Necessary storage as a signature of discharge variability: towards global maps

Takeuchi, Kuniyoshi; Masood, Muhammad

doi:https://doi.org/10.5194/hess-21-4495-2017

Articles | Volume 21, issue 9

https://doi.org/10.5194/hess-21-4495-2017

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

Special issue:

Observations and modeling of land surface water and energy...

https://doi.org/10.5194/hess-21-4495-2017

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

Articles | Volume 21, issue 9

Research article

|

11 Sep 2017

Research article |

| 11 Sep 2017

Necessary storage as a signature of discharge variability: towards global maps

Kuniyoshi Takeuchi and Muhammad Masood

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Final revised paper (published on 11 Sep 2017)
Preprint (discussion started on 12 Oct 2016)

Interactive discussion

Status: closed

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

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RC1: 'Review of paper HESS-2016-525 Indicators of Necessary Storages for Flood and Drought Management: Towards Global Maps.', Anonymous Referee #1, 01 Nov 2016
- AC1: 'Reference Number: hess-2016-525 RESPONSE TO THE REVIEWER #1’S COMMENTS', Kuniyoshi Takeuchi, 01 Jan 2017
RC2: 'Comment on HESS2016-525', Anonymous Referee #2, 08 Nov 2016
- AC2: 'hess-2016-525 RESPONSE TO THE REVIEWER #2’S COMMENTS', Kuniyoshi Takeuchi, 01 Jan 2017
RC3: 'Review of “Indicators of Necessary Steps for Flood and Drought Management: Towards Global Maps”', Anonymous Referee #3, 15 Nov 2016
- AC3: 'hess-2016-525 RESPONSE TO THE REVIEWER #3’S COMMENTS', Kuniyoshi Takeuchi, 01 Jan 2017
RC4: 'Review of "Indicators of Necessary Storages for Flood and Drought Management: Towards Global Maps"', Anonymous Referee #4, 22 Nov 2016
- AC4: 'hess-2016-525 RESPONSE TO THE REVIEWER #4’S COMMENTS', Kuniyoshi Takeuchi, 01 Jan 2017
RC5: 'Review comment', Anonymous Referee #5, 04 Dec 2016
- AC5: 'hess-2016-525 RESPONSE TO THE REVIEWER #5’S COMMENTS', Kuniyoshi Takeuchi, 01 Jan 2017
EC1: 'Editor - Final Comments', Murugesu Sivapalan, 01 Jan 2017

Peer-review completion

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

ED: Publish subject to revisions (further review by Editor and Referees) (01 Jan 2017) by Murugesu Sivapalan

The authors have been well-served by the comments from 5 reviewers, who have offered very constructive comments and criticisms on the paper. I am also glad that the authors have responded positively to these comments.

The following is a summary of the outcomes of the public discussion on the paper so far:

1. There has been a misunderstanding in the minds of most (all) reviewers about the main aim of the paper, and the authors have partially clarified these. Really, the main of the paper is to characterize the global patterns of variation of long-term hydrologic variability (in time), of droughts and floods. For this purpose the authors have decided to use a composite measure, which is the reservoir storage needed to meet an average demand (or something similar to this). This paper is a paper on hydrologic variability and not on reservoir design, as some of the reviewers misunderstood. It is important that the authors take particular care to present these clear aims at the beginning so this misunderstanding does not arise.

2. In the same spirit, the paper will become clearer and will have high impact if the authors can simplify the paper and reorganize it so that the main message comes out more clearly in the rest of the paper and does not veer off beyond the main message.

3. Also in this respect, all reviewers agree that the analysis of climate change impacts does not add much to the paper, and only distracts from the main message. I am glad the authors have already agreed to remove it from the paper, which I encourage. Depending on subsequent reaction to this paper, the authors may decide to look at a subsequent paper looking at how climate change affects the global-regional patterns long-term, temporal variability (as measured in terms of reservoir storage). I am not sure if it will make any contribution to climate change research.

4. There was some discussion about the appropriateness of the FDC approach to reservoir size estimation. The authors defended it, and I support their argument. The FDC approach was indeed used for reservoir sizing more than 50 years ago, and has now been forgotten, and superseded by more modern methods like range analysis etc. However, as a simple rule of thumb it is quite useful since one can easily see the connection between hydrologic variability and reservoir size. I don't mind the authors reviving the approach here - but they should explain its meaning for the average reader, and how good a measure it is about hydrologic variability.

In conclusion, this is an unconventional paper, and I am so glad that the reviewers did not dismiss it out of hand. If one takes a higher level and long-term historical perspective, and look at understanding the world as it is and finding ways to characterize hydrological variability globally, this may be a very interesting approach and I applaud the authors for introducing it. It is entirely appropriate for a special issue in honor of Professor Eric Wood. It draws a connection between modern hydroclimatology as seen in the many other papers submitted to the special issue to approaches used more than 50 years ago when Professors Wood and Takeuchi started their careers, and learn how much has changed and how much has not. The rest of the hydrologic community can benefit from this broader perspective.

For this reason I encourage the authors to resubmit a substantially revised paper (along the lines suggested by the reviewers and the authors themselves), which I will consider for further (non-public) review by some of the critical reviewers before final consideration for publication in HESS.

