Joint Use of Optical and Radar Remote Sensing Data for Characterizing the 2020 Aniangzhai Landslide Post-Failure Displacement

Round 1

Reviewer 1 Report (Previous Reviewer 3)

I do think the authors didn't hit the point. The novelty of this paper still not reaches a satisfying level.

Author Response

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Reviewer 2 Report (Previous Reviewer 1)

To assess the deformation characteristic and spatial-temporal evolution of the reactivated ANZ landslide during the post-failure stage better, This study investigated the potential of synergistic use of time-series Interferometric Synthetic Aperture Radar (InSAR) and optical pixel offset tracking (POT). The results showed that the analytical results of the proposed method were in line with the actual situation and had richer information than the single monitoring method. However, there are still some problems with the paper.

 

1. The main sliding direction of the ANZ landslide was not illustrated in the paper.

2. Figures 1 (c) and (d) are not clear enough to see the local details; In addition, the deformation in (c) and (d) mentioned in the paper was not marked and explained in the figure, which is easy to cause confusion in reading.

3. What direction horizontal displacement meant in the POT method was not explained in the paper.

4. The specific displacement direction was not indicated in Figure 3, Figure 6, and Figure 7.

5. Only the landslide deformation was described in detail based on INSAR and Optical Image data, and the causes of the deformation were less analyzed.

6. The highlight of this paper is that the monitoring time range is longer than that of the predecessors, and the method of synergistic optical pictures and radar remote sensing data is used to analyze deformation and failure. Among them, the long monitoring time can get more information, but the deformation analysis technology theory base on INSAR and Optical Pictures has been relatively mature. Although the combination of the two methods can indeed obtain richer deformation information, the paper described the two methods and their results separately and did not combine them, failing to reflect the advantages of synergy, causing the innovation to be not very strong.

7 Please consider citing the following references,

Deformation monitoring of earth fissure hazards using terrestrial laser scanning

UAV and airborne LiDAR data for interpreting kinematic evolution of landslide movements: The case study of the Montescaglioso landslide (Southern Italy)

Author Response

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Reviewer 3 Report (Previous Reviewer 2)

This version is much better than before. 

The researches on the SED , SAD  and TB is interesting and with enough innovation in this field. However, in the 3. methodology chapter there are no equation and mehtods  discription for the SED, SAD  and TB.  The subsect 3.2 is liking a literature review should not be put in this part. 

My suggestion is that the author should add the method and equations for SED, SAD and TB  in section III.

 

Author Response

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Reviewer 4 Report (New Reviewer)

The manuscript titled "Synergy of Optical and Radar Remote Sensing Data for Characterizing the 2020 Aniangzhai Landslide Post-failure Displacement" by Kuang et al. presents a post-failure characterisation study of a landslide in China. The study utilises SAR as well as optical satellite data for this purpose. The authors have used the Advanced DInSAR technique on both ascending and descending data of the Sentinel-1 satellite. Also, Planetscope data were used, and pixel offset tracking was used. The relationships between sun illumination differences, the temporal baseline of correlation pairs and the uncertainties were analysed. the use of SED and SAD for controlling the uncertainties looks nice.

The manuscript is well-written except for a few minor flaws. The methodology is described meticulously and can be well understood by readers. The results are well presented and nicely discussed. I have one suggestion that authors can apply for the betterment of the manuscript.

1. It would be better if the authors could provide a methodology flowchart depicting each step.

 

 

 

 

Author Response

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Round 2

Reviewer 1 Report (Previous Reviewer 3)

The key innovation of the work lies in the joint use of InSAR and POt to detect landslide postfailure, while these two parts have been mentioned and conducted in several papers. ie. Hu et.al's NC paper. The remained technical issue, i.e., phase unwrapping with such sparse points is still left and could not see any improvement after your revisions. I still hold the reject decision.

Reviewer 2 Report (Previous Reviewer 1)

My concerns have been addressed by the authors.

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

General comment:

First of all, thanks editor for inviting me to review this manuscript. 

 

The authors presented a post-failure displacement monitoring of an ancient landslide using the synergy of optical and radar remote sensing data. The study is very interesting, but there are several flaws presented in this study. The details about the reviews of this manuscript are as follows:

 

Detailed comments:

 

1. Introduction: The literature review focused on only the ANZ landslide, but in the state of art, it is highly suggested to summarize the relevant background, challenges, why did you select this topic, and the novelty of your study in a general point, rather than a case study.

2. Because this study was conducted based on a specific case, I indeed think this title is not suitable for your study.

3. Please redraw the China map in the inset in Figure 1.

4. Please reorganize the content on Page 6, and there are so many blanks on this page.

5. Please redraw Figure 3 to improve the quality of this figure.

6. It is very important to verify your finding. Therefore, please compare your monitoring results with other methods, such as in-situ monitoring.

Reviewer 2 Report

 

This paper investigates the post failure processing of the landslide area in Sichuan Danba Aniangzhai Village by Sentinel-1 SAR satellite and planet satellite. The results sounds good and revealed the evolution and this landslide area.

However, there are already lots of literatures in this landslide area by remote sensing data. The author should emphasis the significant contributions about this paper both the data processing and new phenomenon discovering. Some of the pictures do have creative new findings and new features of this landslide, but these interesting discovery are not summarized into the conclusion part. Therefore, the conclusion part should be revised according to those new findings.

There are some other important things missing in this paper, such as the onsite exploration are excluded from this research which makes the conclusion of the salability of this landslide area doubtfully. As from the recently open media there are still some emergency affairs about this landslide area ( http://www.sc404.com/new/Article/ShowArticle.asp?ArticleID=671). And the VI landslide area are not so reasonable yet, the upper part landslide area should include the north part of the dashed lines.

  

 

Some suggestions for improving:

1.      Table1 is too big and some of the contents are useless for this paper yet. Such as “TOPS”， “VV+VH”， .

2.      Figure.3 should be deleted because it is just a command data processing chain.

3.      The landslide serial number is not so reasonable yet. Part V is another landslide area not related to part I, II, III and IV. What is more. Part III should be regarded as two parts because from the previous literature, The south part of III include part of the bed rock area which can not be regarded as the landslide area.

 

4.      The layout the all the figures and tables should be rearranged for the readers. 

 

Reviewer 3 Report

I reviewed a paper entitled “Synergy of Optical and Radar Remote Sensing Data for Characterizing Reactivated Landslide Post-failure Displacement” by Kuang et.al.

The authors introduced their post-failure displacements of the Aniangzhai landslide from InSAR and POT data. They declared the potential synergistic usage of InSAR and POT data, which is commonly seen now. Further, the authors discussed on the sharp acceleration and deceleration of the displacement evolution. In general, this language of this paper should be further improved. The topic of this paper should be highlighted. That is the authors should address the novelty. I recommend that a decision of major revision or a reject and resubmit is required. I share with you some major comments as below. Please check them. Comments are listed as follows.

 

Major Comments:

Q1. My first major concern is results of fig.4 presented by the authors. I am confused by the point density. How can you unwrap successfully based on so sparse points? How to prove their accuracy?

Q2. Why POT can get more data points? How to validate these results?

Q3. Can you provide more insights on the derived sparse 3D displacements? Now the scientific background is relatively poor.

Q4. Please redraw all figures excluding Fig.1.

Q5. Please provide more validation.