Influence of Gate Dams on Yellow River Delta Wetlands

Round 1

Reviewer 1 Report

See attached review report

Comments for author File: Comments.pdf

Author Response

Abstract

Q1: Title The title is reflects the content of the paper, but is far too long. Suggestion: “Influence of gate dams on Yellow River Delta wetlands”. N.B. I tend to call the mouth area of the Yellow River a delta, rather than an estuary

R: We sincerely thank Reviewer #1 for carefully reviewing our work. We accepted the reviewer's suggestion and revised the title to " Influence of gate dams on Yellow River Delta wetlands".

 

Q2: The abstract is difficult to understand, partly due to poor English.

(1) For example: - line 14: what is ‘the reconstructed area in the Yellow River Estuary’?

R: We add an explanation in Materials and Methods (line 130/131): ‘We refer to the area between the gate dam and the nearshore side of the tidal creek as the reconstruction area.’

 

(2) line 14: 6 scenarios of what?

R: We complemented this sentence as ‘under 6 scenarios of gate dams’. Line 13.

 

(3) line 15: what are the gate-dams meant for?

R: A large number of water retaining structures are distributed in the Yellow River Delta, such as canals, roads, dams and so on. We simulate the dam as these buildings to explore its impact on the hydrological environment. We explore ways to restore the hydrological connectivity of the region by creating gates.

 

(4) line 15: what is a stabilized water depth fluctuation?

R: The variation in flooding depth with time is relatively small. We correct this sentence ‘… was more conducive to stabilizing the water depth fluctuation’ to ‘… was more conducive to reduce the variation range of water depth’.

 

(5) lines 17-19: how must the sentence ‘The variations of .... similar to water depth’ be interpreted? That the effects of the gate-dams on surface water salinity, etc. were similar to those on the water depth?

R: In scenarios S1-S5, the cumulative water depth of surface ponding decreases in turn, as do the flooding frequency and cumulative flooding time. When the surface water depth increases, the salinity and infiltration rate of surface water show an upward trend.

 

(6) lines 19-20: should ‘The rapid changes of soil water and soil salt appeared ...’ be ‘Rapid changes of soil water and salt content occurred in each scenario in periods without flooding.’?

R: Thanks. We accepted the reviewer's modification suggestions

(7) lines 21-22: what is the meaning of the phrase ‘... was close and higher than those ...’?

R: I'm very sorry to confuse you with my language expression. This statement means that ‘the difference between the former and the latter is higher, but not significant’. We modified this sentence to read ‘...was relatively larger than …’

 

(8) line 23: ‘The’ at the beginning of the sentence has to be omitted. These differences have not been mentioned before. And line 25-27: suggestion to rephrase this to: ‘Our results contribute to the understanding of the functioning of gate-dams in controlling soil water and salt content in coastal wetlands.’

R: Thanks. We accepted the reviewer's modification suggestions

 

 

Introduction

Q1: Instead of clearly stating the problem, what has been done about it before or elsewhere, and what this paper will contribute, the first part of the introduction is messy and refers to situations that have nothing to do with the subject of the paper. Examples: high dams and weirs in rivers, dikes, etc. I happen to know the case of the Scheldt estuary (lines 42-42 and ref [9]), where a dike breach was not restored in order to allow the polder behind it to become a natural wetland, again. This has nothing to do with controlling soil water and salt content by manipulating the tidal water level variation with gate dams.

R: Thanks. Following this advice, we have restructured the paragraphs in the introduction chapter and removed some descriptions to make this chapter more concise.

We cite the example of the ‘Scheldt estuary’ in order to draw the conclusion that the dam blocks the hydrological connection, and the construction of gates on the dam (similar to the gap of the dam) helps to restore the natural wetland. This example illustrates the importance of establishing the gate on the dam. Although there are few studies on the movement of soil water and salt in the Yellow River Delta, this is also the innovation of this paper. We have made clear the significance of the research. Please look at lines 96-98.

