Detection Ground Deformation Characteristics of Reclamation Land with Time-Series Interferometric Synthetic Aperture Radar in Tianjin Binhai New Area, China
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis article uses the SBAS-InSAR method to analyze the surface deformation of Tianjin Binhai New Area from January 2017 to December 2022. It deeply analyzes the relationship between land subsidence and the time and land use type of reclamation projects, which is of great significance for ensuring the safety of infrastructure, and planning the design of artificial reclamation in Binhai New Area. The paper is sufficiently well written and clear. The Reviewer has only the following suggestions to improve it.
1) L128 What is the role and meaning of Precision? What does the its value represent? Here you need to provide a detailed explanation. This method refers to other references, so there should be corresponding references here.
2) L33 Is the land use type based on visual interpretation of GF-1 and GE-2 images or is it automatically extracted by computer? Need to explain.
3) The validation of SBAS-InSAR results using Precision is not convincing, and it is better to verify with leveling or GPS results. If these data cannot be obtained, their reliability can be verified with other InSAR methods, such as PS-InSAR results, which will be more convincing.
Author Response
Dear Reviewer:
Thank you comments our manuscript entitled “Detection Ground Deformation characteristics of Reclamation Land with Time-Series InSAR in Tianjin Binhai New Area, china”. Those comments are all valuable and very helpful and improving our manuscript, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections. Modifications are in the uploaded file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript utilizes SBAS-InSAR technology to monitor surface deformation in Tianjin Binhai New Area from 2017 to 2022, and analyzes the relationship between land subsidence, reclamation projects time, and land use types. The research results of the manuscript have good reference value for guiding coastal development and construction planning.
1.Page 4, Line 121, " a spatial baseline threshold of 10% were set" is difficult to understand, please explain it.
2. Page 4, "A total of 710 image pairs were acquired". Is all image pairs used for this study? It is recommended to only count and display the image pairs used for this study.
3.Formula 1, is there a reference for this accuracy estimation method? If there are any, please provide them. If there are no references, please explain their meanings.
4. Figure 2, as most of the numbers are overlap and cannot be recognized, it is recommended not to display them in the figure.
5.Please provide the reference area for ground deformation in Figure 3 and explain it in the text.
6.Figure 3, please explain the reason for the difference in land subsidence rate between P2 and P3 points after 2020.
7.5 Conclusion, it is recommended to simplify. The conclusion is not a repeated description of the experimental results, but a summary of the rules or experiences obtained from the experimental results, and should have a high degree of generality.
Author Response
Dear Reviewer:
Thank you comments our manuscript entitled “Detection Ground Deformation characteristics of Reclamation Land with Time-Series InSAR in Tianjin Binhai New Area, china”. Those comments are all valuable and very helpful and improving our manuscript, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections. Modifications are in the uploaded file.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper does not describe well the Sentinel data used, for example it doesn't say if they correspond to an ascending or descending orbit, or a combination of both. If it is just one orbit, why did not you used the other one?
Why did not used Sentinel-1B data?
Master image used to coregister the entire dataset is not the first one, is this for some reason? Did you take into account this to assess the deformation?
What is the anchor point used to measure deformation, because to the southwest part of the polygon that delimits the study area, there are zones close to Tianjin Central Urban Area in orange, yellow or green that correspond to magnitudes of deformation above -80 mm according to the colorbar used. It means that those zones have a very high deformation contrary to what you have been saying in the document where you say that surface deformation gradually intensifies from west to east. How can this be explained?
Did you carry out some atmospheric correction?
In the paper in some parts it is not clear why you talk about deformation in east-west direction, in areas like for example Hangu Port that it is not oriented in the same way that the other ports or in line 182 where it is not clear if you are talking about a decomposition of the deformation. In my opinion, the reference should be the sea, not east or west.
In case you are talking about component east of the deformation, you should describe how it is estimated. In order to obtain some component of the deformation, it is not enough with only one pass, so, if there are no ascending and descending passes, it is not appropriate to talk about this component in the paper but about a deformation in Line Of Sight (LOS).
Check the text format, spaces, on page 2, line 51, there is a reference that is not printed, it appears as [?].
In the document you say that Landsat5, Landsat7 and Landsat8 images were used for the analysis of changes in the coastline from 1986 to 2023, however, in the document results appear from 1995 and in the conclusions it is written that images up to 2022 were used.
Figure 1 should be referenced in the text.
In the methodology, line 121, the baseline threshold is not appropriately informed. 10% of what? It is not measured as a percentage.
Line 148 Hangu Port has more deformation in the "western" area, this is not opposite to the deformation you have been mentioning?
Sometimes it is not easy to check the profiles or the letters in available figures. In figure 8, for example, it is not clear the letter "C" in the figure and also it is too difficult to check the profile line F-F'.
Author Response
Dear Reviewer:
Thank you comments our manuscript entitled “Detection Ground Deformation characteristics of Reclamation Land with Time-Series InSAR in Tianjin Binhai New Area, china”. Those comments are all valuable and very helpful and improving our manuscript, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections. Modifications are in the uploaded file.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for Authors1. In the first paragraph of the introduction, please write from global to the local issue.
2. In the introduction section, especially line 73, please explain more about the multi-time series InSAR, SBAS, and why you chose the SBAS method. The reason for the SBAS method you have employed should be more substantial based on scientific reasoning.
3. In the Datasheet sub-section, line 105, please explain how to choose the data related to the normal baseline. And why did you choose that datasheet?
4. In the methodology sub-section, please explain the coherence threshold of your processing and other relevant parameter in more detail.
5. In line 136 about result and validation, it is essential to validate SBAS results with other methods, such as Leveling, GNSS, ground sensor, etc.
6. Regarding driving factors of land subsidence in Tianjin, please make a statistical analysis of the dominant factor of land subsidence.
Author Response
Dear Reviewer:
Thank you comments our manuscript entitled “Detection Ground Deformation characteristics of Reclamation Land with Time-Series InSAR in Tianjin Binhai New Area, china”. Those comments are all valuable and very helpful and improving our manuscript, as well as the important guiding significance to our researches. We have studied comments carefully and have made corrections. Modifications are in the uploaded file.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for Authors- The document indicates that it estimates the vertical component of the deformation, however it is not appropriate to calculate that component using just a single orbit unless you state there is no horizontal component in the deformation, otherwise there may be an over/under estimation on this component:
Sami, et al. On the effect of horizontal deformation on InSAR subsidence estimates. En Fringe 2009, Proceedings of the workshop Held 30 November-4 December 2009, in Frascati, Italy. Edited by H. Lacoste. ESA-SP Vol. 677. ISBN: ISBN: 978-92-9221-241-4, 2010, id. 39. 2010.
- Check in depth spacing, references that appear with a [?] and so on.
- In line 115 they say they used images until 2023, however in the rest of the document they talk about 2022. Correct this.
- Again it is not clear to me why the results and maps start from 1995, 9 years after the first image used which is in 1986, where are the analyses of the previous results?
Author Response
Dear reviewer:
Thank you for your invaluable feedback on our article. Your insightful suggestions have greatly contributed to its improvement. We have carefully incorporated the necessary revisions according to your recommendations. Additionally, the revision notes and the updated manuscript have already been uploaded.
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe revised manuscript meets the previous review.
Author Response
Dear reviewer:
Thank you for your invaluable feedback on our article.
