A well considered rebuttal with changes that address all of the primary concerns.
I am very happy to recommend publication.
Daniel R. Parsons

The authors have made some significant changes in light of the first review. These address the majority of the comments. However, there remain a few, still substantive, issues that need to be addressed via some minor to moderate revision prior to publication ....doing so will ensure that the paper has a broader reach.

In essence the issue centres on the fact that this paper still reads in most part like a methods paper - which in itself is not a problem, as Esurf accepts and publishes methods-based papers. However, methods papers need to be novel and this is not as novel as it could be - a smaller scale Metronome paper already exists that explains the majority of the background physics and theory. To counter this, the authors include some primary science elements - which are welcomed - but these would typically require some novel scientific conclusions. But, these read, at present, very secondary to the methodological elements of the paper. As such the paper occupies some uncomfortable middle ground.

To address this I suggest that the authors refocus some of the text to address the below two remaining points:
1. Highlight the scale of the facility compared to the smaller test facility and detail how the scale means that the large facility is able to capture qualitatively new behaviours from the smaller facility? i..e what is the novel aspects of behaviour that can be modelled by making the facility bigger?
2. In driving more towards an enhanced methods paper I would also like to see some additional detail on the methods included. At present there is not sufficient detail so that others could re-produce the experiments. Including these additional details (even as supplementary) would ensure that the paper would be used and cited a greater number of times.
Addressing these two points constitute minor to moderate revisions and I recommend that the paper be accepted once these have been attended to and I believe a final editor-only review will be sufficient.
Daniel R. Parsons

The authors have made some notable changes in light of the additional review. I am content that the novelty in the work and the methods by which this novelty is achieved is now at a sufficient level to guide the reader appropriately.
On the methods / supplementary - I wondered whether the authors considered publishing more technical details and information - in a way that modelling code is made open - the technical details of the flume construction would be useful and I am sure wold be used by other and mean the paper generated additional citations as a result - I leave this for the authors to consider and do not insist on this.
Regards
Daniel R. Parsons

Dear Authors,
Thank you for all your hard work on the manuscript in its revisions. I am delighted to inform you that it has now been accepted for final publication in ESurf subject to technical corrections. I have left this option open - as the AE has indicated that further improvements could be made by publishing more details on the flume construction - in the same way computer code is openly made available. However, this is left at the authors discretion - but it is worth considering that these relatively small details may make the paper more noteworthy and cited.
All the best,
Tom Coulthard