Environmental Sustainability of Water Resources in Coastal Aquifers, Case Study: El-Qaa Plain, South Sinai, Egypt

Round 1

Reviewer 1 Report

Dear Distinguished Professors,

The article entitled “Environmental Sustainability of Water Resources in Coastal Aquifer, Case Study: El-Qaa Plain, South Sinai, Egypt” established the El-Qaa Plain aquifer sustainability and recharge processes using some very important instruments: mathematical flow modeling, hydrochemical composition, environmental isotopic signature, watershed modeling system (WMS) and remote sensing (RS), taking into account the fact that this aquifer is the South Sinai main source of high quality water. The results showed that there is a recharge process, the aquifer water being mixed with the rainwater. Three dams have been proposed in order to boost the aquifer groundwater recharge. At the same time, 10 new production wells can be drilled without any risk.

All the tools and methods, appropriately depicted by the authors and used in this valuable article, serve as an integrated management system for water resources, which can be applied in arid or semi-arid coastal areas.

The study topic is very important for the Sinai Peninsula future, knowing that the study area suffers from the water scarcity. The results of this study can be subsequently applied in other territories or regions with the same climate and the same water problems.

The study is very well documented and the mathematical, graphic and modeling elements are outstanding, sustaining the paper objectives and hypotheses, and supporting the scientific analysis.

The manuscript is consistent, analytic and systematic, its structure is very well balanced and the study elements and results are clearly interpreted and presented.

The references are contemporary and there is no abnormal/high number of self-citations.

The conclusions are in accordance with the modeling results, and they are very synthetically expressed, emphasizing the study importance. The English language is fine.

In my humble opinion, the present article is a precious contribution to the Water journal, Hydrology studies, and Climate Change studies too. The manuscript may be published immediately, no change being necessary. I congratulate the authors for their hard work and I wish them a very fruitful 2023 year.

My best regards,

Yours sincerely,

The reviewer

Comments for author File: Comments.pdf

Author Response

The authors wish to express their gratitude to reviewer for the valuable comments that added to the work

Reviewer 2 Report

Dear Authors,

I had the chance to read your paper. Unfortunately, the content has many areas that need to be improved. The main problem is that the amount of data that you have for such a huge area is not adequate for building a MODFLOW model. As a result, the scenarios you try to propose are not based on a solid model, making them not very trustworthy. In addition, the connection between the modelling activities and the hydrochemical analysis is not clear. 

Some minor issues are also the following:

L30: Better express that as "five scenarios using MODFLOW" or similar

L34-35: This seems irrelevant here

L44-47: Seems like all those formations are important aquifers. Please clarify

From L52 to appx. L66 the text is more appropriate for a "Study area" section. As a result, the Introduction section needs to be written in a different way, enriching the content with other background information

Section 1.1 needs to be excluded from the Introduction and form another "Study area" section

Fig. 2: Some fonts are very small, also in a) it would be better use some background for the legend

Fig. 3: Consider making the map larger (if possible)

Section 2.2: Correct the indentation

L156: This is not the correct way to cite, use "data collected from Author et al., [26]"

Section 2.3: I suggest putting this info in a Table

L177: As in L156

L200-201: MODFLOW is a modelling code, not a program (strictly speaking)

L262: "severe"

Fig. 5: Provide a figure in better resolution

L302: Use either enriched" or "depleted"

L335-340: Make this sentence shorter

Section 3.2 has several spelling mistakes, read again and correct them

Section 3.3 need a different structure. I would suggest not to use different subsections (3.3.1, 3.3.2 etc) or write the text in a different way without "titles" like "model layers", :model grid" etc

L414: When you say "specific storage capacity" it is unclear which parameter is that, especially when also looking at the value range that you are giving. Please clariy

L436-451: This info is general and refers to basic knowledge. I suggest that you remove it entirely

I find that this paper needs man improvements to become scientifically sound.

Author Response

The authors wish to express their gratitude to reviewer for the valuable comments that added to the work

Reviewer comment: I had the chance to read your paper. Unfortunately, the content has many areas that need to be improved. The main problem is that the amount of data that you have for such a huge area is not adequate for building a MODFLOW model. As a result, the scenarios you try to propose are not based on a solid model, making them not very trustworthy. In addition, the connection between the modelling activities and the hydrochemical analysis is not clear. 

Authors response: Regarding the amount of data used for building the MODFlOW model, the authors used the most trustful database from the already operated wells. The hydrochemical data were used to envisage the fingerprints of recent groundwater recharge, which highlights the necessity of the modeling approach to control the withdrawal policies and sustain the aquifer system by the implementation of runoff water harvesting techniques.

