Technical note: Analytical sensitivity analysis and uncertainty estimation of baseflow index calculated by a two-component hydrograph separation method with conductivity as a tracer

Yang, Weifei; Xiao, Changlai; Liang, Xiujuan

doi:https://doi.org/10.5194/hess-23-1103-2019

Articles | Volume 23, issue 2

https://doi.org/10.5194/hess-23-1103-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-23-1103-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 23, issue 2

Technical note

|

25 Feb 2019

Technical note |

| 25 Feb 2019

Technical note: Analytical sensitivity analysis and uncertainty estimation of baseflow index calculated by a two-component hydrograph separation method with conductivity as a tracer

Weifei Yang, Changlai Xiao, and Xiujuan Liang

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Final revised paper (published on 25 Feb 2019)
Supplement to the final revised paper
Preprint (discussion started on 11 Oct 2018)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'comment to hess-2018-492', Anonymous Referee #1, 26 Oct 2018
- AC1: 'Response to Reviewer#1', Changlai Xiao, 26 Nov 2018
- AC4: 'Marked revised manuscript', Changlai Xiao, 26 Nov 2018
RC2: 'Comments on: Analytical sensitivity analysis and uncertainty estimation of a two-component hydrograph separation method which uses conductivity as a tracer” by Weifei Yang et al.', Ian Cartwright, 28 Oct 2018
- AC3: 'Response to Ian Cartwright (Referee)', Changlai Xiao, 26 Nov 2018
- AC5: 'Marked revised manuscript', Changlai Xiao, 26 Nov 2018
RC3: 'Review', Anonymous Referee #3, 07 Nov 2018
- AC2: 'Response to Reviewer#3', Changlai Xiao, 26 Nov 2018
- AC6: 'Marked revised manuscript', Changlai Xiao, 26 Nov 2018

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (10 Dec 2018) by Markus Hrachowitz

AR by Changlai Xiao on behalf of the Authors (11 Dec 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (13 Dec 2018) by Markus Hrachowitz

RR by Anonymous Referee #2 (04 Jan 2019)

RR by Anonymous Referee #3 (09 Jan 2019)

Suggestions for revision or reasons for rejection

The technical note by Weifei Yang and coauthors has improved with respect to previous version. I am still unsure that, by considering the uncertainty due to random measurement errors only, the authors are proceeding in the right direction, but as the paper can already be useful to some part of the scientific community I am glad to recommend it for publication subject to minor revisions. Please find below a note of general character (that does not need to be addresses in the revision) and then a few minor points that could help improve the final manuscript.

Assumptions behind the two-component hydrograph separation method: I think the crucial point was not to add a list of the assumptions underlying the method, but to discuss what might happen when the assumptions are not met. Equation (1) might not be good for baseflow separation, especially when soil water has a major contribution to streamflow and its conductivity is not constant over time. Then, the assumed conductivity of baseflow and surface runoff (parameters BFc and Roc) are to some extent arbitrary: the authors show from the beginning (Page 2) that different choices can be made to characterize those parameters and the parameters may also vary at event or seasonal scale. All these sources of uncertainty are potentially larger than the simple random measurement errors considered in the manuscript.

MINOR POINTS

As already mentioned in my previous comments, I think the title is too general. The authors specifically focus on the baseflow index (BFI) and I believe this should be reflected in the title.

English grammar is improved, but many sentences are still rather unclear. Here a few examples:
P2, l14: the term “experimental” seems out of place
P4 : what is a “random analysis error” in this context? I suspect the term “analysis” is misused.
“conductivity two-component hydrograph separation method” is repeated multiple times: consider introducing an abbreviation
Page 6 and 7: you can simply specify once that the terms W are a standard deviation “multiplied by the t-value (α=0.05; two-tail) from the Student’s distribution” instead of repeating it each time.

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ED: Publish subject to minor revisions (review by editor) (14 Jan 2019) by Markus Hrachowitz

AR by Changlai Xiao on behalf of the Authors (18 Jan 2019) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (21 Jan 2019) by Markus Hrachowitz

AR by Changlai Xiao on behalf of the Authors (26 Jan 2019) Author's response Manuscript

ED: Publish as is (05 Feb 2019) by Markus Hrachowitz

AR by Changlai Xiao on behalf of the Authors (05 Feb 2019) Manuscript

Short summary

This paper analyzed the sensitivity of the baseflow index to the parameters of the conductivity two-component hydrograph separation method. The results indicated that the baseflow index is more sensitive to the conductivity of baseflow and the separation method may be more suitable for the long time series in a small watershed. After considering the mutual offset of the measurement errors of conductivity and streamflow, the uncertainty in baseflow index was reduced by half.