Evaluating Characteristics of an Active Coastal Spreading Area Combining Geophysical Data with Satellite, Aerial, and Unmanned Aerial Vehicles Images

Round 1

Reviewer 1 Report

The authors presents an article on the development of a methodology of coastal erosion monitoring in the Maltese Islands. The approach consists of satellite remote sensing and field surveys with technologies such as LIDAR and aerial photogrammetry acquired by Unmanned Aerial Vehicles (UAV) to allow the detailed identification of fractures in the rock blocks of the cliffs. Geophysical investigations (ERT, GPR) are also added to the geomatics, useful for identifying the fractured areas that contribute to landslides.

The introductory and methodological chapters show an extensive bibliographic search, a clear exposition of the state of the art and a solid general knowledge of the topics covered. All the geomatic and geophysical acquisitions are presented in a systematic and accurate way, the results are discussed with criterion and a robust interpretation is given. The geomatic and geophysical results are quite robust and are used with some success for the estimation of the volumes of the rock blocks and for dynamic simulations of the collapses. The elaboration of the text is adequate, and the data presented are generally of good quality. General terms and scientific concepts are clearly and authoritatively defined, with reference to the appropriate recent literature.

In conclusion, based on these observations, I recommend to accept the paper in its present form.

Comments for author File: Comments.pdf

Author Response

We thank the Reviewer for the positive comment

Reviewer 2 Report

Generating 3D geological models are great of interest but this paper against the claimed in line 30-31 absolutely not only cannot be categorized as approach but also is not new and in compare with many distinguished works with more complicated 3D models as some of them are mentioned in the comments fails with several technical problems.

Overall, the whole of process is routine data collection and integrating on GIS which prevented to recommend this work for publication.

Just for example, one of the first and main problem here is assigned to perquisite requirement of the unified pixel size for GIS. Resizing or resampling never can be the response and for overlaying the image fusion or image enhance processing must be carried out. What was the solution??? A novel approach for image fusion can be found at https://www.sciencedirect.com/science/article/abs/pii/S0341816219303674.

As another problem, L86-87: ‘More recently, other results deriving from advanced Syn-86 thetic Aperture Radar (SAR)’??? which results??? I just would like to know how the problem filtering step and the unwrapping phase step which are sensitive have been treated?? Or solution for temporal changes in the physical or geometrical nature of the geo-material lead to a decorrelation in radar echoes??? Or interpreted displacement along the line of sight in 2D between satellite and field, or ……

Some of the other technical and general comments are listed below:

Technically:

1.           English must and have to be refurnished by native expert. Several linguistic flaws, repeated words, vague statements , … must be rephrased. The job has been done so it is past, why use of present and future tenses?

2.           Poor introduction and shallow literature review. It is very hard to outline what the main problem is and which goal is pursued. The Abstract talks about the 3D modeling while here nothing concerning that can be characterized. What are the main gaps of previous works? Which limitation and according to which criteria is going to be filled? With what method? what motives for? what is the main novelty of this work? the main advantage of this work over previous ones? Any characterized significant of contributions??

3.           difficulty of quantifying the reliability of tomographic images due to the source of uncertainty in tomographic inversion and data error must be discussed.

4.           How the problem of spatial subsurface distribution for the area with the gap of data has been overcome?? The distance between the measured strikes???, … Something like discussed at https://www.nature.com/articles/sdata2018238,  https://datascience.codata.org/articles/abstract/10.2481/dsj.6.S652/

5.           Any individual test points for collecting the observational data??

6.           The results of the used dipole-Dipole array due to constraints cannot be representative for long extrapolation. Any technical discussion on that??

7.           How did you overcome on the lateral dispreading issue???? The interpretation of deep  investigations for geological structures complexities??? Accuracy of depth determination??? Searching for permeable beds??? Raised difficulties from the occurrence of brine bearing deposits near the coast, and water from the depths with a high salt content???

8.           Due to constraint and limitation of geoelectrical sounding, this is not possible for long extrapolation.

9.           GPR data collection requires for relatively flat to be ensure optimal penetration. Where di this limitation has ben discussed in your results??

10.         Another well recognized concern but totally lacked here is referred to time dependent data, where due to subsurface heterogeneity cannot provide any generalization from a single study. I cannot see any analyses for them as because in your study it seriously suffers from accurately identifying the correct model to represent the data. Moreover, the past time dependent data are not enough to predict the future. Multiple additional features should be considered to get good forecasts. How did you judge the efficiently dealing with outliers?

11.         The inclusion the uncertainty for clean datasets is high. What about the uncertainty of applied inputs and presented output?? You have done an experimental job, therefore, definitely uncertainty is involved. This issue must be clarified and thus looking at papers dealing on uncertainty like https://link.springer.com/article/10.1007/s12583-021-1434-y, https://www.sciencedirect.com/science/article/abs/pii/S0375674218302954?via%3Dihub, https://www.searchanddiscovery.com/abstracts/html/2016/90259ace/abstracts/2381772.html, … are  highly advised.

12.         How the overlay procedure in GIS has been carried out? With what strategy? I curiously would like to know how the weights are assigned and saved? the given results only uncover the samples and won't determine what variables have the most influence. Extraneous variables might interfere with the information and thus outcomes can be adversely impacted by the quality of the work. Therefore, looking at https://www.sciencedirect.com/science/article/abs/pii/S0169136817309927, https://www.sciencedirect.com/science/article/abs/pii/S0013795217314734?via%3Dihub,  https://doi.org/10.3390/geosciences8110405 or ... are highly recommended.

