Simulating Uneven Urban Spatial Expansion under Various Land Protection Strategies: Case Study on Southern Jiangsu Urban Agglomeration
Round 1
Reviewer 1 Report
The article ‘Simulating uneven urban spatial expansion under various land protection strategies: Case study on Southern Jiangsu Urban Agglomeration’ deals with the application of the Minimum Cumulative Resistance (MCR) model to assess the urban spatial expansion (USE). The Southern Jiangsu Urban Agglomeration (SJUA), eastern China, was provided as case study.
I read with interest this paper that provide a research worth of interest to consider for publication in the International Journal of Geo-Information. I consider it publishable after providing the revisions detailed in the following rows and that I consider as major ones.
General comments
In the abstract, no quantitative information concerning the obtained results was provided. Moreover, it not explained what is the contribution, the focus of the proposed research article. The Author must provide this information.
I appreciated the problem statement provided in the introduction section. By the way, I also suggest to consider the issue of urban-rural gradient structure in discussing about the urban spatial expansion.
The methodology is clearly explained. Nevertheless, some concepts such as proportion of water (POW), traffic advantage (TA) need a clarification. In other words, it must be clarified what these concepts state for and how the referring data are obtained and processed. Furthermore, concerning the base data used in implementing the model, it is mandatory to provide information on metadata (DEM, Land use, population density, etc.).
In the results section, four different scenarios are analysed. Anyway, in the methodology section the authors should provide a sub-section in which he explains how this scenarios are modelled.
To improve the conclusion section I suggest to add something about the model pros and cons. In the same way, it could be useful to delineate expected or potential future directions.
Technical issues
Along the paper, the author refer with plural (e.g., we first conduct, we chose, etc…). Actually, the Author is just one, thus I whether suggest to use the neutral form or to rewrite these sentences.
Lines 44-45: What does the Author means in the following sentence ‘It has been researched in this regard at international [6], national [7], and regional scales [8,9]’? I suggest to rewrite it.
Line 178 and following: in explaining the land use suitability evaluation. From a methodological point of view, Land Suitability Evaluation (LSE) is a method for assessing the suitability of an area for a specific land use and is based on the explicit identification of constraints and opportunities (e.g., doi: 10.4018/ijaeis.2014070101,doi: 10.1016/j.compag.2013.07.006). Moreover, along the paper and in figure captions (e.g., fig. 4), the Author simply refer to land use suitability. Suitability for what? It must be explained that we are referring to land use suitability for new urbanization.
Author Response
Response to Reviewer #1
Comment 1:
I read with interest this paper that provide a research worth of interest to consider for publication in the International Journal of Geo-Information. I consider it publishable after providing the revisions detailed in the following rows and that I consider as major ones.
Response:
We thank you for your approval! We made detailed modifications in the revised manuscript considering all comments from four reviewers.
Comment 2:
In the abstract, no quantitative information concerning the obtained results was provided. Moreover, it not explained what is the contribution, the focus of the proposed research article. The Author must provide this information.
Response:
Thank you for your comment. We agreed that the original abstract is weak in highlight main results and contributions, and then rewrote it. We added main quantitative information concerning the obtained results, and also brief contributions, the research issues and conclusions (P1, L11-32).
The detailed content is: The urban spatial expansion (USE) is an uneven process affected by various natural and human factors, and land use regulation policies are of significance. To indicate the potential effects of different policies at the regional scale and then improving them under the context of increasing emphasis on land protection, we take Southern Jiangsu Urban Agglomeration (SJUA) in eastern China as a case study. Based on regional scale USE simulation with Minimum Cumulative Resistance (MCR) model under four scenarios considering major land use regulation policies including arable and ecological lands protection, we analyze spatial differentiation of newly added urban construction lands and examine the effect on regional urban system with fractal analysis. Results indicate the allocations of newly added urban lands differ by scenario as well as total expansion amount, and larger cities tend to grow faster basically. The share of four largest cities (Suzhou, Nanjing(S), Wuxi, and Changzhou) is mostly higher than 40%. Accordingly, the final area of all cities is linearly corrected with their extant sizes in 2010. However, the differentiated allocations of newly added urban lands related to both increasing expansion amounts and different scenarios cause differences in said linear relationship and also urban rank-size in different degree. It is concluded that land protection strategies do not induce dramatic changes to the basic structures of regional urban system, but they are slightly different when dissimilar land protection strategies are considered. The spatial distribution of protected lands is significant in terms of the differentiation of both the predicted expanding amount of different cities and the regional urban systems. It is of importance to optimize the spatial distribution of protected lands to properly regulate regional scale USE pattern and also urban system.