 

Q2: Lines 46-51 are very confusing, as they refer to quite different situations from those with low tidal control dams in coastal wetlands. Lines 57-69 refer to applications of Delft3D that are very different from the present case. This part can just as well be omitted. The quality statement of Delft3D and Hydrus 1D can then start with referring to model system inter-comparisons like those in refs [17] and [18]. Please don’t refer to the authors as ‘scholars’, but mention their names or rephrase the sentence anonymously. Furthermore, lines 70-87 would fit better under the heading ‘Methodology’ than in the Introduction.

R: Thanks. We have omitted lines 46-51 and lines 57-69. We have revised the quality statement of Delft3D and Hydrus 1D start by referring to model system inter-comparisons. And we use the word ‘researcher’ instead of ‘scholar’.

Q4: Suggestion to introduce a series of figures showing the location of the Yellow River Delta wetlands. Fig. 1 makes too large steps, so it would be better to split it into one showing the location of the wetlands and one showing the location of the study site within those wetlands.

R: Thanks. We added Figure 1B to make it easy for readers to understand the location of the study site

 

Q5: As far as I know, the ‘migration route from East Asia to Australia’ (line 89) is officially called ‘West Pacific Flyway’. Please use this name.

R: Thanks. We corrected the word ‘migration route from East Asia to Australia’ to ‘West Pacific Flyway’.

 

Study area

Q1: Suggestion to bring the description of the study area (lines 131-159) under a separate heading. As stated above, the present Fig. 1 takes too large steps to understand where the study area is located.

R: Thanks. We have placed this section under a separate heading ‘study area’, and modified the Figure.

 

Q2: How come the average tidal period (line 133) is different from the usual M2-period of 12 h 25 min?

R: Thanks. This section cites the conclusions of others. [Fang-fang W, et al. Decomposition characteristics of vegetation litter of Suaeda salsa and Spartina alterniflora in saltmarsh of the Yellow River Estuary. Journal of Natural Resources, 2020, 35(2): 02000480.] and [Luo M. Characteristics of hydrological connectivity and its ecological effects in a typical tidal channel system of the Yellow River Delta[J]. 2018, 54(1): 17-24.]. We think that the region is influenced by the unique topography and Yellow River runoff, which creates irregular semi-diurnal tidal features and a unique hydrological environment.

 

Q3: Line 152: altitude with respect to what? If to ordnance datum, than what is the mean sea level with respect to this datum?

R: Thanks. The altitude in this paper is determined by positioning software, but the result is not accurate. We corrected the altitude to - 1.3 - 0.7 m through map calibration. The altitude is obtained relative to the local average sea level (0 m).

 

Q4: I miss an accurate description of the gates. The name suggests an adjustable structure, but the range of adjustability is not described, nor the way it is operated through the tide. The description of the scenarios, on the other hand, does not mention gate operations, just the location of the dam and the size of the gate opening. This suggests that the gates are not operated, at all. please clarify.

R: Thanks. The gate can adjust and limit the flow. Our study focuses on the hydrological connectivity in the case of maximum flow (the gate is fully open), which depends on the tidal height.

 

Methodology

Q1: Suggestion to introduce a heading ‘Methodology’, and insert lines 123-130 there as a general introduction.

R: We adjusted the structure of this chapter. Thank reviewer’s suggestions, which will be very helpful to my writing in the future.

 

Q2: Figure 3 does not indicate the location of the dams. It suggests that the model has 4 open boundaries, a notoriously difficult model to drive. A description of the boundary conditions, however, is lacking. The only information provided is that the model is driven by data from observation point 1 and validated against data from point 2 (lines 166-168), but even the location of these points is not indicated in Fig. 3. This makes judging the quality of the model very difficult.

R: Thanks. We have added the dam location, boundary conditions and observation points to figure 3. There are two kinds of boundaries in the model: open boundary of water level and closed boundary of land. The location of the observation point is in Figure 1D, and we have made notes at the end of this sentence.

 

Q3: What justifies the choice of the Manning coefficient (line 195)? 0.013 seems rather low for flow over vegetated wetlands.

R: Thanks. For this explanation, we refer to this literature. [Dong, C. Numerical study on the difference of geomorphic dynamics between the current and abandoned estuary coasts of the Yellow River. 2019, 35, 14-24.] And the vegetation distribution at the site is relatively sparse.

 

Q4: In Figure 4, please replace the panel indicators A-F by S1-S6.

