What Have We Learned from the Past? An Analysis of Ground Deformations in Urban Areas of Palermo (Sicily, Italy) by Means of Multi-Temporal Synthetic Aperture Radar Interferometry Techniques
, Pietro Miele 1, Luigi Petti 2, Domenico Guida 2, Francesco Maria Guadagno 3, Raffaele Moschillo 1 and Annamaria Vicari 1Round 1
Reviewer 1 Report
The paper concerns an interesting application of the InSAR remote sensing methodology to investigate the ground deformation pattern in the urban area of Palermo (Sicily). To-date, there is a great interest to novel applications of Earth Observation technologies for studying the geological hazards in urban areas interested by rapid urbanization processes and anthropic activities. Then, papers about this topic are welcomed and must be encouraged.
The overall organization of the manuscript is quite good, the approach used for processing and analyse the SAR images is robust, and sounds with the current state-of-the-art.
I have only few comments.
- In the paragraph "Discussion" more details and analyses about the correlation between lithologic properties of the shallow layers and the spatial patterns of ground deformation could increase the interest for the scientific results.
- There are no information about the possible errors and/or limits in the selection of the PS grid;
- The multilooking factor technique used for improving the Signal-to-Noise Ratio could be better described.
- The captions of the Figg. 6 and 7 are not completely informative.
The paper can be considered suitable for publication after a fast minor revision.
The quality of the English form is good, I suggest only a fast revision.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work submitted to me for evaluation raises an interesting and important problem, not only from a scientific perspective, regarding the detection of land subsidence in an urban area (Palermo, for example) using remote sensing tools and GIS techniques. I believe that the work has publication potential but requires a few corrections. First of all, its innovative aspect should be emphasized more. What is the new achievement of this work compared to previous research? The discussion of research results also requires improvement. In its current form, it is too laconic. The introduction to the problem of land subsidence in urban areas should also be expanded in relation to works from different parts of the world, e.g:
Nádudvari, Ádám. "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
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
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 (Springer, 2011).
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. https://doi.org/10.1016/j.rse.2012.10.015 (2013).
-
Dai, L. Preventing and Controlling Land Subsidence in Shanghai—towards more integrated and effective land use and ground water governance in the Yangtze Delta. http://meetingorganizer.copernicus.org/EGU2016/EGU2016-16451.pdf (Accessed 5 May 2019) (2016).
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Dear authors, thank you for the manuscript. It concerns InSAR monitoring of Palermo city and comparison with in-situ results.
There is nothing novel in the article; however, I only have few minor comments.
- figure 2: mentioning "thick red line", do you mean the black line A'-A in the upper figure?
- coherence threshold of 0.75: this way you only find points moving in a linear way over 7 years (+ thermal component). Higher non-linearities may remain hidden however more dangerous
- spatial reference of the two tracks was not mentioned, however it may affect especially the E-W component
- chapter 3: "targets with velocity rates faster than 2 mm/Y": up, or down?
- chapter 5: why do you consider 1 mm/y as a threshold? Do you evaluate velocity accuracy?
- chapter 3: "PSs velocity values ranging" etc.
- chapter 4: "the obtained results by MT-InSAR described approach"
- chapter 5: "PSs with velocities larger" -> higher
- chapter 5: "frequency (8-16 days) SAR satellite constellations"
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The article has been corrected and supplemented, so I believe it can be published in the current version.
