On Physical Urban Boundaries, Urban Sprawl, and Compactness Measurement: A Case Study of the Wen-Tai Region, China
Round 1
Reviewer 1 Report
The authors provide a new assessment of urban sprawl in the Wen-Tai region of China. Overall, I think the authors' emphasis on the importance of scale in the analysis of urban sprawl is very appropriate. The issue of scale is a significant challenge in many studies of urban growth and urban sprawl. I had a few minor comments on the paper. In the opening sentence of the paper, the authors state that urbanization is the main driver for economic growth in China. I'm not sure this is accurate, as urbanization usually develops symbiotically with economic development. What is the source of this observation? To me, I think there are many drivers of economic growth in China. With that in mind, I don't think this is a critical aspect of the paper, so I would suggest revising the sentence to state that urban development and urban sprawl in China has increased in concert with China's economic boom (or something similar). I feel the sentence is there to set context for the paper, as opposed to making an observation about the nature of urbanization in China.
Second, on page 4, line 26, you state there are 106 megacities in China. You do not define megacities in your study. Megacities are generally understood as cities with a population greater than 10 million. From a quick search, most people put the number of megacities at less than 40 in the world. If you are using a different criteria, that is critical to your research, I would suggest you include that in your discussion. However, I was the author, I would use a term other than "megacity" to avoid any confusion.
Finally, I would proofread the paper prior to your next submission. You have some stylistic issues, primarily from some questionable word choices throughout the paper. For example, on page two, line 12-13, you mention the proportion of built up area is "usually poor." I'm not sure what "poor" means here. Is it of a lower quality of construction? A lower value? I would have someone read your paper and identify the word choices that impact readability. I also think my concerns with the relationship between economic development and urban sprawl, and megacities, is primarily a word choice issue, as opposed to anything substantive.
Overall, I think you have a solid literature review that situates your paper and identifies a gap in the literature you hope to address. Your methods are appropriate to your research question and your results logically flow from your methods. I enjoyed your manuscript and I think it is an important topic. I would suggest you spend some time addressing readability and word choice to make the article more accessible to future readers. Thank you for the opportunity to review the article. I really enjoyed your research.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors
Thanks for submitting this paper for evaluation and possible publication.
The maps are lack of coordinate systems, no lat-long represented in any of the maps you have shown in the manuscript. Please replace all figures, after placing coordinate in each figure, without this maps are meaningless.
rest are fine to me.
Decision: The paper can be accept after minor correction.
Thanks and good luck
Reviewer
Date: 09 Sep 2022, Time: 8.45PM
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The paper describes some methods for measuring urban sprawl and uses them to study the urban development of the region of Wen-Tai, China.
The work is well written and the analysis quite detailed.
The conclusions also appear to be quite interesting and potentially useful for further analysis.
On the other hand, the methodology is not very clear, which in my opinion should be better explained with examples. In particular as regards the formulas (although well known) of section 4.3.
For example, the RI index could be better explained with a simple geometric example of the type shown in the attached file, where A = 4 in the three cases and P is 4, 10 and 16 respectively. The same for the other indices. With elementary examples it is also possible to better explain the ranges of the indices and its urban sense.
A great effort is currently underway to determine a common methodology for measuring the spatial dispersion of cities and this paper can be a good contribution to the discussion.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I want to thank the authors for their revisions on this paper. I think this version of the paper is much easier to read. I think the authors do a fine job developing a method of defining urban sprawl that moves beyond traditional methods of administratively defining urban settlements. This is especially important in regions with urban sprawl. Overall, I think the authors do a fine job situating the research in the larger academic community. The methods logically follow from the gap in the literature the authors define. The conclusions logically flow from the discussion and add to the academic discourse.
Overall, I think the paper is well written and adds to the academic discourse. Thank you for the opportunity to review the paper. I enjoyed the paper. Best of luck in the future.
Author Response
The co-authors and I would like to thank you for your enjoyment. We are honored to receive your high approval of our paper. Have a nice day.
Best regards.
