Dear Authors
Thank-you for your revised manuscript addressing most of the referees’ comments. In due course I intend to send it back to the referees; however, I think it is not yet ready for them to see again.
Firstly, I have not found a proper response to referee 1 point 6 about validating model currents and waves other than tides. Indeed (lines 294-295) “substantial agreement . . particularly in regions where tidal currents are predominant” suggests that other currents (e.g. due to winds) are not so well modelled and there is nothing about waves.
Secondly, there are many inconsistencies and confusions as in the following Detailed comments.
Therefore I am asking for revision before sending it back to the referees.
Yours sincerely
John Huthnance (editor)

Detailed Comments.
Line 9. “downstream” is an adjective; it should describe a noun, e.g. “downstream reaches”. Later (line 13) you use “lower reaches”. Anyway here you need to describe how much of the Changhua River is included.
Equation (4) looks correct for u* so line 112 “u* is the bed concentration” seems wrong. “us” in (3) needs definition. “V” in (7) needs definition here, not later. If (line 112) “Ca is the kinematic viscosity” then what is ν in (9)? Line 113: symbol for shear stress is missing.
Line 110. I do not understand “which under the current”. “Shield” –> “Shields”.
In equation (12) the second term inside the square-root has the wrong dimension.
You need to state whether you actually use (1) or (10)-(13) for the suspended load.
Line 140. This is not clear – missing verb with “usually”?
Line 179. The 40 points are in the lower reaches; you do not want to refer to the estuary here.
Lines 176 to 182. All these values might be better in a small table. Do the % values really help?
Figure 3 and Tables 2, 3. The location labels in figure 3 are very hard to read. If you think the tables are useful then you need to relate each table row to a location in Figure 3.
Similarly the sample numbers in Figure 4 should be related to locations in Figure 3.
Line 200. “used in” –> “is used in the”
Line 214. I think NSE can be negative – very poor!
Lines 220-225. Is FVCOM 3D? You need to say. If so it may need more than tidal level data at an open boundary.
Line 227. “ADCP collection points” are very unclear in Figure 6(b). Better to refer to Figure 8?
Line 245. “upper” –> “upstream”
Table 5, rows “Time Period”. For the first row here, I think seven days imply you mean “Spring to neap tide”. In the second row, I do not understand “High water period” of more than one month.
Line 294 and Figure 9 caption (twice). Replace “velocity” by “speed”. Refer to figure 9 in the text.
Figures 9 to 11. If the model is 3D you need to state the depth (or height above bottom) of the model current shown, and also the depth (or height above bottom) of the ADCP bin in figure 9.
Lines 341-342. “The sand spit at the downstream estuary” – which estuary is this?
Lines 380-382. “The maximum error . . at . . the end of the month . . may be due to the use of monthly average flow and sediment data”. I think this will not explain why the model sustains larger concentrations during 21-25 July than before or after that period. However, you should be able to diagnose the reason from the inputs to the model.
Figure 13 caption. “deposition” –> “concentration”
Line 397. Which “figure”?
Lines 399-401. I think you mean (line 400) “. . and take this point to represent the whole area. . .” However, this is an arbitrary choice and you cannot say “Therefore . .”
Line 422. The overall increase in deposition thickness of 0.59 cm was from April 23rd (not 27th) to 30th.
Line 424. I do not understand “The second phase” here.
Lines 426-427. I think you should refer to figure 16. Figure 16 needs hours on the time axis; the same date at four times is not useful.
Lines 429-430. Please check what you mean here. If fine grains can settle then surely coarse grains can settle too. Maybe you mean that only fine grains are available to settle.
Lines 435-443 should refer to figure 17.
Lines 489-490. “potentially hindering the river's natural evolution”? This is unclear. I think you have just described natural evolution.
Lines 504-505. “after removing the periodic astronomical tide” is confusing since you then go on to have the residual “depend on the strength and duration of the ebb and flood tidal velocities”
Line 508. In principle I think the Lagrangian residual current IS the result of the long-term tracking of real particles but that you want to state that HERE it is estimated as “the result of the superposition of Eulerian residual current and Stokes’ drift”
Lines 503-514. There is much repetition within these paragraphs.
Line 518. “tidal current field data from hydrodynamic numerical simulation”. If the information is from “numerical simulation” then it is not “field data”. Omit “data”.
Lines 520-521. “thereby enhancing the credibility of the residual flow field.” Only if you include the model estimates in Table 8 and show a good comparison.
Table 8 caption. “spring neap” is meaningless. You need to state the averaging period for the values in the table, and also the basis for the elevations involved in calculating the Stokes’ drift.
Lines 523-524. There is no need to repeat figures from Table 8. The speeds you give in the text are not those in the Table.
Lines 528, 530-531 and figure 21. You must define “low water period” and the averaging you are using to obtain the Eulerian residual current. Perhaps see comment on line 553.
Line 538. “below” –> “south of”?
Line 546. “. . opposite to the southern one may exist north of Topped . .”?
Lines 551, 554 and figure 22. You must define “high water period” and the averaging you are using to obtain the Eulerian residual current. Perhaps see comment on line 553.
Line 553. What do you mean by “flood season”. Is this related to river flow? If “low water” and “high water” refer to river flow than please use different terms so as not to confuse with tidal high and low water. Maybe you should always use “dry season” and “wet season” as later.
Line 569. What is the evidence for “successfully applied a wave-current coupled sediment transport model”? Figure 13 does show reasonable modelled sediment concentration but transport is a further step and deposition (convergence of transport) yet another step.
Line 587. “beneath” –> “south of”
Line 588. “above” –> “north of”

