the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Sep 2024
LM4-SHARC v1.0: Resolving the Catchment-scale Soil-Hillslope Aquifer-River Continuum for the GFDL Earth System Modeling Framework
Abstract. Catchment-scale representation of the groundwater and its interaction with other parts of the hydrologic cycle is crucial for accurately depicting the land water-energy balance in Earth system models (ESMs). Despite existing efforts to describe the groundwater in the land component of ESMs, most ESMs still need a prognostic framework for describing catchment-scale groundwater based on its emergent properties to understand its implication to the broader Earth system. To fill this gap, we developed a new parameterization scheme for resolving the groundwater and its two-way interactions with the unsaturated soil and stream at the catchment-scale. We implemented this new parameterization scheme (SHARC, or Soil-Hillslope Aquifer-River Continuum), in the Geophysical Fluid Dynamics Laboratory land model (i.e., LM4-SHARC) and evaluated its performance. By bridging the gap between hydraulic groundwater theory and ESMs' land hydrology, the new LM4-SHARC has been applied to the Providence headwater catchment at Southern Sierra, NV, and tested against in-situ observations. We found that LM4-SHARC leads to noticeable improvements in representing key hydrologic variables such as streamflow, near-surface soil moisture, and soil temperature. In addition to enhancing the representation of the water and energy balance, our analysis showed that accounting for groundwater convergence can induce a more significant hydrologic contrast with higher sensitivity of soil water storage to groundwater properties in the riparian zone. Our findings indicate the feasibility of incorporating two-way interactions among groundwater, unsaturated soil, and streams into the hydrological components of ESMs and further need to explore the implications of these interactions in the context of Earth system dynamics.
Competing interests: Some authors are members of the editorial board of Geoscientific Model Development (GMD).
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.-
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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.
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Preprint
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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.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-2005', Anonymous Referee #1, 22 Nov 2024
The manuscript presents LM4-SHARC v1.0, a novel parameterization scheme that integrates catchment-scale soil, groundwater, and river interactions into the GFDL land model. This study addresses a critical limitation in current Earth System Models (ESMs) by improving hydrologic predictions and enhancing the representation of energy-water flux dynamics. The results, validated using observational data from Providence Creek, are compelling. I support publication with minor revisions. Below are my detailed comments:
General Comments
The manuscript's most significant issue lies in the methods section, which lacks clarity despite being central to the paper. From my understanding, the model uses baseflow observations and Equation (19) to derive parameters a and b, which are then used in Equations (20) and (21) to determine other parameters. During the simulation, Equation (1) calculates ql, and Equation (6) calculates Q. However, the purpose of the other equations remains unclear. The authors should explicitly outline the role of each equation, the model's calibration process, and the input-output structure. Additionally, the distinction between analytical and numerical solutions is difficult to grasp and warrants better explanation.
Furthermore, the section on energy transport methods could be shortened, as the hydrological components are more critical to the study.
Regarding model evaluation, while improvements are demonstrated for the Providence Creek catchment, they could stem from calibration against local streamflow data. Without such data in other regions, how can the authors ensure similar improvements? The discussion on future global tuning using remote sensing data is insufficient. Since this scheme is intended for global implementation, the manuscript should address how effective parameters can be derived at a global scale at this time. Expanding this section would significantly strengthen the manuscript.
Specific Comments
- L86: "The properties of the groundwater were…"
If soil and bedrock types are stable, why should groundwater parameters vary over time? The reasoning for developing time-varying parameters is not sufficiently convincing. - L111: "Then, the catchment-scale hydrologic structure…"
What is meant by "inter-tile connection"? Has this been fully implemented in the land model? - L127: "Sierra National Forest…"
What criteria led to the selection of this catchment? - L190-205:
This paragraph is unclear. The relationship between Equations (4)(5)(6) and Equations (2)(19), as well as their roles within the model, should be explicitly explained. - L402: "The k was set to 1…"
Why was k=1? Even in a headwater catchment, different types of hillslopes could exist. - L541: "Baseflow observation…"
The baseflow observation method derived from Szilagyi and Parlange (1998) should include a discussion of its accuracy. Since baseflow is a minor yet essential component in model calibration, its uncertainty warrants consideration. - L576: "The evaluation was performed for four years…"
Why wasn’t the model evaluated against streamflow/baseflow observations?
Conclusion
This manuscript is a valuable contribution to Earth system modeling. With improved clarity in the methods section, expanded discussion on global parameterization, and more detailed explanations for specific concerns, it would be well-suited for publication.
