Technical note: Representing glacier geometry changes in a semi-distributed hydrological model

Seibert, Jan; Vis, Marc J. P.; Kohn, Irene; Weiler, Markus; Stahl, Kerstin

doi:https://doi.org/10.5194/hess-22-2211-2018

Articles | Volume 22, issue 4

https://doi.org/10.5194/hess-22-2211-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-22-2211-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 22, issue 4

Technical note

|

09 Apr 2018

Technical note |

| 09 Apr 2018

Technical note: Representing glacier geometry changes in a semi-distributed hydrological model

Jan Seibert, Marc J. P. Vis, Irene Kohn, Markus Weiler, and Kerstin Stahl

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Final revised paper (published on 09 Apr 2018)
Preprint (discussion started on 30 Mar 2017)

Interactive discussion

Status: closed

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

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RC1: 'Comments on “Technical Note: Representing glacier dynamics in a semi-distributed hydrological model”', Anonymous Referee #1, 29 Apr 2017
- AC1: 'Response to valuable comments', Jan Seibert, 10 May 2017
RC2: 'Review of Seibert et al.', Anonymous Referee #2, 19 May 2017
- AC2: 'Response to valuable comments #2', Jan Seibert, 08 Jun 2017

Peer-review completion

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

ED: Reconsider after major revisions (further review by Editor and Referees) (03 Sep 2017) by Jim Freer

I'm sorry for the delays in this processing, a number of personal issues have come up. I find this very difficult to make an opinion on this technical note for 2 core reasons. Firstly a technical note for HESS is detailed as thus:
Technical notes report new developments, significant advances, and novel aspects of experimental and theoretical methods and techniques which are relevant for scientific investigations within the journal scope. Manuscripts of this type should be short (a few pages only). Highly detailed and specific technical information such as computer programme code or user manuals can be included as electronic supplements. The manuscript title must start with "Technical note:". For manuscripts focused on the development and description of numerical models and model components, we recommend submission to the EGU interactive open-access journal Geoscientific Model Development (GMD).
Whilst to some extent the authors acknowledge a lack of 'novelty' due to previous use of these formulations. I'm going to have to see a better justification in the final response to say why this is a standalone technical note that fits the comments about HESS technical notes detailed above. There are comments made to the extent that a paper was justified to enable the model to be 'reproducible'. I'm sorry but I then do not see enough technical depth (many which the reviewers raise) to make this so. So again more work is needed here to justify publication.
Secondly the authors responses to some very good critical analyses are very general. The author response is meant to clarify what changes will be made to answer the points raised by reviewers. That is often very limited and I have no clear idea as to what the new paper would look like at this moment in time.
So recuasse of these two points then i will need to confirm publication once a clearer development of the paper and revisions is realised and more of a clear justification as to why a technical note is justified. Either due to novelty or to explain to the audience how this helps researchers directly implement these methods and resolves some of the practical aspects in doing so.... Also the reviewers did request seeing the revised manuscript again, Jim

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AR by Jan Seibert on behalf of the Authors (14 Sep 2017) Author's response Manuscript

ED: Publish subject to revisions (further review by editor and referees) (16 Nov 2017) by Jim Freer

ED: Referee Nomination & Report Request started (17 Nov 2017) by Jim Freer

RR by Anonymous Referee #2 (22 Nov 2017)

Suggestions for revision or reasons for rejection

The authors have provided a well-formulated and complete revision of their manuscript. Most of the comments raised by the reviewers were addressed and new analysis has been added to the paper. The article presents the method (glacier retreat scheme for lumped hydrological models) in a clear and reproducible way and will be helpful to the community. Nevertheless, there are some (mostly minor) issues with the present version of the article that should be addressed before final acceptance.

- Page 5, line 15: The reasoning is somewhat unclear here. Obviously, the authors have a complete snow redistribution model available (is this described in Freudiger et al, 2017? – the text seems to provide this hint) but decide not to use it and go for an extremely simple approach. I would avoid mentioning the “other” approach for removing “snow towers” and just describe what has been done.

- Page 5, line 19: Please shortly explain how the parameters were chosen and if there was any possibility to validate them.

