Coastal Defences on Low-Lying Reef Flats: A Laboratory Study of Seawall Shape and Position
Round 1
Reviewer 1 Report
This manuscript presents laboratory experiments about wave attenuation by implementing a seawall on a reef flat. Various factors, such as the wave forcings, reef depth, and seawall shapes are considered in the physical model. It was found that the higher protection efficiency is reached for small waves, shallow water depths, seaward position and stepped seawall shape. The results provided by the authors is novel and interesting. The topic is within the scope of JMSE. The English and the structure of the paper is adequate. Therefore, I do recommend publication after addressing the comments described below.
1. The major concern is the design of the scaling strategy of the physical model. The authors used a vertical scale of 1/60 so that the offshore water depth is only about 1.2 m. Is that reasonable? I’d like to see more discussion about the issue.
2. Line 61. High nonlinearity waves can also be found on the reef flat due to the enhancement of wave triads interactions by the steep forereef slope. I suggest to cite the below reference.
Li Y, Zhang C, Chen S, et al. Influence of Artificial Sandbar on Nonlinear Wave Transformation: Experimental Investigation and Parameterizations[J]. Ocean Engineering, 2022, 257:111540.
3. Fig. 2, the size of seawall should be provided.
4. Figs. 3A and B, it seems that waves begin to break before reaching the reef, please clarify.
5. What does /gamma_s mean in the line below Eq. 3.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors carried out comprehensive flume experiments on wave attenuation by a single seawall defence deployed on an archetypal reef flat. As the authors claim themselves, their work will supplement the understanding about the deployment of seawall defense over low-lying coral reef flats. The presented experimental results may be good references for practical designs as well as the on-going development in the field of seawall effect at the complete reef system scale. Before accepting for publication, I have several comments and questions as can be found in the followings, to which I recommend the authors pay due considerations and revise the manuscript accordingly.
1. The title of the manuscript, "Coastal defences on low-lying reef flats: a laboratory study", is not focused enough and covers a wide range of areas. It is recommended to reconsider the title and further modify it.
2. It is mentioned that dissipative beach in line 88 of the manuscript, please mark it in Figure 2-A.
3. Does the experiment consider the secondary reflection caused by the water tank, and how to deal with it?
4. There are only 4 working conditions of experimental water depth in Table 1. Please check the statement about experimental water depth cases on line 95.
5. It is mentioned that γs=0.85, 0.9, 1, 1.1 and 1.3 for SLS, CFS, VS, CS and STS. What is the basis for defining these values?
6. Please redesign the icon in Figure 3 to make it more beautiful.
7. The unit variables in Table 1 should not be expressed in italics, and the font is not uniform. The same problem occurs on line 180, 184, 206 of the manuscript, please check and correct the full text. Change the variables in the figure3, 4, 5, 6 to italics. Units on line 180 and 206, etc. should not be italicized.
8. Please check the references citation format on line 63.
9. The expression of page and volume numbers in references are not uniform, such as pp. on line 286, 362, 372 and p. on line 338, 370, and Vol. in 306, 362. Please refer to the reference format requirements of the target journal for uniform modification.
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The present paper study the deployment of seawall defense over low-lying coral reef flats based model experiments. The results are meaningful. However, some items are proposed to be cleared before its publication.
1. The wave flume is short. How to deal with the effect of the multi-reflection between the structure and wave maker? This should be cleared.
2. Infragravity waves (IG) is defined as F < 0.5Fp. Please give some explanation why 0.5Fp is taken as the critical value.
3. Surf similarity parameter is used. Its definition is proposed to be given.
Author Response
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Author Response File: Author Response.pdf
