Please review the new reports from the Referees and update the manuscript accordingly. Reviewer 3 works in the field and has asked that the clarity of the prose be streamlined and improved. I agree with this - and that such a modification would enhance the final paper.
Daniel R. Parsons

Review:

Overall, this is a reasonably well done experiment that examines the control of the initial slope, and volume, of a gravity current on its mixing dynamics and boundary shear stress in a controlled lock-exchange approach.
The paper has been through two rounds of review; from the second round, one reviewer requests major revisions while the other recommends to publish as is.
I have reviewed the paper myself, and detailed suggestions are below.
My recommendation is between the two authors - I feel the paper needs further significant changes to be published, but that these are in the 'minor' category because they related to readibility rather than science substance. I would like to review the paper after revision to check for readability, but it should not have to go out for another round of review.
The paper contains numerous sentences that are rather indirect, and sometimes structurally unsound. While I have some specific examples below, there are too many examples to point out each one. I appreciate that significant effort has been put in to improve the English already, but this paper needs to be thoroughly edited by a native speaker. The science is sound, but it took me many readings to determine that.
There are a few minor issues with the presentation of the scientific results, or the interpretation of them. Overall, however, I believe the paper is a significant contribution to understanding how the initial conditions of gravity currents influence their runout dynamics through entrainment and boundary stress. Some additional context in the abstract and introduction should help the readers to envision how these findings may help to understand turbidity currents.

My comments from the response to Reviewer 2:
4. "Gravity currents are LIKELY experiencing two phases...an initial acceleraton takes place...then the current accelerates...At the point where the measurements are taken, the gravity currents are experiencing this second phase."
-> It seems that this is something that the authors should know, rather than guess about. I get that the ADV measurements are at a fixed point, but the aren't there at least movies or photographs showing the propagation of the head in order to deduce the front speed through time?

-> As for the reviwer's concern about return flow, this could be checked with the velocity profile, right? In other words, if flow velocity becomes negative at or above the current interface - and if this effect becomes larger for steeper slopes - then the reviewer's point is valid. Showing that this does NOT happen would demonstrate that the reviewer's concern is not important. From figure 5 it looks like there is significant return flow, and that it might be dependent on slope. Please explain.

My specific comments about the paper:
Abstract:
Some movitation sentence should come FIRST, before the sentence that states the experiments that were run.
Experimental sentence is not clear, for example: "...for horizontal and four inclinations".
The second sentence (motivation) is also unclear: you talk about changing the slope upstream of a lock gate, but the reader has not been introduced to the experiment so does not know what this means. It seems to me that the motivation is that you want to examine the influence of initial conditions of a gravity current on its runout and entrainment capacity over a horizontal bed. You can then explain how you modify these initial conditions; in this experiment you examine primarily the slope. ALSO, your sentence discussing the main point of the experiments does not agree completely with the title; for consistency, you should talk about transport capacity or entrainment potential, but NOT BOTH. It becomes confusing to the reader.

The rest of the abstract does not include results and a conclusion; it talks about what will be discussed in the paper, rather than summarizing the paper. As such, the abstract is not that helpful. I suggest a re-structuring:
1. Motivation of the runout and entrainment of gravity currents, and how the initial conditions may govern these dynamics - including pointing out something that is uknown or unexpolored.
2. Then say that you have built an experiment to explicitly test the control of some factors (identified in the first sentence) on the flow dynamics and sediment entrainment potential of gravity currents. You should also make clear that your gravity currents are saline and nor particulate.
3. What was the range of conditions explored?
4. What were the main findings?
5. End with a sentence about the implications of your work for broader considerations of turbidity currents.

--------------------
Introduction
-First sentence is almost impossible to read.
-Many of these sentences are written in a rather indirect way. Sentence structure should be more simple, direct and make use of more straightforward words. For example, I notice the authors changed the sentence on katabatic winds from the first draft to make it more readable, but it is now even LESS readable. A better style would be "Katabatic winds are an example of an atmospheric gravity current, which arises due to...".
-Sand storms are NOT examples of particulate gravity currents. The sand concentrations are too low to contribute to density contrast. Rather, cold atmospheric currents can be gravity currents that pick up sand and dust - but the particles act as tracers of the flow, not drivers of it.

-Top of page 2: "...able to self-sustaining itself and to outrun the slower moving body of the flow..."
First, "self-sustaining itself" must be changed. Second, how does this new idea relate to the classic Parker work of auto-suspension and also the process they have outlined for heads breaking away from the bodies of currents?

p.2 line 18: The lock-exchange component is an experimental initial condition. The paper makes it sound as if lock conditions are an important component for gravity currents in nature. They are not. Rather, experiments choose a lock exchange geometry simply because it is controllable and reproducible. So it is not of "fundamental importance" generally for gravity currents.
p. 2 bottom: I do not know what "increment of friction means".

p.4. Please define all variables as they are presented.

Thank you for making these changes, and apologies for the delays on our end.