Photogrammetric Monitoring of Rock Glacier Motion Using High-Resolution Cross-Platform Datasets: Formation Age Estimation and Modern Thinning Rates

Round 1

Reviewer 1 Report

Dear authors,

 

The manuscript presents the results of multi-temporal and multi-platform image processing on four rock glaciers and interprets the obtained results with additional modelling approaches. The underlying methodology is based on the application of a photogrammetric workflow and change detection analysis to quantify surface velocities and elevation changes. Currently, the multiplatform workflow is an ongoing and expanding research niche, and papers demonstrating the benefits of this approach are highly valuable. However, the study has methodological and conceptual flaws that make this paper unsuitable for publication in its current form.

 

The authors may also benefit from reading more relevant literature related to rock glaciers, geomatic techniques, and error analysis. In this regard, I can suggest classic references such as Kääb (2005) ,where the difference between dynamics and kinematics is explained, and also Taylor (1997), where error analysis is thoroughly developed.

 

 

General comments:

 

 

Methodology:

The area and number of stable points used for the CIAS uncertainty analysis should be shown on at least one figure. A table showing each period and the associated uncertainty should also be provided.

 

Results:

There is a clear error in the SfM processing at Galena. As can be seen from the Methashape processing reports, the camera calibration in 2022 appears to indicate an anomalous pattern in the camera lens. Comparing this with the processing in 2020, this looks more like a standard result with the concentric pattern of the 1" CMOS camera in a Phantom 4 RTK. Such anomalous pattern can lead to some derived erroneous results in the orthormosaic and especially in the derived DEMs, leading to some pincushion or doming effects for example.

 

 

Discussion:

 

The uncertainty analysis should be placed first (4.1) and then the flow history interpreted (4.2).

 

Detailed comments:

Please, see the attached document

 

References

 

Kääb, Andreas. 2005. Remote Sensing of Mountain Glaciers and Permafrost Creep. Schriftenreihe Physische Geographie. Vol. 48. Zürich: Geographisches Institut der Universität Zürich.

Taylor, John R. 1997. An Introduction to Error Analysis: The Study of Uncertainties in Physical Measurements. American Journal of Physics. Second. Sausalito, CA: University Science Books. doi:10.1119/1.13309.

 

 

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents analysis of the surface velocity and surface height changes on four rock glaciers -- two in Wyoming and two in Alaska. Rock glaciers form in various ways. Three of these appear to be stagnant glaciers that have become covered with debris, and the 4th has not been studied sufficiently to know how it formed. The information is derived from both piloted and unpiloted aerial photography taken in the last decade. The method is matching features in aerial photo pairs taken in different years. The techniques are not particularly new, but the authors do a good job of describing the methods and issues using images with different resolutions and sources, and from a technical point of view that may be the biggest contribution here.

 

In general, this is a well-written, understandable paper, however it runs a little long and I think there are some small sections that do not contribute much to the understanding of these four glaciers.

 

I did not find Figure 6 and the related discussion in 3.2.1 particularly useful. It mostly demonstrates that the algorithm used for the velocity calculation is not particularly good when the interval is small so that the displacement is also small. This is better demonstrated by the Figure 8 and the related discussion in 3.2.2, where the change from a random jumble of velocities to a coherent picture is obvious through the sequence of figures. 

 

The surface fhinning shown in Figure 9 is also not particularly illuminating, beyond the fact that there is a warming signal showing thinning in Wyoming and essentially nothing in Alaska. 

 

Figure 10a bugged me because it enhances the concern I had about Figure 3b, where the big spikes in speed are not visibly correlated with the slopes in Figure 3a, at least to my vision. I think these two regions of very high speed are not sufficiently explained. 

 

Because my particular work does not use the CIAS algorithm, I did not get much out of Figures 13 to 15. 

 

Minor points: 

 

L156 -- For decades, I have felt discussing the hardware on which an algorithm was run is irrelevant unless this is pushing the limits of what can be done. These computers will seem trivial soon, but documenting the algorithms is important. 

 

L691 mismathched (only typo I noticed)

Author Response

Please see the attachment; original reviewer comments are in black, and the author's responses are in red. 

Author Response File: Author Response.pdf

Reviewer 3 Report

Four North American rock glaciers were investigated using photogrammetric data acquisition techniques in the reviewed manuscript. Although it is a comprehensive study, the manuscript could be more well-organized. The sections were intertwined, so the manuscript's structure is too complicated. Therefore, all sections should be improved. All in all, the manuscript cannot be published without correcting them. I recommend resubmitting it after major revision.

My further recommendations are as follows:

The study's aims need to be obviously stated, and the research questions should be clearly outlined. Furthermore, the manuscript's novelty should be explicitly emphasized and compared with previous studies (a comprehensive literature review is required). 

The method and data used should have been briefly mentioned in the Introduction.

The methodologies of the manuscript are highly complex to understand, and it could be explained in a separate section. Also, the methodological steps could be represented by diagrams to simplify.

Figures should be standardized by the same representations, i.e., location of legends, scale bars, etc. Furthermore, the figure names should be shorter, and the interpretations should be added to the text.

There is a problem with Figure 1c. It belongs to Alaska, according to line 115, but Wyoming is written on the figure.

In lines 360-363: The authors removed velocity vectors with magnitudes greater than 1.8m/yr due to no correlation to the surrounding data points. How did the authors reach this conclusion? Did they investigate it through any statistical analysis? 

In lines 386-387: The last sentence can be moved to the Conclusions.

The differences between radiocarbon ages and velocity-derived ages should be clearly shown. 

Author Response

Please see the attachment; the original reviewer comments are in black, and the author's replies are in red. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I would like to express my gratitude to the authors for significantly enhancing the manuscript.  From my perspective, the present condition of the work is deemed appropriate for dissemination.

 

Reviewer 3 Report

I want to thank the authors for considering my recommendations. I think the corrected figures will be added to the text. The manuscript can be published in the journal.