Comment 3:
I appreciated the problem statement provided in the introduction section.
Response:
We thank you for your approval!
Comment 4:
I suggest to consider the issue of urban-rural gradient structure in discussing about the urban spatial expansion.
Response:
Thank you for your comment. As the focus of this research is the spatial expansion of urban construction lands, and urban-rural gradient is mostly adopted to analyze the patterns and changes of landscape/ecosystem/land cover structure caused by land urbanization, the issue of urban-rural gradient structure is of low relationship with the main research topic. However, we still added some references related which analyzing the effect of urban spatial expansion (P2, L49-50). More issue about urban-rural structure will be considered when effects of urban expansion are analyzed along this gradient.
Comment 5:
The methodology is clearly explained.
Response:
We thank you for your approval!
Comment 6:
Some concepts such as proportion of water (POW), traffic advantage (TA) need a clarification. In other words, it must be clarified what these concepts state for and how the referring data are obtained and processed.
Response:
Thank you for your comment. We added the detailed meaning of the concepts, and also clarified how the referring data are obtained and processed by providing data sources, classification standard and related references (P6, L224-249).
Comment 7:
Concerning the base data used in implementing the model, it is mandatory to provide information on metadata (DEM, Land use, population density, etc.).
Response:
Thank you for your comment. Similar with Comment 6, we expanded original part concerning the meaning of selected indicators, and also their assessing process and classification standard (P6, L224-249).
Comment 8:
In the results section, four different scenarios are analysed. Anyway, in the methodology section the authors should provide a sub-section in which he explains how this scenarios are modelled.
Response:
Thank you for your comment. We added a sub-section to explain how multi-scenario USE were realized and how the USE amount and urban area of different cities were calculated (See 2.2.3 Calculation of USE amount and urban area of different cities; P8, L292-310).
Comment 9:
To improve the conclusion section I suggest to add something about the model pros and cons. In the same way, it could be useful to delineate expected or potential future directions..
Response:
Thank you for your comment. We added something contents about the model pros (P17, L563-571) and cons (P19, L663-669).
The detailed pros are as follows: The MCR model is feasible as its convenience in dealing with other expanding scenarios. In this research, the edge-expansion of original urban patches has been predominant [80], which is also the common phenomenon in other regions – especially flatlands, which have relatively few topographical limitations [81]. However, some newly added and relatively isolated urban patches might appear during rapid urbanization. The MCR model provides the convenience of adding urban patches to the “sources”, which would expand with other cities. Moreover, if more restricted lands are not allowed to be occupied by urban expansion, it is easy to erase them from the resistance surface, or assign them significantly higher resistance value to build barriers for urban expansion.
The detailed cons are listed as the limitation in the CONCLUSION: However, there are still some limitations in our research. The first one is related with the design of resistance surface with resistance value 1 - 9. Although the assignment is relatively rational, it is still lack of scientific inadequacy. More practical expanding process should be analyzed to detect more explicit resistance values. Secondly, regional scale expansion is a complicated process of a group of cities, and their interactions should be considered through the modification of MCR model.
Comment 10:
Along the paper, the author refer with plural (e.g., we first conduct, we chose, etc…). Actually, the Author is just one, thus I whether suggest to use the neutral form or to rewrite these sentences.
Response:
Thank you for your comment. As another contributor was added as the Corresponding author, we kept the plural form in the revised manuscript.
Comment 11:
Lines 44-45: What does the Author means in the following sentence ‘It has been researched in this regard at international [6], national [7], and regional scales [8,9]’? I suggest to rewrite it.
Response:
Thank you for your comment. Actually, we meant that “Related researches (on the uneven USE) have been carried out at international, national, and regional scales.” We changed it to make it clearer (P2, L68-69).
