Time-Series Monitoring of Dust-Proof Nets Covering Urban Construction Waste by Multispectral Images in Zhengzhou, China

Round 1

Reviewer 1 Report

The authors have satisfactorily addressed my remarks, I clear publication but suggest they check the text again for typos and other minor issues.

Author Response

Reviewer #1:

The authors have satisfactorily addressed my remarks, I clear publication but suggest they check the text again for typos and other minor issues.

Response:

We gratefully appreciate for your valuable comment and have checked the manuscript carefully.

Reviewer 2 Report

This paper reports on the potential of multispectral remote sensing to monitor urban construction waste and proposes a multi-layer classification method to identify construction waste and dust-proof nets. Construction and demolition activities can cause significant air pollution from windblown dust. Dust-proof nets have been successfully used to limit this pollution in line with UN Sustainable Development Goal target 11.6 so it is important to monitor and evaluate their efficacy. This is generally an interesting paper with practical utility.

Lines 79-88: This sentence is too long and difficult to follow – needs editing.

Figure 1 legend: Replace ‘Build-up zone’ with ‘Built-up zone’.

Line 102: ‘By 2017…’ Need to indicate from when, e.g. ‘Between 20xx and 2017…’

Table 1 caption: Replace ‘band’ with ‘bands’.

Lines 206-208: ‘Since there were no blue dust-proof nets before 2019, temporary buildings and construction waste covered with blue dust-proof nets from 2015 to 2018 were not to be sampled.’ This does not make sense – if there were none, then there is no danger of them being sampled. Sentence needs rewriting.

Line 210: To what does ‘a considerable amount’ refer?

Lines 571-573: ‘The fine image makes the information of the objects under the dust-proof nets clearer, but the characteristics of the dust-proof nets itself are weakened…’ Why is this so?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

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.

Round 1

Reviewer 1 Report

According to the author's statement in the article, this study holds the promise of being a means to monitor construction waste and dust-proof nets, paving the way for better urban environmental governance and surveillance actions in the future, especially involving big data. Therefore, this paper should have the potential to be accepted for publication in a "Remote Sensing" journal, but authors are still advised to revise their article based on the following review comments.

1.      The description of "2.2.2. Fieldwork data" can add some important information (for example: process...)

2.      Please explain why there are only “four” types of ground objects.

3.      According to the information in Table 6, the satellite image classification results in February are better (higher accuracy). Please explain whether the classification effect is related to the season?

4.      According to statistics of bare soil and dust-proof nets areas, the proportion of dust-proof nets in Zhengzhou from 2015 to 2020 are 66.38%, 59.57%, 12.33%, 44.70%, 80.23%, 86.12%, respectively. Please add the reason why the "dust-proof nets" was particularly low in 2017. Whether it is because of the image classification accuracy?

5.      The author mentioned in the article: "When we made a rough count of images from more time periods, we found that within a one-year time interval, there were sometimes quite different results from the present study.". Please try to suggest possible solutions.

6.      The author mentioned in the article: "The air quality becomes better as the mulch coverage increases, which confirms the effectiveness of the dust net.". However, this conclusion is not particularly surprising. It is suggested that the author may present more research findings or technological breakthroughs to demonstrate the value of this research.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Dear authors,

The paper entitled “Time-series Monitoring of Dust-proof nets covering Urban Construction Waste by Multispectral Images in Zhengzhou, China” proposes an innovative method to detect dust-proofs nets and solid waste on urban construction by using time-series multispectral images. The topic of the paper is very interesting and well presented. Moreover the topic is of interest for the journal “Remote Sensing” of MDPI. The paper could be accepted after some minor revisions as follows:

 - I suggest to “split” the introduction paragraph where a state of the art is presented with another chapter about the “ case study” where Zhengzhou city is described

- please use the international system of units for all variables

- please consider a deeper proofreading. Several misprints are present in the paper and I will suggest to contact a professional English proofreading and editing services.

