Review Reports

Round 1

Reviewer 1 Report

The submitted manuscript analyzes the patterns of urban expansion (as derived from land use land cover data) in the Yangtze River Delta Urban Area from mid 1990s to 2018 by using different indices. The proposed analysis looks interesting, although some improvements are needed in the methodology. Indeed, it is not totally clear to me the distinction between build-up land expansion and landscape patterns (ll. 114-116). I found this classification quite confusing (especially Figure 3, which shows a flowchart, where the meaning of horizontal arrows is not clear to me. Also, why is there an arrow connecting the spatial autocorr analysis with the speed of urban expansion?). As a personal view point, I would suggest to simply list the variables your are using in the forthcoming analysis and not distinguish between build-up areas and landscape patterns, since, I suppose, you assess landscape patterns based only on built-up areas.

Furthermore, is there any difference between U_i (total area in epoch i - I suppose total URBAN area -- if this is the case, please update the manuscript) and ULA_i (urban land-use area)?

Did you define a threshold to identify urban patches (i.e. minimum number of built-up grid cells at 30m resolution)?

When you focus on landscape indices, you state in ll. 155-156 that you consider 2 characteristics: class and landscape? Could you please provide further details about this? What is the difference between class and landscape? Then, when you describe Moran's I you should contextualize the meaning of variables n, x_i to the ones cited before. Also, how did  you compute values for weights w_ij? Finally, how does Lagged UESI is computed (see Figure 5)? I totally miss this information from the manuscript. Given all my above listed requests/comments, at this stage I cannot provide additional comments related to Figure 6 (where a counterintuitive choice of colors is shown, being in contrast with Figure 7) and Figure 7.

Also, I believe there could be a major flaw in the analysis in relation to section 3.3. All the comments provided therein are related to the selection of classes in each sub-period. However, given the selected classification and the associated colors, it is not possible to compare results across different epochs. I would suggest to define classes in a unique manner (i.e. same ranges across time periods).

Given all this comments, I would suggest a depth revision of the submitted manuscript.

Minor issues:

l. 95: please refer to Table A1

l. 192: maybe "peak-to-peak". I do not understand what "peak-thorugh-peak" means.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

You can find comments in the attached file.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

the work is not groundbreaking from a scientific point of view. the monologue is an application of methodology commonly used in these topics. 
I have included some comments in the pdf file. 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 4 Report

The problem of urban sprawl is one of the most important research topics today. These studies can be of great interest for planning sustainable urban development. The article is very well organized and presents very important results for urban research.

However, we feel that the “Introduction” (section 1.) should be developed further. One of the urban problems with the greatest impact is the urbanization of coastal areas, namely the very dense urbanization that causes great environmental pressure. There are many studies, both analytical and methodological, that prove the evidence for this information. For this reason we feel that these references should be made to improve the Introduction:

1 - https://www.sciencedirect.com/science/article/pii/S0048969719300452 (Understanding urban expansion combining macro patterns and micro dynamics in three Southeast Asian megacities)

2 - https://www.sciencedirect.com/science/article/pii/S0048969719304875 (Urban land expansion in China's six megacities from 1978 to 2015)

3 - Magarotto, M.G., da Costa, M.F., Tenedório, J.A. et al. Vertical growth in a coastal city: an analysis of Boa Viagem (Recife, Brazil). J Coast Conserv 20, 31–42 (2016). https://doi.org/10.1007/s11852-015-0415-7

4 - Tenedório, J. A., Rebelo, C., Estanqueiro, R., Henriques, C. D., Marques, L., & Gonçalves, J. A. (2014). New Developments in Geographical Information Technology for Urban and Spatial Planning. In N. Pinto, J. Tenedório, A. Antunes, & J. Cladera (Ed.), Technologies for Urban and Spatial Planning: Virtual Cities and Territories (pp. 196-227). IGI Global. http://doi:10.4018/978-1-4666-4349-9.ch010

5 – https://www.sciencedirect.com/science/article/pii/S0143622818302054 (Spatio-temporal analysis on built-up land expansion and population growth in the Yangtze River Delta Region, China: From a coordination perspective)

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I am satisfied with the revised version. The paper can be accepted for publication

Reviewer 3 Report

With the modifications you make, the work is more readable. 

Reviewer 4 Report

Very good job of improving the article. Congratulations.