Landslide Identification in Human-Modified Alpine and Canyon Area of the Niulan River Basin Based on SBAS-InSAR and Optical Images
Round 1
Reviewer 1 Report
March 19, 2023
Manuscript: Landslide Identification in Human-Modified Alpine and Canyon Area of the Niulan River Basin Based on SBAS-InSAR and Optical Image.
This study used SBAS-InSAR, optical images, and field surveys to identify landslides in the Niulan River area. The article is well-written and suitable for publication in MDPI Remote Sensing after minor revisions.
********************************
Title: The title effectively reflects the content of the article and captures the reader's attention.
Abstract: The abstract provides a clear and concise overview of the study's objective, methodology, and results. No changes are necessary for this section.
Introduction: The introduction contains sufficient up-to-date information on the use of InSAR technology and optical imaging for landslide risk assessment. This section sets the stage for the rest of the article and does not require further revision.
Study Area and Data & Methods: The narrative in this section is clear and concise. However, I would like to recommend two minor modifications:
Line 145: If the images used were taken from Google Earth Pro, please indicate this in the text.
Lines 188-190: Add at least one relevant bibliographical reference for the Goldstein filter (line 188) and Delaunay's MCF unwrapping method (lines 188-189).
Results: The narrative of this section is clear and concise. However, I would like to propose two minor modifications:
Line 261, Figure 6: For clarity, ensure that the colors of the histogram match those used in the legend and maps.
Line 412, Figure 15: To enhance clarity, indicate the coefficient of linear correlation between the cumulative deformation values derived from SBAS-InSAR and monitoring stations in each panel. This metric allows for a quick quantitative comparison.
Discussion: The narrative of this section is clear and concise, effectively analyzing the results and their implications. No revisions are needed.
Conclusions: The narrative of this section is straightforward and well-aligned with the previous sections. The conclusions effectively summarize the study's main findings and their significance. No revisions are required.
Comments for author File: 
Comments.pdf
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on our manuscript. We have carefully considered the suggestion and make some changes. We have tried our best to improve and made some changes in the manuscript. Revision notes and point-to-point upload as attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The study applied InSAR and optical imagery and field survey to identify landslides. Although the exact methods have been applied to many other study sites, this study still has its value. The data analysis and interpretation are reliable, and the length is enough. Thus, I suggest a minor revision.
Major comments
1. The SBAS-InSAR is the main method and is the most important part of this manuscript. What does SBAS stand for? The description under 3.1 is not clear enough, and not detailed enough. It is OK to add a few equations.
2. Authors should be more careful when explaining the cause of landslides. The HP08 was selected as a typical (L343) landslide and it is next to the reservoir. But most other landslides are not next to the reservoir. How typical is HP08? Does the upstream limit of the reservoir reach the confluence near HP12? Even so, there are still many others not close to the reservoir. Does the water level along those tributaries fluctuate as much as at HP08? Thus, authors should acknowledge the limitation of section 5, or add another example such as HP25 (field verified).
3. The writing is often verbose, and authors should make it more concise (readable) to readers. I will point out some examples, but authors are recommended to revise the manuscript thoroughly.
Line specific comments
L10: “Very difficult” is inappropriate. The methods presented here do not sound very difficult.
L11: Spell SBAS-InSAR. Spell other acronyms in the introduction.
L13: where is the river?
L14: method should be goal. Delete “in the research area”; we all know it’s in the research area.
L17: delete “on the asc… data”. This was just said above.
L18: delete “the landslide” and start with “Field surveys”.
L20: delete “in the study area”. We all know it.
L21: delete “Through … results,” We all know it.
L36: delete “events”, “the safety of”.
L38: limitation should be complexity.
L74: Where is the objective of this research?
Fig 1: mark the boundary of the reservoir and flow direction.
L99-100: if it’s a canyon then most is not the bank. Is this the canyon slope or the bank slope?
Fig 2: Where was the topography data from? This figure comes before where the text talks about DEM. Fig 3 can be merged with Fig 2. The lithology was not discussed in the manuscript, so I think it’s not very important. Honestly, moving Fig 3 to the appendix does not hurt the current manuscript. Further, add rock names in the figure caption.
Fig 4: I suggest deleting this figure. The dates (or image IDs) can go to the text. Figures in general should highlight very important information.
L188-190: add references for Goldstein filter and Delaunay.
