Modelling liquid water transport in snow under rain-on-snow conditions – considering preferential flow

Würzer, Sebastian; Wever, Nander; Juras, Roman; Lehning, Michael; Jonas, Tobias

doi:https://doi.org/10.5194/hess-21-1741-2017

Articles | Volume 21, issue 3

https://doi.org/10.5194/hess-21-1741-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-21-1741-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 21, issue 3

Research article

|

24 Mar 2017

Research article |

| 24 Mar 2017

Modelling liquid water transport in snow under rain-on-snow conditions – considering preferential flow

Sebastian Würzer, Nander Wever, Roman Juras, Michael Lehning, and Tobias Jonas

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Final revised paper (published on 24 Mar 2017)
Preprint (discussion started on 03 Aug 2016)

Interactive discussion

Status: closed

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

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RC1: 'Comment', Anonymous Referee #1, 31 Aug 2016
- AC1: 'Reply to RC1', Sebastian Würzer, 28 Oct 2016
RC2: 'comments', Anonymous Referee #2, 12 Sep 2016
- AC2: 'Reply to RC2', Sebastian Würzer, 28 Oct 2016

Peer-review completion

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

ED: Publish subject to revisions (further review by Editor and Referees) (05 Nov 2016) by Carlo De Michele

AR by Sebastian Würzer on behalf of the Authors (10 Dec 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (12 Dec 2016) by Carlo De Michele

RR by Anonymous Referee #1 (29 Dec 2016)

Suggestions for revision or reasons for rejection

Authors have clearly addressed my previous comments and changed the manuscript accordingly. I can, therefore, suggest publication of the revised manuscript. I have only a few minor points that I would like to see in the final paper, if authors agree:

- Line 16-17 page 1: authors correctly point out that the presented model can / will be operationally used (see for example line 29 page 15), whereas some previous attempts of including PFP in 1D were presented in e.g. Marsh and Woo (1985 – see line 3 page 3). I would probably specify this here too (see for example the first sentence at line 10 page 3);
- Line 30 page 2: while I certainly agree with authors that energetic exchanges complicate the description of liquid water flow in snow, I suggest clarifying the sentence “snow can therefore …. porous medium” as this is a well-known issue even for some types of soils (see for example doi:10.5194/tc-5-469-2011);
- Line 22 page 4: I suggest to replace “on the available snow” with “on infiltration through the available snow” (see also line 14 page 14);
- Line 11 page 7 (and caption of Figure 1): is it a vertical cut rather than a horizontal one?
- Line 28 page 7: (Wever et al. 2014a) -> Wever et al. (2014a);
- Line 20 page 8: The -> the
- Line 22 page 8: “not completely isothermal”: I would suggest removing “completely” for brevity and clarity;
- Lines 17 – 32 page 11: because boxplots for RE and PF in Figure 8a are rather close to each other, I would suggest authors include some numeric data here. For example, you could report in the text the median and the quartiles of R2 at WFJ, which are quite similar, or specify the values of the interquartile range at line 23. The improvement using the PF scheme is visible, but numbers may help the reader to quantify this.
- Lines 17 – 29 page 13: in my understanding, the 1st ROS event in Davos occurred when the snowpack was still relatively fresh (see line 25-26 page 9). In this case, the porosity is high and I agree with the comments at lines 21 – 24. On the other hand, a “cold and non-ripe” snow could be characterized by a much higher density (hence a relatively lower permeability), but still be prone to instability. While process understanding of PFP in snow is still limited, it may be that the initial wetness condition of snow (dry / wet) may play an additional role in triggering preferential flow (see also Fig. 1). If authors agree, they could include this here.
11. Table 4: this is a good way of isolating the effect of specific snow properties on the simulations and I believe that this Table provides new insight into the manuscript. Authors may consider replacing the r2 with the Pearson coefficient, which has a similar meaning and keeps the sign information.

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RR by Anonymous Referee #2 (18 Jan 2017)

ED: Publish subject to technical corrections (29 Jan 2017) by Carlo De Michele

AR by Sebastian Würzer on behalf of the Authors (06 Feb 2017) Manuscript

Short summary

We discuss a dual-domain water transport model in a physics-based snowpack model to account for preferential flow (PF) in addition to matrix flow. So far no operationally used snow model has explicitly accounted for PF. The new approach is compared to existing water transport models and validated against in situ data from sprinkling and natural rain-on-snow (ROS) events. Our work demonstrates the benefit of considering PF in modelling hourly snowpack runoff, especially during ROS conditions.