Evaluation of Groundwater Storage Depletion Using GRACE/GRACE Follow-On Data with Land Surface Models and Its Driving Factors in Haihe River Basin, China

Round 1

Reviewer 1 Report

Comments to the Article “Evaluation groundwater storage depletion using satellite gravity data with land surface models and its driving factors in Haihe River Basin, China”, by Guo Yi al.

 

The authors in this article addressed the importance of detecting variations in groundwater storage, namely in Haihe River Basin, China.

The article contains expected components (Introduction, Materials and Methods, Results, Discussion and Conclusion). The literature review is well-organized. The Introduction section properly introduces the problem in analysis.The images presented are clear and communicative. The Materials and Methods section, as well as the Results and Discussion sections, are exhaustive and illustrative.

Methodological concepts used in the analysis are well introduced and their importance to answer the research questions are clearly justified.

The comparison of findings with results from other studies is mentioned.

Limitations of the study, and subsequent areas of further investigation, are also mentioned.

Some clarifications should be addressed by the authors:

• In the Abstract, line 23, is it GRACR or GRACE?
• In the Introduction section, line 83 mentions CSR and JPL. The meaning of these is only introduced two pages ahead, in lines 143 and 144. Should the description be transferred to line 83?
• Equation (5), line 214, is after all, the standard deviation of GWSA. What is the meaning of “D” in the square root? Is it a typo?
• The legend of the figure in line 299 isn’t correct. It should be Figure 6.
• Also the legend of figure 7 contains something not clear in line 325. Which letter for each city?
• English language and style should be revised. For example, the sentence in lines 249-251 is not clear.

Author Response

Dear reviewer,

We are very grateful for such good comments and suggestions, which are very useful not only for this study, but also for the further study. Now, we respond the above suggestions and clarifications one by one.

Clarifications 1: In the Abstract, line 23, is it GRACR or GRACE?

Ans: We are grateful to the reviewer for such careful scrutiny of this work. We are sorry for the spelling mistake. Now, the GRACR is revised by GRACE. For detail, please see page 1, line 24.

 

Clarifications 2: In the Introduction section, line 83 mentions CSR and JPL. The meaning of these is only introduced two pages ahead, in lines 143 and 144. Should the description be transferred to line 83?

Ans: We would like to thank the reviewer for such careful scrutiny. Following reviewer’s reminder, we add the descriptions for CSR and JPL in the Introduction section. For detail, please see page 2, line92, we use the sentence “one from Center for Space Research and the other from Jet Propulsion Laboratory” replace the original “CSR and JPL”.

 

Clarifications 3: Equation (5), line 214, is after all, the standard deviation of GWSA. What is the meaning of “D” in the square root? Is it a typo?

Ans: Many thanks for this very important reminder and you are so scrupulous. The Δ in the equation is spelling mistake, and we are sorry for the careless work. Now we correct the mistake, and for detail, please see the inserted description on page 6, line 223.

 

Clarifications 4: The legend of the figure in line 299 isn’t correct. It should be Figure 6.

Ans: Many thanks for this very important reminder. Following your suggestion, now, we replace the Figure 6.

 

Clarifications 5: Also the legend of figure 7 contains something not clear in line 325. Which letter for each city?

Ans: Many thanks for this very important reminder. We correct the legend of Figure 7. For detail, please see on page 13, line 334.

Clarifications 6: English language and style should be revised. For example, the sentence in lines 249-251 is not clear.

Ans: We are grateful for the reviewer’s invaluable suggestion. We exhaustively check the manuscript and makes appropriate corrections for the mistakes with the help of a native speaker.

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the rev. paper

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

We are very grateful for such good comments, which are very useful not only for this study, but also for the further study. Now, we detailed respond these comments one by one.

Comment 1: “Evaluation groundwater storage depletion using satellite gravity 2 data with land surface models and its driving factors in Haihe 3 River Basin, China” What is satellite gravity data? Was that GGM plus data?

