Impact of the Xiaolangdi Reservoir Operation on Water–Sediment Transport and Aquatic Organisms in the Lower Yellow River During Flood Events

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article has a clear structure as in the introduction, methodology, results, discussion and conclusion, the article has used a very large number of references which are appropriate for the field, the article is very detailed both in the statistical aspect and in the interpretation of the results, The figures presented are well-designed and clearly illustrate the findings. The discussion section compares various studies and is articulated in a very coherent and thoughtful manner. The conclusion is also clearly presented and summarizes the main findings effectively.
I would recommend that the socio-economic aspect be addressed more explicitly, particularly by discussing why low-income countries have fewer studies of this nature.
 I recommend that it be accepted after these small comments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The present manuscript examines the impact of the Xiaolandgi Reservoir on the discharge and sediment dynamics during flood events in the Lower Yellow River. The study's findings, derived from a comprehensive analysis of pre- and post-reservoir construction data, reveal a substantial alteration in sediment and discharge conditions resulting from reservoir operation. Additionally, a theoretical model was developed to link sediment transport and hydraulic conditions, and the results of this model were then compared to the impact of other related parameters, such as the runoff variation coefficient.

The manuscript under consideration addresses a highly relevant topic that aligns well with the scope of the Sustainability journal. It is generally well-written, and the authors provide valuable insights into sediment and discharge dynamics in the Lower Yellow River. However, I have several issues with the manuscript. My main concerns are:  

1. The Results chapter is quite long, making it difficult to read in a focused manner. In particular, it contains repetitions of information that has already been mentioned, as well as phrases that do not require such detailed explanation since they are either illustrated in the figures or are logically comprehensible, and also some discrepancies (More details can be found below). Additionally, this chapter contains many discussion points that are more appropriately situated in the Discussion chapter. Consequently, a thorough revision of the Results and Discussion chapters is necessary.
2. I have major concerns about the coverage of river ecology in the manuscript, as it only addresses sediment and discharge conditions during flood events while a comprehensive treatment of the topic is lacking. However, the title of the manuscript anticipates this. Many topics relevant to river ecology are not considered, such as conditions during periods of low water and the impact of reservoir construction on longitudinal continuity. Furthermore, some topics are incorrectly related. For example, ecological base flow is unrelated to discharges during flood events. Since the manuscript is already quite long (see point 1), I recommend removing this topic. This would also require changing the title of the article.
3. In the paper, the authors examine 688 flood events over 64 years. However, in my understanding, high discharge conditions that occur approximately 10.75 times per year are not flood events. Is there a specific reason why this term is used in the manuscript? Furthermore, it is unclear how the lower limit of these "flood events" was defined. Why was 500 m³/s used, which is quite low compared to the maximum of 6,778 m³/s? I recommend reconsidering the use of "floods" in this context. Some findings may also need to be reconsidered, such as line 25: “… floods with average sediment concentration below 20 kg/m³ accounted for approximately 89.03%.”

Further comments on the manuscript:

4. The manuscript contains many references to reservoirs, stations, and places whose locations are not explained in detail. Consequently, it is sometimes difficult for a non-Chinese or non-Asian reader to understand the connections and meanings. Therefore, I recommend revising the manuscript in this regard, beginning with line 17, by adding the country name.
5. As in line 22, the authors often write "after the operation of the Xiaolangdi Reservoir," which may be misleading and imprecise. More appropriate alternatives are "after the operation of the reservoir began" and "after the construction of the reservoir." These changes must be made throughout the manuscript.
6. The manuscript would benefit from a clearer and more precise explanation of its novelty, especially in the Introduction chapter. Since many studies have examined sediment and discharge dynamics in relation to the Xiaolangdi Reservoir, the authors must clearly explain the unique aspects of their approach.
7. In the introduction chapter in particular, the authors often group all related references together after many sentences, making it difficult to trace where the information comes from. I suggest adding at least one reference after each sentence that needs one.
8. The terms "runoff" and "discharge" are often used interchangeably in the manuscript. Please revise the manuscript accordingly, as these terms generally do not mean the same thing.
9. As a general recommendation, references to the figures are often included at the end of the paragraph in the Results chapter. However, to underscore your results, it would be more appropriate to reference the figures in the first sentences when presenting the results.