Citation: https://doi.org/10.5194/egusphere-2024-2005-RC1 -
AC2: 'Reply on RC1', Minki Hong, 13 Jan 2025
The authors thank the reviewer for feedback and for providing insightful recommendations on improving the manuscript. We have responded to all the reviewer's comments in the attached PDF. The reviewer's comments are in black, and our responses are in red.
- L86: "The properties of the groundwater were…"
-
RC2: 'Comment on egusphere-2024-2005', Anonymous Referee #2, 01 Dec 2024
This paper presents a new parameterization scheme that cooperate the groundwater component to the ESM model, which is a good starting point of considering the effect of groundwater on the energy component in the ESM model.Â
In general, the manuscript is written in very good and comprehensive english and it is easy to read and follow. However, I find the manuscript is too long and with some redundant information that reduces the readability. I do agree with the first reviewer that the part describing the energy transport makes the manuscript discontinued, which might be better to put to as a supplementary. I believe with some more efforts for revision, this manuscript could reach the standard of a publication.Â
Here follows some specific comments.Â
1. Figure 1 appears to be difficult to understand. especially when it appears, there was no proper explanation of what is a "height band" until I read section 2.4. I suggest to have a good explain of the following terms at the begining: what is soil columns, tiles, height band and characterisitc hillslope, repectively and what are their potential relationship. and also the meaning of the black dots and what does the size of the dots mean in each soil layer is not clear.Â
2. line 183 states rho is r_j ^j , which does not make sense. and if rho is density, then could you check the unit consisensy of this equation?
3. line 196 eq 6 seems is the spatial derivative of the "stream" discharge instead of the time derivative of the "steam" discharge? 195 has typo "steam discharge" as well.Â
4. Figure 3: the analytical area is not explained anywhere (or I missed it), if you present it there, it is better to give some explanations.Â
5. Line492 "Following the extraction criteria(section 3.3.2).... there is section 3.3.2
6. Figure 7 (a)(b)(c): the first subfigure with legend "VWC", which is not explained anywhere. according to the caption it is the soil moisture, then should it SMC? (according to line 581). And what is the meaning of fprec in the third figure? how to interpret it?
7. Line 636-648 + Figure 9 : It is not clear why reducing spin-up time matters. it is an interesting discovery, but I don't find it important. Do you have any important reason to keep this discussion in the main body of the manuscript? Otherwise consider move it as a supplementary mateiral.Â
8. Section 4.4 is very important since it finally hits the point that the modeled LAI has difference after involving the groundwater to the model, which lead to the potential improvement of the modeled transpiration. It would be better if there are more statistics given to show how much improvement between the lm4 and lm4-sharc.Â
9. I see all the catchments the authors selected are headwater catchment. so before discussing applying the sharc scheme to global scale, could the author elaborate more on how to apply the scheme to downstream catchments where the drainage networks are more complicated? I think the accuracy of the analytical solution of those catchments should be more challenging.Â
Â
Citation: https://doi.org/10.5194/egusphere-2024-2005-RC2 - AC1: 'Reply on RC2', Minki Hong, 13 Jan 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2024-2005', Anonymous Referee #1, 22 Nov 2024
The manuscript presents LM4-SHARC v1.0, a novel parameterization scheme that integrates catchment-scale soil, groundwater, and river interactions into the GFDL land model. This study addresses a critical limitation in current Earth System Models (ESMs) by improving hydrologic predictions and enhancing the representation of energy-water flux dynamics. The results, validated using observational data from Providence Creek, are compelling. I support publication with minor revisions. Below are my detailed comments:
General Comments
The manuscript's most significant issue lies in the methods section, which lacks clarity despite being central to the paper. From my understanding, the model uses baseflow observations and Equation (19) to derive parameters a and b, which are then used in Equations (20) and (21) to determine other parameters. During the simulation, Equation (1) calculates ql, and Equation (6) calculates Q. However, the purpose of the other equations remains unclear. The authors should explicitly outline the role of each equation, the model's calibration process, and the input-output structure. Additionally, the distinction between analytical and numerical solutions is difficult to grasp and warrants better explanation.
Furthermore, the section on energy transport methods could be shortened, as the hydrological components are more critical to the study.
Regarding model evaluation, while improvements are demonstrated for the Providence Creek catchment, they could stem from calibration against local streamflow data. Without such data in other regions, how can the authors ensure similar improvements? The discussion on future global tuning using remote sensing data is insufficient. Since this scheme is intended for global implementation, the manuscript should address how effective parameters can be derived at a global scale at this time. Expanding this section would significantly strengthen the manuscript.