Dear Authors
Thank-you again for your revised manuscript. I now have referee comments (copied below in case you have not seen them) as well as my “Detailed comments” (also below and previously sent to you). Please take all into account in revising your manuscript.
Yours sincerely
John Huthnance (editor)

Referee Comments
I have read the most recent version of the manuscript by Wu et al.2024. The authors have improved the quality of their paper and answered satisfactorily the points I raised in my first review. They have also extended their results analysis by including a chapter where they are looking at the effect of residual currents on sediment transport.
However, I reckon that the science of this paper is undermined by the way it is presented. I would ask the authors to try and make their paper more concise and reconsider the way their results are illustrated in the figures. I am not aware of any limit on the number of figures, but I find that they are too many and there are certainly options for grouping them and merge content from different ones. Another solution could be to move some of these in the Supplementary. Very often, geographical info is repeated while on the contrary some critical elements are missing (e.g., calibration stations). In my comments, I made some suggestions which could be useful.
I would also ask that they check the numbering of their figures and tables. In many instances, they refer to the wrong figure number in their manuscript which makes it very confusing for the reader.
Even though, these are largely minor comments, there is still an obscure point regarding a discrepancy in their sediment transport calibration which needs to be clarified.

Abstract:
Line 15,18 and 22. I would recommend avoiding mentioning specific locations in the abstract. At this stage, the reader is unaware of the geographical context. The abstract should be written in a way that captures the attention of the reader based on the scientific outcomes of the study.
Line 17 There is no theoretical method in the new version. This must be removed.

Introduction
Figure 1 I reckon most of the information regarding stations should be included here in separate figure panels. For example, the current map provides an overview of the study case (although the upper and middle reaches are not really of interest). There could be one more panel with the sampling points (Figure 3) and another one with the ADCP stations and calibration stations. I couldn’t find any figure showing where the Baoqiao and Bosua stations are. Giving their coordinates is not enough. Such changes could make the manuscript more concise and precise.
Line 81-91: This paragraph is important as it gives the motivation and goal of this study. To my understanding, what this paper tries to highlight is the role of wave action on determining sediment transport in multi-channel estuaries with small sediment concentrations and the need to use coupled wave - current and sediment transport models for this purpose. A general comment is that the abstract and conclusions do not emphasize on how these results prove this statement.

