Preprints
https://doi.org/10.5194/tc-2021-151
https://doi.org/10.5194/tc-2021-151

  15 Jun 2021

15 Jun 2021

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

Drainage of an ice-dammed lake through a supraglacial stream: hydraulics and thermodynamics

Christophe Ogier1,2, Mauro A. Werder1,2, Matthias Huss1,2,3, Isabelle Kull4, David Hodel5, and Daniel Farinotti1,2 Christophe Ogier et al.
  • 1Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
  • 2Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
  • 3Department of Geosciences, University of Fribourg, Fribourg, Switzerland
  • 4Geotest AG, Zollikofen, Switzerland
  • 5Theiler Ingenieure, Thun, Switzerland

Abstract. The glacier-dammed Lac des Faverges, located on Glacier de la Plaine Morte (Swiss Alps), drained annually as a glacier lake outburst flood since 2011. In 2018, the lake volume reached more than 2 × 106 m3 and the resulting flood caused damages to the infrastructure downstream. In 2019, a supraglacial channel was dug to artificially initiate a surface lake drainage, thus limiting the lake water volume and the corresponding hazard. The peak in lake discharge was successfully reduced by over 90 % compared to 2018. We conducted extensive field measurements of the lake-channel system during the 48-days drainage event of 2019 to characterize its hydraulics and thermodynamics. The derived Darcy-Weisbach friction factor, which characterizes the water flow resistance in the channel, ranges from 0.17 to 0.48. This broad range emphasizes the factor’s variability, and questions the choice of a constant friction factor in glacio-hydrological models. For the Nusselt number, which relates the channel-wall melt to the water temperature, we show that the classic, empirical Dittus-Boelter equation with the standard coefficients is not adequately representing our measurements, and we propose a suitable pair of coefficients to fit our observations. This hints at the need to continue the research into how heat transfer at the ice/water interface is described in the context of glacial hydraulics.

Christophe Ogier et al.

Status: open (until 10 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-151', Anonymous Referee #1, 21 Jun 2021 reply
  • RC2: 'Comment on tc-2021-151', Anonymous Referee #2, 19 Jul 2021 reply

Christophe Ogier et al.

Data sets

Data and Results Christophe Ogier, Mauro Werder https://people.ee.ethz.ch/~werderm/pm-data/

Model code and software

PlaineMorteLake_hydro_thermodynamics.jl Christophe Ogier, Mauro Werder https://people.ee.ethz.ch/~werderm/pm-data/

Christophe Ogier et al.

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Short summary
Glacier-dammed lakes are prone to drain rapidly when the ice dam breaks, and constitute a serious threat for populations downstream. Such a lake drainage can proceed through an open-air channel at the glacier surface. In this study, we present what we believe to be the most complete data set to date of an ice-dammed lake drainage through such an open-air channel. We provide new insights for future glacier-dammed lakes drainage modelling studies and hazard assessments.