the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Jan 2025
Representation of a two-way coupled irrigation system in the Common Land Model
Abstract. Human land–water management, especially irrigation water withdrawal and use, significantly impacts the global and regional water cycle, energy budget, and near-surface climate. While land surface models are widely used to explore and predict the impacts of irrigation, the irrigation system representation in these models is still in its early stages. This study enhances the Common Land Model (CoLM) by introducing a two-way coupled irrigation module. This module includes an irrigation water demand scheme based on soil moisture deficit, an irrigation application scheme considering four major irrigation methods, and an irrigation water withdrawal scheme that incorporates multiple water source constraints by integrating CoLM with a river routing model and a reservoir operation scheme. Crucially, it explicitly accounts for the feedback between irrigation water demand and supply, which is constrained by available surface water (i.e., runoff, streamflow, reservoir storage) and groundwater. Simulations conducted from 2001 to 2016 at a 0.25° spatial resolution across the contiguous United States reveal that the model effectively reproduces irrigation withdrawals, their spatial distribution, and water source proportions, aligning well with reported state-level statistics. Comprehensive validation demonstrates that the new module significantly improves model accuracy in simulating regional energy dynamics (sensible heat, latent heat, and surface temperature), hydrology (river flow), and agricultural outputs (yields for maize, soybean, and wheat). Application analyses highlight the potential of the enhanced CoLM as a valuable tool for predicting irrigation-driven climate impacts and assessing water use and scarcity. This research offers a pathway for a more holistic representation of fluxes in irrigated areas and human-water interactions within land surface models. It is valuable for exploring the interconnected evolution of climate, water resources, agricultural production, and irrigation activities, while supporting sustainable water management decisions in a changing climate.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(12648 KB) - Metadata XML
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Supplement
(9567 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-4093', Anonymous Referee #1, 26 Feb 2025
In the manuscript entitled “Representation of a two-way coupled irrigation system in the Common Land Model”, the authors implemented several new features regarding irrigation water applications and withdrawals in a land system model and evaluated the model with new features based on observation-based datasets. Although these new features are mainly adopted from other models, it is impressive that the authors implemented them in a different land model. I congratulate the authors for this huge amount of work and believe that it is qualified to be published on EGU HESS. However, there is still some room for improvement in the manuscript, which are listed below.
Major Comments
- Materials and Methods:
- Before introducing the crop module, it would be better to first describe the sub-grid cell level structure of the model CoLM. How are the calculations conducted over different land-use tiles? How are rainfed and irrigated cropland differently treated? Etc.
- Results:
- Evaluation:
- The authors adopted the crop model used in the Community Land Model version 5 (CLM5) and activated the crop model, which means that the crop phenology is simulated. I think it is important to also compare the simulated and observed LAI at some single points to show how the model reproduces the phenology of different crop types.
- I do not think comparing the simulated and observed energy fluxes averaged over all irrigated regions in the USA is enough. I would compare them over single grid cells with intense irrigation, or at least, average across the irrigated regions in different climate zones.
- Similarly, I would do some evaluations of streamflow over some bigger catchments (which can consist of several sub-catchments that the authors used) with intense water withdrawal. In the supplementary Figure S7, it would be nice to also plot the boundaries of catchments. A map showing the difference between simulated and observed streamflow will be better than the bar plots in Figure 8.
- For the crop yield, I would also like to see a map showing the difference between simulated and observed crop yield in administrative regions, rather than the bar plot in Figure 9.
- It is always recommended to add maps showing difference between simulations and observations in Figure 3 and 4.
- It would be interesting to add some results showing the new features of CoLM irrigation module. For example, showing the simulated water withdrawal from different sources, showing simulated terrestrial water storage, showing how lakes or reservoirs change with irrigation water withdrawal (if they do), etc. This will help readers to know what can they use the model to do.
- Evaluation:
- Discussion
3.1 I have to admit that I am a bit disappointed that all the evaluation work was done solely in the USA. I understand that in the USA there are generally more abundant observations, but it should at least be discussed in the discussion that some efforts are needed if other researchers want to use this model for studies over other regions.
Minor comments
L193 What is this crop growth stage? When crop LAI > 0?
L205-207 Is this coefficient identical in all grid cells? Or can we assign different values in different regions?
L221-222 A table showing the main difference among them would be helpful.
Figure 6 I would change the tick of y-axis because it is not clear to see the absolute number of irrigation water withdrawal.
Citation: https://doi.org/10.5194/egusphere-2024-4093-RC1 -
AC1: 'Reply on RC1', Shulei Zhang, 03 Apr 2025
We sincerely appreciate your thoughtful review and encouraging feedback. Your insights have been invaluable in improving the manuscript. Below, we provide detailed point-by-point responses to your comments, along with the corresponding revisions in the manuscript.
