Characterization and evaluation of controls on post-fire streamflow response across western US watersheds

Saxe, Samuel; Hogue, Terri S.; Hay, Lauren

doi:https://doi.org/10.5194/hess-22-1221-2018

Articles | Volume 22, issue 2

https://doi.org/10.5194/hess-22-1221-2018

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

Special issue:

Vegetation changes under a changing environment and the impacts...

https://doi.org/10.5194/hess-22-1221-2018

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

Articles | Volume 22, issue 2

Research article

|

13 Feb 2018

Research article |

| 13 Feb 2018

Characterization and evaluation of controls on post-fire streamflow response across western US watersheds

Samuel Saxe, Terri S. Hogue, and Lauren Hay

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Final revised paper (published on 13 Feb 2018)
Preprint (discussion started on 10 Oct 2016)

Interactive discussion

Status: closed

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

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RC1: 'Interesting study with a novel dataset, some figures need to be corrected', Anonymous Referee #1, 02 Nov 2016
- AC1: 'Response to RC1', Samuel Saxe, 28 Dec 2016
RC2: 'Review of "Characterization of post-fire streamflow response across western U.S. watersheds"', Anonymous Referee #2, 07 Nov 2016
- AC2: 'Response to RC2', Samuel Saxe, 28 Dec 2016
RC3: 'Review of “CHARACTERIZATION OF POST-FIRE STREAMFLOW RESPONSE ACROSS WESTERN U.S. WATERSHEDS"', Anonymous Referee #3, 20 Nov 2016
- AC3: 'Response to RC3', Samuel Saxe, 28 Dec 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) (29 Dec 2016) by Nadia Ursino

AR by Samuel Saxe on behalf of the Authors (22 Feb 2017) Author's response Manuscript

ED: Publish subject to revisions (further review by Editor and Referees) (03 Mar 2017) by Nadia Ursino

ED: Referee Nomination & Report Request started (03 Mar 2017) by Nadia Ursino

RR by Anonymous Referee #2 (07 Mar 2017)

RR by Anonymous Referee #3 (11 Apr 2017)

Suggestions for revision or reasons for rejection

Review of “Characterization and Evaluation of Controls on Post-Fire Streamflow Response Across Western U.S. Watersheds" revised submission

Journal: Hydrol. Earth Syst. Sci. Discuss.
Manuscript ID: hess-2016-533

Samuel Saxe, Terri S. Hogue, and Lauren Hay

General comments
This manuscript is a revision on an earlier version that describes a study that investigates the effects of wildfires on subsequent watershed flow regimes, focussed on hydroclimatic regions in the western United States. The study provides a summary of 82 watersheds affected by wildfire, and examines changes in post-fire streamflow characteristics.

The authors have done an admirable job in pulling together the results and analysing them from a range of studies in a broad range of climate zones. The results of this confirm what has been discovered before in those studies.

One major limitation of the first submitted manuscript was that it stopped short of providing detail on the driving factors of the post-fire streamflow responses. My feeling was that this is really required for this publication to be considered suitable for HESS. It is good to see that the authors have decided to include material earmarked for a second publication, into this manuscript. While this was to provide additional information on the geophysical factors controlling the post-fire flow response, I feel that discussion around this is still insufficient.

The discussion of results, while it now includes some information on geophysical factors, is still very light on. The results and discussion section is, by and large, focussed on results, with some light discussion of the results in terms of the analyses performed, and little discussion of how results relate to catchment or fire characteristics.

Also disappointing, is that many of the suggestions I made in the first draft (many of which were to clear up vagueness) have not been adopted. The authors claim that major overhauls of the manuscript were required, and therefore, direct notations of changes in the manuscript were not feasible as they believe this updated manuscript reflects an almost entirely new paper. I noticed that the majority of this paper includes whole sections from the first draft. There is still vagueness, and use of unfamiliar terms still occurs throughout the manuscript which makes following and understanding it difficult. For example, the text around whether responses are similar or different is sloppy in terms of whether differences are significantly different or not. The term ‘significant’ is, at other times, used inappropriately. I made suggestions about this in the first draft.

I have provided my main comments and suggestions below, and have included an annotated pdf version of the manuscript with edits and additional comments. I feel this manuscript requires further major revision before being suitable for publication in HESS.

1. The term "slight trends" or "slight response" is used. There appears to be no test of significance on these relationships to test whether they actually exist.
2. Claims are made that flow increases with variable X and Y, yet there is no discussion about the range of X and Y, nor is there are acknowledgement of the correlation that may exist between variables X and Y. It is claimed these variable are independent, but some are not. ie rainfall may be higher in upland catchments that have steeper slopes. Soils maybe shallower on steeper slopes, and this will also effect flow response.
3. Furthermore, there is little explanation of the processes behind how X and Y may be influencing the observed post fire flow changes. For example, how does NDVI relate to forest type and how does this affect flow response as shown in the results? Possibly discuss why AI is correlated with flow response. Does is depend on whether a catchment is water supply or demand limited? ie high, or low AI? Another example: "watersheds with greater than these slopes demonstrate much greater high flow, runoff ratio, and peak flow in the 1st year than those with gentler slopes". No further discussion is provided, yet it would be interesting to provide a physical description of why this might be.
4. In the discussion, there are claims not supported by evidence. For example "This is a reasonable assumption considering that steeper slopes lead to less time available for soil absorption, thus increasing the volume of water contributed to streamflow". The fact that soils may be shallower higher in upland catchments (ie where slopes are steeper) is not even mentioned.
5. The authors note that geophysical characterisation of flow response is somewhat inconsistent and suggest this may result from small sample size. I think that it could also have something to do with pre and post fire rainfall/climate. The wetness state of a catchment can have an important effect on flow response. This is not analysed or discussed.
6. Many of the figures are too small to be easily readable/understandable.

Referee Report: PDF

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ED: Reconsider after major revisions (further review by Editor and Referees) (02 May 2017) by Nadia Ursino

AR by Samuel Saxe on behalf of the Authors (27 Jul 2017) Author's response Manuscript

ED: Publish as is (28 Jul 2017) by Nadia Ursino

Short summary

We investigate the impact of wildfire on watershed flow regimes, examining responses across the western United States. On a national scale, our results confirm the work of prior studies: that low, high, and peak flows typically increase following a wildfire. Regionally, results are more variable and sometimes contradictory. Our results may be significant in justifying the calibration of watershed models and in contributing to the overall observational analysis of post-fire streamflow response.