Comment 12:
Line 178 and following: in explaining the land use suitability evaluation. From a methodological point of view, Land Suitability Evaluation (LSE) is a method for assessing the suitability of an area for a specific land use and is based on the explicit identification of constraints and opportunities (e.g., doi: 10.4018/ijaeis.2014070101, doi: 10.1016/j.compag.2013.07.006). Moreover, along the paper and in figure captions (e.g., fig. 4), the Author simply refer to land use suitability. Suitability for what? It must be explained that we are referring to land use suitability for new urbanization.
Response:
Thank you for your comment. We expanded this part and explained that Suitability here refers to land use suitability for land urbanization. We added more content in this part, i.e. The LUS Evaluation is a method for assessing the suitability of an area for a specific land use and is based on the explicit identification of constraints and opportunities for the conservation and future development of the territory [54-56]. In this research, it refers to the suitability of an area for land urbanization, and also indicates the suitability for transform into construction land (P6, L211-215).
Reviewer 2 Report
The following comments and suggestions, arranged according to the sections of the manuscript, should be addressed to improve the quality of the paper
Introduction
Lines 35-36: There is a need for the author to provide some empirical evidence of the extent of urban spatial expansion (USE) in the world or in Asia. For example, the paper cited by the author (Seto et al., 2011) reported a global increase in urban land area by about 58,000 km2 or 9% between 1970 to 2000.
L39-40: the author mentioned early studies but cited only one study. L45: Why are developing countries of “particular concern” recently? This study would benefit from acknowledging the following projection according to the World Development Indicators 2016: “About 90% of the estimated growth in the global urban population between 2014 and 2050 (about 2.5 billion people) will happen in Asia and Africa alone.
The major limitation of the section is it lacks the theoretical foundation of the discussed issue (USE). For example, the urban growth machine, growth pole theory and/or urbanization theory (natural population increase and migration) can be used to explain why the USE phenomenon occurs.
Study Area and methodology
L141: There is a need to acknowledge that USE is not only a physical process but also socioeconomic.
L173: Which version of ArcGIS software was used? The use of the phrase “urban development land” instead of “urban construction land” is more suitable as it is more encompassing.
The methodology section should convince the reviewer that the selected method has comparative advantages over the existing methods for the study area.
Results
What have you found that is new or expected?
There is also a need to relate the findings to the research questions raised in the introduction section.
Discussion
The authors have nicely discussed some policy implications.
However, what is the justification for concentrating the discussion on mainly China?
How does the present study compare with prior studies outside China and the likely explanations?
Conclusion
Are the results generalizable, that is, can they be applied more broadly?
What are the limitations of the study and directions for future research?
Author Response
Response to Reviewer #2
Comment 1:
The following comments and suggestions, arranged according to the sections of the manuscript, should be addressed to improve the quality of the paper.
Response:
We thank you for your careful review on our manuscript, and made detailed modifications in the revised manuscript.
Comment 2:
Lines 35-36: There is a need for the author to provide some empirical evidence of the extent of urban spatial expansion (USE) in the world or in Asia. For example, the paper cited by the author (Seto et al., 2011) reported a global increase in urban land area by about 58,000 km2 or 9% between 1970 to 2000.
Response:
Thank you for your comments. We added more detailed results about the USE in the world and in Asia, i.e. The urban land area is reported to increase by 58,000 km2 or 9% from 1970 to 2000 globally [2]. The developing countries and regions are of increasing share, and China is a typical case with unprecedented urbanization where developed land increased from 13,148 km2 to 35,633 km2 during the period from 1990 to 2012 [3]. Among which, urban agglomerations or megacities expand faster in both developed and developing countries [4]. Six Chinese megacities (i.e. Shenzhen, Guangzhou, Chongqing, Shanghai, Tianjin and Beijing) have all undergone extensive physical expansion from 1978 to 2018, and their annual growth rates are 11.02%, 8.07%, 5.80%, 5.37%, 4.56% and 3.46%, respectively [5] (P1-2, L37-46).
Comment 3:
L39-40: the author mentioned early studies but cited only one study.
Response:
Thank you for your comment. We added more literatures here (P2, L49-50).