Section 2
Figure 2 I don’t think this figure is really needed. Citing Van Rijn’s paper where this figure can be found should be enough. Otherwise, it is just an unnecessary waste of space. I would also recommend moving some of the figures and tables to the Supplementary. For example, Figure 4 and 6b could be moved there.
Figure 7 Add units
Line 122 Shields parameter
Line 126 Influence

Section 3
Figure 6 I’m afraid there is still an inconsistency between the lat and lon stated in line 210 and what we see in panels a and c. Especially in c, the right limit is cut at 108⁰ 43’ and not 108⁰ 50’. Please remove the ‘open’ and ‘land’ boundary indications in Figure 6c, these are not correctly placed, and the boundary locations are quite obvious from the bathymetry. Figure 6 b could go in a Supplementary. I would suggest following the pattern of Figure 5, having the bathymetry over a basemap so that everything is given in one panel. The lat and lon coordinates in Figure 5 seem correct and in accordance with line 210. The study area has also been given in Figure 1. No need to repeat it.
Line 234 what means accuracy of 1cm?
Line 235 The authors need to mention what the abbreviation ECMWF stands for
Be careful with the exponents in the units (e.g., line 239 and line 241).
Line 248 I deem this sounds a bit superfluous. Are there really limitations in FVCOM for wave calculations? If yes, they need to be mentioned.
Line 249 Being a model package issued by Deltares, I recommend that the authors cite SWAN by referring to its manual as e.g., (Deltares, 2024) or whatever version of the model they are using.
Table 4 Manning equal to 28 is unrealistic. Do you mean 0,028? I recommend removing Shoreline and Bathymetry from the table, these are not really parameters. Info about bathymetry is already given in the manuscript. There is no mention of GSHHS in the manuscript.
Line 250 Table 5 not 6
Figure 7 Add units in the axes

Section 4
Line 278 The location of the Basuo station needs to be included in Figure 9 together with the ADCP stations. Giving only its coordinates is not useful.
Figure 10 It would be good to add hours in the x axis in panel b where results are given only for one day.
I think the results analysis described in this section does not correspond to the figures mentioned. In the manuscript, lines 303-307 mention Figure 10b and c but they obviously mean
Figure 11. Please check these inconsistencies throughout the manuscript as this makes it very difficult for the reader to understand the arguments.
Line 305 It is probably better to say ‘outside of the lower reaches of Changhua River’ and not outside the estuary.
Line 316 Figure 12 and not 11
Line 317 The authors name A,B and C as estuaries but later in the conclusions they refer to them as channels. First, there needs to be a consistency in the terminology throughout the manuscript. Second, whether these can be defined as estuaries or channels can be subjective. Personally, I see these more as sub estuaries and not real estuaries.
Figure 12 Choose a different colour for the flow vectors or change the colourmap. The arrows can’t be seen.
Figure 13 I find the type of figures presented here a nice addition to the paper. I believe the results could be better communicated through such figures. It would be nice to have the speed and the arrows on top for selected time moments but for the entire field. The content of Figure 11 and 12 could be presented in this way. The authors could reduce the spacing of the arrows if there are concerns about the figures’ clarity. It is much helpful to be able to assess the flow field in the entire domain.

Section 5
Line 371 where is Baoqiao station? I can’t find it in the figures. Figure 14 not 13
Line 376 Wrong figures number
Line 390 Figure 14 . Separate the figure’s panels into a and b and add units at the y axis of the absolute error graph.
Line 381-386
I don’t understand this. It is implied that for a 5-day period, the authors get lower currents in their model than the real ones and yet higher suspended sediment concentrations. I would expect lower currents to result in lower suspension of sediments through a section. Even if the sign of the wave and tide induced currents counteracts with each other, this cannot happen for five days. Later in the text (line 426), the authors themselves claim that slower current lead to further sediment deposition. This is a bit confusing. Which of the two arguments is true?
The authors also mention a second possible reason for this discrepancy which has to do with the grain size distribution. I tend to believe more this because if the grain size is not accurate it could lead to an underestimation of settling velocities or overestimation of bed shear stresses. On the other hand, Figure 3 shows a quiet dense field of samplings. From what is shown in Figure 7, the waves calibration seems successful. Have they checked their results in other stations?
Figure 15 is not mentioned at all in the manuscript. It needs to be mentioned when a channel is referred so the reader can understand which area we are looking at.
Figure 16 The caption needs to be more detailed. The authors should describe better what is depicted in the figures.
Line 417 Figure 16h and not 14
Line 425 I think you mean under the influence of the neap tide.
Line 426 Saying that slower currents led to enhanced sedimentation is enough. You don’t need that sentence.