Ans: Thanks very much for this comment. Dear senior, you may have great attrition in satellite gravity or gravity satellite research. We are just expressing our humble opinions.

First, I am not sure if “GGM” stands for Gravimetric geology model or not. The satellite gravity data in this study indicates the mascon solutions from GRACE gravity satellite and GRACE Fellow On gravity satellite.

Second, there are many famous gravity satellites, for example CHAMP, GRACE and GOCE. Among them, GRACE has shown the unique contributions to geodesy, hydrology, oceanography and glaciology, and proved by many studies, such as:

1.GRACE Measurements of Mass Variability in the Earth System Byron D. Tapley et al. Science 305, 503 (2004);

2.Crustal Dilatation Observed by GRACE After the 2004 Sumatra-Andaman Earthquake Shin-Chan Han, C. K. Shum, Michael Bevis, Chen Ji and Chung-Yen Kuo Science 313 (5787), 658-662.

3.Identifying Climate-Induced Groundwater Depletion in GRACE observations. Brian F. Thomas, James s. Famiglietti. Nature,9,1 (2004)

Comment 2: Figure 1. Land use map of Haihe River Basin. What year is this?

Ans: Thanks for reviewer’s careful comment. This map is the average data of the year of 2000, 2005, 2010, 2015 and 2020. These remote sensing data are from Resource and Environment Science and Data Center ( https://www.resdc.cn/data.aspx?DATAID=335)

 

Comment 3: Conclusions Where is the satellite gravity data?

Ans: Thanks for this question. Actual, GRACE and GRACE Follow On data are the satellite gravity data in this study. Combined the comment 1 and comment 3, we correct the title, replace satellite gravity data by GRACE and GRACE Follow On directly.

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript presents the results of a research in which the authors have used satellite gravity data with land surface models and its driving factors to estimate the monthly groundwater storage variations in HRB from 2003 to 2020 in Haihe River Basin (China). The paper presents an interesting topic of worldwide interest, the satellite gravity data (GRACE) in any location helps to the sustainable use of groundwater. 

1. General comments:

• The English of the paper should be significantly improved. I advise the authors to find a proofreader with good written scientific English skills.

• There are many typographic and spelling errors throughout the manuscript. Please, revise the paper carefully.

• Some figures are illegible? e.g., Cities in the figure 1 are illegible? Please upload illustrations with a high resolution (e.g. dpi>650)

1.1. Comments on the abstract:

Line 12-14: The sentence "In this study, monthly...Data Assimilation System (GLDAS)." is incoplete.

Line 23: Replace "GRACR" by "GRACE"

Add the concluding statement at the end of abstarct.

The abstract must be rewritten as:

• context;
• problematic;
• objectives
• methodology
• main quantitative and qualitative results
• concluding statement.

1.2. Coments on the introduction: 

Line 34: Replace " in Unite States" by "in the United States"

Line 50-52: This sentence needs to be reformulated, because there is two type of stored water; the first one is in the earth surface (snow, surface water, soil moinsture and biomass water) and the 2nd is stored below the surface. Please restructure this sentence.

Line 64: Replace "mm/a" by "mm.yr^-1"

Line 86: Replace " in suit data" by "in situ data"

Line 103-104: replace "The average annual precipitation" by "The annual average precipitation".

1.3. Discussion:

The discussion of the paper needs to be enhanced. It's hard to follow the sequence of ideas.

The novelty of the work must be established in sections of introduction and discussion. It must be supported by recent research.

2. Specific comments: 

I have some questions to the authors:

1) How did you distinguish between deep and shallow aquifer using GRACE/FO product?

2) What is the resolution of GRACE product? 

Author Response

Dear reviewer,

We are very grateful for such good comments and suggestions, which are very useful not only for this study, but also for the further study. You are so conscientious, and now, we detailed respond these comments one by one.

