Monitoring Seasonal Movement Characteristics of the Landslide Based on Time-Series InSAR Technology: The Cheyiping Landslide Case Study, China

Round 1

Reviewer 1 Report (Previous Reviewer 1)

This paper uses two MT-InSAR technologies: PS InSAR and SBAS InSAR. From the results, it seems that the application of PS InSAR technology is not very useful. At present, many papers have demonstrated the limitation of PS InSAR application in mountainous areas. Please analyze the reason why PSinSAR is used in this paper in detail.

The interpretation of the slow deformation mechanism of the Cheyiping landslide is relatively superficial. The analysis of time series deformation and rainfall is carried out in this paper, but the analysis is relatively simple, so it is suggested to separate seasonal deformation for further analysis.

Author Response

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Reviewer 2 Report (New Reviewer)

The article titled "Monitoring Seasonal Movement Characteristics of the Landslide Based on Time-series InSAR Technology: The Cheyiping Landslide Case Study, China" by Gou et al. presents an analysis of a Landslide using the InSAR Technique. Please find the specific comments for this manuscript. Authors should incorporate the following remarks for getting published in this journal.

The Study is indeed very interesting to read. The authors have tried to present the study in a good way. 

The language used is easy to comprehend though it has a few mistakes, which I suggest can be done with proofreading by a third person.

I would suggest redrawing maps. There is a very basic error in the maps drawn. the way of depicting units is incorrect in few maps. According to the Bureau Internationale des Poids et des Mesures' guidance, (https://www.bipm.org/documents/20126/41483022/SI-Brochure-9.pdf/fcf090b2-04e6-88cc-1149-c3e029ad8232) from the SI Brochure (PDF; see p. 147 for English) clause 5.2: They are printed in lower-case letters unless they are derived from a proper name, in which case the first letter is a capital letter. I find k of kilo in capitals.

The authors can refer to other studies on Landslides of similar conditions in the Literature review (recent studies). This will surely strengthen the importance of the study, for, eg.

Tang, H., Wasowski, J., & Juang, C. H. (2019). Geohazards in the three Gorges Reservoir Area, China–Lessons learned from decades of research. Engineering Geology, 261, 105267.

Yao, J., Yao, X., & Liu, X. (2022). Landslide Detection and Mapping Based on SBAS-InSAR and PS-InSAR: A Case Study in Gongjue County, Tibet, China. Remote Sensing, 14(19), 4728.

Soltanieh, A., & Macciotta, R. (2022). Updated understanding of the Ripley landslide kinematics using satellite InSAR. Geosciences, 12(8), 298.

Jia, H., Wang, Y., Ge, D., Deng, Y., & Wang, R. (2022). InSAR Study of Landslides: Early Detection, Three-Dimensional, and Long-Term Surface Displacement Estimation—A Case of Xiaojiang River Basin, China. Remote Sensing, 14(7), 1759.

Jiao, R., Wang, S., Yang, H., Guo, X., Han, J., Pei, X., & Yan, C. (2022). Comprehensive Remote Sensing Technology for Monitoring Landslide Hazards and Disaster Chain in the Xishan Mining Area of Beijing. Remote Sensing, 14(19), 4695.

Mishra, V., & Jain, K. (2022). Satellite based assessment of artificial reservoir induced landslides in data scarce environment: A case study of Baglihar reservoir in India. Journal of Applied Geophysics, 205, 104754.

 

Cite references from literature for the usage of The Goldstein adaptive filtering method (used to remove noise), and the Delaunay MFC method (used for phase unwrapping).

Why use the word "super master"? I know in previous studies, this term is used, but in the SBAS process, there is no " super master" as there is no common image used as a master for all other images, as is the case of PSI. I would suggest using some other term.

Under heading 5.4 authors have mentioned "A landslide is a downward movement of weathered debris or unstable rock and soil on a slope, which occurs under the influence of gravity". It is a common language. Remove the redundancy.

In 5.4.2. Lithology is described. It would be better if the authors can produce a geological map of the area.

 

 

 

Author Response

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Reviewer 3 Report (New Reviewer)

The article is well presented and written fluently in English. The contents are understandable and expressed based on Time-series InSAR Technology. However, my opinion in this regard is that the work does not present in terms of contents and results adequate quality to be published in a journal such as Remote Sensing. Below I report the perplexities that lead me not to consider this article suitable for publication in this journal, suggesting a redirection of the same work to a different destination:

(1) The abstract was not well organized. It is difficult for readers to determine the method and innovation of the article.

(2) In the introduction part, the traditional methods do have many shortcomings (lines 44~47). However, their effectiveness should not be questioned because they are currently widely used and the results can be verified. Furthermore, the data obtained from remote sensing must be further confirmed through field investigation technically to ensure its effectiveness. Remote sensing is only part of establishing a comprehensive landslide prevention and control system. It is suggested for the authors refer to the related papers published by Prof. Qiang Xu, Chengdu University of Technology. The perspective of this article may deviate from the reader's understanding of relevant fields.

(3) Line 71. The article needs to be further improved in terms of professional terms. We generally use “ancient landslide” instead of “old landslide.”