Some minor issues are also the following:

Reviewer comment 1: L30: Better express that as "five scenarios using MODFLOW" or similar

Authors response: Done (Line 30; Page 1 ).

 Reviewer comment 2: L34-35: This seems irrelevant here

Authors response: Deleted (Lines 34-35; Page 1).

Reviewer comment 3: L44-47: Seems like all those formations are important aquifers. Please clarify

Authors response: Additional clarification was added (Lines 59-63; Page  2 ).

Reviewer comment 4: From L52 to appx. L66 the text is more appropriate for a "Study area" section. As a result, the introduction section needs to be written in a different way, enriching the content with other background information.

Authors response:This text was moved to site description section (Lines111-114; Page 3). Additional content was added to the introduction section (Pages  2 and 3). 

Reviewer comment 5: Section 1.1 needs to be excluded from the Introduction and form another "Study area" section

Authors response:

Section 1.1 was excluded from the introduction to site description section. (Line 112; Page 3)

Reviewer comment 6: Fig. 2: Some fonts are very small, also in a) it would be better use some background for the legend.

Authors response:The resolution of the figure was enhanced. A white background was added for the legend. (Page  5).

Reviewer comment 7: Fig. 3: Consider making the map larger (if possible)

Authors response: The resolution of the figure was enhanced and became larger (Page  6).

Reviewer comment 8:Section 2.2: Correct the indentation

Authors response: The indentation was corrected (Became section 4.1). (Page 6).

Reviewer comment 9:L156: This is not the correct way to cite, use "data collected from Author et al., [26]"

Authors response: The citation was corrected (Line 203; Page 7).

Reviewer comment 10:Section 2.3: I suggest putting this info in a Table

Authors response:A new table was added (Table 1;Page  8).

Reviewer comment 11:L177: As in L156

Authors response: The citation was corrected (citation No. 42; Page 8).

Reviewer comment 12:L200-201: MODFLOW is a modelling code, not a program (strictly speaking)

Authors response:Corrected (Line 260; Page 9 ).

Reviewer comment 13:L262: "severe"

Authors response: The phrase is correct and justified with a reference [ 56  ].(Line 320;  Page 10).

Reviewer comment 14:Fig. 5: Provide a figure in better resolution

Authors response:The figure was enhanced in a better resolution (Page 11).                                                       

Reviewer comment 15:L302: Use either enriched" or "depleted"

Authors response: Done (Line 364; Page 12)

Reviewer comment 16:L335-340: Make this sentence shorter

Authors response: Done (Lines 392 -394; Page 13).

Reviewer comment 17:Section 3.2 has several spelling mistakes, read again and correct them

Authors response:The spelling mistakes were corrected. (section 5.2 Pages 13 and 14).

Reviewer comment 18:Section 3.3 need a different structure. I would suggest not to use different subsections (3.3.1, 3.3.2 etc) or write the text in a different way without "titles" like "model layers", :model grid" etc.

Authors response:subsections were deleted (Pages 15 and 16).

Reviewer comment 19:L414: When you say "specific storage capacity" it is unclear which parameter is that, especially when also looking at the value range that you are giving. Please clariy.

Authors response: Changed to storage capacity (Line  486 ; Page 17)

Reviewer comment 20:L436-451: This info is general and refers to basic knowledge. I suggest that you remove it entirely.

Authors response: The general information were removed (Lines  509-523;  Page 18 ).

I find that this paper needs man improvements to become scientifically sound.

Thank you.

Reviewer 3 Report

Environmental Sustainability of Water Resources in Coastal Aquifer, Case Study: El-qaa Plain, South Sinai, Egypt

It focuses on the Environmental Sustainability of Water Resources in Coastal Aquifer, Case Study: El-qaa Plain, South Sinai, Egypt. The article is an interesting case study but needs a thorough revision before acceptance. The overall look of this manuscript is like a lab report kindly rearrange it into a normal case study style. Authors are requested to revise it and follow the following suggestions to improve their work. In my opinion, some details on the experiment should be presented in a methodology that validates your results with filed data. This case study looks very localized and needs to add some literature on other countries or regions which have faced the same problem sand make it more readable globally. Make a clear research motivation and why you think it is necessary to carry on this work. The research gaps need to be clearly articulated.

Introduction

Introduction is poorly framed. Very localized introduction! I suggest the authors to revise it completely into a new format as suggested papers. The authors need to clarify the novelty and objectives and significance in the introduction section. This section is not clearly explaining overall picture of your paper. It is suggested to add some literature globally and make it more attractive for readers. Specific issue of your study area and finally problem formulation and scope of the research.

