Thanks for your thorough and careful revision of your paper. Thanks also for providing a comprehensive response to reviewers document that makes it clear how you have addressed each comment. I have a handful of very minor edits to for you to consider, but otherwise I am happy to recommend this paper for publication and think that it will be a very useful addition to the research literature in this area.

Comments by line number (in the tracked changes version):
53: You define roundness later on, but I think that it would be useful to add a brief definition here to clarify that you are talking about perimeter shape rather axes ratios.
100: Another reference that might be useful to add to this section is Bodek and Jerolmack (2021), who also used image analysis to quantify particle shape in rotating drum experiments and calculated IR: https://esurf.copernicus.org/articles/9/1531/2021/esurf-9-1531-2021.html
200: Do you mean perimeter instead of contour?
337: Do you mean bounding instead of bonding?
414: I’m not sure what ‘negative of the R-squared values’ means, as I would assume that R-squared is always positive?
462: Change consist to consists.
512: It’s not clear to me what alluvial fans you are referring to. Maybe remove this?
Figure 13: Use the same number of decimal places throughout the caption, so 0.975 rather than 0.98.

Thanks for making those minor edits. I'm pleased to recommend this paper for publication.

Dear Prakesh and co-authors,
I am delighted to inform you that your paper has been accepted for final publication in ESurf. I would like to thank you for all your work with the edits - as noted by the Associate editor. Thank you for publishing your research in ESurf we look forward to the final version coming out.
All the best
Tom Coulthard