R: Thanks. We modified Fig. 4.

 

Q5: Suggestion to organize this section differently, with the equations (+ symbol definitions) placed directly where they are mentioned in the text. This will improve readability a lot.

R: Thanks for your suggestion that is very meaningful to my writing. We revised the relevant content to make the description more accurate.

 

Q6: Figure 5 is difficult to read. Please split into separate figures for water depth and salt content.

R: Thanks. We modified Fig. 5.

 

Q7: I am not convinced of the agreement of the computed and measured water levels (too few data points) and fail to see how this can lead to an R2 -value of 0.96 (line 259).

R: Thanks. We think this is because we included the water level verification data (0 cm) in the no flooding period in the verification process, resulting in high verification results. In fact, there is still a certain deviation between the calculated water level and the measured water level.

 

Q8: I miss in the hydrodynamic results a projection onto the tidal prism, which is an important parameter for predicting the morphological effect of the gate-dam.

R: Thank you very much for your professional review. In the research results, we focus on the parameters such as flooding depth, flooding frequency and flooding time (above the ground) and infiltration (underground). We will study and consider the tidal prism and morphological effect of the gate-dam in future research.

Q9: In Figure 6 the scale for the flooding frequency (formally: inverse frequency) is lacking. In the absence of a dam (case S1), flooding would occur approximately twice a day, so about 60 times in 30 days, but the flood frequency column reaches to 450 times on the left scale and 110 times on the right scale.

R: I am awfully sorry. Because of my mistake, I marked the name and position of the legend incorrectly. Now figure 6 has been modified.

 

Q10: Figures 8 and 9 show the key results of the paper. It would help the reader if the conclusions drawn from them were not only expressed in a host of numbers, but also in a text on the extent to which the various scenarios meet the objectives of the scheme. Parts of the text under ‘Discussion’ may help here.

R: We are grateful to the reviewer for providing so many professional and constructive comments and advice on our manuscript.

 

Q11: In Figures 8 and 9, please replace A-F by S1-S6.

R: Thanks. We modified Figures 8 and 9.

 

Discussion

Q: The discussion section is a summary of results, rather than a critical discussion on the validity and the limitations of the approach taken.

R: Thanks. Following the author's suggestion, we have adjusted the content of this chapter. (Line 355-372) We have added a description of the article summary in lines 349-351.

 

Conclusions

Q: The conclusion section is nicely brief and to the point.

R: Thanks very much for your comments.

 

Referencing

Q: The reference list is very long (71 items) and not all references are necessary to support the paper (also see the comments on the Introduction). I suggest to review the list critically and maintain only the reference that have an immediate relationship with the content of the paper.

R: We followed this advice and deleted 20 references. However, we added 3 new references to address the issues raised by the reviewers. Therefore, a total of 54 representative references were cited in the revised manuscript.

Reviewer 2 Report

The authors have made minor amendments to their manuscript, which have addressed some of the concerns previously expressed. The use of the term "dam" in this case may be misleading for readers seeking  information on coastal impoundments--as previously noted, terms such as "polder", "weir", "berm" etc may be more descriptive of the actual low head structure described in the paper. However, this would appear to be a personal choice of the authors. 

Line 68: the word "cured" seems out of place in this description, perhaps "curved" may be the word intended?

Line 72: "lever" should be "level" (also lines 168, 199

Line 73: a paragraph break might be warranted here

Line 79: "augment" should be "augmentation"

Line 82: "Queensland coastal" would be better stated as "the Queensland coastal zone"

Line 83: "tidal" would be better stated as "tide"

Line 91: "is great significant" would be better stated as "has great significance"

Lines 97/98: rephrase this sentence as "the decrease in food quality and quantity of birds and crustaceans."

Line 125: "of" should be "in the"

Line 127: insert "in" between "variation" and "results"

Line 143: provide a reference to the USDA classification system as add references to the other methods mentioned in this section.