I would like to ask to cite to the similar latest publication. I suggest following paper for your guideline.

Gleeson, T., Wada, Y., Bierkens, M. et al. Water balance of global aquifers revealed by groundwater footprint. Nature 488, 197–200 (2012). https://doi.org/10.1038/nature11295

Ahmad, N.; Khan, S.; Ehsan, M.; Rehman, F. U.; Al-Shuhail, A. Estimating the Total Volume of Running Water Bodies Using Geographic Information System (GIS): A Case Study of Peshawar Basin (Pakistan). Sustainability 2022, 14 (7), 1-23. DOI: https://doi.org/10.3390/su14073754.

Dawood, F., Akhtar, M. M., & Ehsan, M. (2021). Evaluating urbanization impact on stressed aquifer of Quetta Valley, Pakistan. DESALINATION AND WATER TREATMENT, 222, 103-113.

Sohail, M. T.; Hussan, A.; Ehsan, M.; Al-Ansari, N.; Akhter, M. M.; Manzoor, Z.; Elbeltagi, A. Groundwater budgeting of Nari and Gaj formations and groundwater mapping of Karachi, Pakistan. Applied Water Science 2022, 12, 1-24. DOI: 10.1007/s13201-022-01795-0.

Line 84 after that this line it is suggested to write a paragraph about your overall work cover letter.

1.1. Site description and Hydrogeological Setting of El-Qaa Plain Aquifer System

Geology and Tectonics, did the authors study the influence of tectonics in groundwater in the study area?

Figures 1-3 are good, but this discussion is very poorly written. It is suggested to write some discussion which describes your figures.

2. Materials and Methods

This section needs cosmetic editing. The aspect should ne arranged like this, data acquisition, data processing, and data interpretation.

2.2. Data sources

This section needs to revise in the true spirit of scientific writing. It is very important to clearly citation of data sources. So, It is suggested to provide a proper weblink where you got this data set.  

3. Results and discussions

Figure 5. Piper diagram of the analyzed water samples.

Fig 5 has poor quality and resolution, filled with many things that make it confusing.

A spatial representation of the results is needed.                                    

The discussion needs to be revised using the implementation of the result.

Figure 9. a) Conceptual (schematic) Cross-section of El-Qaa Plain (after [26]) ; b) Model grids show-409 ing rows, columns, active and inactive cells; c) Model boundary conditions.

On what basis did you develop figures 9 b and c. How you calibrate your results.

Authors should make a comparative analysis of regional countries and present the effective solution that is vital to cater to such situations.

Line 435 Model Calibration

This section looks like a lab manual report. It is suggested to reshape scientific papers.

Figure 10. a) Aquifer simulated piezometric heads; b) Directions of groundwater flow; c) Piezometric heads of observed wells and those of the piezometric heads calculated in their locations for the simulated model with RMS calculations.

Figure 10 c, the data point is very limited, it is suggested to add some more data points to validate your results.

Line 473 Selection and Testing Scenarios

It is very confusing for the reader, it is suggested to make it more clear on what basis you design Testing Scenarios.

4. Conclusions

It is suggested to remove your results from this section. This section should be precise and represents your key finding.

Author Response

The authors wish to express their gratitude to reviewer for the valuable comments that added to the work

Introduction

Introduction is poorly framed. Very localized introduction! I suggest the authors to revise it completely into a new format as suggested papers. The authors need to clarify the novelty and objectives and significance in the introduction section. This section is not clearly explaining overall picture of your paper. It is suggested to add some literature globally and make it more attractive for readers. Specific issue of your study area and finally problem formulation and scope of the research.

I would like to ask to cite to the similar latest publication. I suggest following paper for your guideline.

Gleeson, T., Wada, Y., Bierkens, M. et al. Water balance of global aquifers revealed by groundwater footprint. Nature 488, 197–200 (2012). https://doi.org/10.1038/nature11295

Ahmad, N.; Khan, S.; Ehsan, M.; Rehman, F. U.; Al-Shuhail, A. Estimating the Total Volume of Running Water Bodies Using Geographic Information System (GIS): A Case Study of Peshawar Basin (Pakistan). Sustainability 2022, 14 (7), 1-23. DOI: https://doi.org/10.3390/su14073754.

Dawood, F., Akhtar, M. M., & Ehsan, M. (2021). Evaluating urbanization impact on stressed aquifer of Quetta Valley, Pakistan. DESALINATION AND WATER TREATMENT, 222, 103-113.