13.         Poor discussion in terms of accuracy performance, validation data, evidential analysis, comparing with other models, uncertainty analysis, sensitivity analysis and … Any discussion on limitations of presented method??? Can you prove the convergence or stability of the model???? Any explicit discussion to illustrate the limitations, pitfalls and practical difficulties of applied model under certainty???? Any computational time analysis??? The work lacks for a prior impact assessment and cost-benefit analysis and did not anticipate solutions for the possible consequences in advance.

14.         Absolutely and without any doubt unjustified and unacceptable conclusion. Definitely must be reformulated and truncated. Most of that is not supported by context. Figure  in conclusion??? Where di you talk about the warning system???? L474-486 is just general lecturing.

General comments:

A.           Keywords should be representative and available in both Abstract and context. All the used keywords just are general terms in which no specificity for this work can be depicted from. Where di you talk about GPR or ERT??? Monitoring of what? geophysics!!! Geomatics!!!

B.           L30-31: Data integration is not an approach. This is very obvious concept.

C.           Each used abbreviation must be defined in full format even they are recognized.

D.          L 25: for which interval time between images???

E.           Abstract actually is very opaque and doesn’t inspire any novelty.

F.           Which part of the Fig 1 has been modified?

Author Response

Please find the answers in the attached file

Author Response File: Author Response.pdf

Reviewer 3 Report

The article presents the result of comparative research on the course of the already existing phenomenon of detachment of rock blocks. The presented test site has been discussed in detail and is a rich material for further observation of the phenomenon on the Selmun promontory. The article is a good case study.

In an objective assessment, however, it should be stated that despite the indicated purpose of these studies, which was to develop an integrated method for monitoring and studying coastal hazards and cliff failures, the paper does not present a method of general application. The formulated conclusions do not constitute a description of the general method of monitoring the phenomenon. The authors should expand their research activities with possible methods of early warning about existing risks and threats.

Author Response

"In an objective assessment, however, it should be stated that despite the indicated purpose of these studies, which was to develop an integrated method for monitoring and studying coastal hazards and cliff failures, the paper does not present a method of general application."

We clarified this issue throughout the manuscript

"The formulated conclusions do not constitute a description of the general method of monitoring the phenomenon. The authors should expand their research activities with possible methods of early warning about existing risks and threats."

We clarified this issue throughout the manuscript

Round 2

Reviewer 2 Report

I read all the responses and to save the time gave them up because almost didn’t satisfy the comments. I just left some words and ignore for the authors text denoting ‘ In our opinion, the reviewer did not read the paper properly and/or is giving comments in a malicious way’.!!!!!

Dear authors

First of all, we are here to help each other for producing high quality but scientific works to attract more readers. Therefore, ‘political’ context cannot be a good reason to document it as the aspect of novelty. Moreover, if this area is an important section based on archipelago definitely the survey and investigation must be much deeper because the results maybe the cultural heritage.

Second, referring to template of Journal, you have the line numbers, and it is expected to see them in the response as it is not the reviewer task to look up the context and find them. For example, ‘Regarding the uncertainty associated with images quality, a few sentences have been added in the discussion section.’,

When we talk about the routine procedure, it directly is assigned to applied method. I curiously would like to know which part of ERT or GPR is novel in this work?? These methods have long been used and the data gathering for primary prospecting by such these methods are obviously well known.

Fourth, concerning the ‘With all due respect, we disagree…’, I read the paper carefully and the left technical comments show that. I think you misunderstood and with respect to your carrier the comments are very scientific and directly referred to the implemented platform of the applied method. If during the last 60 years, the cliff area against the other neighborhoods hasn’t been studied is not the case and can be attributed to many several scientific reasons. A scientific concern exactly was left in #7 and you pretty responded that ‘there are no major complexities at depth’. Just this response is enough to understand why since last 60 years this area didn’t have been attracted other scholars.

Fifth, In geological concept the lack of data for such areas can be common because of many problems like lack of equipment, hardness to access, haulage systems, operational difficulties, … and the whole of your work is an attempt to map this small-scale area. I curiously would like to know that what was the main reason that since last 60 years no scholar have focused on this area, however as you mentioned the neighborhoods were investigated?? This is exactly against

Sixth, technically, you have gathered ERT data for a length of 155m with 32 electrodes, and then GPR. For one line or several lines??? If several lines, the distance between them? Scientifically, which part of ERT based on your response is novel? What about the GPR? Then this data in GIS and through the utilized toolboxes are interpolated to show the results.

Seventh, in Line 86-87 and then now in lines 87-89, ‘other results deriving from advanced Syn-87 thetic Aperture Radar (SAR) interferometric analysis made it possible to measure the 88 speed (ranging from 1 to 7 mm/year) and trend of the deformations over a period of about 89 20 years [14].’ This is your exact statement. I also exactly asked which results??? Filtering problem??? and … you referred me to ‘

 We kindly ask the Reviewer to refer to the authors of the paper for any further clarification needed’?????? Did you have used this data or not????

Eights, I asked for English revision. You have done the job why use of present tenses??? Why not be consistent in utilizing third passive voices??? Why ‘we’, ‘our’, …

Author Response

Please see the attachment

Author Response File: Author Response.docx