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AR by Kuniyoshi Takeuchi on behalf of the Authors (19 Mar 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Apr 2017) by Murugesu Sivapalan

RR by Anonymous Referee #2 (24 Apr 2017)

Suggestions for revision or reasons for rejection

The authors made substantial revision, I admit. Nevertheless, I would argue that Results and Discussion is not described in an organized way, which means major revision is still necessary. I would say this is not a draft that is fully elaborated before submission. I also do not think figures are very much elaborated before submission.

The authors mention there are three objectives.
1) to propose necessary storages to smooth out discharge variation during flood and drought as a new indicator of discharge variability in time.
2) to analyse the geographical distribution of such the indicator to relate hydrological variability with various hydrological heterogeneity of a basin.
3) to introduce an efficient methodology to calculate necessary storage at all grid points of a basin to make their geographical analyses possible, that is, the flood duration curve and drought duration curve (FDC-DDC) method.

1st and 3rd objectives are met to a certain extent. However, 2nd objective is not well achieved. That is equal to what I wrote “Results and Discussion is not described in an organized way.”

I would continue more on 2nd objective.

It is difficult to get organized results from Figures 8-11. Well, those figures could be just basic information. Then, Figure 12-17 should bring us organized messages to achieve 2nd objective. But, what I can see is that the new index is generally correspondent to SD or CV of discharge. (That is somewhat contradictory to what the authors intended to, because the authors want to show us a new index which can show us something different from CV and/or SD. ) Anyway, any key messages are not brought to me.

What’ seen for the main streams and what’s seen for tributaries must be clearly separated. Then, both for the main streams, and for tributaries, the authors are recommended to clearly show results and discussion for 2nd objective. Current analyses are descriptive and in a very much scattered way, and it is not sure whether horizontal axis used in Figure 12-17 are adequate enough. The authors are encouraged to try to deeply think about how to best convey their messages to the audience by showing much adequate figures, rather than by just showing quickly made figures.

Something interesting must be embedded in this paper. But, presentation particularly in Results and Discussion is not enough. I am not saying what’s written in Results and Discussion is wrong. Rather, text and figures are not presented in an organized way. Those are presented in a way such as a young student presenting in a hurry his/her material to his/her teacher. For example, geographical distributions shown in Figures 16-17 could be interesting, but it is difficult to get organized discussion and conclusions from those figures and its corresponding main text.

The authors wrote "its relation with geophysical and geographical conditions was examined" (in Abstract) and "By this, the relation between hydrological variability and geographical heterogeneity can be better understood" (in 1.1.2). However, what the authors wrote as such is not much realized/shown in this paper.

By the way, even Abstract is far from adequate. In general, Abstract is not divided into paragraphs. In addition, too-much specific details and long introductory description should be deleted from Abstract.

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RR by Anonymous Referee #4 (05 May 2017)

Suggestions for revision or reasons for rejection

I think the authors have done a good job addressing the comments from the reviewers. However, I make the following comments which, if possible, should be addressed or clarified:
1. In my original comment #2 I mentioned that the proposed FDC-DDC method has a flaw in that it assumes stationary hydroclimatic conditions. I still don’t see where this is acknowledged or addressed.
2. In my original comment #4 I mentioned that I was confused about whether PET was an input or whether it was computed within the hydrological model. In the original version of the paper it was misleading because you seemed to indicate that both were happening (i.e. you said PET came from CRU but then you also said it was computed within the BTOPMC as per the Zhou et al. (2006) method). In response you say you removed the confusing paragraph and replaced it with more simplified text. It is true that there is now no confusion as to whether CRU data is used for PET or whether PET is calculated within BTOPMC as per Zhou et al. (2006) but that is because all mention of PET is now removed……and also the reference to Zhou et al. (2006) is removed……so, in short, I am still confused about what you did to get PET? Sect 3.1 covers precip, temp and discharge data used……but nothing on PET which suggests PET is calculated within the model (since you don’t describe the PET input data)…..but then Sect 3.2 and Sect 3.3 (the bits on how discharge is calculated and model set up and validation) don’t explain how PET was obtained or used either. I suggest you need to clarify this……if PET is not an input and is calculated via BTOPMC as per Zhou et al. (2006) then that reference needs to be brought back in and some summary info on the method provided…..if PET is an input and not calculated within the model then where does it come from? And how is the model set up to use it?
3. Following from previous comment…..APHRODITE data was previously mentioned as something that was used…..now there is no mention of APHRODITE……and you indicate that WFD was used instead for precip and temp….was there any comparison or sensitivity analysis done to assess possible implications of this decision? Do APHRODITE and WFD perform similarly over your study area for precip and temp? How did you decide that WFD info was satisfactory?

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ED: Reconsider after major revisions (further review by Editor and Referees) (05 May 2017) by Murugesu Sivapalan

AR by Kuniyoshi Takeuchi on behalf of the Authors (11 Jul 2017) Author's response Manuscript

ED: Publish subject to technical corrections (27 Jul 2017) by Murugesu Sivapalan

AR by Kuniyoshi Takeuchi on behalf of the Authors (01 Aug 2017) Author's response Manuscript

Short summary

There are many global maps of hydrology and water resources, but none on necessary storage to smooth out discharge variability. This paper provides a methodology to create such a map, taking the Ganges–Brahmaputra–Meghna basin as an example. Necessary storage is calculated by a new method, intensity–duration–frequency curves of flood and drought (FDC–DDC). Necessary storage serves as a signature of hydrological variability and its geographical distribution provides new insights for hydrology.