Minor issues:

10. Line 25: “… floods with average sediment concentration below 20 kg/m³ accounted for approximately 89.03%.” Without further context, it is unclear what is meant here. Why is 20 kg/m³ important? Also consider point 3 in this regard.
11. Lines 46-47: If I understand correctly, "particularly" might be the wrong word here. "Not only" might be more appropriate.
12. Line 59: It is unclear why “sediment transport efficiency has decreased markedly” in this context.
13. Lines 60-61: It is unclear why "deepens longitudinally, broadens horizontally and stretches downstream from the area near the dam" is used here since these processes generally do not occur simultaneously.
14. Line 63: The term "non-biological elements, such as river runoff and sediment" could be misleading in its current form and may benefit from revision.
15. Line 66: It is unclear why "consequently" is used in this context. What connection does it have with the previous lines?
16. Lines 66-69: The text is missing references.
17. Line 70: I recommend adding "typically" after "has."
18. Line 72: The abbreviation "LYR" has only been introduced in the abstract, not in the main text. Therefore, it must be introduced here.
19. Line 72: In order to understand the context, more basic information about the Xiaolandji Reservoir is needed (see point 4). Furthermore: Where does the LYR begin? Is it downstream of the reservoir?
20. Line 73: To my understanding, "channel" refers to the "downstream river reach." Please clarify.
21. Line 78: “… conducted 31 water and sediment regulation.” This statement is unclear and should be explained more precisely.
22. Lines 80-81: It would be beneficial to include more information on how biodiversity and the ecological environment have greatly improved.
23. Lines 81-86: The text is missing references.
24. Line 87: It is unclear what you mean by "scientific river management." Please clarify.
25. Lines 104-108: It is unclear how these lines relate to the previous lines since you used "however." Please check.
26. Line 108: The phrase "since 2010" seems to be misaligned with the reference cited from 2011.
27. Lines 112-114: “However, …” It is unclear how these lines differ from the previous one.
28. Line 115: Why did you use the plural "downstream rivers" in this context? Please check. This also applies to line 505.
29. Lines 115-116: Instead of "based on previous research," I recommend using "based on these" (or something similar) because the former would require references.
30. Line 136: A reference is needed after “bottom.”
31. Lines 138-139: It would be helpful to note whether Tiexie, Gaocun, etc., are cities or stations (see point 4).
32. Line 139: [56] should be moved before "as shown in Figure 1."
33. Line 140: It should be "1.7 to 2.7," with the lower number first. The same applies to line 146.
34. Line 141: In my opinion, "sea" would be more appropriate than "beach." The same applies to line 152.
35. Lines 146-148: Are these river reaches natural or altered by anthropogenic factors, such as river restoration projects? Furthermore, the connection to line 152 is unclear.
36. Lines 154 and prior: The text lacks references.
37. Lines 170-172: “The morphology …” Consider deleting or removing this sentence, as it does not fit between the reservoir sentences.
38. Lines 173-174: It is unclear whether the Wanjiazhai and Sanmenxia reservoirs are upstream of the Xiaolangdi Reservoir (see point 4). Adding this information would be beneficial.
39. Line 179: “out to date” Please be more specific and include a year to avoid any misunderstandings.
40. Line 185: It might be helpful to refer to Figure 1 here.
41. Line 186: Including references here might be beneficial. The same applies to line 214.
42. Line 187: As I understand it, this is the maximum flow discharge of the flow events, not the average? Please clarify.
43. Lines 189-190: It would be beneficial to explain why small-flow processes are irrelevant to the results and were excluded. Furthermore: Can you rule out the possibility that small-flow processes occurred with high sediment concentrations?
44. Line 197: Adding references addressing the sediment discharge ratio and its importance could be useful.
45. Lines 202-203: When SDR > 1.0, erosion dominates in the river section. However, it's possible that there are some areas where sediment aggradates. Therefore, I recommend using "dominates" instead of "takes place." The same applies to SDR < 1.0.
46. Equation (2): Why do you introduce this equation if it won't be used later in the manuscript? Please clarify. Furthermore, as I understand it, SDR_a can become negative if W_s,d is much higher than W_s,in, which seems illogical.
47. Line 217: Where is Xiaoheiwu Station? (see point 4) The same applies to line 556.
48. Lines 224-225: I recommend adding "approximately" here: "Flood events contribute approximately 72% of the yearly runoff." The same applies to line 226.
49. Line 227: What exactly do you mean by "table"?
50. Line 239: "...the downstream river channel was considered a 'natural flood.'" What does this mean in this context? Is a word missing here?
