Development and evaluation of a variably saturated flow model in the global E3SM Land Model (ELM) version 1.0

Bisht, Gautam; Riley, William J.; Hammond, Glenn E.; Lorenzetti, David M.

doi:https://doi.org/10.5194/gmd-11-4085-2018

Articles | Volume 11, issue 10

https://doi.org/10.5194/gmd-11-4085-2018

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

https://doi.org/10.5194/gmd-11-4085-2018

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

Articles | Volume 11, issue 10

Model description paper

|

11 Oct 2018

Model description paper |

| 11 Oct 2018

Development and evaluation of a variably saturated flow model in the global E3SM Land Model (ELM) version 1.0

Gautam Bisht, William J. Riley, Glenn E. Hammond, and David M. Lorenzetti

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Final revised paper (published on 11 Oct 2018)
Supplement to the final revised paper
Preprint (discussion started on 02 Mar 2018)

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

SC1: 'Code Availability', Lutz Gross, 15 Mar 2018
- AC1: 'Response to SC1', Gautam Bisht, 26 Jun 2018
RC1: 'Reivew of Manuscript by Bisht et al.', Anonymous Referee #1, 30 Mar 2018
- AC2: 'Response to RC1', Gautam Bisht, 26 Jun 2018
RC2: 'Confidential Review A review for Development and evaluation of a variably saturated flow model in the global E3SM', Anonymous Referee #2, 02 Jun 2018
- AC3: 'Response to RC2', Gautam Bisht, 26 Jun 2018

Peer-review completion

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

AR by Gautam Bisht on behalf of the Authors (26 Jun 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Jul 2018) by Jatin Kala

RR by Anonymous Referee #1 (29 Jul 2018)

RR by Anonymous Referee #3 (10 Aug 2018)

Suggestions for revision or reasons for rejection

1. The authors tried to demonstrate the robustness of ELMv1-VSFM by conducting several experimental simulations. However, there may be inaccuracies in numerical solutions due to differences in the size of spatial and temporal mesh (El‐Kadi & Ling, 1993). The authors used outputs from simulations with different configurations (e.g. spatial resolution of grid-cell, soil column depth, spatial discretization) to support the robustness of global analysis. Moreover, temporal resolutions used in the experimental simulations are not indicated in the paper. Since information required for ensuring numerical stability of the model is not indicated, I am not sure whether or not ELMv1-VSFM converges well at a spatial-temporal resolution of 1.90 (latitude) × 2.50 (longitude) with a 30 [min] time-step.

2. The authors mentioned that there are advantages to using variably-saturated flow model (variably saturated Richards’ equation) rather than applying different governing equations for each flow domain noted in the previous work. However, they did not specify what the relative strengths of using variably saturated Richards’ equation are compared to adapting different equations (e.g., computational cost). The reason why they intended to unify the treatment of soil hydrologic processes should be stated.

3.The authors used ILAMB package to show additional consideration of saturated zone does not degrade the model’s predictive capabilities in other hydrologic processes. However, without any explanation of the interaction between groundwater and other components (e.g., streamflow, LH/SH), it is difficult to accept the author’s claim saying further consideration about groundwater-surface water interaction does not degrade other predictions.

4. The authors mentioned this work has a focus on representing groundwater-surface water interactions but all the outputs appear to be related addressing subsurface hydrology using VSFM. The authors may want to specify what they did to emphasize their focus on groundwater-surface water interactions by adding more results regarding that (e.g., interactive effect between runoff and groundwater level)

Referee Report: PDF

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ED: Reconsider after major revisions (10 Aug 2018) by Jatin Kala

AR by Gautam Bisht on behalf of the Authors (06 Sep 2018) Author's response Manuscript

ED: Publish subject to technical corrections (11 Sep 2018) by Jatin Kala

AR by Gautam Bisht on behalf of the Authors (11 Sep 2018) Manuscript

Short summary

Most existing global land surface models used to study impacts of climate change on water resources routinely use different models for near-surface unsaturated soil and the deeper groundwater table. We developed a model that uses a unified treatment of soil hydrologic processes throughout the entire soil column. Using a calibrated drainage parameter, the new model is able to correctly predict deep water table depth as reported in an observationally constrained global dataset.