Water Budget, Biological Water Use, and the Soil Hydrological Cycle across Typical Ecosystems of the Heihe River Basin

Round 1

Reviewer 1 Report

The authors have not described how the cropland is irrigated.  For example flood vs sprinkler irrigation will have a dramatic effect on the results.  Also there needs to be more information of study site slope, soil types and other sources of water inputs such type of irrigation, depth to groundwater and surface water inputs such as flooding or adjacent site irrigation.

Line 8-9:  Document requires a good edit.   Many translation issues.  For example line 8-9 ….. but still challenge for the sustainable…  should be …but stall a challenge…. And on the next line 9-10 .. data were used to analyzed the monthly… should be data were used to analyze the….

Line 15:  There were also differences in water budgets due to external inputs as discussed in the paper.  This should be included in the line 15 statement.

Line 26-27:  How this information on a river basin can be extrapolated to arid inland HRBs requires more discussion.

Line 44-45:  ….with unique water system from… to with a unique  water system…  Minor correction but a good technical edit will take care of these small errors.

Author Response

Response to comments from Reviewer 1

Reviewer #1: The authors have not described how the cropland is irrigated. For example, flood vs sprinkler irrigation will have a dramatic effect on the results. 

• Thanks for your valuable comments, the information of crop irrigated was added in Manuscript. The cropland is located at Daman Irrigation District in ZhangYe City, Gansu Province. Maize was planted on the late April and harvested on Mid to late September. It is mainly flood irrigated from the Heihe River. During the growing season, flood irrigation was generally performed four times (e.g., May ,June, July and Aug).

Also there needs to be more information of study site slope, soil types and other sources of water inputs such type of irrigation, depth to groundwater and surface water inputs such as flooding or adjacent site irrigation.

• I’m sorry for my carelessness, we have added more descriptions including soil type, vegetation type, irrigation, and groundwater for study area and study site.

Line 8-9:  Document requires a good edit.   Many translations issue.  For example, line 8-9 ….. but still challenge for the sustainable…  should be …but stall a challenge…. And on the next line 9-10 .. data were used to analyzed the monthly… should be data were used to analyze the….

• Thanks for your helpful comments, and these sentences have been modified according to this comment.

Line 15:  There were also differences in water budgets due to external inputs as discussed in the paper.  This should be included in the line 15 statement.

• Thanks for your comments, and we have added the factor of external inputs in the line 15 statement.

Line 26-27:  How this information on a river basin can be extrapolated to arid inland HRBs requires more discussion.

• Thanks for your suggestions. The information on a river basin can be extrapolated to arid inland HRBs were discussed.

Line 47-48:  ….with unique water system from… to with a unique  water system…  Minor correction but a good technical edit will take care of these small errors.

• Thank you for your correction, and it was corrected.

Author Response File: Author Response.docx

Reviewer 2 Report

Thank you for the paper entitled " Water budget, biological water use, and the soil hydro-logical cycle across typical ecosystems of the Heihe River Basin", submitted to the Water journal. Overall I found the paper quite interesting as issues related to water cycle and use are extremely significant in the context of climate change, anthropopressure, and environment degradation. In my opinion the manuscript brings some new practical findings, while its technical and language level is generally satisfactory. However, I recommend some changes and improvements before publication within Water journal. My general remarks are listed below:

a) The introduction section should more precisely highlight the novelty of the work and how the paper differentiates from the wide literature on the subject, e.g. what new or modified methods were applied? Please rewrite the objectives to be more sophisticated.

b) In the study area section please provide the information about the type of the climate; the Köppen-Geiger climate classification is recommended to use due to its global recognition.

·       c) Although the methods and analytical procedures were described exhaustively, there is no explanation about the types of vegetation, which were representative for measurement sites. For example, what species dominate in the apline meadows? Moreover, if in site KZZ vegetation type was the Kalidium foliatum, it means that only this species was found in this place? This should be explained. Finally, in my PDF version of the manuscript there is lack of equations 2, 3, and 4.

·       d) I recommend enlarge the figure 3 to improve clarity.

·    e) In discussion section, please provide short explanation how the climate changes can alter the water balance of the investigated region, both directly and indirectly (by changes in the vegetation type).

Author Response

Response to comments from Reviewer 2

Reviewer #2:Thank you for the paper entitled " Water budget, biological water use, and the soil hydro-logical cycle across typical ecosystems of the Heihe River Basin", submitted to the Water journal. Overall, I found the paper quite interesting as issues related to water cycle and use are extremely significant in the context of climate change, anthropo pressure, and environment degradation. In my opinion the manuscript brings some new practical findings, while its technical and language level is generally satisfactory.

• Thanks for your quite positive comments.

However, I recommend some changes and improvements before publication within Water journal. My general remarks are listed below:

1. The introduction section should more precisely highlight the novelty of the work and how the paper differentiates from the wide literature on the subject, e.g., what new or modified methods were applied? Please rewrite the objectives to be more sophisticated.

• Thank you for your opinion and we have revised the objectives, methods and related parts.

1. In the study area section please provide the information about the type of the climate; the Köppen-Geiger climate classification is recommended to use due to its global recognition.

