Why increased extreme precipitation under climate change  negatively affects water security

Eekhout, Joris P. C.; Hunink, Johannes E.; Terink, Wilco; de Vente, Joris

doi:https://doi.org/10.5194/hess-22-5935-2018

Articles | Volume 22, issue 11

https://doi.org/10.5194/hess-22-5935-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/hess-22-5935-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 22, issue 11

Research article

|

21 Nov 2018

Research article |

| 21 Nov 2018

Why increased extreme precipitation under climate change negatively affects water security

Joris P. C. Eekhout, Johannes E. Hunink, Wilco Terink, and Joris de Vente

Download

Final revised paper (published on 21 Nov 2018)
Supplement to the final revised paper
Preprint (discussion started on 04 Apr 2018)
Supplement to the preprint

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC1: 'Review', Anonymous Referee #1, 10 Jul 2018
- AC1: 'Response to review', Joris Eekhout, 26 Jul 2018
RC2: 'Review of the manuscript by Eekhout et al.', Rens van Beek, 12 Jul 2018
- AC2: 'Response to review', Joris Eekhout, 26 Jul 2018
AC3: 'Manuscript and supporting information with track changes', Joris Eekhout, 26 Jul 2018

Peer-review completion

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

ED: Reconsider after major revisions (further review by editor and referees) (28 Jul 2018) by Nunzio Romano

AR by Joris Eekhout on behalf of the Authors (30 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Aug 2018) by Nunzio Romano

RR by Anonymous Referee #1 (19 Sep 2018)

RR by Rens van Beek (20 Sep 2018)

Suggestions for revision or reasons for rejection

Upon reading the revised manuscript by Eekhout et al. I find the text much improved.

Significant improvements are (i) the better positioning and definition in the introduction, (ii) more complete description of the modelling procedure -particularly in the SI- and additional information on the methods and (iii) a stronger discussion that is better connected to existing literature,

My assessment of the revised manuscript is generally positive and it addresses most of the points that were raised by the other reviewer and myself. I'd say my decision would tend towards technical corrections if there would be not some minor aspects that could be included and that would qualify as minor revisions.

Some weaknesses remain that are due to the complexity of the modelling involved. Personally I find a spin-up period of a single year short but this will not greatly affect the outcome. Also, I'd prefer to see information on the calibrated parameters (which ones and the imposed range and eventual value) and the resulting performance in the main text.

At the same time, the procedure has become more traceable and the quality of the model study, which I would rate overall as very good, better to assess. In particular, the climate scenarios (2.3) is much clearer and underlines the high quality of this part of this study. My suggestion, therefore is still to include information on the (changed) parameter values, even if it were only in the SI.

Also, the indicators used to assess water security are complementary of relevant and their relation to water security in this particular basin is much better explained. Still, I miss an assessment of reliability of the water supply (hence my remark on the changing frequency and magnitude of low flows) and the connection to demand. This aspect for irrigation is, however, now included in the discussion. And some aspects that are very relevant for water security in a managed catchment such as reservoir operations and irrigation are not included and this is not mentioned in the document.

I believe this would be good to include still and this is one of my further suggestions to revise the manuscript.

Also, the model description in the SI clarifies how infiltration excess overland flow is include. However, this uses a reduced, effective infiltration rate and overlooks the effect of the changing gradient due to a propagating wetting front in the soil. This means that the model may overestimate the effect of infiltration excess overland flow as the effect of suction at the start of the event -when rainfall intensities are high according to the model- is underestimated. Also, the effect of saturation excess overland flow is not covered and this may become more important as more water can infiltrate and the available storage exhausted before the rainfall intensity becomes higher than the infiltration capacity. Partly, the calibration of lambda may counteract this problem but this has the disadvantage that it is calibrated on the current climate and as such may be invalid in the future when high intensity rainfall becomes large. Furthermore, the higher rainfall intensities for the future scenarios may lead to a dry bias and overemphasize the impact of higher rainfall intensities under these conditions. I acknowledge it is hard to find an approach to cover these effects rigorously: finer time steps with the full Green & Ampt model, a parameterized version of the Green & Ampt model and disaggregating rainfall to finer (subdaily) temporal resolution will all add additional uncertainty. Yet, given the scope of the paper and the impact on the findings I am convinced this should at least be mentioned in the discussion and ideally be quantified by means of a sensitivity analysis with the full Green & Ampt model and the reduced version used here.

Textually, I have little remarks. Note that Figure 1e gives the soil classification, not the soil texture. Please note that line 10 on page 12 in the discussion is not fluent and near the end of that page that while the delta method is still used, more and more impact assessments -like the ISI-MIP for example- use more sophisticated methods to deal with climate change, changing extremes and climate uncertainty.

The few points I raise here are due to greater understanding after rereading the revised manuscript. Overall, I believe the remarks of my fellow reviewer and myself are well addressed and have led to a better study of which the results will find easier acceptance within the hydrological community. I hope these final additions help to tidy up the last lose ends.

Hide

ED: Publish subject to revisions (further review by editor and referees) (06 Oct 2018) by Nunzio Romano

AR by Joris Eekhout on behalf of the Authors (09 Oct 2018) Author's response Manuscript

ED: Publish subject to revisions (further review by editor and referees) (18 Oct 2018) by Nunzio Romano

AR by Joris Eekhout on behalf of the Authors (18 Oct 2018) Author's response Manuscript

ED: Publish subject to minor revisions (further review by editor) (11 Nov 2018) by Nunzio Romano

AR by Joris Eekhout on behalf of the Authors (12 Nov 2018) Author's response Manuscript

ED: Publish as is (13 Nov 2018) by Nunzio Romano

AR by Joris Eekhout on behalf of the Authors (13 Nov 2018) Manuscript

Short summary

Extreme weather, like heavy rainstorms and droughts, will become more frequent under climate change, jeopardizing water availability. We show that climate change in a large Mediterranean catchment leads to a redistribution of water from soil to reservoirs and to increased crop stress. Furthermore, increased soil erosion threatens the storage capacity of reservoirs. We conclude that climate change may affect rainfed and irrigated agriculture potential and threatens overall water security.