Attributing the 2017 Bangladesh floods from meteorological and hydrological perspectives

Philip, Sjoukje; Sparrow, Sarah; Kew, Sarah F.; van der Wiel, Karin; Wanders, Niko; Singh, Roop; Hassan, Ahmadul; Mohammed, Khaled; Javid, Hammad; Haustein, Karsten; Otto, Friederike E. L.; Hirpa, Feyera; Rimi, Ruksana H.; Islam, A. K. M. Saiful; Wallom, David C. H.; van Oldenborgh, Geert Jan

doi:https://doi.org/10.5194/hess-23-1409-2019

Articles | Volume 23, issue 3

Hydrol. Earth Syst. Sci., 23, 1409–1429, 2019

https://doi.org/10.5194/hess-23-1409-2019

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

Hydrol. Earth Syst. Sci., 23, 1409–1429, 2019

https://doi.org/10.5194/hess-23-1409-2019

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

Articles | Volume 23, issue 3

Research article 13 Mar 2019

Research article | 13 Mar 2019

Attributing the 2017 Bangladesh floods from meteorological and hydrological perspectives

Sjoukje Philip et al.

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Final revised paper (published on 13 Mar 2019)
Supplement to the final revised paper
Preprint (discussion started on 23 Jul 2018)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'hess-2018-379', Anonymous Referee #1, 28 Aug 2018
- AC1: 'reply to Anonymous Referee #1', Sjoukje Philip, 20 Sep 2018
RC2: 'Comments to “Attributing the 2017 Bangladesh floods from meteorological and hydrological perspectives” by Philip et al.', Anonymous Referee #2, 19 Oct 2018
- AC2: 'reply to Anonymous Referee #2', Sjoukje Philip, 02 Nov 2018

Peer-review completion

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

ED: Publish subject to revisions (further review by editor and referees) (10 Nov 2018) by Bob Su

AR by Sjoukje Philip on behalf of the Authors (07 Dec 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Jan 2019) by Bob Su

RR by Vahid Rahimpour Golroudbary (11 Jan 2019)

RR by Anonymous Referee #3 (08 Feb 2019)

Suggestions for revision or reasons for rejection

To my understanding, this is a revised version for an attribution study. I do carefully read the responses as well as the manuscript, and find previous comments are addressed appropriately. The authors combined climate models and hydrological models to analyze a pluvial flooding event, and found the anthropogenic fingerprint was not detectable both for the 10-day precipitation and basin discharge. The attribution method is very comprehensive, and the uncertainty analysis is rigorously conducted. I would like to recommend for the publication besides addressing a few minor comments below, basically for clarifications.
1. The major focus is to detect anthropogenic climate change signal for the flooding event, but the abstract also mentioned the responses of the extremes to 2-degree warming. The authors found that the anthropogenic climate change is not detectable, but there is a clear response to the 2-degree warming. This makes the conclusions confused. I would suggest focusing on the attribution part, rather than the responses to future warming.
2. Abstract. “One climate model shows a significant positive influence of anthropogenic climate change, whereas the other simulates a cancellation between the increase due to greenhouse gases and a decrease due to sulphate aerosols.” I would be better to mention this conclusion is based on large ensemble simulations, not just from two model realizations.
3. Introduction. “In this paper we for the first time do an attribution study using observational precipitation and discharge data and a combination of GCMs and hydrological models.” A few published literatures (e.g., Yuan et al., 2018) could be mentioned when reviewing the combination of GCM and hydrological models for attribution of extreme events.
4. Is there any oceanic background (e.g., anomaly in the Indian Ocean) for this extreme flooding? In fact, there was also a severe flooding over the middle and lower reaches of the Yangtze River basin in July 2017, which was associated with the decay phase of an El Nino and warming over the Indian Ocean.
5. P5L2, “drought” or “flood”?

Reference
Yuan, X., Y. Jiao, D. Yang, and H. Lei, 2018: Reconciling the attribution of changes in streamflow extremes from a hydroclimate perspective. Water Resources Research, 54, 3886–3895, doi:10.1029/2018WR022714

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ED: Publish subject to minor revisions (review by editor) (09 Feb 2019) by Bob Su

AR by Sjoukje Philip on behalf of the Authors (14 Feb 2019) Author's response Manuscript

ED: Publish as is (14 Feb 2019) by Bob Su

AR by Sjoukje Philip on behalf of the Authors (14 Feb 2019) Author's response Manuscript

Short summary

In August 2017 Bangladesh faced one of its worst river flooding events in recent history. For the large Brahmaputra basin, using precipitation alone as a proxy for flooding might not be appropriate. In this paper we explicitly test this assumption by performing an attribution of both precipitation and discharge as a flooding-related measure to climate change. We find the change in risk to be of similar order of magnitude (between 1 and 2) for both the meteorological and hydrological approach.