Identification of Metropolitan Area Boundaries Based on Comprehensive Spatial Linkages of Cities: A Case Study of the Beijing–Tianjin–Hebei Region

Round 1

Reviewer 1 Report

The study of Identification of Metropolitan Area Boundaries Based on Comprehensive Spatial Linkages of Cities plays an important role in the development of the new-type urbanization in China. Beijing-Tianjin-Hebei region is becoming one of the important battlefields with the remarkable improvement of China's socio-economic. The topic of the manuscript has important practical significance. Nevertheless, there are still certain uncertainties that need they clarify. Some recommendations for improving the detailing of the manuscript are as follows:

 

1. The discussion part needs to be further deepened, such as highlighting the impact of the identification of metropolitan areas on the coordinated development of Beijing-Tianjin-Hebei.

2. It is recommended to label the city locations in Figure 8, Figure 9 and Figure13 to better reflect the results of each section.

3. The author pointed out that the goal of this manuscript is to explore a universal identification method of metropolitan area, but this paper only uses the Beijing-Tianjin-Hebei region as a test area for verification. How to ensure the applicability of the method in other regions? And in the application of this method in different regions, are there parameters and indicators that can be adjusted or changed? please explain.

4. In the second paragraph of 4.3.3, the author pointed out that "but the two centers around more peripheral cities at present have not yet reflected its role as central city radiation drive.", and the last sentence said "Apart from the JingJinLang metropolitan area, which was in the mature stage of development, the other metropolitan areas were in the initial phases of development.”. Are these two sentences inconsistent? Please explain the basis for judging the "mature stage" of the development of the metropolitan area.

5. There are grammatical errors in the manuscript, please check and revise the manuscript thoroughly.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper proposes an effective empirical method to identify metropolitan area boundaries based on spatial network data. This work is very interesting, and I am willing to recommend the article’s publication. However, I have some concerns I believe the authors should address.

1) The proposed method is validated by comparing the resulting metropolitan areas with those identified by the isochrone map. Therefore, this validation strategy implicitly assumes that the isochrone map provides the true and objective representation of the metropolitan areas’ boundaries. I think the authors should justify and explain this assumption. In other words, it should be clarified why the comparison with the isochrone map is the proper way to validate the results.
However, if the isochrone map method delineates the actual “true” metropolitan areas, why cannot we simply use such a method instead of introducing a new, apparently less objective approach. If the authors argue that the isochrone map is the best way to identify metropolitan areas, what is the usefulness of the proposed approach?           

2) The results are obtained considering the data of a specific region of China (the Beijing-Tianjin-Hebei region) while ignoring the data about the neighboring regions. This implies that selection bias may potentially affect the results due to border effects. Is it possible to check if the results are robust to border effects?  

3) While I think this manuscript has excellent value because of the importance and relevance of metropolitan area delineation, it needs to move from a purely exploratory, despite sophisticated, narrative to a framework allowing to test some research hypotheses directly via introducing explicit relationships among variables of interest. Only in this way it is possible to claim some conclusions that will have some substance. I mean, how can the resulting pieces of evidence be of any use? For example, are they beneficial to inform and help economic policymakers? In what way? Do they provide insights into spatial economics, economic geography, or regional science theories? I think the authors should make some efforts in this direction.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The article approaches the issue of metropolitan area boundaries based on comprehensive spatial linkages of cities.

The abstract should include more simple phrases, with clear messages. In addition, it is not clearly stated the problem addressed by this work.

The approach of the analyzed topic should be more internationalized. There are too many references from China. 

Which are the steps followed in the article for reaching the article objectives? Please add some paragraphs at the end of Introduction section.

Please provide more explanations on the relevance of figure 3.

Please improve the quality of figure 9.

Please improve the quality of figure 10 and provide more explanations on the links provided there.

Please check the reference list since many of them are not following the MDPI rules.

Overall this is a very well written article. The methodology is adequately described as well as are the results.

More explanations should be provided on the relevance of this work and on the practical applicability.

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The Authors have done a good job in revising the paper according to all my previous comments. I have no further comments.