Regional Groundwater Flow and Advective Contaminant Transport Modeling in a Typical Hydrogeological Environment of Northern New Jersey

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors used GMS to model groundwater flow and thus contaminant transport, which is of great interest for regional water resource management. The paper is ready for publication after major revision.

1. At the end of this section of the introduction, the authors need to enhance the novelty and research significance narrative of the model.
2. How the authors of the model's source and sink items are set up needs to be clarified.
3. What's a mathematical model?
4. How many observation wells were utilized in the modeling and what is the period of the dynamic data?
5. How are the hydrogeological parameters of the model set? Please mention the parameter partitioning diagram.
6. The identification and validation performed by the model is less expressed in the manuscript, and the authors should add the fitted curves of observed and simulated values of wells to demonstrate the accuracy of the model. This is very important.
7. The authors can conclude the study with some recommendations and measures on groundwater pollution prevention based on the results of the study at the end of the discussion, but not in the conclusion.
8. The conclusion has to be reorganized, which is not in line with the way conclusions are written for academic papers.

Author Response

Thank you very much for taking the time to review this manuscript. Please see attached

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

This is a solid research report with valuable content. However, to meet the standards of an academic paper, several revisions are necessary.

First, the manuscript lacks a clearly defined scientific question. After a thorough read, it feels more like a case study presented in a rather monotonous manner, which makes it difficult to stay engaged.

Second, groundwater simulation appears to be the core of this study. However, the model construction, parameter calibration, and validation processes are not described in sufficient detail. I recommend adding a table summarizing the model parameters along with an analysis of parameter sensitivity to enhance the transparency and scientific rigor of the study.

Third, the formatting of the article requires attention. For instance, in lines 560–567, the use of numbering (1, 2, 3) for subheadings is confusing and should be revised. A similar issue appears in the conclusion section.

Additionally, in line 130, "km2" should be corrected to "km²".

In summary, while this report contains the foundation of strong research, it does not currently meet the expectations of a well-structured academic paper.

Author Response

Thank you very much for taking the time to review this manuscript. Please see attached

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for providing the opportunity to review this manuscript which focuses on using MODFLOW and MODPATH to investigate the transport dynamics of deicing substances within a sedimentary rock formation. Overall, I felt the manuscript was well-written, organized and the study well-developed and assessed. My main concern involves the author’s assumptions in using chloride as a surrogate to understand other substances. As the authors indicate, chloride is a conservative substance. However, it is not completely conservative. Free Cl- may be exchanged with other negatively charged anions if concentration becomes high enough. Chloride may be useful in delineating particle and groundwater pathways, but not useful in understanding the fate of reactive contaminants/substances.

Specific comments:

Abstract

Line 23: I think it would be more accurate to say “confirm chloride in groundwater, that may originate from road salt application, can reach…”

Line 48: What is meant by “get into”? “Infiltrate” may be a better word.

Line 96: How is chloride a good surrogate for certain organic contaminates? Chloride at trace to mid-level concentrations is conservative in aqueous systems, while organic substances, at any level, are non-conservative.

Page 7: I assume the authors manually calibrated the MOD models? Autocalibration? State whichever method was used.

Figes 5 and 6: Why not just show Figure 6? Figure 6 appears to be a more complete rendering of the flow paths.

Line 458: I suggest saying “after a period of time (see details below)”

Page 13: Did the authors release any chloride substances into groundwater and monitor well concentrations to confirm the chloride model output?

Lines 523-524: What does this statement mean? Do you mean that any sort of point or non-point discharges or precipitation that falls or originates from MSU will not contribute to recharge in the municipal wells?

Author Response

Thank you very much for taking the time to review this manuscript. Please see attached

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

 Accept in present form

Reviewer 2 Report

Comments and Suggestions for Authors

No further comments.