Model study of the impacts of future climate change on the hydrology of Ganges–Brahmaputra–Meghna basin

Masood, M.; Yeh, P. J.-F.; Hanasaki, N.; Takeuchi, K.

doi:https://doi.org/10.5194/hess-19-747-2015

Articles | Volume 19, issue 2

https://doi.org/10.5194/hess-19-747-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/hess-19-747-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 19, issue 2

Research article

|

04 Feb 2015

Research article |

| 04 Feb 2015

Model study of the impacts of future climate change on the hydrology of Ganges–Brahmaputra–Meghna basin

M. Masood, P. J.-F. Yeh, N. Hanasaki, and K. Takeuchi

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Final revised paper (published on 04 Feb 2015)
Supplement to the final revised paper
Preprint (discussion started on 02 Jun 2014)

Interactive discussion

Status: closed

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

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- Supplement

RC C1936: 'review report', Anonymous Referee #1, 20 Jun 2014
RC C2100: 'climate impact assessment', Anonymous Referee #2, 27 Jun 2014
AC C3363: 'Response to Reviewers' comments', Muhammad Masood, 26 Aug 2014
AC C3377: 'Response to Reviewers' comments (with revised figures)', Muhammad Masood, 26 Aug 2014

Peer-review completion

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

ED: Reconsider after major revisions (10 Sep 2014) by Fuqiang Tian

AR by Muhammad Masood on behalf of the Authors (22 Oct 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (07 Nov 2014) by Fuqiang Tian

RR by Anonymous Referee #3 (01 Dec 2014)

Suggestions for revision or reasons for rejection

Review for hess-2014-156 by Mr. Masood et al.
The topic is interesting to me, and the authors have addressed most of the previous comments by the editor and reviewers.
However, I think the following major issures should also be carefully addressed, before the paper can be accepted.

（1）Fig A1: It is not meaningful to compare the observed and simulated streamflows over mis-matched time periods, under the climatic changes.
why not performing longer simulations for all the three uppper basins from 1980 or earlier, given that WATCH data covers 1950s-2000s?

（2）Table 4 and Figure 5:
A major problem of this study is the simple calibration with only the discharge data while not evaluating other intermediate variables (e.g., "evapotranspiration", "soil moisture", and "net radiation") before performing their projections. With the clibration for only one hydrological variable (discharges), how can you confirm the reliability of the other three variables ("evapotranspiration", "soil moisture", and "net radiation")? In my experience, to achieve a good calibration of streamflows is not difficult in hydrological modeling as you did in three rivers (Bahadurabad site at Brahmaputra river, Hardinge bridge site at Ganges river, and Bhairab bazar site for Meghna river). However, perfect discharge reproduction does not necessarily mean that you have simultaneously achieve reliable estimates for "evapotranspiration", "soil moisture", and "net radiation".
My suggestion is to carefully evaluate your simualted historical values for these variables as well besides streamflows, before the projections for near-future and fast-future could be performed.

(3) A description of cryospheric components by the H08 model is desired in the study. This will enhance our understanding that how the glacier and snow melts are dealt with in the upper basins of Brahmaputra and Ganges.

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RR by Anonymous Referee #2 (08 Dec 2014)

Suggestions for revision or reasons for rejection

The revision was done properly, all points were responded. However, there are still a few things that require corrections. Besides, there are some language problems, which need attention of the authors. Therefore, a minor revision is suggested before publishing the paper.
After implementing all suggested corrections the paper should be checked by a native English speaker.

Minor corrections needed:
- p. 13, l. 5-6: the indicated numbers are probably seasonal maxima of mean monthly values, but not overall maxima, yes? Please correct.
- P. 13, l. 14-15: “which suggest ET is at the potential rate” – why? Only because it is stable? It seems to be wrong. Please add additional arguments, or delete.
- P. 14, l. 21: Also the smallest coefficient 0.29 is statistically significant???
- P. 14, l. 31-32: “trend in precipitation is not pronounced”: are you sure? At least, for the Ganges it may exist. Please check the trends for all three basins
- P. 19, l. 8-9, and in the Conclusions (p. 20, l. 12): maybe to add also that (a) the representation and parameterization of soil in the model, and (b) a good regional soil map are also important, and could lead to better and more reliable simulation of soil processes?
- Table 1: description of origin and major properties (1st row) should be moved to the main text.

