss these aspects with relation to glacier dynamics and paraglacial geomorphological history. South-facing slopes (true left of HLG) showed more destabilization and higher PSF activity than north-facing slopes. We observed annual average rates of downslope sliding for type B PSFs of 1.6–2.6 ± 0.04 cm d−1, whereas the average upward denudation rate for type C PSFs was 0.7–3.39 cm d−1. We show that type A PSFs are non-ice-contact rock collapses that occur as a long-term paraglacial response following glacier downwasting and the exposure of steep rocky cliffs and which could also be influenced by precipitation, freeze-thaw cycling, earthquakes or other factors. In contrast, type B and C PSFs are a more immediate response to recent glacier downwasting. We further argue that the accelerating downwasting of glacier are used as a preparatory or triggering factor, which could directly or indirectly cause the PSFs.

Yan Zhong et al.

Status: open (until 14 May 2021)

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Yan Zhong et al.

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Short summary
Slope failures exists in many paraglacial regions and is the main manifestation of the interaction between debris-covered glacier and slope. We mapped paraglacial slope failures (PSFs) along the Hailuogou Glacier (HLG), Mt. Gongga, Southeastern Tibet Plateau. We argue that the accelerating downwasting of glacier are used as a preparatory or triggering factor, which could directly or indirectly cause the PSFs.