A global algorithm for identifying changing streamflow regimes: application to Canadian natural streams (1966–2010)

Zaerpour, Masoud; Hatami, Shadi; Sadri, Javad; Nazemi, Ali

doi:https://doi.org/10.5194/hess-25-5193-2021

Articles | Volume 25, issue 9

https://doi.org/10.5194/hess-25-5193-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-25-5193-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 25, issue 9

Research article

|

24 Sep 2021

Research article |

| 24 Sep 2021

A global algorithm for identifying changing streamflow regimes: application to Canadian natural streams (1966–2010)

Masoud Zaerpour, Shadi Hatami, Javad Sadri, and Ali Nazemi

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Final revised paper (published on 24 Sep 2021)
Supplement to the final revised paper
Preprint (discussion started on 31 Aug 2020)
Supplement to the preprint

Interactive discussion

Status: closed

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

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RC1: 'Review of A novel algorithmic framework for identifying changing streamflow regimes: Application to Canadian natural streams (1966-2010)', Anonymous Referee #1, 30 Sep 2020
- AC2: 'Response to Reviewer 1', Masoud Zaerpour, 24 Nov 2020
RC2: 'Review of "A novel algorithmic framework for identifying changing streamflow regimes: Application to Canadian natural streams (1966–2010)"', Anonymous Referee #2, 08 Oct 2020
- AC1: 'Response to Reviewer 2', Masoud Zaerpour, 24 Nov 2020

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (21 Dec 2020) by Kerstin Stahl

AR by Masoud Zaerpour on behalf of the Authors (24 Feb 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (23 Mar 2021) by Kerstin Stahl

RR by Anonymous Referee #1 (20 Apr 2021)

Suggestions for revision or reasons for rejection

The authors are to be congratulated on their revision, which has greatly improved the paper. I was very pleased to see that their analyses now include ecozones, and the paper is much stronger for it.
The figures are very attractive.

Unfortunately, the results are undermined by the writing.
I am providing some suggestions, but the paper would benefit from a thorough editing to tighten the writing, and
to remove the many grammatical errors, poor word choices, and excess verbiage.

General comments
The paper is riddled with cliches:
“to name a few”
“We recognize that”
“Considering the available data”
“Looking however at the drainage basins”
“First and foremost”
“sets the scene”

These are unnecessary, and colloquial. Please delete them.

The terms “higher”, and “lower”, unless you are talking about elevations, should be “greater” or “larger” and “smaller”.

Detailed comments
Line 27
“early settlements”
These are things, not points in time.
I think you mean “the times of the first human settlements”

L 29
“reveal”
This word is used far too often, and incorrectly.
I think that “indicate” is what you mean.

L 20
“some”
I think that “others” is more useful

L 50
“it is”
Disagreement in number. Should be “are”

L 60
“relativity”

This is rather confusing in a scientific paper, particularly when you refer to “time and space”!
It’s also a bit vague.
What is relative to what?

L 77
“some of which with”
Replace “with” by “have”

“dynamics”
I’m not sure what this means

L 78
“with characteristics”
Should be
“of characteristics”

L 81
“makes”
I think that “creates” would be better.

L 126
“in a way”
Would advise inserting “such” after “in”

L 142, eq. 2A
It would be nice to have a verbal description of the objective function. Does it have a reference?

L 177
I was confused in this section.
The meaning of the baseline isn’t really explained very well.

L 190
“sum of memberships in each timeframe is one”
I suggest that you use “1” as “one” could be part of a phrase, like
“one of the ....”

L 191
“one or more clusters”.
This is confusing. Shouldn’t it be “other clusters”?

L 218
“transparency”
How it this method more transparent than others?

L 219
“is tied up with attribution”
Could be shortened to “attributed”

L 221
“Black and red lines”
Please add a leading “The”

“expected annual hydrographs”
What are these – how are the values expected? Please explain.

L 236, 3 Case study and data
A lot of the following information could be summarised in a table.

L 237
“With the total catchment area equivalent to”
Replace with “With a total catchment area ”

“roll coast to coast to coast and during their journey”
Unnecessary, please delete

L 245
“largest water bodies”
Not a very good description. Perhaps you could say some of the largest lakes other than the Great Lakes.

L 246
“Mackenzie”
Should be preceded by “The”

L 250
“While drainage basins”
“While” is usually used to mean “at the same time as”.
I would suggest using “Although”

“in which the streamflow is traced from headwaters to oceans”
Unnecessary, please delete

L 254
“patch of terrestrial land”
Unless we are talking about other planets, “land” implies “terrestrial”
Suggest replacement with
“terrestrial region”

“distinc”
Misspelled – should be “distinct”

L 256
“only major Canadian region outside the Rockies”
Really? Isn’t this contradicted by the existence of every other ecozone?