Conclusion
The same comment for the abstract applies here. The readers will want to know the conclusions and key messages and may have not read the entire manuscript to know where these specific locations are. In addition, as mentioned in a previous comment, there is an inconsistency about A,B and C which to this point, the authors always referred to as estuaries but here they refer to them as channels. In any case, a potential reader may have not read the full manuscript so it is useless to mention them as A,B and C. I would recommend to include more general statements in the conclusions so that the value and significance of the results can be emphasized and also how these contribute to the research on this topic.

Editor’s “Detailed Comments.”
Lines 113-118. “V” in (7) needs definition here.
Line 132. This is not clear – missing verb? Maybe “The model of sediment transport calculates the influence . .”?
Lines 168-169. “median grain diameters (0-1φ)”; please explain “φ”.
Line 172. “. . (Table 2) . .”
Table 2. Grain size cannot be negative. Please explain “-1φ – 0”.
Line 184. “. . (Table 3) . .”
Line 246. “(Table 4).”
Line 250. “(Table 5).”
Line 252. 36 or 40 directional sectors?
Figure 10. You need to state the depth (or height above bottom) of the model current shown, and also the depth (or height above bottom) of the ADCP bin.
Line 305. “. . Figure 11b and 11c depict . . . Figure 11b shows . .”
Line 316. “. . River. Figure 12a shows . .”
Line 322. “. . Figure 12b . .”
Line 376. “. . Fig. 14 . .”
Line 402. I think you mean “. . and take this point to represent the whole area. . .”
Line 417. “Finally, Figure 16h . .”
Line 425. Avoid “spring neap” which makes no sense. Better “. . influence of decreased tidal amplitude . .”
Line 426. Better “. .sizes, including finer particles.”
Line 552. “upward” –> “northward”?

Dear Authors
Thank-you for your re-revised manuscript. “Detailed comments” are below. Please take all into account in revising your manuscript. After these “Technical corrections" you should upload your revised manuscript to the EGU/Copernicus Editorial system for publication. This means that I will not review it again. However, you should be aware that on publication all the comments (by referees and myself) will be accessible, so that readers will able to see how the comments have been responded to.
There will be copy-editing and you should check that your intended meaning is retained.
Thank-you for publishing in Ocean Science
Yours sincerely
John Huthnance (editor)

Detailed comments.
Line 117. “V is an average velocity” is not precise: “the depth-average”?
“of the fluid flow” can be omitted.
Line 122. “. . Shields”
Line 126 “. . Van Rijn specifies its variation as a function of D . .” and refer here to figure S1.
Line 168. (Wentworth, 1922) has the concept of a logarithmic scale but I did not see any such scale as φ defined there. Maybe a paper by Udden also needs to be cited.
Line 180. Refer to figure S2.
Line 203. “value range of NSE is 0 to 1. When . .”
Except that NSE < 0 is possible.
Table 4. Your response to the reviewer was that the Manning number should be 0.028
Line 250. “. . sectors. We calibrate . .”
Figure 6 caption. Better “Depth-averaged current speed and direction verification. (a) speed . .”?
I think It would be good to add hours in the x axis in all panels (as already done in panel b).
Figure 7 caption. Omit “across the water column” because you already stated “depth-averaged”.
Figure S3. I have not found a reference to this figure in the text, and I don’t see where in the text it would be relevant. Please omit Figure S3 or give it relevance and refer to it.