51. Line 243: "This is due" might be a better choice here than "at the same time." Please consider this.
52. Lines 261-265: As I understand it, this is just a reiteration of the results from the previous page. Please consider removing or shortening it (see point 1). The same applies to lines 275-277.
53. Line 280: Regarding this caption, it might be useful to add "entering the LYR" after "flood events."
54. Line 283: Please reconsider using abbreviations for frequently used terms in the manuscript. For example, "sediment discharge ratio" was abbreviated as "SDR" in equation (1). This would shorten the manuscript and make it easier to read (see also point 1).
55. Figure 4: Equation (1) and lines 202–203 introduce SDR > 1.0 as "erosion takes place in the river reach." However, Figure 4 states that aggradation occurs when SDR > 1.0. Please clarify this discrepancy.
56. Figure 4: The reason for the peaks in (e) from 2004 to 2006, which are higher than the peaks in (a) through (d), is unclear. How is this possible?
57. Figure 4: The reference to Figure 4 should appear in the main text before the figure itself (see also point 9). The same applies to most subsequent figures.
58. Lines 300-301: After the reservoir began operating, the sediment discharge ratio varied as well. Do you mean the tendency? Please clarify.
59. Lines 304-305: "...the median particle size of the bed sediment in the downstream river channel may increase 1-2 times." This is the first time you have written about particle sizes. Where does this information come from? Was it measured? The same applies to lines 309–310 and later. Information about particle sizes should be explained precisely in the methods chapter.
60. Lines 306: "...the continuous sediment discharge..." In which figure is this shown? It is unclear what you mean. I suppose there was also a continuous sediment discharge before the operation of the reservoir?
61. Lines 313 and 324: Where are the Senmenxia and Longyangxia reservoirs? Are they upstream of the Xiangjiadian Reservoir? (see point 4)
62. Lines 314-315: “As fine-graned sediment was released during heavy currents, the downstream river channel received clear water,…” Is this not a contradiction? Furthermore, why is "currents" used here and not "floods"?
63. Line 319: “… small water…” This wording seems strange. I recommend using "a small amount of water" or "little water" instead.
64. Lines 323-324: It is unclear why “this phenomen gradually led to an increase in the SDR”. Could you please explain?
65. Line 337: What happened after 2018 in Figures 4a and 4e is unclear. Could you please explain this behavior in the main text?
66. Lines 342-343: The definitions of the inflow sediment coefficient and the runoff variation coefficient should be included here. Otherwise, understanding will be difficult. It is unclear why these parameters are described much later in the manuscript (lines 456–457 and 525-529). These definitions should be moved to where the parameters are first mentioned.
67. Lines 343-346: If you write, "these four runoff and...," you can delete the last sentence in this paragraph, as your meaning is already clear. (see also point 1)
68. Figure 5: This figure shows negative values on the y-axis. However, it is not possible to have negative values for the flow discharge, for example. Please adjust the y-axis so that zero is the lowest value displayed.
69. Line 354: The reason the flow discharge is lower for the final river reach than for the reaches upstream is unclear. The same applies to lines 357-358. Please provide an explanation.
70. Lines 358-359: "From Tiexie to Lijin..." It is unclear which figure shows this behavior. Please clarify.
71. Lines 359-361: "The median flow…" This is already apparent in Figure 5a, so it can be deleted here to shorten the text. The same applies to lines 377-379, 395-397, and 409-412.
72. Lines 365-366: The first sentence in this paragraph is a repetition. (see point 1)
73. Lines 376-377: "The median …" This is a repetition of what was already explained in the previous sentence. The same applies to lines 390-391 and 412-414. (see point 1)
74. Lines 379-383 "By comparing..." This is only valid for the first period, however, not after the reservoir is constructed.
75. Line 417: I noticed that "we" is used only once in the entire manuscript. This might sound strange, so I recommend changing it.
76. Lines 435-436: "The sediment discharge..." Is this sentence valid for both periods? The same applies to 441-442.
77. Lines 442-445: "The effect of…" What do you mean here? Could you please provide a clearer explanation?
78. Lines 456-458: As I understand it, the second sentence reiterates the meaning of the first. However, it might be beneficial to leave it in. Please reconsider.
79. Line 478: I recommend adding "to the sea" after "estuary" because, in my understanding, this might not be valid for all rivers, especially those in mountainous areas.
80. Lines 498-501: In my understanding, the SDR is clearly defined by equation (1) as depending on water and sediment conditions. Therefore, it is strange that you mention it here as a finding. Please reconsider.