Kind regards

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

In this manuscript, the authors propose a method for monitoring urban construction waste based on remotely sensed data, considering also dust nets as a factor reducing spread of particulate matter from waste heaps. The authors identified a case study on an urban area in China, produced ground reference data including waste and dust nets, used Landsat-8 and Sentinel-2 data to classify land cover in the area, and finally analyzed correlations between waste, dust nets and air pollution.

 

The idea of investigating relationships between waste and air particulate matter, with a focus on dust nets as an improvement factor is valuable. The scientific novelty in the field of remote sensing, however, is completely absent. This is not acceptable in my opinion in a submission to a remote sensing journal. Remotely sensed data is pre-analyzed with standard methods and the classification is carried out using classifiers that are long known in the remote sensing context, with no significant novelties introduced.

 

The value of the manuscript lies in its analysis of the correlation between construction waste, dust nets and atmospheric particulate matter, and is more suitable for submission to a journal with a focus on environmental matters or on urban policies. Even in this case, however, some issues should be addressed:

• if I understood correctly, the authors merge waste and bare soil into a single thematic class (page 5, rows 166-167). This makes it more difficult, perhaps impossible, to separate dust generated by bare soil and dust generated by waste, undermining the conclusions;

• page 5, rows 127-131: why do the authors use a composite index merging several indexes some of which are completely unrelated with waste? Wouldn't the PM alone go more straight to the point?

• the geographical extent of the case study is somehow too small, and does not permit to draw more general conclusions applicable to other urban contexts

 

Other issues include:

• check for typos (e.g. page 2, row 75: “We takeS … and useS …”)

• page 4, figure 2(b): it is difficult to make sense of this picture, which looks severely distorted

 

• page 5, rows 146-147: “The sample collection was constructed based on the spectral and geometric features of construction waste”. Does it mean that ground reference data was built by visual interpretation? If so, please use this standard term.

• page 13, row 304: “which demonstrated that Sentinel-2 has higher spatial resolution”. Does it need to be demonstrated? It is a fact, in this context.

I suggest the manuscript be rejected and resubmitted to a journal on environmental or urban policy topics after addressing the above problems.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

This reviewer thanks the authors for their paper on an applied use of remote sensing to solve an Earth monitoring conundrum. I think though that the authors need to reorganise the paper to achieve the aims they specify.

In their introduction, the authors note that the aims of their paper are to:

• Validate remote sensing instruments for dust net identification; and
• Verify that the dust nets impact aerosol production.

The first aim is well achieved. The second aim is not embedded in the science process.

The methods and results of comparing the aerosol data with the dust net location is left to the discussion section of the paper only. Since it is a key aim, the authors could note the methods and results of statistically comparing aerosol data in the relevant sections first – and then discuss the two aims further in the discussion section.

This reviewer would like to see:

• How the confusion matrix was populated from ground truthing (were sites visited).
• The description of how aerosol and dust net colocation analysis was conducted in the methods section – particularly spatial parameters with respect to pixel size and data set co-location.
• The aerosol and dust net correlation results moved to the results section.
• The discussion section addresses the limitation of the method with respect to dust advection from varying source locations under varying wind conditions.

The paper uses some English turns of phrase and inappropriate tenses that could be ironed out.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author has made revisions and responses to the review comments.  I have no other comments and suggest that this paper can be accepted for publication.

Reviewer 3 Report

The authors have addressed some of the minor issues but the main one remains in place: from a remote sensing perspective, the work is not relevant as it is basically a land cover classification carried out using basic (and, to some extent, outdated) methods. Some of the explanations provided vs. remarks to the previous version are not convincing; for example, I suggested PM indexes were more suitable than AQI to describe the impact of dust nets, but the authors reiterated that AQI should be used because it is a standard index of air quality. At page 19, however, they state that "surprisingly" PM indexes are more correlated with dust net presence than AQI is. Hence, there appears to be inconsistence in their reply with respect to the added content. Once more, I see not much value from a remote sensing perspective; it may have from other standpoints, which I do not feel qualified to judge. I suggest rejection and submission to another journal focusing on environmental issues, where specialised reviewers can judge the environmental aspects better than I.

Reviewer 4 Report

I thank the authors for their corrections - I believe my comments have been well accounted for.