Dear authors,
Thanks for submitting your revision, which I consider an adequate response to both constructive reviews that your manuscript had received. The "author's response" file brings a wealth of explanation that were needed, and is a very illustrative and positive example of a constructive discussion between authors and reviewers.
I appreciate the idea of splitting the ms in two, which also is a response to one of the weaknesses outlined by the reviewers. I consider this work is now ready for publication and I thank you again for submitting. Thanks also to both reviewers for their work.
Sincerely,
Sebastien

Dear authors,

I am pleased to confirm acceptance of your work for publication in esurf, now in the form of a 2-part series of papers. I appreciate you careful and thoughtful attention to the comments from the reviewers and AE. Like the AE, I think splitting the manuscript into two parts was a good outcome of this process.

As noted by the AEs and reviewers, this work adds a great deal to our toolkit for analyzing topography, and to our general understanding of divides and divide migration -- a topic of great interest in recent literature. Thank you for choosing esurf as venue (and I am sorry the final decision has been slightly delayed, while I was clarifying how it would work to have your single original submission published as two separate papers -- that should be fine from here).

I have a number of very small editing suggestions below, including a few grammatical corrections. You might consider making these corrections prior to submitting your final files for typesetting; alternatively, most could be addressed during copy editing if you do not want to delay further.

Thank you again!

Part 1

Line 17: no comma after junctions
Line 20: “a stream and hillslope relief,” (remove the and add comma)
Line 22: in addition to divide instability, could such differences relate to structural controls (e.g., for tilted sedimentary layers)? if so, perhaps worth qualifying slightly here
Line 37: I think “eastern Tibetan Plateau” (small e)
Line 55: comma after directions
Line 92: no comma after one
Line 108-109: I think it would be useful to add a parenthetical comment after this sentence to define what you mean by “cycles” (I assume that this refers to divides that form complete closed loop, or something similar, but a formal definition would help readers, I think)
Line 131: no comma after network
Line 140: odd wording; perhaps better as “the more detailed the stream and divide networks will be”
Line 168: comma not semicolon after segments
Line 170: no comma after Rb
Line 184:
Line 186: comma not semicolon after the citation
Line 208: “As a consequence”
Line 228: “increases linearly as 0.36 x divide order” (as not with seems more appropriate)
Line 238: check for missing superscript 2 on 1 km^2
Line 239: I don’t think this is a good use of cf. (generally this abbreviations means “compare to”; you have used it in contexts that seem like you are asking readers to refer to a reference or figure, not compare to it, so I am encouraging you to rethink its use)
Lines 246-247: “averages… are” or “average… is” (perhaps the former)
Line 258: see note about regarding use of cf.
Line 261: “enquire” doesn’t seem right here; perhaps “query”?
Line 277: see note about regarding use of cf.
Line 278: “its”, not “it’s”
Line 288: you say “or” here, but I would have thought this could be “and”?
Line 299: no comma after scheme
Line 335: “lends itself to topological analysis”
Figure 1 caption: specify which type of divide order is shown here? (Topo, I think?)
Figure 1: consider adding a north arrow?
Figure 3 caption: specify what the black lines are; also maybe note where this topography is from?
Figure 4 caption: no comma after remaining
Figure 9 caption: no comma after order
Figure 10 caption: check for missing superscript 2 on 1 km^2
Figure 12: maybe consider labeling Chilao Flats on the map and/or images, since it receives particular attention in the Discussion?


Part 2

Lines 13-14: I found this confusing; you might consider rewording, perhaps along the lines of, “when considering divide segments with divide end points that are a minimum distance of ~5km from river confluences.” Or something like that…
Line 31: argued, not argue (to keep tense the same in this paragraph)
Line 34: argued, not argue (as above)
Line 39: holds, not hold (shape is singular)
Line 44: no comma after mobility
Line 49: I wonder if you could add a short sentence here to point out the features of your new analysis tool that allows you to do more than has been done before? You allude to this later in the paragraph, but could perhaps be explicit about how what you is enabled by your new capabilities.
Line 60: and, not as well as
Line 75: see note about regarding use of cf.
Line 79: I am unclear about the meaning of the “-“ in “50-%”; is this supposed to refer to the fact that you reduced the quantity by 50%? In this case I think it is clear just to say “50% reduced”
Line 80: “representative of”
Line 81: no comma after landscape
Line 83: “resulted in the resistant layers regularly sweeping from”
Line 84: see note above about “-“ in “75-%”
Line 92: see note about regarding use of cf.
Line 111: see note about regarding use of cf.
Line 116: no comma after distance
Line 153: I find the meaning of “factor on divide order” slightly unclear
Line 157: no comma after parameters
Line 165: are, not is
Line 177: this wording is awkward; perhaps “attains temporally-averaged values in the perturbed models that are quite similar to the constant values”
Line 192: add a comma after notable
Lines 209-201: “occupy the centre [OF WHAT?] as well as the centers of the four quadrants” (specify of what)
Line 212: see note about regarding use of cf.
Line 224: “recording similar” is a bit unclear; consider rewording?
Line 228: see note about regarding use of cf.
Line 232: “has become a popular tool” may be a bit better wording?
Line 234: remove “eventually”
Line 236: “and”, not “as well as”
Line 246: see note about regarding use of cf.
Line 248: comma after bins
Line 255: perhaps “these values and their variability”?
Line 259: demands, not demand (scatter is singular)
Lines 266-267: it struck me that stochastic divide migration (e.g., mass wasting events) adds another complexity in natural systems that is not captured in this version of the numerical model (I think?)
Line 275: “and long divide distances”?
Line 279: comma, not semicolon
Line 192: no comma after (Cj)
Line 293: consistent, not consistence
Line 303: remove “thus”?
Figure 1: add north arrow, and specify UTM zone in caption?
Figure 2 caption: see note above regarding “50-%” and “75-%”