Line 164: "meter" should be "meters"

Lines 166/170: Please note that "data" are plural, so "was" should be "were" in this section

Line 183: "divide" probably should be "devise"

Line 194: "Manning" should have an upper case "M"

Line 204: insert "to a" after "similar"; review this page (especially) to ensure that the use of articles (a, an, the) is consistent with standard English usage

Lines 260/261: the word "law" is unusual and could be deleted

Line 299: "much closed" probably should be "closest"

Lines 313/316: scenarios S1-S3 are closely related as are scenarios S4 and S5, but the latter appear significantly different from the former; this section should be reworded

Line 351: there are six ranges given but only five scenarios noted in the text--the range for scenario S6 should be moved to line 352/353

Line 358: delete the extraneous "t"

Lines 379/420: review this page to ensure that there is number agreement between the nouns and verbs--plural noun forms should be followed by the verb "were", for example

Line 432: insert "Zhao et al" in front of "[60]"

Line 449: delete the initial "was"

Line 458: insert "rates of" in front of "water loss" and insert "that" after "soil layers"

Again, review the entire manuscript to ensure that the articles are used in accordance with standard English usage.

This paper has a good message and should be a substantial contribution to coastal wetland restoration.

Author Response

Q: The authors have made minor amendments to their manuscript, which have addressed some of the concerns previously expressed. The use of the term "dam" in this case may be misleading for readers seeking information on coastal impoundments--as previously noted, terms such as "polder", "weir", "berm" etc may be more descriptive of the actual low head structure described in the paper. However, this would appear to be a personal choice of the authors.

R: Thank you very much for suggestions. Storm surges occur frequently in this area. In order to prevent storm surge disasters, we think the high head structure will be more suitable.

 

Q: Line 68: the word "cured" seems out of place in this description, perhaps "curved" may be the word intended?

Line 72: "lever" should be "level" (also lines 168, 199

Line 73: a paragraph break might be warranted here

Line 79: "augment" should be "augmentation"

Line 82: "Queensland coastal" would be better stated as "the Queensland coastal zone"

Line 83: "tidal" would be better stated as "tide"

Line 91: "is great significant" would be better stated as "has great significance"

Lines 97/98: rephrase this sentence as "the decrease in food quality and quantity of birds and crustaceans."

Line 125: "of" should be "in the"

Line 127: insert "in" between "variation" and "results"

Line 164: "meter" should be "meters"

Lines 166/170: Please note that "data" are plural, so "was" should be "were" in this section

Line 183: "divide" probably should be "devise"

Line 194: "Manning" should have an upper case "M"

Line 204: insert "to a" after "similar"; review this page (especially) to ensure that the use of articles (a, an, the) is consistent with standard English usage

Lines 260/261: the word "law" is unusual and could be deleted

Line 299: "much closed" probably should be "closest"

Lines 313/316: scenarios S1-S3 are closely related as are scenarios S4 and S5, but the latter appear significantly different from the former; this section should be reworded

Line 351: there are six ranges given but only five scenarios noted in the text--the range for scenario S6 should be moved to line 352/353

Line 358: delete the extraneous "t"

Lines 379/420: review this page to ensure that there is number agreement between the nouns and verbs--plural noun forms should be followed by the verb "were", for example

Line 432: insert "Zhao et al" in front of "[60]"

Line 449: delete the initial "was"

Line 458: insert "rates of" in front of "water loss" and insert "that" after "soil layers"

Again, review the entire manuscript to ensure that the articles are used in accordance with standard English usage.

This paper has a good message and should be a substantial contribution to coastal wetland restoration.

R: We sincerely thank Reviewer #3 for carefully reviewing our work. According to the reviewer's comments, we corrected the inappropriate description in the article. It helps a lot to improve my writing and learning

 

Q: Line 143: provide a reference to the USDA classification system as add references to the other methods mentioned in this section.

R: Thanks. We rewrite the sentence as ‘According to the USDA soil classification system[1] , the soil texture of the study site was classified as silty loam.’ The references we cite are [United States Soil Survey Staff. Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys[M]. US Government Print., 1975]. Plus, we supplement the references of other methods, as follows [Reynolds W D, et al. A reexamination of the constant head well permeameter method for measuring saturated hydraulic conductivity above the water table1[J]. Soil Science, 1983, 136(4): 250.] and [O’Kelly B C. Accurate determination of moisture content of organic soils using the oven drying method[J]. Drying Technology, 2004, 22(7): 1767-1776.].

