Research on Spatial–Temporal Characteristics and Driving Factors of Urban Development Intensity for Pearl River Delta Region Based on Geodetector

Round 1

Reviewer 1 Report

The paper analyzes the evolution of urban areas in the Pearl River Delta to characterize the urban intensity, and to identify the main driving forces under its expansion. The results are aimed to inform public policies.

Methodology and concpets

The paper explains clearly the methodology, but refers once and again to concepts that are not defined, and might generate confusion. I.e L60 what do you mean by " revealing the development laws of the region" L92  strongest comprehensive strength. What does this mean?

secondary and tertiary industries. Do you refer to secondary and tertiary econcomic sectors? Tertiary is services?

My main concerns are related to the use of indicators.

- L121. First of all "development intensity" is expressed in % (urban surface/total surface). In my opinion this does not properly reflect the idea of intensity, which in physics should include time (new urban areas developed per year, per decade...).

- L124 surface refers to land use, but when dealing with intensity the z axis it is also important. m2 Constructed, not only the m2 occupied by urban uses.

-   I recommed the authors to include usual indicators that help to the  understanding of urban expansion and population concentration processes, such as density (i.e, evolution of inhabitant/km2 urban area, as well as m2 urban area per capita). It is problematic that no data about population is provided at all , size, increase, what comes first urban development or inmigration, etc.

Results

Another concern relates to the identification of drivers. Factors such as population and urban expansion are of course related. And the paper states that population is the driver, whereas in other researches the conclusion is that urbanization together with economic strenghts are the drivers attracting new populations.

L256 Please could you include references supporting your statement "According to international practice, a region's land development intensity reaches 30% is already a warning line."

L284-285 The overall development intensity has also greatly improved. This assertion does not correlate well with the results.

I woul suggest to move the interpretation of results to the discussion section. And much of these interpretations are not justified. i.e. L235 "the increase in grassland area showed that people’s awareness of environmental protection has gradually increased" how did you come to this conclusion?

Discussion

I also suggest to review the discussion section, as it introduces prescriptions which are not deducible from the results. I.e -515 "it is necessary to accelerate the transformation of industrial structure". 

Or "narrowing the gap between rich and poor," I agree, but it is strange that no previous reference to disparity is found in the paper 

Finally , I would also suggest to explain the planning context. Throughout the paper it seems that the urban evolution is "spontaneous" or derived from the eocnomic, demographic (and geographical) situation. Only at the end the reader gets to know that there is legislation and plans that shape the urbanization. It deserves more importance, and it should be explained at the beginning..  

English language is appropiate, although a final review by native speaker would be appreciated.

Author Response

Dear Reviewer 1:

We are very grateful for your comments. We revised the manuscript in accordance with your advice carefully. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The article deals comprehensively with the quantitative aspects that have regulated the development of an important area in southern China. the research is well structured and the methodology is well described, articulated, and documented.

in order to add value to the article, I think it would be useful to link the urban development of the region under study to qualitative aspects. namely it will be interesting to link the theme of urban development to the socio-economic dynamics mentioned in Chapter 4.1.

I think it is interesting to correlate the theme of variations in land use also to demographic trends that have occurred in the area and mainly to the urban policies of the creation of public value that underlie the dynamics. 

To this end, it may be useful to take as a reference the results of the Cost action PuVaCa: "public value capture of increasing property values". 

these topics can be useful to deepen what is specified in the discussions and can be food for thought to be included in the concluding chapter in order to define possible future developments of research. 

Author Response

Dear Reviewer 2:

We are very grateful for your comments. We revised the manuscript in accordance with your advice carefully. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper has substantially been improved.