Land Subsidence Monitoring and Dynamic Prediction of Reclaimed Islands with Multi-Temporal InSAR Techniques in Xiamen and Zhangzhou Cities, China
Round 1
Reviewer 1 Report
The authors propose a study on land subsidence in areas affected by recent and uncompleted land reclamation. They process the SAR images by using different satellite interferometry techniques, also applying a sequential method and a geotechnical model in order to predict the amount of vertical land deformations. The work is overall clear although there are several aspects to be improved, especially to clarified the innovative scope of their study.
Major comments are listed below:
Introduction:
The introduction attempts to give an overview of land reclamation, Earth observation satellite techniques and proposed study. Perhaps the topic of land reclamation in relation with land subsidence and effetcs, which is mentioned in a few lines, should be better described.
A very important point concerns the sequential technique applied to SAR images and geotechnical models. These issues are central to the study and are not covered in the introduction. In fact, it is preferred to give very general references (land reclamation, DInSAR techniques etc.), but not deal with these central aspects. In my opinion, more emphasis needs to be given to these issues by better explaining their state of the art.
It is also not clear which is the novelty of the study.
2.1 Study area:
the reclamation project is described and the progress of work reclamation is shown, but neither the description of the subsoil on which the islands are located in geological terms, nor the possible use of other materials to perimeter the reclaimed areas, to build levees, etc., is addressed.
2.2 Data:
It lacks a description of how the images were acquired (band, polarization, etc.) or the source and the details of SAR images.
In addition, it may be useful to introduce a table showing, for example, the study areas with respect to the period of coverage of the SAR images and the used SAR processing techniques (e.g., SBAS etc.). It improve the readability of next paragraphs avoiding repetitions (e.g. 212-215).
Finally, it may be appropriate to describe here the reasons for using one processing technique rather than another, moving and expand these parts from the "Results" section (e.g. 226-229).
Line 201: I suggest better describing what is meant by a geotechnical model by first making a distinction between empirical curves (statistical models) and physically based numerical models. The geotechnical model is not clarified in the previous sections and there are no explicit bibliographical references. For these reasons it becomes difficult to understand where the proposed formulation comes from, whether this is a novelty introduced by them, whether it is a formula modified by other authors, etc.
Minor comments are added in the paper in the form of comments (see pdf file).
Comments for author File: 
Comments.pdf
Author Response
see seperate attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Editor/Authors,
I have read the manuscript remotesensing-1740087 entitled “Land subsidence monitoring and dynamic prediction of reclaimed islands with Multi-temporal InSAR techniques in Xiamen and Zhangzhou cities, China”, written by Li et collab., and submitted for publishing to Remote Sensing Journal. In general, the paper is well written, with good results in the evaluation of past land subsidence of two recent islands from SE China. The method used is well described and the results present a real scientific interest. Some revisions should be made in order to increase the scientific impact of the paper: (i) parts of the 5th part are results and not discussions; (ii) a discussion part must frame the current results in a broader presentation of the subject, by taking into consideration similar approaches (so, I recommend rewriting entire Discussion part).
Other suggestions in the *.pdf file attached.
Best regards and congratulation for good work !
Comments for author File: Comments.pdf
Author Response
see seperate attachment.
Author Response File: Author Response.docx
Reviewer 3 Report
The paper monitors land subsidence and uses these measurements for dynamic prediction of reclaimed islands with nSAR techniques.
Regarding the land subsidence measurements, they are interesting. It is recommended to study possibly seasonal (yearly) fluctuation in ground subsidence due to the raining seasons and in this respect it will be interesting to compare vertical settlement at the same month per year.
Regarding the dynamic prediction, the paper claims that it used a “geotechnical model”. Yet, no geotechnical data of soil profile is given. Indeed, prior to the reliable prediction of future settlement rate, the 1-d consolidation theory must be briefly discussed, the underlying soil materials as obtained by geotechnical investigations should be discussed, the soft fine-grained soil layers causing consolidation should be detected and their expected response should be discussed and compared, with (or calibrated by) field measurements. If the comparison is successful, then the 1-d consolidation theory with the adequate model parameters may be applied for future settlement predictions. If the above are not performed, the “predictions” presented are not reliable. This should be discussed in the paper, with the procedure described above to achieve better predictions. Even better it would be to apply the procedure outlined above to predict future settlement.
References
Chai J. C., Shen S. L., Zhu H. H. and Zhang X. L. 2005. 1D analysis of land subsidence in Shanghai, Lowland Technology International, Vol. 7, No. 1, 33-41, June
Lambe T., Whitman R., 1969, Soils Mechanics, John Wiley & Sons, Ch.12, p.156
Stamatopoulos C., Petridis P., Parcharidis I., Foumelis M. 2018. A method predicting pumping-induced ground settlement using back-analysis and its application in the Karla region of Greece. Natural Hazards volume 92, pages 1733–1762
Author Response
see attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
I think that the manuscript has undergone significant changes. In my opinion, a moderate revision in English could be done. Finally, two references could also be added at the beginning of the Introduction, so that the statements do not appear too general.Example:
Shuai Jiang, Nan Xu, Zhichao Li, Conghong Huang,2021: Satellite derived coastal reclamation expansion in China since the 21st century. Global Ecology and Conservation, 30, e01797.https://doi.org/10.1016/j.gecco.2021.e01797W.
Chen, D. Wang, Y. Huang, L. Chen, L. Zhang, X.Wei, M. Sang, F. Wang, J. Liu, B. Hu (2017): Monitoring and analysis of coastal reclamation from 1995-2015 in Tianjin Binhai New Area, China. Sci. Rep., 7,1-12. 10.1038/s41598-017-04155-0
Author Response
I think that the manuscript has undergone significant changes. In my opinion, a moderate revision in English could be done. Finally, two references could also be added at the beginning of the Introduction, so that the statements do not appear too general.
Example:
Shuai Jiang, Nan Xu, Zhichao Li, Conghong Huang,2021: Satellite derived coastal reclamation expansion in China since the 21st century. Global Ecology and Conservation, 30, e01797.https://doi.org/10.1016/j.gecco.2021.e01797W.
Chen, D. Wang, Y. Huang, L. Chen, L. Zhang, X.Wei, M. Sang, F. Wang, J. Liu, B. Hu (2017): Monitoring and analysis of coastal reclamation from 1995-2015 in Tianjin Binhai New Area, China. Sci. Rep., 7,1-12. 10.1038/s41598-017-04155-0
>>We would like to thank you for the positive comments. We have checked and revised the English expression carefully. Besides, two references have been added at the beginning of the introduction, see lines 32-34 of the revised manuscript.
Reviewer 2 Report
Accept as is
Author Response
Many thanks for your comments.
Reviewer 3 Report
The paper can be published in its present form
Author Response
Thanks for your comments.