Comment 4:
L45: Why are developing countries of “particular concern” recently? This study would benefit from acknowledging the following projection according to the World Development Indicators 2016: “About 90% of the estimated growth in the global urban population between 2014 and 2050 (about 2.5 billion people) will happen in Asia and Africa alone.
Response:
Thank you for your comment and instructions. We made modification according to your suggestion, i.e. Developing countries have been of particular concern as most USE and population growth in recent decades happen there [20], and Asia and Africa alone are estimated to dominate the future growth of the global urban population between 2014 and 2050 [21]. Moreover, the uneven USE is related with the inequality of regional development and human life that need to be emphasized [22] (P2, L69-73).
Comment 5:
The major limitation of the section is it lacks the theoretical foundation of the discussed issue (USE). For example, the urban growth machine, growth pole theory and/or urbanization theory (natural population increase and migration) can be used to explain why the USE phenomenon occurs.
We added some researches and also related theories.
Response:
Thank you for your comment. It is obviously the theoretical foundation of the discussed issue, and we added one paragraph to discuss related theories including what you pointed out in your comments. This paragraph is listed as follows:
As a geographical and socioeconomic process, the USE is inherently uneven due to the different location and uneven opportunities [6]. The uneven occurrence is explained by different theories and affected by various factors, which is related with both the growth of individual cities and the different extant size and expanding speed of a group of cities. As the foundational support of industries and population, the industrial development and population growth are the basic driving forces of urban expansion; hence their difference would bring different need of urban space and then dissimilar urban expansion [7,12]. The theory of urban growth machine explores how economic and population growth affects patterns of urbanization, and indicates the effects of different factors [13]. The growth poles theory points out that economic growth is not uniform over an entire region, but takes place around a specific pole (or cluster), which implies the uneven growth and formation of growth pole over certain region [14]. According to the researches in developing countries including China, the uneven USE is indicated to be related with various factors including uneven public resource allocation and land systems, unequal ecological carrying capacities, and also different process of globalization and economic growth [15].
Comment 6:
L141: There is a need to acknowledge that USE is not only a physical process but also socioeconomic.
Response:
Thank you for your comment. We made changes according to your suggestion throughout the revised manuscript.
Comment 7:
L173: Which version of ArcGIS software was used? The use of the phrase “urban development land” instead of “urban construction land” is more suitable as it is more encompassing.
Response:
Thank you for your comment. ArcGIS 9.3 was used here, and we made changes accordingly. About the phrase “urban construction land”, the concept “construction land” is widely accepted and it is rational to indicate the land use type in our research. Therefore, we still used “urban construction land” in the revised manuscript.
Comment 8:
The methodology section should convince the reviewer that the selected method has comparative advantages over the existing methods for the study area.
Response:
Thank you for your comment. MCR was designed based on landscape theory and widely used to simulate species migration from a “source” through landscapes with different resistance [47,48]. Considering the similarity between USE and species migration, MCR model reflects the spatial proximity and land suitability factors of USE as well as constant constraints from environmental and ecological factors (e.g., species conservation areas) by defining “unusable lands” as necessary [49]. Moreover, the MCR model is with well-designed and widely adopted module in ArcGIS 9.3 and also lower data requirement, which is also proven to be feasible in simulating USE [31,49,50]. Therefore, we chose MCR model to simulate USE under different land protection scenarios (P5, L173-186).
Comment 9:
What have you found that is new or expected?
There is also a need to relate the findings to the research questions raised in the introduction section.
Response:
Thank you for your comment. The general topic of this research is “Simulating uneven urban spatial expansion under various land protection strategies and proposing suggestions on optimizing the strategies”, and the section of RESULT aims to express the USE pattern under different scenarios. Here, the main new findings include: 1) Different USE patterns cause significant differences in the allocations of newly added urban construction lands (see the 2nd paragraph in sub-section 3.3 and also 3.4); and 2) Larger cities tend to grow faster, but the existing differentiated allocations of newly added urban development lands related to both increasing expansion amount and scenario still cause significant differences in urban rank-size in SJUA (see sub-section 3.5).
