Sensitivity of subglacial drainage to water supply distribution at the Kongsfjord basin, Svalbard

Scholzen, Chloé; Schuler, Thomas V.; Gilbert, Adrien

doi:https://doi.org/10.5194/tc-15-2719-2021

Articles | Volume 15, issue 6

https://doi.org/10.5194/tc-15-2719-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/tc-15-2719-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 6

Research article

|

17 Jun 2021

Research article |

| 17 Jun 2021

Sensitivity of subglacial drainage to water supply distribution at the Kongsfjord basin, Svalbard

Chloé Scholzen, Thomas V. Schuler, and Adrien Gilbert

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Final revised paper (published on 17 Jun 2021)
Preprint (discussion started on 20 Nov 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review: Sensitivity of subglacial drainage to water supply distribution at the Kongsfjord basin, Svalbard', Anonymous Referee #1, 21 Dec 2020
- AC1: 'Reply on RC1', Chloé Scholzen, 23 Feb 2021
RC2: 'Review of “Sensitivity of subglacial drainage to water supply distribution at the Kongsfjord basin, Svalbard”', Christine Dow, 06 Jan 2021
- AC2: 'Reply on RC2', Chloé Scholzen, 23 Feb 2021

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by editor and referees) (04 Mar 2021) by Valentina Radic

AR by Chloé Scholzen on behalf of the Authors (12 Apr 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (22 Apr 2021) by Valentina Radic

RR by Christine Dow (07 May 2021)

Suggestions for revision or reasons for rejection

I would like to thank the authors for their adjustment of their manuscript and study in response to my review. Using the lower sheet conductivity makes the system look a lot more realistic and so I have much more faith in the outputs being produced. Again, including a spin-up year also helps with output validity. The results and analysis are well presented and are interesting for analysis of Svalbard Glaciers compared to lower latitude glaciers.

I have no major comments and my points below are primarily suggestions for tightening the language for clarity.

9 – ‘modulates ice velocity’.
16 – ‘which instead is controlled…’
17 – ‘which we attribute to small surface gradients’
18 – ‘The findings of our study are potentially applicable to most Svalbard…’
31 – ‘been found to be concurrent’
49 – Perhaps ‘in reality’ rather than ‘In nature’. And ‘usually is a result of water accumulation over a catchment on the glacier surface’.
53 – also by fractures (in addition to englacial conduits)
67 – ‘distributed supply rates’ is confusing
76 – ‘75% is currently ice-covered’
92 – ‘nunataks are present in the lower parts’ rather than ‘peak through’
94 – ‘ice thickens to a maximum of 740m’
107 – this point about temperate ice is important as it raises the question of where it might not be temperate at the bed. It would be good to briefly expand on this, perhaps in the discussion.
109 – put ‘measured in 2012’ into the brackets with the reference as otherwise it suggests that the maximum speed was in 2012 and it has slowed since.
146 – ‘drainage system was achieved’
152 – ‘associated with’
155 – ‘we apply the Glacier’
164 – what is the value of that uniform basal melt rate you apply?
170 – ‘we direct readers’
184 – ‘values different from Werder et al (2013)’ Other literature discussing GlaDS uses these values.
185 – ‘below the channel’
205 – suggest you replace ‘supraglacial hydrology’ with ‘supraglacial drainage network’
222 – ‘associated with’
235 – not directly from Fig 2c. What were they specifically identified from? The supraglacial drainage network and…?
237 – ‘catchments are also adjusted in order to’
242 – ‘analysis was carried out’. Check rest of paragraph/manuscript for correct tenses.
274 – ‘different sizes of surface area contributing water’
302 – ‘this figure’ still confusing. Delete ‘supports model results for basal water pressure (Fig 3 and 4) an’ so it reads ‘This figures shows that, at…’ Otherwise it is redundant as you’re discussing the same model outputs.
305 – ‘typically approaches overburden pressure’
308 – ‘Over the annual period’
309 – ‘recurrent pattern in all seasons is’
346 – how does the Praminik hydrological analysis affect your confidence in your outputs vs the observations by How et al and Everett et al? Does the Praminik study back up or counter your GlaDS results and why?
351 – I’m not sure how this is implied? Can you see evidence of that in your model results?
384 – how rapid is the closure?
401 – ‘However, results from this experiment’
410 – ‘less’ instead of ‘poorer’
443 – ‘channelization occurs only with high pressurisation’. I’m not sure that follows – you also have channelization when you applied your previous higher sheet conductivity with overall much lower pressure levels.
530 – ‘less water supply to their beds compared to lower latitude glaciers’.
533 – last sentence needs work. Instead of ‘standard configuration’ how about contrary to what would be expected in Greenland outlet or Alpine glaciers.
Figure 7 caption ‘subglacial channel distribution’

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ED: Publish subject to minor revisions (review by editor) (08 May 2021) by Valentina Radic

AR by Chloé Scholzen on behalf of the Authors (12 May 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (18 May 2021) by Valentina Radic

Short summary

We use a two-dimensional model of water flow below the glaciers in Kongsfjord, Svalbard, to investigate how different processes of surface-to-bed meltwater transfer affect subglacial hydraulic conditions. The latter are important for the sliding motion of glaciers, which in some cases exhibit huge variations. Our findings indicate that the glaciers in our study area undergo substantial sliding because water is poorly evacuated from their base, with limited influence from the surface hydrology.