Reviewer 3 Report

The article is interesting. Research has been done correctly. The methodology was chosen perfectly. My doubts:
1. What does the Delf 3D model mean nested in the Hydrus 1D model? I don't know exactly what's going on with that? Can the authors explain this?
2. Validation and calibration of the model. Maybe you can do it using the Nash-Sutcliffe efficiency coefficient and P-Bias? They are statistical measures commonly used to evaluate the calibration and validation of hydrodynamic (and other) models.
I have no further comments.

Author Response

Q1: The article is interesting. Research has been done correctly. The methodology was chosen perfectly. My doubts:1. What does the Delf 3D model mean nested in the Hydrus 1D model? I don't know exactly what's going on with that? Can the authors explain this?

R: We are highly grateful for the reviewer’s appreciation on our work. It took the water depth and water salinity data in observation point 1 as the open boundary condition of Delft 3D, so as to simulate the variation in results of flooding depth and salt content of infiltration water in observation point 2 (Figure1 D). We took these two output results as the parameter settings of Hydrus 1D model, so as to simulate the effects of different gate dam scenarios on soil water and salt variation in the construction area.

 

Q2: Validation and calibration of the model. Maybe you can do it using the Nash-Sutcliffe efficiency coefficient and P-Bias? They are statistical measures commonly used to evaluate the calibration and validation of hydrodynamic (and other) models.

R: Thank you very much for your professional review. Soil water and salt transport model (Hydrus 1D) often uses R² and RMSE to calculate the simulation effect of the model. We think that in order to unify the error expression method in the article, we still continue to use R2 and RMSE. I will learn the methods recommended by reviewer #3 in subsequent research.

Round 2

Reviewer 1 Report

The paper has improved a lot, but there are still a few points that need improvement. As this is the second review, I will stick to the authors' answers to my first one.

Section 2, Q2: the answer to my question is not quite satisfactory (a systematic deviation from the M2-period would ultimately lead to a large mismatch with the main tidal component) and is not reflected in the text.

Section 2, Q3: The modified sentence is still not clear. Suggestion: 'The altitude of the experiment site ranged from MSL -1.3 m to MSL +0.7 m.'

Section 2, Q4: My question is answered, but the answer is not reflected in the text. Please check the section numbering throughout.

Methodology section: This section has the same number as the previous one.

Methodology section, Q2: The experiment area is open to all sides, but the model has closed boundaries almost all arround. This implies the implicit assumption that filling and emptying of the flood area happens entirely via the gully, i.e. there is no cross-shore overland flow. Suggestion to state this explicitly.  

Results section: My question is answered, but the answer is not reflected in the text. Please state explicitly that the zero values are included in the R2-score.

Finally, the English, especially in the newly added parts, is still limping here and there.

Author Response

Study area

Section 2, Q2: the answer to my question is not quite satisfactory (a systematic deviation from the M2-period would ultimately lead to a large mismatch with the main tidal component) and is not reflected in the text.

R: Thanks for the reviewer's suggestion. As the reviewer said, the M2-period is the regular semi-diurnal tide period (usually 12 h 25 min). However, the tide in the study area is an irregular semi-diurnal tide period. Because one or more partial tides play a major role in the tide period, the period of study area does not coincide exactly with the M2 partial tide period. Flowing the reviewer's advice, we have reflected the reasons in the text. （Line 81-83）We have found the following references that can support our conclusions. Please see:

[1] Luo, M.; Wang, Q.; Qiu, D.D.; Shi, W.; Ning, Z.H.; Cai, Y.Z.; Song, Z.F.; Cui, B.S. Hydrological connectivity characteristics and ecological effects of a typical tidal channel system in the Yellow River Delta. Journal of Beijing Normal University (Natural Science). 2018, 54, 17-24.

[2] Dongxue Li, Yuqin Li， Kehao Zhang, et al. Characteristics of carbon and nitrogen distribution in typical tidal creeks of the Yellow River Delta[J]. Journal of Natural Resources, 35(2): 02000460.