Together with the description of methodology, the sub-sections 3.1 and 3.2 constitute the basis of carrying out USE simulation, which answer the 1st research question, i.e. How can the geographical expansion of different cities in SJUA be simulated at the regional scale under the restriction of different land protection scenarios? The uneven allocations of newly added urban construction lands and induced differentiated USE of different cities (see sub-section 3.4 and 3.5) answer the 2nd research question, i.e. Will the regional urban system change as cities expand unevenly? Will the differences in various expansion scenarios be related to different land protection policies?
Comment 10:
The authors have nicely discussed some policy implications.
Response:
We thank you for your approval!
Comment 11:
However, what is the justification for concentrating the discussion on mainly China? How does the present study compare with prior studies outside China and the likely explanations?
Response:
Thank you for your comment. Up to now, there are not a lot of researches on regional scale USE simulation, and we carried out such research to detect the feasibility of MCR model and the potential effect of different land protection policies on future regional scale USE. Considering the former topic, it is of low necessity to pay much attention on researches outside China. Besides, similar researches are also infrequent. This is the most important reason.
For the later topic, the background of land urbanization and proposed policies are quite different, especially from the perspective of policies effect. We paid more attention to the potential differences among four scenarios instead of prior studies outside China.
However, we still made necessary discussions which is related with studies outside China. The first on is about the feasibility of MCR model, which could also be used in other countries when different land use regulation policies are proposed (P17, L572-579). Secondly, some theories developed in other countries and related conclusion are also considered here such as “Agglomeration Shadows” (P18, L603-605) and “Green Belt” effect (P18, L630-632).
Comment 12:
Are the results generalizable, that is, can they be applied more broadly?
Response:
Thank you for your comment. It is quite a challenging questions. Similar with all case studies, their applicability (or generalizability) is always emphasized, or even questioned. For geographical researches, the particularity of different regions makes it more debatable. Just as what we discussed about the feasibility of MCR model, it could be widely used in simulating regional scale USE. This indicate the adopted model can be applied more broadly (P17, L564-579).
Considering the obtained results, the effect of different land protection policies help us propose suggestions on optimizing them, and those suggestions could be referred by other regions. Moreover, the potential spatial pattern obtained in our research is also a reference for other rapidly expanding urban agglomerations.
Comment 13:
What are the limitations of the study and directions for future research?
Response:
Thank you for your comment. No researches are perfect, and most obtain certain results from certain perspective, to certain extent, or with certain purpose. The model selection and its application is used to simulate the potential process of regional scale USE and detect the different effect of various land use policies, which is effectively realized to certain extent. However, there are limitations obviously, and we pointed them out in the CONCLUSION, and also directions for future. The detailed content is as follows: However, there are still some limitations in our research. The first one is related with the design of resistance surface with resistance value 1 - 9. Although the assignment is relatively rational, it is still lack of scientific inadequacy. More practical expanding process should be analyzed to detect more explicit resistance values. Secondly, regional scale expansion is a complicated process of a group of cities, and their interactions should be considered through the modification of MCR model.
Reviewer 3 Report
The well-written article on urban spatial expansion investigates different scenarios of urban expansion. It uses a rather simple model to explore how the ranking of cities would change under different scenarios. While the article is interesting as it is, it requires some methodological amendments. With the information provided, the methodological rigour cannot be fully judged.
Please clarify how you computed the overall suitability and why the default natural break is meaningful to build categories; is it a simple multi-criteria analysis? Please justify all your choices and sources (e.g. how suitability values are assigned, by means of adequate literature sources; who are the experts who provided expert judgement? Etc.). This includes the sources of the equation. Please provide a more detailed description of the scenarios, as these are fundamental to the analysis Please include information on how the suitability model has been validated; how realistic are the possible growth scenarios? Land ownership has not been included in the model, while I could imagine that it is an important variable. Please proof-read your article, some words are missing etc.
Author Response
Response to Reviewer #3
Comment 1:
The well-written article on urban spatial expansion investigates different scenarios of urban expansion. It uses a rather simple model to explore how the ranking of cities would change under different scenarios. While the article is interesting as it is, it requires some methodological amendments.
Response:
We thank you for your interest and approval!