Minor technical corrections needed:
- better not to include abbreviation in the title, only in the text;
- please use one of terms: GBM basin or GBM basins, but not both;
- p. 12, l. 7-8: the listing is a bit too long. Maybe a Table including all five criteria instead?
- P. 12, l. 12: please add a sentence in the main text summarizing the model evaluation for the upstream gauges.
- It is not necessary to repeat full gauge names in Table 2, short names are sufficient

Language corrections needed:
- p. 2, l. 21: increase  increasing
- p. 3, l. 19: “well constrained”  “fully reliable”, or “trustworthy”
- p. 4, l. 9 and l. 10: will be  was
- p. 11, l. 30: parameter  parameters
- p. 11, l. 31: will be  were
- p. 12, l. 7: ranges  range
- p. 12, l. 9: suggest the model performance  suggest that the model performance
- p. 12, l. 9: overall  overally
- p. 12, l. 12: summarized presented  summarized and presented
- p. 12, l. 15: model is applied to simulate for …  model was applied for …
- p. 12, l. 18: are  were
- p. 12, l. 30: differed differ
- p. 13, l. 2: occurs  occur
- p. 13, l. 4: corresponded very well with  corresponds very well to
- p. 13, l. 22: magnitude differs  magnitudes differ
- p. 14, l. 17: range  ranging
- p. 14, l. 31: show  shows that
- p. 15, l. 4: variability  variabilities
- p. 15, l. 5: To remove “that can be observed”
- p. 15, l. 8: from precipitation  for precipitation
- p. 15, l. 9: relatively less  not
- p. 16, l. 8: warmer by  warmer, with
- p. 16, l. 11: The  the
- p. 16, l. 12: than that  than
- p. 16., l. 28: found  found that
- p. 15, l. 10: To remove “from this modelling study”
- p. 17, l. 5: the warmer  higher
- p. 17, l. 6: will be  is expected to be
- p. 17, l. 19: will  would
- p. 17, l. 23: about  almost
- p. 18, l. 11: parameter  parameters
- p. 18, l. 24: indicates  indicates that
- p. 18, l. 32: that  the fact that
- p. 19, l. 1: is expected as the model is  could be expected as the model was
- p. 19, l. 18: parameter  parameters
- p. 19, l. 24: to remove “respectively”
- p. 19, l. 29: To remove “from this modelling study”
- p. 19, l. 30: warmer  higher
- p. 20, l. 3: to increase 19.1% whereas it is 6.7% …  to increase by 19.1% whereas it is by 6.7% …
- p. 20, last paragraph: please check punctuation marks , . and ;
- p. 20, l. 18: which are not  they were not
- p. 20, l. 18: constraint  constraints
- p. 20, l. 19: land-scape  landscape
- p. 20, l. 22: are not  were not
- Table 5: Pricipitation  Precipitation

Reformulations are needed:
- p. 2, l. 28: encompasses a number of countries including parts of China, India, Nepal, Bhutan and Bangladesh  is shared between a number of countries: China, India, Nepal, Bhutan and Bangladesh
- p. 5, l. 9: “study” is repeated 3 times in one sentence, it should be reformulated, e.g. “Our modelling study makes advances compared to previous investigations …”
- p. 5, l. 16: are studied in this study  are studied
- p. 5, l. 20: hydrology  hydrological and climatic characteristics
- p. 14, l. 26-27: from using 5  from simulations driven by 5
- p. 14, l. 28-29: of each individual GCM  of variables corresponding to individual GCMs
- p. 15, l. 10: To remove “from this modelling study”
- p. 15, l. 12: The changes in the seasonal cycles  The long-term average seasonal cycles
- p. 15, l. 13: are comparing  were compared
- p. 16, l. 5-7: the indicated range 1-4.3°C probably relates to the both future periods, but it could be understood as related to the near-future period only. Please reformulate.
- P. 18, l. 3: “Multiple parameter sets can reproduce the observations with the similar accuracy”: this phrase is not clear. How can parameter sets reproduce observations? Do you mean models with the multiple parameter sets? Similar to what? Please reformulate.
- P. 18, l. 13: “future precipitation is not more than 15% drier or 20% wetter …”: please reformulate; precipitation cannot be drier or wetter, it can be lower or higher
- P. 18, l. 22-25: Probably, these two sentences “From Fig. …” and “It can be seen …” should be combined in one. At least, the first one is only a part of a sentence.
- P. 18, l. 29-31: Please reformulate the sentence “Lower uncertainty …” to make is clear and understandable.
- p. 19, l. 2-6: please change “prediction” to projection” (3 times)
- P. 20, l. 1: hydrology  hydrological processes
- p. 20, l. 7-9: please change “prediction” to projection” (3 times)
- Table 1: what means: “regulated by upstream India”? To reformulate.

Referee Report: PDF

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ED: Publish subject to minor revisions (Editor review) (19 Dec 2014) by Fuqiang Tian

AR by Muhammad Masood on behalf of the Authors (28 Dec 2014) Author's response Manuscript

ED: Publish as is (07 Jan 2015) by Fuqiang Tian

Short summary

A hydrologic model H08 is calibrated and validated on the Ganges-Brahmaputra-Meghna basin by addressing model parameter-related uncertainty. The impacts of climate change on runoff, evapotranspiration, net radiation and soil moisture are assessed by using five CMIP5 GCMs. The paper reveals the higher possibility of flood occurrence in the Meghna Basin due to the highest increase in runoff. Findings provide indispensable basis for scientifically based decision-making in climate change adaptation.