L 340
“glacial-fed or lake-dominated streams”
This would be a good place to add a statement on the effect of storage to the slow responses of these streams.

L 345
“other processes such as fill and spill”
Agreed. However the process should probably be explained for readers not familiar with it.

L 381
“belongingness to”
This isn’t the right word in this context, as it refers to an emotional state. I would use “member of”

L 386
“less”
Should be “fewer”

L 413
“vibrant”
Not a good word to use as its meaning is unclear in this context.

L 434
“percentage”
Looks like the fraction to me

L 436
“second cell from right” – I would say “left hand cell”
“first cell from the right” – I would say “right hand cell”

L 450 Figure 9
I couldn’t tell what the sizes of the squares mean – are they a function of some value?
If not, it would make the colour differences more visible if the squares were the same size.

L 479
“choosing”
I would say “selecting”

L 485
“due to the insufficiency”
Of what?

L 494
“not significant changes”
I may have missed this – where was the significance test?

L 496
Figure 10
What are Dimension 1 and 2? I know that they are referred to in line 489, but it would be nice
to see an explanation.

L 519 - 5.2 Validation in unseen streams
I think that “unseen” is a bit confusing. Perhaps you could refer to the out of sample streams.

L 523
“because the majority of annual streamflow volume is contributed from mountainous headwaters outside of Prairies”
This is true of the large rivers, as well the smaller streams you examine in the extreme western portion of the ecozone (such as the Waterton River near Waterton Park and Belly River near Mountain View), however it is not true of the other prairie streams that you feature.

“fact that large proportion of the land does not contribute into the streamflow”
This needs a citation. Also, it is not true for some basins in the region, and is not always true for the remainder, as the contributing fractions of these basins vary over time.

Another issue is that many Prairie streams only have seasonal records, which can mess up analyses requiring entire years of records.

L 529
“Waterton River near Waterton Park (S69) and Belly River near Mountain View (S70)”
Since you are referencing the streams in Figure 12 by their WSC gauge IDs, you should also list the IDs here

L 532
“are sorted from the east to west”
I would use “ordered” rather than “sorted”.

L 545
“a fully algorithmic framework”
I don’t understand what this term means

Finally, I was disappointed to see that all of the analyses were done using a closed-source language.
This is particularly troubling because the analyses include significance tests, where the value of a
calculated statistic is compared to a fixed threshold (i.e. p = 0.05), resulting in acceptance or
rejection of a null hypothesis. A small error in the statistic can therefore result in a very large effect, and we can
have no understanding of how the statistic was calculated. I would encourage the authors to
use open-source languages in the future for their analyses.

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RR by Anonymous Referee #2 (09 Jun 2021)

Suggestions for revision or reasons for rejection

The paper presented by Zaerpour and colleagues has much improved and I second the author’s effort to increase the clarity of their Work while making the text more compact at the same time. Overall, I very much appreciate the effort of the authors to put their methodological development into context. I also welcome that the case study now revolves around the analysis of climatologically distinct ecozones in Canada. With these significant additions, I find that the paper is almost ready for publication in HESS.
Nonetheless, a few comments remain:

P5, L 523: It is not clear what X and Y are. I suspect X = mean and Y = sd but making this explicit would help.

Notation of Equation 2a and related text: I suggest to use a capital C for denoting the cluster number to indicate that this is not an index. Similarly: consider to replace the index k with small c, which might increase the readability.

Mix of Kendall-statistics and R2 for the attribution work: I still find it unconventional to first rely on a rank-statistic for identifying significance and then use a conventional R2 for quantifying the strength of the association. To me it would be more natural to either (a) pair the Kendall statistics with the (squared) rank correlation coefficient or (b) rely on the (squared) Pearson correlation coefficient alongside a standard test for significance for this metric. Note that rank-correlations (e.g. Spearman’s coefficient) should indicate even higher degrees of association in case the data have a non-linear relation. Note, however, that I am confident that the choices made here will not have a significant impact on the conclusions.

Fig. 1: indicating what NSF_1 or NSF_2 are in the caption would make it easier to understand the concepts.

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ED: Publish subject to minor revisions (review by editor) (20 Jun 2021) by Kerstin Stahl

AR by Masoud Zaerpour on behalf of the Authors (01 Jul 2021) Author's response Author's tracked changes Manuscript

ED: Publish as is (18 Aug 2021) by Kerstin Stahl

AR by Masoud Zaerpour on behalf of the Authors (29 Aug 2021) Manuscript

Short summary

Streamflow regimes are changing globally particularly in cold regions. We develop a novel algorithm for detecting shifting streamflow regimes using changes in first and second moments of ensemble streamflow features. This algorithm is generic and can be used globally. To showcase its application, we assess alterations in Canadian natural streams from 1966 to 2010 to provide the first temporally consistent, pan-Canadian assessment of change in natural streamflow regimes, coast to coast to coast.