Comment 2:
With the information provided, the methodological rigour cannot be fully judged.
Response:
Thank you for your comment. In the revised manuscript, we improved the METHODOLIGY by providing more reasons about model design and detailed contents about data preparation and processing. Besides, more than 10 new references were added to provide support our methods (see sub-sections 2.2.1. USE model and 2.2.2. Multi-scenario resistance surface designs).
Comment 3:
Please clarify how you computed the overall suitability and why the default natural break is meaningful to build categories; is it a simple multi-criteria analysis?
Response:
Thank you for comment. The LUS evaluation involves various aspects including indicator selection and assessment and then integrating them. Based on the selection of 6 major indicators and their evaluating results, we chose to multiply them with formula (2) in the manuscript to magnify the differences between the different grids. The theoretical range of the calculated value is from 1 to 15625, which is significantly broader than most existing researches related with MCR simulation, such as 1 – 5 [50] and 1 – 9 [31,49]. As LUS is relative values without definite assignment, we divided all grids with calculated value from 1 to 15625 into 9 sub-groups according to existing researches. The reason why we adopt the method of “Reclassification by Natural Breaks (Jenks)” in ArcGIS 9.3 as it is based on natural groupings inherent in the data and identifies break points as per class breaks among similar values as differences between classes are maximized (P7,L260-273).
Comment 4:
Please justify all your choices and sources (e.g. how suitability values are assigned, by means of adequate literature sources; who are the experts who provided expert judgement? Etc.). This includes the sources of the equation.
Response:
Thank you for your comment. As similar comment are proposed by other reviewers, we expand related sub-section, i.e. 2.2.2.1 Land use suitability (LUS) evaluation. We added more explanations on indicator selection, standard of classification, and data sources and processing. Moreover, more targeted references were added. Please turn to the sub-section 2.2.2.1 Land use suitability (LUS) evaluation (P6-7, L209-252).
Comment 5:
Please provide a more detailed description of the scenarios, as these are fundamental to the analysis.
Response:
Thank you for your comment. It is really an important issue, and we expanded 2.2.2.2 Resistance surface designs based on your comment. To be specific, BS scenario was designed directly based on LUS result. As higher suitability means lower resistance to USE, the grids with LUS value 1 - 9 were assigned resistance value 9 - 1 for USE. Accordingly, the resistance surface is obtained and each grid has its resistance value, which was defined as the resistance surface of Basic Scenario (BS). The other scenarios were designed through erasing different protected land from the resistance surface of Basic Scenario. The detailed content is showed from Line 275 to L293.
Comment 6:
Please include information on how the suitability model has been validated; how realistic are the possible growth scenarios?
Response:
Thank you for your comments. The feasibility of the suitability model could be proved in two ways. The first is that they are integrated results of widely adopted indicators, which was clearly expressed in sub-section 2.2.2.1 Land use suitability (LUS) evaluation (P6-7. L209-283). The second is the consistency between the spatial distribution of existing urban construction lands and the spatial pattern of LUS, indicating most existing urban lands are located as regions with high suitability (see Figure 3(a) and 4(g)).
The predicted growth scenarios is basically realistic for several reason. Firstly, the predicted results of USE continued the historical pattern in SJUA, and the possible area of these cities is linearly corrected with their extant sizes in 2010. This is in line with the general law of urban development (P17, L546-550). Secondly, the adopted MCR model is basically feasible. USE is a physical and socioeconomic process initially driven by human demands for space and habitable lands [25,26]. The process is similar with the species migration from a “source” through landscapes with different resistance, which is the theoretical foundation of MCR model (P5, L166-183). Thirdly, similar researches have been carried out with MCR model and their results are considered to be realistic (P5, L184-185).
Comment 7:
Land ownership has not been included in the model, while I could imagine that it is an important variable.
Response:
Thank you for providing an interesting topic considering land ownership. It is of higher importance in some countries where the ownership is complicated, and sometimes private lands form barriers to urban expansion. However, it is quite different as part of the lands surrounding extant cities are state-owned, and the rest are owned by rural collective economic organizations which could be turned into state-owned ones easily [83] (P17, L573-580).
Comment 8:
Please proof-read your article, some words are missing etc.