[3] Wang X, Yan J, Bai J, et al. Influence of hydrological connectivity of coastal wetland on the biological connectivity of macrobenthos in the Yellow River Estuary[J]. J. Natural Resour., 2019, 34(12): 2544-2553.

[4] Fang fang W, Jia-guo Y A N, Xu M A, et al. Decomposition characteristics of vegetation litter of Suaeda salsa and Spartina alterniflora in saltmarsh of the Yellow River Estuary, China[J]. Journal of Natural Resources, 2020, 35(2): 02000480.

 

Section 2, Q3: The modified sentence is still not clear. Suggestion: 'The altitude of the experiment site ranged from MSL -1.3 m to MSL +0.7 m.

R: Thanks for the reviewer's guidance, we have completed the revision. （Line 100）

 

Section 2, Q4: My question is answered, but the answer is not reflected in the text. Please check the section numbering throughout.

R: Thanks. We added the modification of this part in the text. （Line 119-120）

Methodology

Methodology section, Q2: The experiment area is open to all sides, but the model has closed boundaries almost all arround. This implies the implicit assumption that filling and emptying of the flood area happens entirely via the gully, i.e. there is no cross-shore overland flow. Suggestion to state this explicitly.

R: Thank you very much for your professional review. The variation of tidal height at the closed boundary is quite small, and the flooding height in the area of observation point B is also small, which has little effect on the simulation results. It has been explained in the text. （Line 155-158）

 

Results

Results section:My question is answered, but the answer is not reflected in the text. Please state explicitly that the zero values are included in the R2-score.

R： Thanks for the reviewer's guidance, we have completed the revision. （Line 374-377).

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The followings are review comments and feedback for the manuscript titled “The simulated study of water and salt transportation under functions of dam and gate valve in wetlands of the Yellow River Estuary”, submitted to the MDPI Land journal for the first round of reviews.

The authors considered a part of the Yellow River wetland to investigate the water and salt transportation mechanism under different dam and gate valve usage scenarios.

But the issue starts for the readers right at the beginning where insufficient explanations of the study area are presented to justify why such a study would ever be important. The reference to the literature is very minimal and does not help the readers to get the point as to why computer simulations should be done, and why the two suggested software programs are even chosen. There is no explanation of either of the programs and their importance compared to other available applications. Such information is not also presented in the “Experimental design” section.

Hence, accessing the Results section without knowing what is exactly simulated and calibrated, and what the outcomes are, is completely irrelevant. Accordingly, the result discussions and other aspects cannot be evaluated at this stage, as is the case for the conclusion.

Author Response

Reply to reviewer #1

Q1: The authors considered a part of the Yellow River wetland to investigate the water and salt transportation mechanism under different dam and gate valve usage scenarios.

But the issue starts for the readers right at the beginning where insufficient explanations of the study area are presented to justify why such a study would ever be important.

 

R: Thanks for the comment. The importance of this study has been added in the third paragraph of the introduction (marked in blue): “The essential nutrients for the biological survival in the coastal intertidal zone are mainly provided through tidal processes. Under the influence of human activities (such as the construction of dams, ditches and roads), the hydrological status of estuarine wetlands has been changed, resulting in the threat to the living environment of the original vegetation community. The population number and distribution density of benthos were significantly reduced, resulting in the food quality and quantity of birds and crustaceans have also decreased”, “The gate dam has a significant impact on the water and salt regime of the estuary wetland.”.

 

Q2: The reference to the literature is very minimal and does not help the readers to get the point as to why computer simulations should be done, and why the two suggested software programs are even chosen. There is no explanation of either of the programs and their importance compared to other available applications.

 

R: Thanks. The 4 new references have been cited to illustrate why computer simulations should be done. In the second paragraph of Introduction, the advantages of computers and the characteristics of these two models were added. “Experiments to explore the effects of dams and gate valves on wetlands can only be carried out under specific conditions, but the hydrological model provided an efficient and economical method”, “Using the Delft 3D model Mohamed et al. estimated water and discharge changes with a long time series in Aswan dam valley, which had an extremely irregular shape. It provided a case for us to study the cured shape of the tidal creek. Delft 3D is appropriate for the simulation of hydrological variations because it can capture flooding depth and salinity under different scenarios. Scholars had compared the publicly available numerical software used to simulate estuarine and coastal hydrodynamic forces. They found that the Delft 3D model has the smallest difference in the simulation of water lever and flow field.”, “Werner et al. used Hydrus 1D to simulate changes of soil salt content in Queensland coastal and concluded that surface salinization was greatly affected by the tidal. Hydrus 1D is appropriate for the simulation of water and salt transport because it can capture the water flow under flooding conditions. This paper creatively nested Hydrus 1D and Delft 3D models, which provides a flexible and comprehensive method for scholars to study the change of the estuarine hydrological environment.”.

