Analysis of Optimal Sensor Placement in Looped Water Distribution Networks Using Different Water Quality Models
Round 1
Reviewer 1 Report
GENERAL COMMENTS
The manuscript presents the results of comparison of use of three different models for determining the optimal placement of sensors in drinking water distribution systems. The comparison results are a useful contribution to the growing literature on strategies for placement of sensors in drinking water distribution systems. In my view, the manuscript will be acceptable for publication after revisions to address some issues of misplaced emphases.
SPECIFIC COMMENTS
1. Title: The main contribution of the work is in the comparison of the three different modeling approaches. This is not conveyed in the current title, which focuses on "impacts of water quality modelling simplifications." I suggest that the title be modified to replace this phrase and make more clear the focus on comparison of three models.
2. Abstract: Here, and in the Conclusions (bullet 4, lines 306-311), the authors focus on the potential influence of laminar flow in drinking water distribution systems. The occurrence of true laminar flow in such systems is likely to be very limited, and the authors made no measurements in their experimental system to verify the presence of laminar flow. I recommend removing the discussion of the occurrence of laminar flow in the Abstract and Conclusions. While laminar flow is included within the hydraulic range of some of the models employed, whether it actually occurs or not in the system of interest is a secondary issue, it is not addressed in the body of the manuscript, is speculative, and does not merit the attention received in the Abstract and Conclusions.
3. p.2, lines 62-66: Related to comment 2, I suggest removing this text about laminar flow.
4. p.2, line 142: The subsection title is too vague. I suggest "Optimization of Sensor Placement"
5. p.2, line 143: It is not clear what is meant by "the optimization problem." This needs to be explained, specifically, and in the context of the study performed. The explanation provided in lines 156-157 should be brought to the beginning of this subsection.
6. pp.5-6, discussion of EPANET: There is no discussion of the effects of different optimization criteria, which have been examined by some investigators, e.g., Isovitch and VanBriesen, J Water Res Planning Mgmt, 2008. I suggest that there be some discussion of the implications of selection of particular optimization criteria.
7. p.7, line 251: It is not clear what is meant by "optimal configurations." This needs to be more specific; indicate explicitly that placement of sensors is what is being discussed.
8. p.9, line 292: It is not clear what is meant by "the optimization problem". Be more specific and clear.
9. p.9, lines 306-311: As discussed in comment 2, I recommend that this conclusion be modified to remove interpretations indicating the actual presence of laminar flow.
10. p.10, line 320: What was the source of the internal funding?
11. Miscellaneous: In the captions for Figures 1 and 2, I suggest inserting the word "experimental" before "water distribution system"
Author Response
The corrections were highlighted in the attached file and in the track change text (in yellow)
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments for author File: Comments.pdf
Author Response
The detailed responses can be found in the attached file and in the track change text (highlighted in Cyan)
Author Response File: 
Author Response.docx
Round 2
Reviewer 1 Report
The authors have addressed adequately my comments on the original version of the manuscript. I recommend that the manuscript be accepted for publication after some minor revisions.
1) page 3, line 120: The revised language here is awkward. I suggest replacing "paragraphs" with "sections", and inserting "as follows" after "structured" and before the colon.
2) page 5, line 170, and elsewhere: The authors use "optimization" in some places, and "optimisation" in others. The copy editor will point this out also, but I suggest that the authors clean up these discrepancies in preparing the final version of the manuscript. The MDPI editor can provide guidance about which spelling is aligned with MDPI format.
3) page 10, line 352: The meaning of the concluding phrase is unclear. I suggest replacing "as are" with "and". The authors should consider this suggestion and clarify the language according to their intended meaning.
4) page 10, line 353: For improved clarity, replace "parameters" with "parameter values"
Author Response
Response to Reviewer 1 Comments
First of all, we would like to thank Reviewer 1 for very useful remarks and suggestions,
which in our opinion helped much to improve the quality of the paper.
The authors have addressed adequately my comments on the original version of the manuscript. I recommend that the manuscript be accepted for publication after some minor revisions.
1) page 3, line 120: The revised language here is awkward. I suggest replacing "paragraphs" with "sections", and inserting "as follows" after "structured" and before the colon.
Response: Done.
2) page 5, line 170, and elsewhere: The authors use "optimization" in some places, and "optimisation" in others. The copy editor will point this out also, but I suggest that the authors clean up these discrepancies in preparing the final version of the manuscript. The MDPI editor can provide guidance about which spelling is aligned with MDPI format.
Response: The notation "optimisation" has been used throughout the manuscript..
3) page 10, line 352: The meaning of the concluding phrase is unclear. I suggest replacing "as are" with "and". The authors should consider this suggestion and clarify the language according to their intended meaning.
Response: The sentence has been rewritten for clarity.
4) page 10, line 353: For improved clarity, replace "parameters" with "parameter values"
Response: Done.
