Review Reports

Round 1

Reviewer 1 Report

COMMENTS TO THE AUTHOR(S)

This study examined the “Assessment of Pleistocene Aquifer Vulnerability to Saline Intrusion in the Coastal Region of Ba Ria – Vung Tau Province using GIS and Entropy-GALDIT”. Given that saline intrusion to aquifer can effect water quality, this paper is timely and could offer new insights in the mentioned area. The manuscript is generally well written and easy to understand. I suggest that the authors revise the manuscript incorporating the following comments and suggestions into an updated version.

·         On what basis the authors selected chloride (Cl-), bicarbonate (HCO3-), carbonate (CO32-), and total dissolved solids (TDS) to assess saline water intrusion in aquifer. Are these the most important parameters for salinity assessment?

·         There are several techniques available in Arc GIS for spatial interpolation like kriging, IDW etc. On what basis the authors selected IDW technique for spatial interpolation in this research work?

·         The authors didn’t assess statistically that which technique (GALDIT or Entropy – weighted GALDIT) gives better results in the study region and why?

Dear Editor,

Minor corrections are required in the article.

Regards,

Dr. Afed

Author Response

Comment 1: On what basis the authors selected chloride (Cl^-), bicarbonate (HCO₃^-), carbonate (CO₃^2-), and total dissolved solids (TDS) to assess saline water intrusion in aquifer. Are these the most important parameters for salinity assessment?

Response: We have revised the manuscript by adding the basis of parameter selection to assess saltwater intrusion according to the reviewers' comments and at the same time added the References section.

Comment 2: There are several techniques available in Arc GIS for spatial interpolation like kriging, IDW etc. On what basis the authors selected IDW technique for spatial interpolation in this research work?

Response: Many thanks to the reviewer for the suggestion. Therefore, we have explained the reason for using the IDW interpolation algorithm in ArcGIS in this study on page 6 lines 196-198.

Comment 3: The authors didn’t assess statistically that which technique (GALDIT or Entropy – weighted GALDIT) gives better results in the study region and why?

Response: We have revised it according to the reviewers' comments in the Discussion and Conclusions section.

Reviewer 2 Report

I congratulate the authors because the great majority of the references are recent but the bibliographical reference is too short, just 22 references

Page 1 Line 32-33: Seawater intrusion into 32 groundwater has been observed in coastal areas around the world [2], it will be better to give more references

Page 2 Line 51: DRASTIC must be defined

Page 2 Line 52 TDS must be defined here not on page 4 line 130

 

Author Response

Comment 1: I congratulate the authors because the great majority of the references are recent but the bibliographical reference is too short, just 22 references.

Response: We agree with the reviewer. Therefore, we added the references at necessary places and at the same time revised the References section.

Comment 2: Page 1 Line 32-33: Seawater intrusion into groundwater has been observed in coastal areas around the world [2], it will be better to give more references.

Response: We agree with the reviewer. Therefore, we added more references to the consideration on page 1 line 32-33.

Comment 3: Page 2 Line 51: DRASTIC must be defined.

Response: We have revised it according to the reviewers' comments.

Comment 4: Page 2 Line 52 TDS must be defined here not on page 4 line 130.

Response: We have revised it according to the reviewers' comments.

Reviewer 3 Report

This manuscript proposed a case study to assess the vulnerability of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province, Vietnam by GIS-based Entropy-GALDIT framework. According to the research results, some countermeasures to prevent seawater intrusion were provided. The topic covered by this manuscript is appropriate for Sustainability. The demonstration is thorough, the analyses and the results seem good. Thus, I recommend acceptance for publication. Some minor issues are listed below.

Comments:

(1) in section 2.1, a plane map or a typical cross section is required to illustrate the local hydrogeological conditions, such as aquifer type, brief groundwater flow dynamics.

Author Response

Comment 1: In section 2.1, a plane map or a typical cross section is required to illustrate the local hydrogeological conditions, such as aquifer type, brief groundwater flow dynamics.

Response: Many thanks to the reviewer for the suggestion. Therefore, we have added hydrogeological cross-section according to the reviewers' comments in the section 2.1.

Reviewer 4 Report

This paper assesses the vulnerability of aquifers in the Vietnamese province of Ba Ria-Vung Tau to seawater intrusion using the GALDIT vulnerability assessment. The paper is generally well-written, though there are a number of sections that require modification.

The related work in the Introduction should be reorganized. The different example use cases of the GALDIT model are good to include, but the conclusions from these different studies would better fit in the Discussion section to compare findings against this paper's findings. Additional model alternatives to GALDIT should be mentioned here, as well as more information about when the Entropy-based improvements or AHP improvements would be preferable and why they were applied to this study. Of particular note is that the authors appear to have published a similar study for Phy My Town within this province; the authors should explicitly note what is unique about this study from that one and include its results in the Discussion section.

The Discussion and Conclusion section needs to be revised and edited. The Discussion and Conclusion should utilize research that was mentioned in the Introduction and discuss this study's findings in light of those other studies. The discussion should also further discuss the differences in the vulnerability maps produced by the GALDIT and Entropy-GALDIT methods for the study area (why they're different, why Entropy version might be better, etc.). The authors should also discuss whether the high chloride levels found inland could be the result of causes other than seawater intrusion. The authors appear to have published a similar paper for Phy My Town within this province; the results of that study should be discussed in light with the findings from this study and should also note what is unique about this study from that one.

