Sensitivity of young water fractions to hydro-climatic forcing  and landscape properties across 22 Swiss catchments

von Freyberg, Jana; Allen, Scott T.; Seeger, Stefan; Weiler, Markus; Kirchner, James W.

doi:https://doi.org/10.5194/hess-22-3841-2018

Articles | Volume 22, issue 7

https://doi.org/10.5194/hess-22-3841-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-22-3841-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 7

Research article

|

19 Jul 2018

Research article |

| 19 Jul 2018

Sensitivity of young water fractions to hydro-climatic forcing and landscape properties across 22 Swiss catchments

Jana von Freyberg, Scott T. Allen, Stefan Seeger, Markus Weiler, and James W. Kirchner

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Final revised paper (published on 19 Jul 2018)
Supplement to the final revised paper
Preprint (discussion started on 18 Dec 2017)
Supplement to the preprint

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC1: 'referee comment', Anonymous Referee #1, 10 Jan 2018
- AC1: 'Response to the interactive comment of Reviewer #1 on hess-2017-720', Jana von Freyberg, 12 Mar 2018
RC2: 'reviewer comments', Markus Hrachowitz, 10 Jan 2018
- AC2: 'Response to the interactive comment of Reviewer #2 on hess-2017-720', Jana von Freyberg, 12 Mar 2018
SC1: '"short comment" from reader', Daniel Wilusz, 25 Jan 2018
- AC3: 'Response to Short Comment on hess-2017-720', Jana von Freyberg, 12 Mar 2018

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (06 Apr 2018) by Ralf Merz

AR by Jana von Freyberg on behalf of the Authors (25 Apr 2018) Author's response Manuscript

ED: Publish subject to revisions (further review by editor and referees) (12 Jun 2018) by Ralf Merz

ED: Referee Nomination & Report Request started (13 Jun 2018) by Ralf Merz

RR by Anonymous Referee #1 (14 Jun 2018)

Suggestions for revision or reasons for rejection

The authors addressed all my comments and either included them in the revised manuscript or explained why they did not. I think the new paper structure significantly improved the readability of the manuscript. Thank you for this highly interesting and relevant contribution. I have just got a few minor comments that you might want to consider before resubmission:

Main text (final version without tracked changes)
• Please update all instances of “Allen et al.,submitted manuscript” as this paper has been published by now.
• Page 4, lines 13-14: "Young water fractions have so far only been used in a global analysis of 254 watersheds...". This is true on the global scale, but there are a few local studies using Fyw, including Song et al., Hydrological Processes, 31(4), 935-947, 2017, doi:10.1002/hyp.11077, and
Stockinger et al., Journal of Hydrology 541, 952–964, 2016, doi:10.1016/j.jhydrol.2016.08.007.
Please mention these as well.
• Page 10, line 3: suggest changing to "we apply the methods 1 and 2 (section 3.4) for interpolating...." to clarify you are referring to the two methods you introduced before.
• Page 16, line 21: suggest adding "The linear slope was determined from linear regression of eq. (10) and the uncertainty in this slope was estimated..." (if I got it right?) to specify how you calculated the discharge sensitivity "directly from the tracer time series".
• Page 17, lines 9-10: good to see you were able to include the short comment. I’d suggest changing to "These values are similar to the "precipitation sensitivities of Fyw" found by Wilusz et al. (2017) for two neighbouring catchments in Plynlimon, Wales." as "those" now reads as if Wilusz et al. (2017) calculated discharge sensitivities as well.
• Page 17, lines 5 and 13: d-1 instead of day-1 for consistency reasons

Figures
• Figure 3 - caption: "those of Seeger and Weiler (2014) and those presented in the Supplement (methods 1 and 2, respectively)". This sounds as if you have used more than two methods. But If I understood correctly, you are comparing method 1 (according to Seeger and Weiler, 2014) and method 2.
• Figure 6: I cannot see any changes to this figure. I’d still recommend increasing the contrast between light blue and grey dots (maybe also with other symbols) as in comparison to the other (very nice) figures, the symbols in this figure are not easily discernible.
• Figure 9: I'd suggest having the same colour coding from low to high values (instead of a reverse coding) for panels a and b to allow for better comparison between Fyw and its discharge sensitivity.

Supplement
• Page 6, lines 11-12: (Seeger and Weiler, 2014), which predicted higher Ap values..."

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ED: Publish subject to minor revisions (review by editor) (14 Jun 2018) by Ralf Merz

AR by Jana von Freyberg on behalf of the Authors (14 Jun 2018) Author's response Manuscript

ED: Publish as is (25 Jun 2018) by Ralf Merz

AR by Jana von Freyberg on behalf of the Authors (29 Jun 2018) Manuscript

Short summary

We explored how the fraction of streamflow younger than ca. 3 months (F_yw) varies with landscape characteristics and climatic forcing, using an extensive isotope data set from 22 Swiss catchments. Overall, F_yw tends to be larger when catchments are wet and discharge is correspondingly higher, indicating an increase in the proportional contribution of faster flow paths at higher flows. We quantify this discharge sensitivity of F_yw and relate it to the dominant streamflow-generating mechanisms.