Specific Comments
- L86: "The properties of the groundwater were…"
If soil and bedrock types are stable, why should groundwater parameters vary over time? The reasoning for developing time-varying parameters is not sufficiently convincing. - L111: "Then, the catchment-scale hydrologic structure…"
What is meant by "inter-tile connection"? Has this been fully implemented in the land model? - L127: "Sierra National Forest…"
What criteria led to the selection of this catchment? - L190-205:
This paragraph is unclear. The relationship between Equations (4)(5)(6) and Equations (2)(19), as well as their roles within the model, should be explicitly explained. - L402: "The k was set to 1…"
Why was k=1? Even in a headwater catchment, different types of hillslopes could exist. - L541: "Baseflow observation…"
The baseflow observation method derived from Szilagyi and Parlange (1998) should include a discussion of its accuracy. Since baseflow is a minor yet essential component in model calibration, its uncertainty warrants consideration. - L576: "The evaluation was performed for four years…"
Why wasn’t the model evaluated against streamflow/baseflow observations?
Conclusion
This manuscript is a valuable contribution to Earth system modeling. With improved clarity in the methods section, expanded discussion on global parameterization, and more detailed explanations for specific concerns, it would be well-suited for publication.
Citation: https://doi.org/10.5194/egusphere-2024-2005-RC1 -
AC2: 'Reply on RC1', Minki Hong, 13 Jan 2025
The authors thank the reviewer for feedback and for providing insightful recommendations on improving the manuscript. We have responded to all the reviewer's comments in the attached PDF. The reviewer's comments are in black, and our responses are in red.
- L86: "The properties of the groundwater were…"
-
RC2: 'Comment on egusphere-2024-2005', Anonymous Referee #2, 01 Dec 2024
This paper presents a new parameterization scheme that cooperate the groundwater component to the ESM model, which is a good starting point of considering the effect of groundwater on the energy component in the ESM model.Â
In general, the manuscript is written in very good and comprehensive english and it is easy to read and follow. However, I find the manuscript is too long and with some redundant information that reduces the readability. I do agree with the first reviewer that the part describing the energy transport makes the manuscript discontinued, which might be better to put to as a supplementary. I believe with some more efforts for revision, this manuscript could reach the standard of a publication.Â
Here follows some specific comments.Â
1. Figure 1 appears to be difficult to understand. especially when it appears, there was no proper explanation of what is a "height band" until I read section 2.4. I suggest to have a good explain of the following terms at the begining: what is soil columns, tiles, height band and characterisitc hillslope, repectively and what are their potential relationship. and also the meaning of the black dots and what does the size of the dots mean in each soil layer is not clear.Â
2. line 183 states rho is r_j ^j , which does not make sense. and if rho is density, then could you check the unit consisensy of this equation?
3. line 196 eq 6 seems is the spatial derivative of the "stream" discharge instead of the time derivative of the "steam" discharge? 195 has typo "steam discharge" as well.Â
4. Figure 3: the analytical area is not explained anywhere (or I missed it), if you present it there, it is better to give some explanations.Â
5. Line492 "Following the extraction criteria(section 3.3.2).... there is section 3.3.2
6. Figure 7 (a)(b)(c): the first subfigure with legend "VWC", which is not explained anywhere. according to the caption it is the soil moisture, then should it SMC? (according to line 581). And what is the meaning of fprec in the third figure? how to interpret it?
7. Line 636-648 + Figure 9 : It is not clear why reducing spin-up time matters. it is an interesting discovery, but I don't find it important. Do you have any important reason to keep this discussion in the main body of the manuscript? Otherwise consider move it as a supplementary mateiral.Â
8. Section 4.4 is very important since it finally hits the point that the modeled LAI has difference after involving the groundwater to the model, which lead to the potential improvement of the modeled transpiration. It would be better if there are more statistics given to show how much improvement between the lm4 and lm4-sharc.Â
9. I see all the catchments the authors selected are headwater catchment. so before discussing applying the sharc scheme to global scale, could the author elaborate more on how to apply the scheme to downstream catchments where the drainage networks are more complicated? I think the accuracy of the analytical solution of those catchments should be more challenging.Â
Â
Citation: https://doi.org/10.5194/egusphere-2024-2005-RC2 - AC1: 'Reply on RC2', Minki Hong, 13 Jan 2025
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LM4-SHARC v1.0: Resolving the Catchment-scale Soil-Hillslope Aquifer-River Continuum for the GFDL Earth System Modeling Framework Minki Hong et al. https://zenodo.org/records/13750071
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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
(22358 KB) - Metadata XML