Comment 1: The English of the paper should be significantly improved. I advise the authors to find a proofreader with good written scientific English skills. There are many typographic and spelling errors throughout the manuscript. Please, revise the paper carefully.

Ans: We would like to thank the reviewer for such careful scrutiny. Now, we exhaustively checked the manuscript and made appropriate corrections for the mistakes with the help of a native speaker.

 

Comment 2: Some figures are illegible? e.g., Cities in the figure 1 are illegible? Please upload illustrations with a high resolution (e.g. dpi>650)

Ans: We would like to thank the reviewer for such careful scrutiny. A new illustration has been upload with dpi of 900.

 

Comment 3: The abstract must be rewritten as:

context;

problematic;

objectives

methodology

main quantitative and qualitative results

concluding statement.

Ans: We are grateful for the reviewer’s invaluable suggestion. Following your suggestion, we rewrite the abstract by the advised structure.

Context:

Groundwater storage (GWS) in Haihe River Basin (HRB), where is one of the most agricultural and densely populated area in China, is of great importance for the ecosystem environment and so-cio-economic development.

Problematic:

Within recent years, large-scale overexploitation of groundwater in HRB makes it is one of global hotspots of GWS depletion.

Objectives and Methodology:

In this study, monthly GWS variations in HRB from 2003 to 2020 are estimated using Gravity Recovery and Climate Experiment (GRACE) and GRACE Fellow−On (GRACE−FO) data combined with three land surface models (LSMs) from Global Land Data Assimilation System (GLDAS).

Main quantitative and qualitative results:

Results show that

(1) GWS has experienced general depletion with mean rate of 1.88 cm.yr-1 from 2003 to 2020 in the HRB, which is equivalent to a volume of 6 billion m3/yr. GWS depletion aggravated since 2014. The GWS depletion is more serious in plain zone (−2.36 cm.yr-1) than that in mountainous zone (−1.63 cm.yr-1).

(2) Climate changes are excluded for GWS depletion due to annual precipitation and evaporation are close to normal throughout the period. In addition, GWS changes show low correlation with meteorological factors

(3) Consumption of groundwater for irrigation and land use/cover changes are confirmed to be the dominant factors for GWS deterioration in HRB.

(4) The effects of inter-basin water transfer projects are not obviously observed by GRACE and GRACE−FO, and more inter-basin water transfer is need for recovering the GWS in HRB.

Concluding statement:

Thence, it is imperative to control groundwater exploitation and carry out a more reasonable and economical agricultural irrigation structure for the remitting of GWS depletion and sustainability of groundwater resources in HRB

 

Comment 4: Line 34: Replace " in Unite States" by "in the United States"

Ans: We are grateful to the reviewer for such careful scrutiny of this work. We are sorry for the spelling mistake. Now, we replace " in Unite States" by "in the United States".

 

Comment 5: Line 50-52: This sentence needs to be reformulated, because there is two type of stored water; the first one is in the earth surface (snow, surface water, soil moisture and biomass water) and the 2nd is stored below the surface. Please restructure this sentence.

Ans: Thanks very much for this suggestion. Following your suggestion, we restructure this sentence as “TWSA derived from GRACE are integrated with all forms of water anomalies stored above and underneath the surface of the Earth, is a combination of snow, surface water, soil moisture, biomass water and groundwater”.

 

Comment 6: Line 64: Replace "mm/a" by "mm.yr-1"

Ans: Many thanks for this very important reminder. Following your suggestion, now, we replace "mm/a" by "mm.yr-1"and "cm/a" by "cm.yr-1". For detail, please see the line 16-18&63&254-258&331.

 

Comment 7: Line 86: Replace " in suit data" by "in situ data"

Ans: Many thanks for this very important reminder and you are so scrupulous. We are sorry for the careless work. Now we correct the mistake, and for detail, please see the inserted description on line 39&87&282&291.

 

Comment 8: Line 103-104: replace "The average annual precipitation" by "The annual average precipitation".