81. Lines 503-504: To my knowledge, there are more factors that define sediment transport capacity. However, I agree that sediment transport rate and flow discharge are important factors. It would be helpful to have a reference here.
82. Line 506: Which equation are you referring to? Please clarify.
83. Equation (3) and line 513: More precisely, the unit of Q_(s,out) should be kg/s, not t/s. Otherwise, the equation requires division by 1000.
84. Equation (4) and line 519: It is unclear why Q_in and Q_out are used here instead of Q_w_in, which is used in equation (3). Please clarify.
85. Equation (5): There is an error in the equation. As I understand it, Q_(out) should be Q_(in). Overall, I do not understand the derivation of the equation. Could you please add a step or provide an explanation?
86. Lines 528-529: How is it possible that the runoff variation coefficient in Table 1 is always less than one? This is difficult for me to understand. Could you please provide an explanation for this phenomenon?
87. Line 536: If I understand correctly, these values only apply to the section from Tiexie to Lijin. Could you verify this? If so, this should be mentioned earlier in the text. The same applies to line 540.
88. Equation (7), as well as this section in general: It is still unclear to me whether the described procedure was developed by the authors or taken from a similar study. Could you please clarify this?
89. Line 559 and 567: It's confusing to me that you wrote "Tiexie" once and "Xiaolangdi" once in the same context. Please standardize this.
90. Lines 592-598: To understand how the findings of the aforementioned studies can be compared with those in the present manuscript, more context is necessary. Which rivers or river segments did the authors investigate? The LYR? Furthermore, this comparison should be included in the discussion chapter (see point 1).
91. Line 600: "... during various periods of the river reach." What do you mean by this?
92. Line 602: "...the constructed water and sediment variables..." What does "constructed" mean in this context?
93. Lines 603-605: "...it was calculated..." Really? Compared to Figure 7, I think it's more of an increase than a decrease. Please check this.
94. Figure 7: Eta_c is undefined. Please provide a definition. Also, reconsider using this variable in the main text, such as on line 606, to shorten the manuscript where necessary. This also applies to Figure 9 and Zeta.
95. Line 610: There is a typo in "(b) TiexieT."
96. Lines 620-621: "The cross-sectional shape transitions..." Where exactly do these transitions occur?
97. Lines 622-623: "...following the operation of..." In my understanding, this is also valid before the operation began. Furthermore, as illustrated in Figures 8a and 8b, the SDR will decrease, not increase. Please check and clarify this.
98. Lines 628-631: “Given the significant…” Is this truly the sole reason for the decrease in the SDR?
99. Line 664: "...affecting the stability of the river ecosystem." If I understand correctly, the stability was greatly impacted prior to the construction of the reservoir due to flooding and other factors. Consider deleting this phrase. However, see also point 2 in this context. No further comments about Section 4.5 are provided in the following.
100. Discussion chapter: The chapter only uses one reference, which is insufficient for a proper discussion of the topic. Please add more references. However, see also point 1 in this context. Some of the findings were discussed in the Results chapter.
101. Lines 723-725: A reference should be added.
102. Line 726: "Transport" is used instead of "discharge" here. Please correct this.
103. Figure 13a: Which database is this figure based on? Please provide more information, perhaps in the Methods chapter.
104. Lines 750-760: The connection between the river restoration project described in this paragraph and the reservoir is unclear. Please provide more information. If there is no connection, I recommend removing the paragraph.
105. Line 752: Where is "Tieshe"? (See also point 4.) The same applies to the locations mentioned in line 756 and in Figure 14.
106. Lines 769-770: When you mention further analysis, it would be interesting if you added potential examples of future studies relevant to the present one. However, this is just a suggestion.
107. Lines 777-778: "It explores..." In my opinion, this sentence could be removed to shorten the manuscript.
108. Lines 785-786: This depends heavily on the definition of "flood events" (see point 3). In my opinion, it would be more beneficial to write about floods over 1,000 m³/s than those below that amount. In this case, the definition would not be a factor. The same applies to lines 788–790.
109. Lines 800-803: It is difficult to understand how the different factors correlate with each other. Could you please explain this more precisely?
110. Lines 808-816: As I explained in point 2, I disagree with the river ecology findings, which seem very biased. I recommend removing this point from the conclusion chapter.

