Towards a simple representation of chalk hydrology in land surface modelling

Rahman, Mostaquimur; Rosolem, Rafael

doi:https://doi.org/10.5194/hess-21-459-2017

Articles | Volume 21, issue 1

https://doi.org/10.5194/hess-21-459-2017

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

https://doi.org/10.5194/hess-21-459-2017

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

Articles | Volume 21, issue 1

Research article

|

25 Jan 2017

Research article |

| 25 Jan 2017

Towards a simple representation of chalk hydrology in land surface modelling

Mostaquimur Rahman and Rafael Rosolem

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Final revised paper (published on 25 Jan 2017)
Preprint (discussion started on 26 May 2016)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Novelty and contribution of the work need to be clarified', Nataliya Le Vine, 01 Jul 2016
- AC1: 'Response to Review Comments by Dr Nataliya Le Vine', Mostaquimur Rahman, 13 Jul 2016
RC2: 'A simple model for the Chalk, but only halfway there', Andrew Ireson, 14 Jul 2016
- AC2: 'Response to review comments by Dr Andrew Ireson', Mostaquimur Rahman, 02 Aug 2016
RC3: 'Calibration essential before consideration', Anonymous Referee #3, 15 Jul 2016
- AC3: 'Response to reviewer comments (Anonymous Referee #3)', Mostaquimur Rahman, 02 Aug 2016
EC1: 'Providing further authors' comments', Nunzio Romano, 29 Jul 2016

Peer-review completion

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

ED: Reconsider after major revisions (10 Aug 2016) by Nunzio Romano

AR by Mostaquimur Rahman on behalf of the Authors (12 Oct 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (14 Oct 2016) by Nunzio Romano

RR by Anonymous Referee #4 (16 Nov 2016)

RR by Andrew Ireson (25 Nov 2016)

Suggestions for revision or reasons for rejection

The paper is much improved, and I think that this is a useful contribution. However, there is a lingering problem that really should be addressed before the paper can be published. The authors have misinterpretted the hydraulic conductivity in the LeVine Paper (cited in the manuscript), which was a bulk hydraulic conductivity and not a matrix conductivity. Moreover, in the optimisation of K, the authors have not sampled K on a log-scale (unless they have and have neglected to say this), meaning that the optimized K is biased towards higher values. As a result, I believe the authors still have a matrix K which is unrealistically large compared with other published estimates. In my opinion, this is important and should be corrected before this paper can be published, which unfortunately means re-running the models.

Another significant error, though easily fixed, is that the revised manuscript still does not include a plot of runoff for the catchment scale application. Such a plot was included in the response to reviewers (Figure R2 in the response), so should be incorporated into the manuscript. I think that the performance in this figure was reasonable. They should also show the default model performance.

If this can be quickly addressed, this will be a nice paper.

I have also identified some minor errors to be corrected, below:

L 65 - "numbers of parameters"

L 80 - to be rigorous you should also show what "K_sb" is when S <= S_0.

L 87 - I believe the authors have misinterpretted the LeVine paper, which has a bulk saturated hydraulic conductivity of 16 mm/d, and not a matrix hydraulic conductivity. This number is at least an order of magnitude too high (see e.g. Ireson et al 2009, Price et al 1993, Price et al 2000, Brouyere 2006, all cited in the manuscript).

Table 2 & 3 should probably use the same units for hydraulic conductivity - m/d is good.

Figure 1 c) has 5 colours, while only 3 legend items.

Figure 4 - Need to label the units of K - and what are these? Not mm/d or m/s as far as I can tell - maybe mm/s? Better to use m/d.

L 106 - the range in Ks considered is good, though I would expect the true value to be right at the bottom of this range. Did you sample Ks in log-space? I assume not - which is a problem as it will bias your sampling to the higher values. This is important - you need to sample in log-space. I think your default and optimized Ks are still too high (i.e. values in Figure 4). Other than this, the optimization approach is good.

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ED: Publish subject to revisions (further review by Editor and Referees) (27 Nov 2016) by Nunzio Romano

AR by Mostaquimur Rahman on behalf of the Authors (07 Jan 2017) Author's response Manuscript

ED: Publish as is (09 Jan 2017) by Nunzio Romano

AR by Mostaquimur Rahman on behalf of the Authors (10 Jan 2017)

Short summary

Modelling water flow through chalk (a fine-grained porous medium traversed by fractures) is important for optimizing water resource management practices in the UK. However, efficient simulations of water movement through chalk are difficult due to the porous nature of chalk, creating high-velocity preferential flow paths. This paper describes a novel approach to representing chalk hydrology in land surface modelling for large-scale applications.