 

The added 4 new added references are as follows:

[13] Hu, Q.; Yang, Y.; Han, S.; Yang, Y.; Ai, Z.; Wang, J.; Ma, F. Identifying changes in irrigation return flow with gradually intensified water-saving technology using HYDRUS for regional water resources management. Agricultural Water Management. 2017, 194, 33-47.

[18] Waldman, S.; Baston, S.; Nemalidinne, R.; Chatzirodou, A.; Venugopal, V.; Side, J. Implementation of tidal turbines in MIKE 3 and Delft3D models of Pentland Firth & Orkney Waters. Ocean & Coastal Management. 2017, 147, 21-36.

[41] Horstman, E.; Dohmen-Janssen, M.; Hulscher, S. Modeling tidal dynamics in a mangrove creek catchment in Delft3D. Coastal dynamics. 2013, 2013, 833-844.

[43] Khanam, M.; Navera, U.K. Hydrodynamic and morphological analysis of Gorai River using delft 3d mathematical model. Proceedings of the 3rd International Conference on Civil Engineering for Sustainable Development (ICCESD). 2016, 12–14 February 2016, 647-658.

Reviewer 2 Report

 Introduction

1. Paragraph2, please supplement the progress from the perspective of nesting – 1d and 3d model and highlight the significance of the proposed method in estuarine studies

 

Materials and methods

1. Why was observation Station 2 located in a non-river area?
2. Does the dams in Figure 1C actually exist? Or is it the result of scenarios settings? If it does already exist, how is the no-dam situation verified in scenario 1?    if not, what are the principles for setting up dams and sluice gates
3. Please elaborate on 1d and 3D nested methods (including in this section, and list the tidal constituent settings in Delft 3D
4. Is the nested model calibrated？
5. Is scenario 6 practical? If no, it is not recommended to keep it.
6. Please clarify all data sources and measurement methods required for modeling

 

Discussion

1. Did not see the use of the 3D DELFT model, please add in the method, results and discussion
2. Due to the limitation of observation points, the influence of dam and gate scenarios on the change and exchange of water and salt along the channel was not obtained in this paper. Please provide supplementary explanations in the discussion

Author Response

Reply to reviewer #2

Q1: Paragraph 2, please supplement the progress from the perspective of nesting – 1d and 3d model and highlight the significance of the proposed method in estuarine studies.

 R: Thanks for the suggestion. The nesting Delft 3D and Hydrus 1D models were one of the innovative aspects of our simulation study. The perspective of nesting 1d and 3d model and highlighting the significance of the proposed method in estuarine studies were added in the second paragraph of the introduction(marked in blue). “This paper creatively nested Hydrus 1D and Delft 3D models, which provides a flexible and comprehensive method for scholars to study the change of the estuarine hydrological environment.”.

Q2: Why was observation Station 2 located in a non-river area?

R: Thanks for the comment. The soil in the river area is often saturated and the soil water content changes little because of tide influence. Therefore, observation Station 2 located in a non-river area can clearly reflect the soil water change under different conditions.

Q3:  Do the dams in Figure 1C actually exist? Or is it the result of scenarios settings? If it does already exist, how is the no-dam situation verified in scenario 1? if not, what are the principles for setting up dams and sluice gates

R: Thanks. The tidal creek in Figure 1C does not have gates and dams in the real environment. We refer to the gate and dam settings of other tidal creeks in this area (such as gate width and construction location.). To make the description of the article clearer, we have added Figure 4 to explain the scenario setting.