Comments on the Quality of English Language

The quality of the English is generally good. However, it could be improved in some places. In particular, sentences could often be more strongly connected by using phrases such as "as a result" and "however."

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments - Questions (to be clarified in the text):

1. Figures 2a, 2b: In the legend, it is more accurate to write "Yearly runoff" instead of "Year".
2. Figure 4: (a) On the basis of which equation is SDR calculated? Equation (1) or Equation (2)? (b) On the basis of Figure 4, if SDR > 1.0, aggradation occurs, while if SDR < 1.0, erosion occurs. It is right?
3. Lines 384 - 389: (a) How is the "inflow sediment coefficient" defined? (b) How do the units kg^.s/m⁶ result?
4. Lines 401 και 402: How is the "runoff variation coefficient" defined?
5. Lines 456 and 457: The "inflow sediment coefficient" should be defined at that point, where it first appears.
6. Table 2: The exponent α+β does not appear at any equation.
7. See annotated manuscript!  

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Some "editorial" errors are given on the annotated manuscript.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for your thorough revision and for carefully addressing the reviewers’ comments. The manuscript's quality has improved substantially, and it is now nearly ready for publication in the journal. However, there are still several points that require attention. Please see my point-by-point comments below.

1. The authors addressed my earlier concern about river ecology in Round 1 by revising the title and main text. However, I remain not fully aligned with how this topic is presented, as it is, in my understanding, a sensitive issue for many. The manuscript considers only conditions during floods, whereas low‑water periods are also of particular importance for aquatic organisms, and the interruption of longitudinal continuity is entirely neglected. To address this concern while still reflecting the valuable findings of the manuscript on these organisms, I recommend clarifying that the findings are limited to flood events. This would require adjustments to the main text, particularly in Chapter 5.3, and to the title. One possible solution for the title would be to add "... during flood events" or "... under flood conditions."
2. As mentioned in Round 1, discharge and runoff are not synonymous. Runoff refers to the portion of precipitation (rain or snowmelt) that flows over land and eventually reaches rivers, lakes, or the ocean. In other words, it is the generation of flow from a catchment area. Discharge refers to the actual volume of water flowing past a specific point in a river or stream per unit of time and is typically expressed in cubic meters per second (m³/s). In the manuscript, both terms are often used interchangeably (e.g., lines 78, 168, 170). I recommend using "discharge" instead of "runoff" where appropriate and reviewing the manuscript to ensure consistency.
3. Line 26: “… floods with average sediment concentration below 20 kg/m³ accounted for approximately 89.03%.” Without additional context, the meaning of this statement in the abstract is unclear. Consider clarifying or rephrasing it to ensure readers understand its relevance.
4. Line 30: The abstract does not make it clear where Gaocun is located. Similar to point 3, I recommend rephrasing it. One potential solution might be the upper and lower downstream reaches.
5. Lines 47-48: The sentence structure is somewhat awkward. Small rivers should not be overlooked. One potential solution might be "... rivers [6]. These impacts are evident not only in major rivers such as the Mississippi [7], Colorado [8], Yellow [9,10], and Yangtze [11,12], but also in many smaller river systems."
6. Line 62: Instead of "performance of the continuous erosion effect," I recommend using "observations of continuous erosion."
7. Lines 64-65: Please provide an appropriate reference here to support this statement.
8. Line 75: Consider using “at Tiexie, just downstream of the Xiaolangdi Dam” here to improve clarity.
9. Lines 91-93: Here, a word such as "started" is missing. Alternatively, it could be "since the implementation of water..."
10. Lines 136-141: To improve readability and comprehension, I recommend rephrasing this long sentence into two or three shorter ones.
11. Line 165: "… a gradient of 1.0…" should be clarified, for example, by adding "on average" or "approximately," to reflect that the value is not exact. I recommend adding such wording to improve accuracy and clarity.
12. Lines 204-207: “… as shown in Figure 1.” should be placed at the end of the first sentence rather than in its current position.
13. Line 216: “lower” is written in lowercase, but it should be written in uppercase.
14. Equation (2): Please add a statement clarifying that this equation was used for the calculations presented in the manuscript. I raised this point in Round 1, but it was only addressed in the response to the reviewer. This response does not sufficiently resolve the issue within the manuscript itself.
