Spatio-Temporal Heterogeneity of Ecological Quality in Hangzhou Greater Bay Area (HGBA) of China and Response to Land Use and Cover Change
Round 1
Reviewer 1 Report
In the manuscript entitled "Spatio-temporal heterogeneity of ecological quality in Hang-2 zhou Greater Bay Area (HGBA) of China and response to land 3 use and cover change", authors tried to analyse and present the long term changes in ecological quality over HGBA region of China and their relationship with LULC using satellite remote sensing datasets. The methodology used in this study is well appreciated. The interpretation and narration of the results in the manuscript is very clear with good language that would grab the interest of the readers. In addition, the graphical representations are very clear with good resoltuion. Thus, I recommend this manuscript can be accepted in the current form.
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Reviewer 2 Report
The work has an important focus and the authors used the right technology.
But the results and conclusions must be improved above all with clarity in the topography used.
For example the authors say:
"We created random points using ArcGIS 10.3 software for training and validating the 264 land use classification."
But where are these points located?
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Reviewer 3 Report
The topic of the article presented appears in different reports of the Chinese government. There are even external works that deal with this issue at a global level. The results are well presented and the discussion is interesting. However, the contribution of the work is limited. The authors should clarify this point at the end of the introduction. Showing what this work contributes with respect to scientific and non-scientific published material. These arguments should also be emphasized in the abstract, discussion and conclusions.
Other comments:
- The methodology needs to be explained in detail. It is not clear what they use the measured data for in the procedure and what additional data they have used to obtain the presented results. Also, it is not shown how the method would be replicable in other parts of the world. This topic is interesting for the scientific community.
- The assumptions and limitations of the methodology used should be explained. It is probably not a methodology developed by the authors, so the sources used should be cited.
I am not a specialist on the subject. However, searching on google, I have seen many studies with similar objectives and results. Authors must make an effort to demonstrate the worth of their work.
- The results are well presented, but there is a disconnect in the text between the results presented and the discussion/conclusions used. The results should be cited in their discussion to understand their implications and also the expected variations in the future.
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Reviewer 4 Report
A brief summary.
The paper addresses the ecological quality in Hangzhou Greater Bay Area of China. Using ~20 multi-temporal datasets generated by the LANDSAT satellite constellation, the spatial distributions of the special index (RSEI) are computed and analyzed, which are further interpreted to study the ecological quality. Possible conjunction of the RSEI and land use dynamics are discussed. The authors of the work present a lot of detailed material, undoubtedly obtained by great effort. However, it is difficult to see the scientific contribution in the field of remote sensing and significant reasoned findings in the results of the work. Specific comments will follow.
General concept comments.
1) The article focuses on the tasks of monitoring the region of interest. The main contribution of the article was aimed at environmental problems, but not at remote sensing problems. In this regard, I would recommend transforming the concept statement of the paper so that the results also include innovation in the methodology of data processing, or clarify the features and limitations of already known methods.
2) The work uses a very sparse time series of satellite observations (with a step of ~5 years), which raises doubts about the validity of the conclusions formulated regarding the dynamics of environmental quality in the study area. In paragraph 4.2 of the article, the authors rightly point out that the work should have been carried out using methods of forming pixel-by-pixel median values for each vegetative season. This is the approach that would correspond to the current world level. In the current version of the formulation of the study it is necessary to discuss and quantify the possible losses in the accuracy and quality of the assessment of ecological quality dynamics, arising with the use of a too poor data bank (what have we lost by taking too rare time serie?).
3) The concept of building the RSEI index itself is interesting, but difficult to understand clearly. Please provide not only references to the works confirming the effectiveness of the RSEI, but also a description of any final actual quantitative results of these worksthat strongly support the validity of RSEI.
4) The methodology of data processing is not described accurately enough and leaves much doubt about the relevance of the results. The authors perform many normalizations at different stages of processing, and the formulas are not written down specifically enough. For example, it is not clear which set is used to calculate MAX and MIN in expression #3 (for each year? for the whole series?). Such uncertainties make it impossible to trust the information products obtained, in particular the series of multi-temporal maps (Fig. 5). The question remains open - what exactly does the comparison of these different-temporal maps show? It is not clear yet. For now, there are only concerns that the comparison of these maps gives irrelevant estimates of the real dynamics of the ecological situation.
Review and comments.
1) Tab. 2. In the expressions, the channels are denoted by numerical indices, for example (?4 - ?3 / ?4 + ?3). But in LANDSAT program(different generation satellites) there is no mutual correspondence of channels by their ordinal numbers. Is there no error in your calculations? It is better to use the band names (pRED, pNIR, etc.) instead of numbers.
2) Fig. 7 b. How to interpret it? Intuitively, it seems that a large flow is directed from the "build-up" class to the "farmland" class (thick blue arrow). Is this the case? It's hard to read the diagram unambiguously.
3) Conclusions. Please give conclusions concerning the scientific field of remote sensing (in current version: only engineering results, descriptive assessment of environmental quality dynamics and assumptions about the relationship of environmental quality to land use can be seen).
Thank you very much for your work!
Author Response
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Round 2
Reviewer 2 Report
In relation to the demands of the previous review, little has been done.
The authors were interested in adding photos of some results without explaining the software used for the calculation of the indices, the topography used to generate the random points in the GIS software, etc.
However, the technique used remains obsolete and not very efficient for the intended purposes.
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Reviewer 4 Report
Dear authors! Thank you for the informative response, the article has been significantly improved. I wish you a speedy publication of the article. However, it seems important to try to extract even more scientific significance from the article for the field of remote sensing, and put it in the conclusion. I think article [75] is a good example. What conclusions about the features and relevance of the RSEI approach (apart from the expediency of percentage stretching) can you find based on an extensive analysis of your wide results? Good luck!
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