(4) The innovation of the remote sensing method used in this paper is not clear. As said before, using InSAR Technology to analyze landslide displacement has been applied in many papers. What can be the validity and applicability of such a technology used in this paper? Correspondingly, most of the content of the article is the description of the survey reports. Although the article provides a lot of site photos, these photos still need to be further calibrated at the location of the landslide. This leads to no in-depth study of any aspect of the article. For example, when the article analyzes the landslide mechanism, it lacks the typical profile.

As a general comment, the feeling when reading and rereading the article, which is well written and presented, is that it lacks relevance in the contents, especially in reference to the quality of the works normally published by this journal.

Author Response

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Round 2

Reviewer 3 Report (New Reviewer)

This paper has been improved to a certain extent and can be acceptted. 

Author Response

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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

This paper used Sentinel-1A SAR data processed by PS-InSAR and SBAS-InSAR methods to monitor the time-series surface deformation. But it is not innovative.

1)      Add compass in the figure 1(b).

2)      L.159 the space baseline is set as 2%? what does 2% mean?

3)      The "super main image" often says as "super master image", and it is suggested as presented as a star in the figure 4 and 5 to make a difference to other images shown as dots in those figures.

4)      It is said that "the ratio of the azimuth looks and range looks is set as 4:1 in multi-look processing." But the resolution for azimuth is worse than that for range direction. So I think there's an error.

5)      L.163 the GCP is how to get? Please overlay the GCPs on a map.

6)      L. 164 "the phase value is obtained by the method of minimum squares" what does "the phase value" mean in physics? How to it obtained by using minimum squares?

7)      And the atmospheric phase is often removed after phase unwrapping for SBAS method. But in this paper, it is removed after the displacement obtained by SVD, what's the difference between the different process flow?

8)      How to evaluate the results from SBAS and PS? How to decide which one is more dependable?

9)      L.192 to L.197 is paradox. it seems the description is disrupted.

10)   The figure 8 is obscure. Please redraw it and explain the angles defined in it, especially explain which direction is the positive direction or which rotate direction to count the angle.

11)   L.208 to L.216 is obscure and hard to understand. It is should be clearer and explain the meaning of the positive and negative sign. if all the values are projected on the slope direction，why there's different sign values?

12)   define the initial point of the profile A in figure 10 and 9.

13)   L.270 to L.274 there are some description paradox based on the figure 12 please check it carefully.

14)   Figure 13 is not easy readable, especially the different scales used for the right axis. I think it's better to use the same scale to highlight the different slope of the different deformation curve.

Author Response

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Reviewer 2 Report

I am not a remote sensing specialist, but I am a geomorphologist. For me this paper appeared as a case study. I did not learn much new about the landslides in general. However, this was very informative of this particular landslide which apparently poses a great threat to the local villagers and existing infrastructure. As a non-specialist, the InSAR methodology appeared to me fairly standard. The English in the paper is reasonably good, meaning that the text is understandable as it is. However, it contains a large number of grammar errors that would certainly distract a potential reader of this paper. The attached pdf file contains more minor suggestions. Perhaps the title should start by words: Case Study...

Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

It is nice piece of research that has been done by authors. I have some suggestion for improving the manuscript before publication as follows:

1. Please define specific objectives in last part of the introduction.

2.  Please add some geological information about the lithological units and geological structures in the study area.

3. Please provide geology map for the study area and added to the Figure 1 components.

4. methodology is well-written. 

5. Please add some updated references (2021-2022) to the discussion section and compare your research with newly published studies.  

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Reviewer 4 Report

The paper entitled "Monitoring Seasonal Movement Characteristics of the Cheyiping Landslide Based on Time-series InSAR Technology" shows the application of two consolidated InSAR algorithms such as PSInSAR and SBAS over a landslide located in the Yunnan province, China.

The paper is not showing any significant content, just showing the mere application of the processing methods and a comparison with possible influencing factor. There is no novelty in the analysis, and the paper sounds more as a technical report rather than an original research.

Besides that, I have doubts also on the processing, which relies only on less than 30 images, showing opposite values within and outside the landslide area. This seems to be a bit weird, considering that the whole slope, besides the landslide identified, cannot move ih the opposite direction. Therefore I suggest to use more images in the processing, and to use also descending  Sentinel-1 images, trying to extract also horizontal and vertical components.
In general, the authors should try to make major efforts to fully characterize the landslide.

Author Response

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Round 2

Reviewer 2 Report

I appreciate the authors revisions to improve the manuscript. They have certainly made it better. The English language still has room for improvement. The added imagery and information on the surficial features makes the manuscript more relatable and interesting to people other than remote sensing specialists. However, I still view this as a case study, which I would highlight in the title. And the wider interest may be limited, unless the remote sensing techniques are somehow unique, which I cannot assess. 

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Reviewer 4 Report

I would like to thank the authors for the kind reply, however I still believe the paper do not present any interesting and relevant content in the actual literature trend on landslide studies and in the InSAR field. Besides, I still have concerns about the results presented, in particular on InSAR data which do not look clear to me. As I mentioned in the previous stage, I believe the processing stage has some major flaw, maybe in the reference point selection, since I do not believe the slope area is moving in two opposite directions.

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