- Page 5, line 25: The “lookup table” seems to be one of the major modifications in comparison to the original dh-parameterisation. It is mentioned for the first time here but unfortunately it remains highly unclear what this table (1) actually is and does, and (2) how it is derived. Regarding (1): This is clarified later in the paper (with the aid of the figure). However, it should be outlined here. Regarding (2): The formulation calls for better explanation. “… a lookup table can be derived from any glaciological model”. So, another model (a glaciological model) is needed to generate this lookup table? Which model was used by the authors? Apparently, this might quite drastically limit the applicability of the authors’ proposed model implementation as not all hydrologists might have a glaciological model at hand to produce this lookup table. Maybe it is just a misunderstanding that can be clarified with a better formulation?

- Page 10, line 28: The area change 1900-2006 is correctly calculated by the full model. However, the two individual periods 1900-1940, and 1940-1973 are completely off. This should also be mentioned. I suggest providing the results for relative area change (observed / simulated) for all four experiments in a table. This would better allow tracking how well the model implementations work.

- Page 11, line 9: A general comment on “glacier advance”. The authors directly link increases in glacier mass to advances of the glacier front. They do not consider a temporal delay. This strongly contradicts observations: Several years or even decades of mass gain are required (depending on glacier size and shape) until ice flow dynamics have changed in a way to make the glacier snout advance. This is completely neglected in the presented approach. I fully understand that this is not feasible, and probably also not necessary (!), for such a model, but this effect should be critically discussed by the authors and formulations should be adapted throughout the paper to not imply equality of glacier mass gain and glacier advance.

- Page 12, line 22: This statement should be corrected. Modern remote sensing data provide elevation changes for virtually all glaciers in the world (see e.g. Brun et al., 2017, NGEO). Glacier-specific elevation changes are also available for all glaciers in Switzerland, for example (Fischer et al., 2015, The Cryosphere).

- Figure 1: Nice! However, I strongly recommend enlarging text size (and reduce unfilled white spaces) to make the figure readable more easily.

- Figure 3c: Maybe show relative instead of absolute errors? This would be more informative. Why is there a difference for the 1900 surface?

- Figure 4a: Why do not all runs start with the same area? Also 1900 should have a dot for an observed area. The dots should have error bars (!) and might be linked with lines to make the figure clearer.

- Figure 4b: This is not observed volume! A well-constrained bedrock topography from the dataset of M. Huss is available for 1973 and 2010 but the volumes for 1940 and 1900 are derived from volume-area scaling, i.e. an extremely simple and highly uncertain model. So, it cannot be used for model validation! As already suggested in my last review, there are actual measurements of ice volume change for the respective glaciers (Fischer et al., 2015). They do not refer to the entire study period but nevertheless would allow validation over several decades.

- Figure 4c: Please change y-axis label. Glacier runoff is normally interpreted as the water leaving the glacier. These water volumes are much higher as they also comprise seasonal snow melt on the glacier surfaces. The authors show cumulative glacier mass loss here, and not runoff. The legend of Figure 4 should be positioned more prominently – I first didn’t find it. Furthermore, I would suggest to not use model abbreviations but more intuitive names.

- Page 26, line 18: Combining volume-area scaling with the ice thickness distribution data set derived by a different methodology seems to be inconsistent, leading to a non-continuous evolution of glacier volume. In any case, the derived volumes for 1900 and 1940 using this method will not be suitable to validate the model regarding glacier mass change (Fig. 4b)! A better discussion is needed.

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ED: Publish subject to minor revisions (review by editor) (23 Nov 2017) by Jim Freer

AR by Jan Seibert on behalf of the Authors (04 Dec 2017) Author's response Manuscript

ED: Publish as is (26 Feb 2018) by Jim Freer

AR by Jan Seibert on behalf of the Authors (01 Mar 2018) Manuscript

Short summary

In many glacio-hydrological models glacier areas are assumed to be constant over time, which is a crucial limitation. Here we describe a novel approach to translate mass balances as simulated by the (glacio)hydrological model into glacier area changes. We combined the Δh approach of Huss et al. (2010) with the bucket-type model HBV and introduced a lookup table approach, which also allows periods with advancing glaciers to be represented, which is not possible with the original Huss method.