Ans: Many thanks for this very important reminder. Following your suggestion, now, we replace "The average annual precipitation" by "The annual average precipitation". For detail, please see the line 65&104.

 

Comment 9: The discussion of the paper needs to be enhanced. It's hard to follow the sequence of ideas. The novelty of the work must be established in sections of introduction and discussion. It must be supported by recent research.

Ans: thanks very much for this common, we think it is very useful to improve this study.  On one hand, we add some information to illustrate the novelty of this work. On the other hand, we think it must be our poor English or expression style, which make you confused. To solve this problem, we ask a native English speaker to help us polish the language. Besides, we want to waste the reviewer's time listening to our discussion logic.

Introduction part:

(1) background

GWS depletion is a hot study aspect→large-scale overexploitation of groundwater in HRB makes it is one of global hotspots of GWS depletion. →there are many methods for studying the GWS changes，GRACE has shown the unique contributions to geodesy, hydrology, oceanography and glaciology, and proved by many studies, so we choose using GRACE/FO data to study the GWS depletion.

 

(2) Scientific problems

There are some prior studies using GRACE/FO data to illustrate the GWS depletion. However, these studies do not compare the results from different data combinations and do not consider systematically the effects of climate changes and human activities. On the other hand, time periods of these studies are not long enough to reveal the impacts of South to North Water Diversion Project (SNWDP) on GWS.

Therefore, the aims of this study are: (1) estimate the GWSA time series in HRB based on two latest GRACE/FO data (one from Center for Space Research and the other from Jet Propulsion Laboratory) and three LSMs (CLSM, NOAH and VIC) from GLDAS; (2) compare the GWS changes characteristics among different GRACE/FO data and LSMs data combinations; (3) evaluate the consistency of GWS depletion based on GRACE/FO and LSMs with in situ data; (4) clarify the spatial−temporal patterns of GWS depletion in different subzones of HRB; (5) illustrate the responses of GWS changes to climate changes and human activities.

Discussion part:

Firstly, in order to make our study more persuasive, we compare our results with in situ groundwater level monitoring data, the data from water resource bulletins, and the prior studies.

Second, we illustrate the impacts of climate changes from four aspects: 1)analysis the climate factors change trends; 2)the correlation between climate factors and groundwater storage changes; 3) compare the relation between groundwater storage changes with drought index(scPDSI); 4)compare the spatial distributions of groundwater storage changes and precipitation. Based on above four aspects, climate changes are not the major reasons for GWS depletion in HRB.

Third, we illustrate the impacts of human activities on groundwater storage changes from 1)Water over-exploitation for irrigation; 2)Land use/cover changes; 3)Urban expansion;4) Inter basin water transfer

 

 

Comment 10: How did you distinguish between deep and shallow aquifer using GRACE/FO product?

Ans: Respected reviewer. This is such a good question, and this is also our study interest. To our knowledge, it is impossible to distinguish the groundwater storage changes between deep and shallow aquifer only using GRACE/FO product. In our study, we compare the results from GRACE/FO and the data from Water Resources Bulletins (which provide the groundwater storage changes in shallow and deep aquifer by in-situ groundwater monitoring data, respectively).

 

Comment 11: What is the resolution of GRACE product?

Ans: Respected reviewer. The spatial resolution of GRACE product is 1°×1°. The grid is 0.25°×0.25°and 0.5°×0.5° for the mascon solution. The coarse spatial resolution of GRACE/FO is more suitable for region with area larger than 20×10⁴ km². For our study, the area of Haihe River Basin is 20×10⁴ km². The time resolution is one month.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

All my comments are adressed by authors.

Still some minors improvements:

Line 27-28: Some what odd? 

Moderate English changes still required

Author Response

Dear reviewer

Thanks very much for you comment. we delete the odd information in line 27-28, and send the manuscripts to the editing services of MDPI to polish the English.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.