• Thanks for valuable suggestions. We have added more information about the type of the climate for each study site and other information. The details of each site were summarized in Table 1.

1. Although the methods and analytical procedures were described exhaustively, there is no explanation about the types of vegetation, which were representative for measurement sites. For example, what species dominate in the alpine meadows? Moreover, if in site KZZ vegetation type was the Kalidium foliatum, it means that only this species was found in this place? This should be explained.

• I am sorry for my negligence and that information was added in the section 2.1 of manuscript. The present study selected typical six ecosystems of the HRB separated by environment gradients (altitude, precipitation, and temperature). The land surface of those selected 6 sites was wide and flat with enough footprints. The characteristics of the selected ecosystems including soil, vegetation type, and climate were summarized in Ta-ble 1. Briefly, two upstream alpine meadows at different elevations, named A’rou(ARC) and Dashalong (DSL) site were selected. Alpine meadow is the main veg-etation type in ARC site, which has a rich variety of plants including Kobresia hu-milis, Stellera chamaejasme L, Poa calliopsis，Potentilla multifida，Medicago Sativa L., Elymus nutans et al. Different to ARC, DSL site belongs to apline swamp meadow, Kobresia pygmaea was the dominant species at the DSL site, and other herbs include Carex atrofusca,Schkuhr subsp, Kobresia tibetica Maxim et al. The cropland at Daman site (DMC) and nature desert at Huazhaizi site (HZZ) in the middle reaches were choose. Maize was planted at DMC on the late April and harvested on Mid to late September. During the growing season, flood irrigation was generally performed four times (e.g., May, June, July and Aug). Kalidium foliatum is the dominate and key plant species in HZZ site where has few other plants. In the lower reaches, two different types of desert riparian forest ecosystems (e.g., P.euphratica and T.ramosissima) which serve as important wildlife Habitat were selected. Here, dominant species were selected to representative vegetation type.

 Finally, in my PDF version of the manuscript there is lack of equations 2, 3, and 4.

• We’re sorry for our carelessness, and have re-upload our revised manuscript.

1. d) I recommend enlarge the figure 3 to improve clarity.

• Thanks for your suggestion. We redraw the Figure 3.

1. e) In discussion section, please provide short explanation how the climate changes can alter the water balance of the investigated region, both directly and indirectly (by changes in the vegetation type).

• Thanks for your valuable suggestions. We discussed how the climate changes can alter the water balance of the investigated region.

Author Response File: Author Response.docx

Reviewer 3 Report

The article is well written and structured. Moreover, it presents a very useful application approach for determining important parameters to be used also for simulations aimed at determining water balances using deterministic techniques based on numerical solutions of conservation equations.

Therefore the article deserves to be published.

3

However, I would suggest an improvement through the introduction of some considerations (after line 161) precisely on the use of the results obtained by the Authors, in applications of CFD (Computational Fluid Dynamics) type calculation codes.

In this regard, an interesting article was recently published that demonstrated the feasibility of determining the water balance not only monthly, but also yearly, in a medium-large river basin, using a deterministic approach based on the shallow water model, a simplified but advanced version of the CFD:

Pasculli, A., Longo, R., Sciarra, N., Di Nucci, C., (2022). Surface Water Flow Balance of a River Basin Using a Shallow Water Approach and GPU Parallel Computing - Pescara River (Italy) as Test Case. WATER Vol. 14, 234.

The related equations are solved numerically by the finite volume method (FVM) with the GPU (Graphical Processing Units) parallel computing technique which reduced the simulation time to 7 days which otherwise, with a sequential solution approach, would have required 7 months!

Therefore I feel to suggest a brief comment on the difference of the two approaches (the approach of the paper under review and the CFD approach whose feasibility has been demonstrated by the cited paper). It should be emphasized that the application of the aforementioned method would also allow the validation of the numerical values of each terms selected by the Authors, in order to perform their balance.

Here are also some minor revisions

Line 10: typo, please change ‘analized’ in ‘analyze’;

Line 16: please indicate the meaning of ET (evapotranspiration?);

Line 85: typo, it is not clear the meaning of ‘…to qualitied..’, peraphs ‘…to quantify…’?

Line 164-183: eq.s (2), (3) and (4) are missed, at least in the paper I downloaded from the Journal situ

Author Response

Response to comments from Reviewer 3

Reviewer #2:The article is well written and structured. Moreover, it presents a very useful application approach for determining important parameters to be used also for simulations aimed at determining water balances using deterministic techniques based on numerical solutions of conservation equations.

Therefore, the article deserves to be published.

• Thank you for your quite positive comments.

