Sentinel-1 InSAR and GPS-Integrated Long-Term and Seasonal Subsidence Monitoring in Houston, Texas, USA
Round 1
Reviewer 1 Report
I recommend accepting the paper in its present form.
Author Response
Dear Reviewer,
Thank you so much for going through the first-round review in such a short time. We have thoroughly revised the manuscript according to the comments from reviewers. A proofreading is conducted.
A point-to-point response to reviewer’s comments is included.
Best,
Yuhao Liu and co-authors
##### Point-to-Point Responses
Review 1
No specific comments.
Reviewer 2 Report
The authors show a case study of using GNSS and Sentinel-1A SAR observations to monitor the surface subsidence over Houston, and indicates the improvement of integrated observations in capturing the long-term and seasonal deformation variations associated with groundwater extraction. The study will provide of sound evidence in urban planning and groundwater management. Overall, I think the topic is interesting and should be published after the following suggestions:
1. Please show more information about GNSS- and InSAR-derived surface deformation results over Houston in the section of Introduction. The authors used plenty of sentences to introduce the GNSS constructing history in paragraph 3. I think this information should be moved to the Section 2.2. The readers may be more interested in the GNSS-derived surfaced deformation results in the last few decades. It is similar with paragraph 4 that the readers are more concerning on the InSAR-derived surfaced deformation results in the past, other than the used datasets.
2. The geological background should be added in Section.2. I suggest the authors to introduce the geological history with the study area since the geological conditions are the controlling factors for deformation pattern.
3. Why not extending the InSAR datasets to 2022?
4. In the InSAR data processing, the authors fitted a residual surface of the difference between InSAR- and GNSS-derived deformation, and then subtracted this surface from the InSAR interferograms. The authors claimed that this operation could mitigate the InSAR atmospheric delay and other error source. I think the authors should clarify which model was used, and how about the performance. It is better to show some interferograms before and after the correction.
Author Response
Dear Reviewer,
We have finished the point-to-point response to your comments. Please see the attachment.
Best wishes,
Yuhao
Author Response File: 
Author Response.docx
Reviewer 3 Report
The work concerns an interesting and at the same time important not only from the scientific point of view problem of the development of land subsidence as a result of groundwater exploitation in Houston, Texas. The work is well designed, written correctly and logically, the way of presentation does not raise any major objections, and the conclusions result from the results and their discussion. However, I have a few critical comments and questions about the research done:
How large are the land subsidences in the study area, globally, during the 100 years already mentioned in the first sentence of the abstract?
Is the rate and course of land subsidence in areas of groundwater exploitation similar to that which occurs in areas of hard coal or oil exploitation?
The downside of the work is a rather small review of the literature (only 42 items), 99% of the literature concerns the Houston area, and there are no references to studies on land subsidence from other parts of the world. It seems to me that it would be worth referring to work from other regions, and those that raise the problem of subsidence as a result of not only water exploitation, but also other raw materials, e.g.:
Persian, Z. (2005). Application of SAR Imagery and SAR Interferometry in Digital Geological Cartography. In: Ostaficzuk, S.R. (eds) The Current Role of Geological Mapping in Geosciences. NATO Science Series, vol 56. Springer, Dordrecht. https://doi.org/10.1007/1-4020-3551-9_22
Nadudvari, Adam. "Using radar interferometry and SBAS technique to detect surface subsidence relating to coal mining in Upper Silesia from 1993-2000 and 2003-2010" Environmental & Socio-economic Studies, vol.4, no.1, 2016, pp.24-34. https://doi.org/10.1515/environ-2016-0003
Przyłucka, M.; Herrera, G.; Border, M.; Colombo, D.; Béjar-Pizarro, M. Combination of Conventional and Advanced DInSAR to Monitor Very Fast Mining Subsidence with TerraSAR-X Data: Bytom City (Poland). Remote Sens. 2015, 7, 5300-5328. https://doi.org/10.3390/rs70505300
Solarski, M., Machowski, R., Rzetala, M. et al. Hypsometric changes in urban areas resulting from multiple years of mining activity. Sci Rep. 12, 2982 (2022). https://doi.org/10.1038/s41598-022-06847-8
Chaussard, E., Amelung, F., Abidin, H. & Hong, S. H. Sinking Cities in Indonesia: ALOS-PALSAR detects rapid subsidence due to groundwater and gas extraction. Remote Sens. Environ. 128, 150–161.
Kaneko, S. & Toyota, T. Long-term urbanization and land subsidence in Asian megacities: an indicators system approach. In Groundwater and Subsurface Environments: Human Impacts in Asian Coastal Cities (ed. Taniguchi, M.) 249–270
Figure 1 needs improvement: Add the outline of the United States and correct the longitude coordinates as they are partially covered.
Author Response
Dear Reviewer,
We have finished the point-to-point response to your comments. Please see the attachment.
Best wishes,
Yuhao
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors addressed all my questions and should be published as the current version.
Reviewer 3 Report
The authors partially addressed my review, omitting some of the comments, however, I will not insist and spit into the wind.