- Materials and Methods:
-
RC2: 'Comment on egusphere-2024-4093', Anonymous Referee #2, 03 Mar 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4093/egusphere-2024-4093-RC2-supplement.pdf
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AC2: 'Reply on RC2', Shulei Zhang, 03 Apr 2025
We greatly appreciate the time and effort you have spent on our manuscript, as well as your encouraging feedback and constructive comments, which have been highly helpful in improving the overall quality of our work. We have provided a point-to-point response to each comment and made corresponding changes in the revised manuscript.
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AC2: 'Reply on RC2', Shulei Zhang, 03 Apr 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2024-4093', Anonymous Referee #1, 26 Feb 2025
In the manuscript entitled “Representation of a two-way coupled irrigation system in the Common Land Model”, the authors implemented several new features regarding irrigation water applications and withdrawals in a land system model and evaluated the model with new features based on observation-based datasets. Although these new features are mainly adopted from other models, it is impressive that the authors implemented them in a different land model. I congratulate the authors for this huge amount of work and believe that it is qualified to be published on EGU HESS. However, there is still some room for improvement in the manuscript, which are listed below.
Major Comments
- Materials and Methods:
- Before introducing the crop module, it would be better to first describe the sub-grid cell level structure of the model CoLM. How are the calculations conducted over different land-use tiles? How are rainfed and irrigated cropland differently treated? Etc.
- Results:
- Evaluation:
- The authors adopted the crop model used in the Community Land Model version 5 (CLM5) and activated the crop model, which means that the crop phenology is simulated. I think it is important to also compare the simulated and observed LAI at some single points to show how the model reproduces the phenology of different crop types.
- I do not think comparing the simulated and observed energy fluxes averaged over all irrigated regions in the USA is enough. I would compare them over single grid cells with intense irrigation, or at least, average across the irrigated regions in different climate zones.
- Similarly, I would do some evaluations of streamflow over some bigger catchments (which can consist of several sub-catchments that the authors used) with intense water withdrawal. In the supplementary Figure S7, it would be nice to also plot the boundaries of catchments. A map showing the difference between simulated and observed streamflow will be better than the bar plots in Figure 8.
- For the crop yield, I would also like to see a map showing the difference between simulated and observed crop yield in administrative regions, rather than the bar plot in Figure 9.
- It is always recommended to add maps showing difference between simulations and observations in Figure 3 and 4.
- It would be interesting to add some results showing the new features of CoLM irrigation module. For example, showing the simulated water withdrawal from different sources, showing simulated terrestrial water storage, showing how lakes or reservoirs change with irrigation water withdrawal (if they do), etc. This will help readers to know what can they use the model to do.
- Evaluation:
- Discussion
3.1 I have to admit that I am a bit disappointed that all the evaluation work was done solely in the USA. I understand that in the USA there are generally more abundant observations, but it should at least be discussed in the discussion that some efforts are needed if other researchers want to use this model for studies over other regions.
Minor comments
L193 What is this crop growth stage? When crop LAI > 0?
L205-207 Is this coefficient identical in all grid cells? Or can we assign different values in different regions?
L221-222 A table showing the main difference among them would be helpful.
Figure 6 I would change the tick of y-axis because it is not clear to see the absolute number of irrigation water withdrawal.
Citation: https://doi.org/10.5194/egusphere-2024-4093-RC1 -
AC1: 'Reply on RC1', Shulei Zhang, 03 Apr 2025
We sincerely appreciate your thoughtful review and encouraging feedback. Your insights have been invaluable in improving the manuscript. Below, we provide detailed point-by-point responses to your comments, along with the corresponding revisions in the manuscript.
- Materials and Methods:
-
RC2: 'Comment on egusphere-2024-4093', Anonymous Referee #2, 03 Mar 2025
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2025/egusphere-2024-4093/egusphere-2024-4093-RC2-supplement.pdf
-
AC2: 'Reply on RC2', Shulei Zhang, 03 Apr 2025
We greatly appreciate the time and effort you have spent on our manuscript, as well as your encouraging feedback and constructive comments, which have been highly helpful in improving the overall quality of our work. We have provided a point-to-point response to each comment and made corresponding changes in the revised manuscript.
-
AC2: 'Reply on RC2', Shulei Zhang, 03 Apr 2025
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Shulei Zhang
Hongbin Liang
Xingjie Lu
Yongjiu Dai
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(12648 KB) - Metadata XML
-
Supplement
(9567 KB) - BibTeX
- EndNote
- Final revised paper