However, I would suggest an improvement through the introduction of some considerations (after line 161) precisely on the use of the results obtained by the Authors, in applications of CFD (Computational Fluid Dynamics) type calculation codes. In this regard, an interesting article was recently published that demonstrated the feasibility of determining the water balance not only monthly, but also yearly, in a medium-large river basin, using a deterministic approach based on the shallow water model, a simplified but advanced version of the CFD: Pasculli, A., Longo, R., Sciarra, N., Di Nucci, C., (2022). Surface Water Flow Balance of a River Basin Using a Shallow Water Approach and GPU Parallel Computing - Pescara River (Italy) as Test Case. WATER Vol. 14, 234. The related equations are solved numerically by the finite volume method (FVM) with the GPU (Graphical Processing Units) parallel computing technique which reduced the simulation time to 7 days which otherwise, with a sequential solution approach, would have required 7 months! Therefore, I feel to suggest a brief comment on the difference of the two approaches (the approach of the paper under review and the CFD approach whose feasibility has been demonstrated by the cited paper). It should be emphasized that the application of the aforementioned method would also allow the validation of the numerical values of each term selected by the Authors, in order to perform their balance.

• I am really appreciating your valuable comments. The paper and method you recommend was very interesting because it uses a numerical simulation approach combine with observations that can better validate and advance our results to carry out the whole basin water balance study. But more complex physical based numerical modeling work has been conducted in this area. Previous numerical modeling work for upper stream has been widely conducted (Yang et al., 2015, Gao et al., 2016, 2018), with observed runoff and soil temperature dataset were used to validation the model. Also, previous numerical modeling work for ground-surface water interaction in middle-lower stream has been conducted (Tian et al 2015., Yao et al., 2018), with observed ground depth/level dataset to validation the model. At the same time, numerical modeling work for evapotranspiration estimation and partitioning were conducted with observed eddy covariance and sap flow dataset to validation the model (Tong et al., 2019). Li et al., (2018) conducted integrated study by coupling upstream and downstream models to illustrate whole basin water budget. However, as we know, modeling always suffers uncertainties from parameters (e.g., soil depth, soil hydraulic function, and boundary of groundwater layer) and variables (e.g., soil moisture, vegetation dynamics), in particular, for natural desert vegetation ecosystem which challenge us for reconstructed vegetation dynamics as well as water budget analysis. Therefore, in this study, we using all in-situ observed dataset which regard as “true” value to analysis the water budget and the soil hydrological cycle characters for typical ecosystems of the Heihe River basin.

1. Yang, D. W., Gao, B., Jiao, Y., Lei, H. M., Zhang, Y. L., Yang, H. B., and Cong, Z. T.: A distributed scheme developed for eco-hydrological modeling in the upper Heihe River, China Earth Sci., 58, 36–45, https://doi.org/10.1007/s11430-014-5029-7, 2015.
2. Gao, B.; Qin, Y.; Wang, Y.; Yang, D.; Zheng, Y. Modeling Ecohydrological Processes and Spatial Patterns in the Upper Heihe Basin in China. Forests 2016, 7, 10. https://doi.org/10.3390/f7010010
3. Gao, B., Yang, D., Qin, Y., Wang, Y., Li, H., Zhang, Y., and Zhang, T.: Change in frozen soils and its effect on regional hydrology, upper Heihe basin, northeastern Qinghai–Tibetan Plateau, The Cryosphere, 12, 657–673, https://doi.org/10.5194/tc-12-657-2018, 2018.
4. Yao, Y., Tian, Y., Andrews, C., Li, X.,Zheng, Y., & Zheng, C. (2018). Role ofgroundwater in the drylandecohydrological system: A case study ofthe Heihe River Basin. Journal ofGeophysical Research: Atmospheres, 123,6760–6776. https://doi.org/10.1029/2018JD028432
5. Tian, Y., Y. Zheng, C. Zheng, H. Xiao, W. Fan, S. Zou, B. Wu, Y. Yao, A. Zhang,

and J. Liu (2015), Exploring scaledependent ecohydrological responses in a large endorheic river basin through integrated surface watergroundwater modeling, Water Resour. Res., 51, 4065–4085, doi:10.1002/ 2015WR016881.

6. Tong, Y.; Wang, P.; Li, X.-Y.; Wang, L.; Wu, X.; Shi, F.; Bai, Y.; Li, E.; Wang, J.; Wang, Y. Seasonality of the Transpiration Fraction and Its Controls Across Typical Ecosystems Within the Heihe River Basin. J. Geophys. Res. Atmospheres 2019, 124, 1277–1291, doi:10.1029/2018JD029680
7. Li, X.; Cheng, G.; Ge, Y.; Li, H.; Han, F.; Hu, X.; Tian, W.; Tian, Y.; Pan, X.; Nian, Y.; et al. Hydrological Cycle in the Heihe River 553 Basin and Its Implication for Water Resource Management in Endorheic Basins. J. Geophys. Res. Atmospheres 2018, 123, 890–914, 554 doi:10.1002/2017JD027889.

Here are also some minor revisions

Line 10: typo, please change ‘analized’ in ‘analyze’;

• It is revised.

Line 16: please indicate the meaning of ET (evapotranspiration?);

• It is added and indicated.

Line 85: typo, it is not clear the meaning of ‘…to qualitied..’, peraphs ‘…to quantify…’?

• It is revised.

Line 164-183: eq.s (2), (3) and (4) are missed, at least in the paper I downloaded from the Journal situ

• I am sorry for this mistake. It was revised.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors addressed all the comments raised by the Reviewer. The manuscript has been improved and the authors have tried to do their best, so I would recommend the acceptance of the manuscript for publication in Water journal.