Round 1

Reviewer 1 Report

Overall summary

The paper analyzed the short-time dynamics of the Vomice earthflow using two UAV flights derived data (2019 and 2022) and field surveys. The software, methodology and results were clearly explained. The methods are widely used in the field of geomorphology and geohazards as well as in other related sciences. The authors made some estimations about the changes in elevation using the DoD method and compute the volume differences.

I find the paper proper to be published in the Geosciences journal, but minor revisions are needed.

Below you can find some of my remarks after reading the article. All of them represent minor issues that must be explained or amended accordingly.

Lines

13: In the manuscript, you wrote ”earth flow” seven times and ”earthflow” 20 times. For the consistency of the paper use the same form.

15: In the manuscript, you mentioned a flight from June 2022. Is the flight from 2021 or 2022?

39: What geotechnical processes?

40: Deformation is not a landslide feature. Landslide deformation is a general term that implies changes in shape and does not imply a unique landslide feature.

49: I do not understand the syntagm”pervasive outcrop” used here.

50: soils... maybe is better to use Varnes's material typology, respectively earth, debris and rock (Varnes 1978). Just my opinion.

78-79: In fact, the structure-from-motion (SfM) is not a recent technique. See Ullman's works during the 70es and 80es (Ullman 1976, 1983). Maybe you wanted to say that it is a relatively new technique used for UAV-derived data.

87-88: Digital Elevation Models (DTMs). Please use the proper abbreviated term – DEM for Digital Elevation Model and DTM for Digital Terrain Model.  

95: Suggestion: located in ”the” NE sector of ”the” Calabria region (Southern Italy).

100: DEMs or DTMs? Also, I suggest finding another word for ”realize” (maybe ”generate”).

108: Figures 6a and 6b are not cited individually in the text.

116: I think the source of data (for the DEM) is needed here for Figure 6a.

117: Dated 2014? Is the correct year?

121-123: Please use only singular or plural for lithology description. You have in the same sentence ”sandstones” and ”sandstone”. Also, you must use the upper case for the ”formation” term (Albidona Formation) because of the proper noun characteristic. I saw that you used the same format for other formations and units (e.g. Saraceno Formation, Sicilide Unit etc.).

133: Figure 2 – Please assure a higher resolution of the geostructural map for publication. Also, you have two different coordinate systems on the grid which makes it difficult to read them. Maybe you can highlight one of them in bold or italic.

154: The investigated area has approximately 36.4 hectares. But in table 1 you indicate 1274 and 1268 hectares. There is a huge disproportion between these values (about 35 times greater). Can you explain this difference?

160: If we use L = 1720 m and difference in height (H) = 330 m, then H/L =0.19. Is this correct?

180: I think worth mentioning what planning software was used.

191: The year is wrong. According to table 1, these values are from 2022.

193-194: Table 4: Again, June 2021 or June 2022?

208: Suggestion: Cite Pix4D photogrammetry software producer (the website or manual); e.g. Pix4D SA.

213: You need to cite this software accordingly (authors of the software and/or the website). From my knowledge is about the work of Lague et al. (2013).

220:  Please use the letters a) and b) for Figure 3 to indicate the year in order to assure the uniformity of the manuscript graphic. The letters must be used for both the image and figure caption.

240: Suggestion: use just ”landslide” instead of ”landslide area”.

254: ”Achieved” instead of ”archived”.

255: Reference no. 67 (Wheaton et al. 2009) is actually from 2010 (Wheaton et al. 2010), not from 2009. It was first published online in December 2009, but the article is part of a volume from February 2010.

271: Worth ”noting” instead of worth ”nothing”.

278: From my point of view, you have a  weird repetition of ”landslide in landslide zones”. Maybe you can find another way to explain that.

290: Caption of Figure 6 has a) and b). In the text, there are cited only Figure 6 and Figure 6b. There is no mention of Figure 6a.

332: ”Landslide inventory map of Vomice landslide”. Maybe you can reformulate this.

352: ”concentrated”.

353: Suggestions: many parts (or areas) of the depletion area were...; ”reactivated” instead of ”re-activated”.

355: remobilized.

360: Suggestion: delete ”for”.

380: Suggestion: replace semicolon (;) with a comma (,), so that the text flows better.

385: Insert ”the” between evidenced and depletion.

398-399: Caption of Tabel 4 mention a DTM from June 2021 instead of 2022.

444: You mention the June 2015 period instead of June 2022. ”Since” probably must be changed with ”between”.

448: Suggestion: ”with a consistent loss of material” instead of ”with a consistent lost material”.

455: ”achieved” instead of ”archived”.

479: Suggestion: ”temporal” instead of ”time”.

486: Again ”June 2021” instead of ”June 2022”.

493: ”remobilized” instead of ”re-mobilized”.

498: Suggestion: UAV-derived data...

Best regards,

References

Lague D, Brodu N, Leroux J (2013) Accurate 3D comparison of complex topography with terrestrial laser scanner: Application to the Rangitikei canyon (N-Z). ISPRS J Photogramm Remote Sens 82:10–26. https://doi.org/https://doi.org/10.1016/j.isprsjprs.2013.04.009

Ullman S (1976) The interpretation of Structure from Motion. Massachusetts Inst Technol Artif Intell Lab AI Memo 476, Oct 1976 1–7

Ullman S (1983) Computational studies in the interpretation of Structure and Motion: summary and extension. Massachusetts Inst Technol Artif Intell Lab AI Memo 706, March 1983 1–25

Varnes DJ (1978) Slope movement types and processes. In: Landslides-Analysis and Control: Transportation Research Board. pp 11–28

Wheaton JM, Brasington J, Darby SE, Sear DA (2010) Accounting for uncertainty in DEMs from repeat topographic surveys: improved sediment budgets. Earth Surf Process Landforms 35:136–156. https://doi.org/10.1002/ESP.1886

Author Response

Dear Reviewer, we revised the manuscript following the notes in the review reports. We studied your comments carefully and made the corrections that we hope meets your approval. All the changes were marked in red in the text. In the attachemnt file you will find point-by-point our responses to your comments

Author Response File: Author Response.pdf

Reviewer 2 Report

The main objective of this study is to investigate the possibility to detect the short time evolution of the slow moving Vomice earth flow, located in north-eastern sector of the Calabria region (South Italy), by combining the information obtained from two different drone flights, carried out in February 2019 and June 2021, with field surveys. The relevantly results have been analyzed, and this achievement demonstrated that the practicality and feasibility of using UAV tools for detecting the short-time evolution of a large landslide. This study was very meaning, overall, I recommend minor revise following the comments below.

1.      If ‘Ln 34 ~ 37’ and ‘Ln 43 ~ 47’ can be merged and reorganize the language, and it may be well.

2.      The previous achievements of landslide dynamic and space-time evolution should be discussed and compared in the introduction section, and you should be summarized advantages and disadvantages of each specific content.

3.      Ln 154 ~ 160: It is recommended to combine the figure for analysis.

4.      The source website of some software was added.

5.      The flowchart was added in the section of materials and methods.

6.      How to verify the accuracy of analysis results?

7.      How to compare and analyze the achievements of others?

Author Response

Dear Reviewer, we revised the manuscript following the notes in the review reports. We studied your comments carefully and made the corrections that we hope meets your approval. All the changes were marked in red in the text. In the attachemnt file you will find point-by-point our responses to your comments

Author Response File: Author Response.pdf