Response:
We thank you for your careful review on our manuscript. We tried our best to eliminated grammatical errors and language using mistakes, and invited a specialist in Earth Sciences and Scientific Writing and Editing to make detailed modification for grammatical correctness, clarity, readability, and fluency.
Reviewer 4 Report
The topic of the paper is very interesting, but it is hard to follow the text because of the intensive use of abbreviations. Example line 363: "Under AS, ES; and DS scenarios , the USE is restricted or even blocked by BASs or EPLs,..." Please write at least at some points the full names instead of the abbreviations. The reader would be very grateful.
Minor checking of the text is recommended. E.g. line 81 to 86 are repetition. In line 246 the parameter N is described but is not part of formula (2) etc.
Author Response
Response to Reviewer #4
Comment 1:
The topic of the paper is very interesting.
Response:
We thank you for your interest and approval!
Comment 2:
It is hard to follow the text because of the intensive use of abbreviations. Example line 363: "Under AS, ES; and DS scenarios, the USE is restricted or even blocked by BALs or EPLs,..." Please write at least at some points the full names instead of the abbreviations. The reader would be very grateful.
Response:
Thank you for your comment which aims to make our expressions clearer. We changed some abbreviations to simple words, such as BAL to arable land and EPL to ecological land. The meaning was kept, while the use of abbreviation decreased significantly. Moreover, full names took the place of the abbreviations where they occurred intensively.
Comment 3:
Minor checking of the text is recommended. E.g. line 81 to 86 are repetition. In line 246 the parameter N is described but is not part of formula (2) etc.
Response:
We thank you for your careful review on our manuscript. We deleted the original line 81 to 86 in the revised manuscript, and proof-read our article to eliminate grammatical errors and language using mistakes.
Round 2
Reviewer 1 Report
Dear Author(s),
I read you revised version and you improved most parts as I asked in my previous comments.
My major concern are about that in the first submission we have just one author while in this second one we have two authors. Quite strange from my point of view.
Having said that, I confirm my very positive opinion in the proposed research and consider it worth of interest in this journal.
What I ask the Authors is to provide a cover letter in which they clearly explain why we have two authors in this revised version and to try to follow all my comments provided in the previous step of the revision process.
Author Response
Response to Reviewer #1
Comment 1:
I read you revised version and you improved most parts as I asked in my previous comments.
Response:
We thank you for your approval!
Comment 2:
My major concern are about that in the first submission we have just one author while in this second one we have two authors. Quite strange from my point of view.
What I ask the Authors is to provide a cover letter in which they clearly explain why we have two authors in this revised version and to try to follow all my comments provided in the previous step of the revision process.
Response:
Thank you for your comment. Although it looks a little strange to add a new author, it is quite necessary as the newly added author (Dr. Hui Cao) made significant contribution in revising the manuscript. To be detailed, his work included rewriting the ABSTRACT, adding contents about urban expansion to the INTRODUCTION, and improving the expressions in the CONCLUSION. This helped finish the timely modification and also improve the manuscript greatly. The original author think the contribution of Dr. Hui Cao is nonnegligible and agree to add him as a new author.
We provided a special cover letter to explain this.
Comment 3:
Having said that, I confirm my very positive opinion in the proposed research and consider it worth of interest in this journal.
Response:
Thank you for your approval! We provided detailed explanations in the mentioned cover letter and also the Authorship Change Form according to IJGI’s requirement.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The author has largely addressed the gaps identified in my earlier review.
While I think that multiplication is meaningful for computing the suitability, I don‘t understand the value of 15625. This is a much larger range than other studies. Or is it that every factor could have 1-9? I would go for standardized values between 0 to 1.
Furthermore, I don‘t find a wide adoption of an Arcgis tool a valid justification. People copy from each other, and wide adoption does not mean that it is scientifically sound.
In my last review I highlighted the need for English editing. This is not really improved, and requires another round of editing, in particular the newly added sections, and the transitions between old and new sections.
I don‘t see a clear elaboration of the scenarios; the authors added a bit, but there is no elaborate description of the assumptions, why etc. This could be improved.
While I see the policy reference in the abstract, it does not show the contribution to the state of the art.