Smaller edit suggestions:

- apply consistent formatting throughout the paper of spaces between numbers and units (see lines 101 and 104 for examples of differences with km and m) 

- Line 107: check translation of "rich land fund". Does this refer to rich soils?

- Line 118: expand acronym Q2 (presumably second epoch of the Quaternary?) or remove

- Line 126: check translation of chlorur and clorur. Likely chlorine or chloride is what the authors mean?

- Line 237: injury risk level -> presumably should be intrusion risk level?

- Line 320: check translation of lesion partition map; there should not be mentions of lesions in this paper.

- It would be helpful to move Table 2 earlier in the text (or at least reference it), closer to when weights and ratings are discussed near Equation 1 since these are input values to the equation.

- The discussion about entropy-weighting can be clarified further if the authors specify what values m and n correspond to and what "each parameter in the evaluation index" refers to (i.e., "in this study, n = 99 and m = 6" or vice versa if appropriate).

- It would be sufficient to cite the use of the IDW algorithm and remove lines 176-180; in-depth explanation is not necessary beyond noting that IDW was used to interpolate data for continuous landscape coverage.

This paper was generally well-written, but the Discussion and Conclusion section requires rewriting for grammar and content.

Author Response

Comment 1: The related work in the Introduction should be reorganized. The different example use cases of the GALDIT model are good to include, but the conclusions from these different studies would better fit in the Discussion section to compare findings against this paper's findings. Additional model alternatives to GALDIT should be mentioned here, as well as more information about when the Entropy-based improvements or AHP improvements would be preferable and why they were applied to this study. Of particular note is that the authors appear to have published a similar study for Phu My Town within this province; the authors should explicitly note what is unique about this study from that one and include its results in the Discussion section.

Response: We have revised the manuscript by adding the reason for using the Entropy method to calculate the expanded weights, as well as adding various examples of the GALDIT model. Also give comments when modifying weights. Please find our revision in the Introduction section (Pages 2-3/Lines 64-115).

Comment 2: The Discussion and Conclusion section needs to be revised and edited. The Discussion and Conclusion should utilize research that was mentioned in the Introduction and discuss this study's findings in light of those other studies. The discussion should also further discuss the differences in the vulnerability maps produced by the GALDIT and Entropy-GALDIT methods for the study area (why they're different, why Entropy version might be better, etc.). The authors should also discuss whether the high chloride levels found inland could be the result of causes other than seawater intrusion. The authors appear to have published a similar paper for Phu My Town within this province; the results of that study should be discussed in light with the findings from this study and should also note what is unique about this study from that one.

Response: We have revised the manuscript by adding the explanation and clarification of differences in the the map of GALDIT and Entropy-GALDIT methods for the study area. Please find our revision in the Discussion and Conclusions section (Page 13/Lines 368-379).

Comment 3: Apply consistent formatting throughout the paper of spaces between numbers and units (see lines 101 and 104 for examples of differences with km and m)

Response: Many thanks to the reviewer for the suggestion. Therefore, we reformated of spaces between numbers and units throughout the paper.

Comment 4: Line 107: check translation of “rich land fund”. Does this refer to rich soils?

Response: We agree with the reviewer that the translation of “rich land fund” was not correct. We have changed the translation to “diverse soil composition” (Page 3/Line 127).

Comment 5: Line 118: expand acronym Q2 (presumably second epoch of the Quaternary?) or remove

Response: We have revised it according to the reviewers' comments.

Comment 6: check translation of chlorur and clorur. Likely chlorine or chloride is what the authors mean?

Response: Many thanks to the reviewer for the suggestion. Therefore, we checked and changed the translation of of chlorur and clorur throughout the paper.

Comment 7: Line 237: injury risk level → presumably should be intrusion risk level?

Response: Many thanks to the reviewer for the suggestion. We have revised the manuscript from “injury risk level” to “intrusion risk level” (Page 8/Line 270).

Comment 8: Line 320: check translation of lesion partition map; there should not be mentions of lesions in this paper.

Response: The translation of “lesion partition map” were revised according to the reviewers' comments (Page 12/Line 368).

Comment 9: It would be helpful to move Table 2 earlier in the text (or at least reference it), closer to when weights and ratings are discussed near Equation 1 since these are input values to the equation.

Response: We agree with the reviewer that weights and ratings in Table 2 should be discussed near Equation 1. However, we do think our current manuscript is acceptable because we want to reflect both weights with classical and extended method frameworks. We have added the reference in the GALDIT index method (Page 5/Line 164).

Comment 10: The discussion about entropy-weighting can be clarified further if the authors specify what values m and n correspond to and what "each parameter in the evaluation index" refers to (i.e., "in this study, n = 99 and m = 6" or vice versa if appropriate).

Response: Many thanks to the reviewer for the suggestion. Therefore, we have specified the values of m and n that correspond to the values in the calculation. Please find our revision in the Materials and Methods section (Page 5/Lines 176-178).

Comment 11: It would be sufficient to cite the use of the IDW algorithm and remove lines 176-180; in-depth explanation is not necessary beyond noting that IDW was used to interpolate data for continuous landscape coverage

Response: We have re-interpreted the purpose of using the IDW interpolation algorithm and do not in-depth explain according to the reviewers' comments. Please find our revision in the Materials and Methods section (Page 6/Lines 196-198).