Q4: Please elaborate on 1D and 3D nested methods (including in this section, and list the tidal constituent settings in Delft 3D

 R: Thanks. The method of model nesting has been described in the first paragraph of Materials and Methods. The detailed parameter setting of the Delft 3D model has been shown in Figure 3 and Table 1.

Q5: Is the nested model calibrated？

R: Thanks. The nested model has compared and calibrated the hydrological conditions in the natural state of the reconstructed area (scenario 1). We supplemented the description of model validation in the first paragraph of Materials and Methods.

Q6: Is scenario 6 practical? If no, it is not recommended to keep it.

 R: Thanks. The tidal creek water system in the wetland area of the Yellow River Delta is completely blocked by a large number of roads, ditches. Scenario 6 was just used to simulate and discuss this situation. Therefore, scenario 6 should be kept in the manuscript.

Q7: Please clarify all data sources and measurement methods required for modeling

R: Thanks. The data sources and measurement methods required for modeling have been clarified in section 2.2.1 of the revised manuscript (marked in blue). Besides the monitoring data, some parameters such as the Manning coefficient are obtained from the reference which has been agreed by the author.

 Q8: Did not see the use of the 3D DELFT model, please add in the method, results and discussion

R: Thanks. We added the parameter setting of the Delft 3D model in the Materials and Methods (see Figures 3-4 and Table 1). In the part of the Results and Discussion, we mainly describe the accuracy of the Delft 3D model (R²=0.96, RMSE=0.41), which can meet our requirements for simulation results.

Q9: Due to the limitation of observation points, the influence of dam and gate scenarios on the change and exchange of water and salt along the channel was not obtained in this paper. Please provide supplementary explanations in the discussion.

R: Thanks for the reviewer's suggestion, we have added a description to the first paragraph of the Discussion: “Due to the limitation of observation points, we did not study the downstream water body of the tidal creek, but focused on the water and salt transport in the reconstruction area (non-tidal channel).”.

Reviewer 3 Report

The authors present their model-based findings on coastal wetland restoration in China. The manuscript needs extensive English language editing (especially in terms of sentence structure and use of the articles, a, an and the). That said, the content of the paper is likely to be very useful for persons engaged in coastal wetland management and maintenance.  The major concern of this reviewer is the use of the term "dam" which seems inappropriate--perhaps a term like "polder" would be a better descriptor as it is commonly used to describe restoration projects in the Netherlands. Inclusion of more detailed site plans would also be very helpful for the reader as the scale of Figure 1 does not really allow the reader to gain a useful view/vision of the six alternatives. In other words, adding a second set of Figures showing the six alternatives in some detail would be helpful. The other Figures and Tables are all useful and pertinent; the references are appropriate and current. There are several misspellings, but these can be corrected as the manuscript is edited.

Author Response

Reply to reviewer #3

Q1: The manuscript needs extensive English language editing (especially in terms of sentence structure and use of the articles, a, an and the).

R: Thanks. A professor who has been studied in the UK was invited to improve the English of the manuscript. The corresponding revision has been made (marked in blue) in the new version.

Q2: The major concern of this reviewer is the use of the term "dam" which seems inappropriate--perhaps a term like "polder" would be a better descriptor as it is commonly used to describe restoration projects in the Netherlands.

 R: Thanks for the suggestion. “Dam” means a barrier that is built across a river to stop the water from flowing. “Polder” means a low-lying land that has been reclaimed and is protected by dikes (especially in the Netherlands). Therefore, we think it would be better to use "dam" to describe hydraulic structures.

Q3: Inclusion of more detailed site plans would also be very helpful for the reader as the scale of Figure 1 does not really allow the reader to gain a useful view/vision of the six alternatives. In other words, adding a second set of Figures showing the six alternatives in some detail would be helpful.

R: Thanks. We have added Figure 4 with six specific scene floor plans to help readers understand the six scenarios.

Round 2

Reviewer 1 Report

NA

Reviewer 2 Report

1. English needs to be improved by native speaker

2. There is no need to list the basic parameters of Delft 3D.  Key paramenters should be moved to Table from text, such as surface roughness (the sediment of Yellow River is distinctive), tidal characteristics ( the study area located in estuary). 

3. Calibration and validation are different, which need to be clarified in manuscript.