15. Line 243: I appreciate the addition of the extra sentence. However, it is still unclear why Ws,d is always smaller than Ws,in. Please clarify.
16. Equation (4): It is unclear to which time span the runoff variation coefficient refers. Does it refer to a flood event, a year, or an hour? Please clarify.
17. Line 253: In my view, writing "10^8" twice in this context is unnecessary.
18. Lines 257-260: Why are these lines located here instead of in the Study Area section? In my opinion, they would be better located there.
19. Line 268: I recommend using "… annual discharge into the LYR…" This also applies to line 270.
20. Lines 270-271: "...steadily declined..." does not accurately account for the observed fluctuations. To convey a more accurate representation, I recommend replacing it with "the long-term average sediment load entering the LYR has decreased."
21. Lines 271-273: "The research shows..." The second sentence is redundant and can be deleted. For improved flow and clarity, the reference to Figure 2b should be moved to the end of the first sentence.
22. Line 275 ff.: From this point onward, the thousands separator in numbers is only used sporadically. Please standardize the notation and apply it consistently throughout.
23. Figure 4: As previously noted, the y‑axes still contain errors in labeling erosion and aggradation. The terms are being used incorrectly. SDR > 1 should correspond to erosion. Please correct this accordingly.
24. Lines 345-347: Why is this described here instead of in line 378, which provides more detailed information about the change in reservoir operations? It would be more appropriate to include it there.
25. Line 362 ff.: Why isn't this reservoir mentioned in Chapter 2, as Sanmenxia is? Is it actually referring to the Wanjiashan reservoir? Please clarify. Additionally, the text lacks information on the distance to the Xiaolangdi reservoir.
26. Lines 403 ff.: It is unclear why the variable or notation introduced in equation (3) is not used for the incoming sediment coefficient in the subsequent main text. The same issue applies to the runoff variation coefficient and equation (4).
27. Line 474-475: Please provide an appropriate reference here to support this statement.
28. Line 477: Qs_out is not defined at this point, but rather only later, after equation (6)—which is too late. Please move its definition to follow equation (5).
29. Lines 477-478: It may be interesting to note that the values of K and α vary depending on the river or river reach under consideration.
30. Line 490: "...beta is indices..." is grammatically incorrect.
31. Lines 537-539: The phrase "studies indicate..." suggests a reference to previous studies or literature rather than the results of the current investigation. A clearer and more accurate wording would be: "The analysis demonstrates..."
32. Lines 539: “… as illustrated in Figure 6.” is redundant and can be deleted.
33. Line 609: I recommend not writing "the main impacts" here (see also point 1). In my opinion, a more suitable formulation would be: "The identified impacts are..."
34. Lines 666: In my view, it is worth noting that sediment transport and discharge conditions have both been altered.
35. Lines 666-674: Specifying "flood conditions" (see point 1) in these lines would be particularly important and valuable.
36. Line 677: To make it clearer, I recommend using "… before and after construction …" instead of "during two periods."
37. Lines 682 ff.: The in-text citation style does not match the reference list. [67] and [68], each with two authors, should be cited in the text using the two-author format (Author A and Author B). The same applies to "Leopold and Maddock [69]." Please review all citations and ensure consistent style throughout.
38. Line 688: Does the phrase "The above research..." also refer to references [69] and [70]? This seems unlikely. Please specify the intended scope, otherwise the meaning will remain unclear.
39. Lines 721-722: Why is "San-guanmiao" written twice with a "-" in the main text but not in the caption of Figure 13?
40. Lines 739-742: The term "currently" seems inconsistent here, as the cited reference is from 2021. A more accurate choice would be "recently." Additionally, could this statement be expanded to include an outlook for future studies?
41. Line 762: To clarify this statement, consider adding the phrase "depending on the reservoir's operating conditions."
42. Line 763: "...factors affecting the..." It might be better to write "… factors identified to affect the..."
43. Lines 768-769: The phrase "with the incoming..." is unclear. Does it refer to a high correlation or simply the fact that this parameter was generally high in the investigations? Please clarify.
44. Conclusions: Although the title refers to "aquatic organisms," the Conclusions section contains no statements on this topic. In my opinion, a key finding related to these organisms should be included (please see point 1 in this context).