L204: Section 3.2 should come before 3.1, as in the result section.
L225: This paragraph is unclear. Did the authors use the SAR results as potential landslide locations and then view the images? Or did they thoroughly analyze the images for the entire study site?
L259: delete “whether the”
L263-276: the two paragraphs should move to the method section.
Fig 7, 8: The figures lack legends and necessary descriptions. How was the deformation threshold determined?
L306-312: This paragraph should move to the methods.
L314: I suggest using false positive or false negative referring to the errors.
L340: delete “in study area”
L352-353: delete the last sentence.
Fig 11: Add the landslide dates to figure caption.
Fig 12: when were the photos taken?
L407: I think the left side is more severe. Check Fig 15.
Fig 15: use the same scale for Y axis. It is not clear how the elevation increased over time. Was it due to new sediments caused by landslides? How were the monitoring points deployed?
Fig 16: The monitoring points had fluctuations and in 2018 a major decrease in elevation occurred. If no landslides occurred at that moment, then it would look like erosion. Erosion is also closely related to landslides. Authors should provide a better interpretation of the existing data. There is more to be explained. Claiming water level change is the cause of landslides seems arbitrary. Further, does the rainfall analysis by Li et al. also apply to the upstream landslides?
L457: Add references for related studies.
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on our manuscript. We have carefully considered the suggestion and make some changes. We have tried our best to improve and made some changes in the manuscript. Revision notes and point-to-point upload as attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
The objective of this paper is to identify potential landslides in alpine and canyon areas by implementing an analysis of terrain visibility, a combination of SBAS-InSAR, optical image and field survey for the Xiangbining Reservoir area.
This is an interesting and well-structured paper, while all necessary sections (Introduction, Study Area and Data, Methods, Results, Analysis of Typical Landslide, Discussion, Conclusions) have been considered. Moreover, the “Study Area and Data”, “Methods”, “Results”, “Analysis of Typical Landslide” and “Discussion” sections are divided into sub-sections, providing additional details. Furthermore, all Figures, Tables and Diagrams are consistent with the analysis provided in the manuscript. However, some changes should be implemented, which will improve the paper. In particular:
· Lines 38-39: This part lacks bibliographic references, related to landslide field surveys in alpine and valley areas. Indicative papers, in which the corresponding information can be obtained, are the following: 1. Cao, C., Zhu, K., Song, T., Bai, J., Zhang, W., Chen, J., & Song, S. (2022). Comparative Study on Potential Landslide Identification with ALOS-2 and Sentinel-1A Data in Heavy Forest Reach, Upstream of the Jinsha River. Remote Sensing, 14(9), 1962. https://doi.org/10.3390/rs14091962, 2. Manoutsoglou, E., Lazos, I., Steiakakis, E., & Vafeidis, A. (2022). The Geomorphological and Geological Structure of the Samaria Gorge, Crete, Greece—Geological Models Comprehensive Review and the Link with the Geomorphological Evolution. Applied Sciences, 12(20), 10670. https://doi.org/10.3390/app122010670, 3. Morelli, D., Locatelli, M., Corradi, N., Cianfarra, P., Crispini, L., Federico, L., & Migeon, S. (2022). Morpho-Structural Setting of the Ligurian Sea: The Role of Structural Heritage and Neotectonic Inversion. Journal of Marine Science and Engineering, 10(9), 1176. https://doi.org/10.3390/jmse10091176. Please, apply.
· Lines 84-96: No references have been included in this part. Please, include the relative references.
· Line 97: Please, provide Figure 1 in a higher resolution. It contains several blur parts in its current form.
· Line 128: Please, provide a lithostratigraphic column and/or a geological cross-section of the study area.
· Line 291: Please, provide a more detailed description in the Figure 7 caption.
· Line 304: Similarly, provide a more detailed description in the Figure 8 caption, please.
· Line 326: Similarly, provide a more detailed description in the Figure 9 caption, please.
· Line 473: The “Conclusions” section should be modified. In the current form, it resembles an abstract rather than conclusions. This section should be comprehensive, while the major findings of the paper should be highlighted. Maybe, numbering of the conclusion remarks could be performed. Please, apply.
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on our manuscript. We have carefully considered the suggestion and make some changes. We have tried our best to improve and made some changes in the manuscript. Revision notes and point-to-point upload as attachment.
Author Response File: Author Response.docx