Sohail, M. T.; Hussan, A.; Ehsan, M.; Al-Ansari, N.; Akhter, M. M.; Manzoor, Z.; Elbeltagi, A. Groundwater budgeting of Nari and Gaj formations and groundwater mapping of Karachi, Pakistan. Applied Water Science 2022, 12, 1-24. DOI: 10.1007/s13201-022-01795-0.

Authors response: The introduction section was modified to clearly explain the overall picture of the paper (Pages 1-3).

Reviewer comment 2:Line 84 after that this line it is suggested to write a paragraph about your overall work cover letter.

Authors response: A paragraph about the overall work cover letter was added (Lines 106-108  ; Page 3).

1.1. Site description and Hydrogeological Setting of El-Qaa Plain Aquifer System

Reviewer comment 3:Geology and Tectonics, did the authors study the influence of tectonics in groundwater in the study area?

Authors‘ response: the structural setting of El Qaa plain area are discussed in lines 169-172 Page 5 with references.

Reviewer comment 4:Figures 1-3 are good, but this discussion is very poorly written. It is suggested to write some discussion which describes your figures.

Authors‘ response: Additional disscussion was added (Lines  131-140 Pages 3&4).

2. Materials and Methods

Reviewer comment 5:This section needs cosmetic editing. The aspect should ne arranged like this, data acquisition, data processing, and data interpretation.

Authors‘ response: This section was arranged (Page 7).

2.2. Data sources

Reviewer comment 6:This section needs to revise in the true spirit of scientific writing. It is very important to clearly citation of data sources. So, It is suggested to provide a proper weblink where you got this data set.

Authors‘ response: The dateset of the present article were collected in the field and from un-published and published articles or reports (not a web-based), whereas the other web-based materials (i.e. satellite images) were presented. However, a new table  (Table 1) was added  to describe the used dataset. (Page 8).

3. Results and discussions

Reviewer comment 7: Fig 5 has poor quality and resolution, filled with many things that make it confusing. A spatial representation of the results is needed. The discussion needs to be revised using the implementation of the result.

Authors‘ response: The resolution of Fig. 5 was enhanced (Page 11). The Piper diagram is used to demonstrate the hydrochemical facies and genesis of groundwater depending on the prevailing cations and anions in groundwater. So, it is a comperhensive diagram that compensate the use of many other spatial maps or diagrams.

Figure 9. a) Conceptual (schematic) Cross-section of El-Qaa Plain (after [26]) ; b) Model grids show-409 ing rows, columns, active and inactive cells; c) Model boundary conditions.

Reviewer comment 8:On what basis did you develop figures 9 b and c. How you calibrate your results.

Authors‘ response: These figures were developed according to the geological and hydrogeological setting of the study area. The active cells represent the investigated aquifer system, which is represented by the Quaternary water-bearing deposits, while the inactive cells represent the impervious boundaries of the eastern basement rocks and the western rocks of Mountain Qabaliat.  (lines 454-456; Page 16). The model was calibrated with the observed and measured records of drilled obervation wells.

Reviewer comment 9:Comment Authors should make a comparative analysis of regional countries and present the effective solution that is vital to cater to such situations.

Authors‘ response: A paragraph was added to indicate the globality of the methods used to solve the objectives of the present work; with references (Lines 425-430; Page 15)

Reviewer comment 10:Line 435 Model Calibration

This section looks like a lab manual report. It is suggested to reshape scientific papers.

Authors‘ response: The general information and basic knowledge paragraph was deleted. (Lines 509-523;Page  18 ).

Figure 10. a) Aquifer simulated piezometric heads; b) Directions of groundwater flow; c) Piezometric heads of observed wells and those of the piezometric heads calculated in their locations for the simulated model with RMS calculations.

Reviewer comment 11:Figure 10 c, the data point is very limited, it is suggested to add some more data points to validate your results.

Authors‘ response: These points represent actually observation wells in the study area.

Line 473 Selection and Testing Scenarios

Reviewer comment 12:It is very confusing for the reader, it is suggested to make it more clear on what basis you design Testing Scenarios.

Authors‘ response: A paragraph was added to discuss the basis on which the testing scenarios were designed (Lines558-563; Pages 20-21).

4. Conclusions

Reviewer comment 13:It is suggested to remove your results from this section. This section should be precise and represents your key finding.

Authors‘ response: The conclusion was rewritten and enhanced according to the reviewer comment (pages 23-24). Thanks to fruitful comment of the reviewer.

Round 2

Reviewer 2 Report

Dear Authors,

The paper has improved, however I still find that there is a loose connection between the modelling and hydrochemical activities.

Reviewer 3 Report

The authors carefully address my comments.