Comments on the Quality of English Language

The English language has improved. While some sentences are understandable in terms of content, they are somewhat awkward in terms of style and grammar for a scientific publication. For example, line 381: "So" is rather unsuitable for a scientific publication, and "will" sounds too much like a future statement. I recommend using the present tense here instead. There are also many redundancies. For example, in line 63, "vertical depth" is redundant; "depth" alone is sufficient. Alternatively, use "channel deepening." Similarly, in line 139, "analyses and studies" is redundant; "studies" alone is sufficient.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Comments:

1. Figure 4: According to Lines 230-233 of the revised paper, if SDR>1, then erosion occurs, while if SDR<1, then aggradation occurs. Figure 4 (y-axis) should be corrected according to the annotated manuscript!
2. See also annotated manuscript for editorial errors!

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

The quality of the manuscript has improved in response to the reviewer’s comments. However, I still have concerns about its overall quality. New issues have arisen since the last review round. For instance, a typo was introduced in the title of the manuscript following the most recent revision. Below, you will find my point-by-point comments on the resubmitted manuscript. In order for the manuscript to be considered for publication, I recommend addressing these points while keeping in mind the comments from previous review rounds and thoroughly checking the manuscript before resubmission.

1. Title: As mentioned above, the title is missing an “r,” and “Flood Events” should be capitalized for consistency.
2. Lines 24-27: As mentioned in a previous review, the number of "floods below 1,000 m³/s" depends heavily on how floods are defined. It would be more informative to address "floods over 1,000 m³/s." Alternatively, flow discharges above 2,000 m³/s or higher could be used as a reference.
3. Lines 25 and 27: Compared to the main text, a space is missing in the abstract between "1,000" and "m³/s," as well as between "20" and "kg/m³." These spaces should be inserted for consistency.
4. Lines 31-32: "Henan Reach" and "Shandong Reach" are only mentioned in the abstract, not the main text, which may cause confusion. To avoid this, consistent terminology is recommended. In the abstract, use terms that are easily understandable without extensive context.
5. Lines 33-36: As with the title, "during flood events" or a similar phrase should be added here to improve clarity and consistency.
6. Line 83: The mention of "China" is unnecessary here if several other locations and rivers in China have already been mentioned beforehand. In fact, "China" should first appear on line 77.
7. Line 105: Why is "sediment discharge ratio" capitalized here, yet written in lowercase in the abstract and in other instances? Consistent usage is recommended, with the lowercase form preferred.
8. Lines 111-113: A reference is required for this statement.
9. Figure 1: For publication, please ensure that Figures 1(a) and 1(b) appear on the same page. The same applies to Figures 2 and 4.
10. Lines 211-213: For clarity, I recommend to place "as shown in Figure 1" at the end of the bracket, not at the end of the sentence, as it refers to the stations.
11. Lines 245-247: The phrase "The following equation..." is no longer appropriate here because no equation follows, only further textual description. Two sentences later, you write, "Using this equation:" Please revise or delete the sentence in lines 245–247.
12. Equations (2) and (3): It remains unclear why Equation (3) is not used for both aggradation and erosion conditions. I suggest reevaluating the necessity of further clarification before publication.
13. Line 264: As mentioned in the previous round, "runoff" is not the correct term here. Use "discharge" or "water load" instead. This also applies to line 266. In contrast, line 279 correctly uses "annual discharge."
14. Line 281: I recommend adding "average" before "annual" to make the sentence clearer and more understandable.
15. Figure 2: Figure 2 uses the term "runoff," whereas the main text uses "discharge." Ensure consistent terminology throughout.
16. Lines 688-689: Add spaces to "alpha = 0" and "beta = 0" to ensure proper formatting.
17. Lines 789-791: Information about when the reservoir operation began is missing (i.e., "... decreased after starting the operation of the reservoir, while..."). Additionally, while other conclusions are written in the past tense, this sentence and the next are in the present. Please ensure consistent tense usage.
18. Line 791: I recommend replacing "it" with "this" in this context because "this" is more precise and appropriate.
19. Line 793: I recommend replacing "increasing the survival rate of..." with "enhancing survival..." to make the text smoother and more concise.

Comments on the Quality of English Language

The English could be improved to make the research clearer.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf