Dear authors,

thanks for the revised manuscript. The reviewers comments have been adequately addressed. Please consider the technical correction below. These include some typos, but also suggestions on improving clarity. I also would appreciate if you could error bars to the data plotted in figure 7.

All the best and thanks,

Jens Turowski

2.28 Furbish et al. have…
3.5 One possible mechanism… is collisional impulses – Grammar, equating a singular with a plural. Maybe something like …is entrainment due to collisional impulses.
Figure 1, caption: ‘A viewing window on the order of 35 cm…’ – unclear whether this is width or height. Please clarify.
Figure 2, caption: May be good to give the experimental run and / or hydraulic conditions.
Figure 3, caption: Please add an introductory sentence describing what is shown in the figure. E.g., schematic side view of the channel with particle outlines in black and colours, or similar. An indication of the scale may also be helpful.
9.29 Consider deleting ‘naïve’ here. It’s a subjective judgement and unnecessary.
Figure 7: Could you please add error bars (e.g., standard error of the mean) to this plot?
Figure 8/9 Used ‘complementary cumulative’ and ‘cumulative complementary’ in the two captions. Please be consistent.
17.3 ‘displacement of mobile particles’ - ‘mobile’ or ‘mobilized’?

Hi Dylan and Doug - I'm very pleased to inform you that your ESurf paper has been accepted for final publication, pending some minor technical corrections. These are best picked up now rather than at the proofing stage.
Thank you,
Tom