Author Response
Response to Reviewer #3
Comment 1:
The author has largely addressed the gaps identified in my earlier review.
Response:
Thank you for your approval! We did try to make as many changes as we could in limited time according to your and also other reviewers’ comments. This process not only improves the quality of this paper, but also help the authors understand more about scientific research and paper writing.
Comment 2:
While I think that multiplication is meaningful for computing the suitability, I don’t understand the value of 15625. This is a much larger range than other studies. Or is it that every factor could have 1-9? I would go for standardized values between 0 to 1.
Response:
Thank you for your comment. The value of 15625 is a theoretical result, which is the multiplication of the suitability value of six indicator. As the extent of the suitability value of each indicator is from 1 to 5, the theoretical range of multiplication is from 1 to 15625. If the suitability values of six indicator are all 5 for one grid, its multiplication, i.e. the theoretical land use suitability value, is 15625. As mentioned in the revised manuscript, the theoretical range from 1 to 15625 is significantly broader than most existing researches related with MCR simulation, so we reclassified them on a scale of 1 to 9. It is not that every factor has values from 1 to 9, but that each grid is with the land use suitability from 1 to 9 after reclassification. The range from 1 to 9 is not an absolute definition, but it looks more reasonable to assign integer values to the grids. Actually, the range definition does not affect the analysis results significantly as the land use suitability values change synchronously under different ranges. See L264-269 in the revised manuscript.
Comment 3:
I don’t find a wide adoption of an Arcgis tool a valid justification. People copy from each other, and wide adoption does not mean that it is scientifically sound.
Response:
Thank you for your comments. We agree with your statement so much that we also think “wide adoption does not mean that it is scientifically sound”. However, it is basically more reasonable to follow a wide adoption than create a new one without much validation. Developed by the international supplier of ESRI, ArcGIS is a geographic information system for working with maps and geographic information, and one of its various applications is sharing, discovering and managing geographic information in a database. The spatial analysis module of ArcGIS is among the widely used tools, which facilitates the simulation of spatial expansion greatly considering its proved technique and low data requirement. As we indicated in the revised manuscript, the ArcGIS tool could help us carry out the analysis of land use suitability and also simulation of urban spatial expansion effectively. There are sufficient contents about this in the sub-section of 2.2.1. USE model, such as L172-185, L199-201, etc.
Comment 4:
In my last review I highlighted the need for English editing. This is not really improved, and requires another round of editing, in particular the newly added sections, and the transitions between old and new sections.
Response:
Thank you for your comment. We checked the whole manuscript carefully in this revision and tried our best to eliminated grammatical errors and language using mistakes. We hope it is improved greatly and can meet the standard of the journal.
Comment 5:
Please include information on how the suitability model has been validated; how realistic are the possible growth scenarios?
Response:
Thank you for your comment. There are two concerns in this comment. For the first one, i.e. how the suitability model has been validated, it was proved to be effective and reasonable by the result that most urban construction lands are distributed at zones with high land use suitability. On the contrary, most ecological lands are at zones with low suitability (Figure 3 and 4). We added some content in L354-356, and we could also provide maps and quantitative results of the comparison between Figure 3 and 4 if necessary.
The second concern is “how realistic are the possible growth scenarios”, it is primary to prove the reality of the Basic Scenario. Related content is provided in the sub-section of 4.1. Feasibility of MCR model in regional scale USE simulations. Moreover, the comparison between simulated and actual pattern of urban construction lands in 2010 also proved the feasibility of MCR model. The simulated pattern is obtained with urban construction lands in 2005 and land use suitability as the input variables of the MCR model. The simulated and actual patterns are highly consistent and about 84% of the construction lands are the same (See L525-527). This implies the feasibility of MCR model and the reality of BS scenario. For other scenarios, the spatial distribution of protected are obtained from public documents of local government. As the protected lands are strictly excluded from potential urban construction lands, the simulated results of related scenarios is realistic for providing insight of future urban spatial expansion.
Comment 5:
While I see the policy reference in the abstract, it does not show the contribution to the state of the art.
Response:
Thank you for your comment. We added some content about the state of the art in the ABSTRACT.
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
