Coastal Protection for Tsunamis

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This research introduces a case study for coastal protection against tsunamis at Caxias beach, Portugal. The authors introduced a numerical simulation to the beach using a 2D shallow water equation model, TUNAMI-N2 model, and field visits to the study area and similar areas in Jaban. In this simulation, they used a generated high-resolution topography (3m) to represent the Caxias City streets. The paper concluded a reasonable solution to mitigate the danger of floodings and proved that by the model.

However, the authors should consider the following items:

In introduction,

1-     The style of introducing different studies by repeating “Another study” is not professional as I think. (Authors names should be mentioned!!).

2-     The paper is well written, however, only the abstract and conclusion need to be rewritten.

3-     Line 58-59, Reference 13, more info should be included about the duration and methodology used.

 

In Materials and Methods,

4-      lines 169-171, this paragraph was not clear to me till the discussion part. The used structures to mitigate the damage or recorded damages were not mentioned in this area (Japanese beaches). … Also, revise English.

 

Results,

5-     Generally, please mention figures in order, lines 177 – 181, figure 5 after figure 6??

6-     One of the main targets of the paper is to highlight the importance of using high-resolution topography (3m) than the previous study (9m), therefore, a comparison between the two results should be presented in the study.

7-     The numerical model verification should be shown in the paper to trust the results.

 

Discussion

8-     Lines 331 – 342 about water quality should be clear about water circulation and residence time inside the trapped area by the breakwater.

9-     Please describe the change of manning coefficient if any after using the green line to protect Caxias beach.

Comments on the Quality of English Language

The paper is well written, however, only the abstract and conclusion need to be rewritten.

Author Response

In introduction,

Comments 1: The style of introducing different studies by repeating “Another study” is not professional as I think. (Authors names should be mentioned!!).

Response 1: thank you very much for the comment. We revised the introduction of the manuscript and all changes are marked with the tracking changes.

 

Comments 2: The paper is well written, however, only the abstract and conclusion need to be rewritten.

Response 2: The abstract and conclusions were revised. Please check the revised manuscript which has the tracking changes.

 

Comments 3: Line 58-59, Reference 13, more info should be included about the duration and methodology used.

Response 3: [Ref 13] analyzed tide gauge data from Portuguese coastline stations from 1980 till 2016. The data show an increase in the mean sea level of about 0.1 m. The authors conducted a time series probabilistic analysis to estimate the sea level rise from 2016 till 2100. They concluded the average rising of the mean sea level would be about 0.7 m for a return period of 50 years.

We revised the paragraph of the manuscript; please check the revised manuscript which has the tracking changes.

[Ref 13] – Antunes, C.; Rocha, C.; Catita, C. Coastal Flood Assessment due to Sea Level Rise and Extreme Storm Events: A Case Study of the Atlantic Coast of Portugal’s Mainland. Geosciences 2019, 9, 239. http://doi:10.3390/geosciences9050239.

 

 

In Materials and Methods,

Comments 4:  Lines 169-171, this paragraph was not clear to me till the discussion part. The used structures to mitigate the damage or recorded damages were not mentioned in this area (Japanese beaches). … Also, revise English.

Response 4: We included more explanation about the Japanese coastal areas, both in the methods and discussion Sections. 

 

 

Results,

Comments 5: Generally, please mention figures in order, lines 177 – 181, figure 5 after figure 6??

Response 5: Thank you for the comment. We revised the text, and all figures are now mentioned in order.

 

Comments 6: One of the main targets of the paper is to highlight the importance of using high-resolution topography (3m) than the previous study (9m), therefore, a comparison between the two results should be presented in the study.

Response 6: The comparison was already conducted in the original submitted manuscript. However, we understand the text was not very clear and we revised the sentences and English. Please check the revised manuscript which has the tracking changes.

 

Comments 7: The numerical model verification should be shown in the paper to trust the results.

Response 7: Thank you very much for the comment. The tsunami source model validation was added to the text. Please check the revised manuscript which has the tracking changes.

 

 

Discussion

Comments 8: Lines 331 – 342 about water quality should be clear about water circulation and residence time inside the trapped area by the breakwater.

Response 8: As indicated in the original version of the submitted manuscript the water circulation is not the scope of this paper. We just want to point out that at the present time the water quality of the beach is not very good, though acceptable for public use. We revised the sentences in the manuscript (English editing), so this point becomes clear. Please check the revised manuscript which has the tracking changes.

 

Comments 9: Please describe the change of manning coefficient if any after using the green line to protect Caxias beach.

Response 9: The Manning coefficient has not been changed since we are not changing the drag. The new sea wall should be constructed between 4 and 7 m in height so that it will be a total barrier to the incoming waves which have a local maximum water level up to 6.8 m.

 

 

 

Comments on the Quality of English Language

Comments 10: The paper is well written, however, only the abstract and conclusion need to be rewritten.

Response 10: Thank you very much for the comment. The abstract and conclusions were revised. Please check the revised manuscript which has the tracking changes.

Reviewer 2 Report

Comments and Suggestions for Authors

Major revision is suggested, please see the attachment.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Moderate editing of English language is required.

Author Response

Comment 1: The first big issue lies on that it is hard to catch what are the innovations for the present manuscript. Is its innovation in research methods or better understanding of physical mechanisms? It would be better to point them clearly out in the abstract, introduction and/or the conclusion.

 

Response 1: Thank you very much for the comment. We modified several paragraphs to show the innovations of the present manuscript. Please check the revised version, which includes tracking changes.

The innovations of this manuscript are:

a. The use of new LIDAR data allows the reproduction of the Digital Elevation Model (DEM) of the study area more accurately. Please keep in mind that the topography data in Portugal is still very limited. This study is very innovative because, to the authors’ knowledge, there is no scientific publication using this type of technology in the Portuguese Territory.

b. The new data allows an upgrade of the tsunami numerical model setting, from 5 computational regions to 6 regions. Previous results obtained in computational region 5 were obtained with a 9 m cell size, being previously published by the authors [ref 16]. The new computational region 6 has a resolution of 3 m cell size and will be applied to Caxias (this study).

c. In computational region 6 the local features are accurately reproduced, including streets and ramps to access the beaches. In addition, it is proposed the construction of more seawalls and a third bridge over the Barcarena Stream to restrict the inundation zone to the beaches.

 

 

 

Comment 2: In the Introduction part, although the studies on coastal harzards investigations related to tsunamis are well reviewed. However, some studies on harbor harzards induced by tsunamis are not mentioned at all, such as the transient harbor resnance phenomenon (On hydrodynamic characteristics of transient harbor resonance excited by double solitary waves. Ocean Engineering, 2021, 219: 108345; Topographic influences on transient harbor oscillations excited by N-waves. Ocean Engineering, 2019, 192: 106548; Effects of offshore fringing reefs on the transient harbor resonance excited by solitary waves. Ocean Engineering, 2019, 190: 106422). Furthermore, some lastest literatures that investigtated the effects of extreme waves on coastal structures are also ignored by the authors (e.g., Numerical investigation of harbor oscillations induced by focused transient wave groups. Coastal Engineering, 2020, 158: 103670). These closely-related studies need to be properly mentioned in the Introduction part.

 

Response 2: We thank the Reviewer for the comment. As mentioned in the manuscript, there are hundreds of papers just published on JMSE (MDPI) directly related to the topic of our manuscript, and it is impossible to cite all of these papers. However, the effect on harbors is not the focus of the study (as in several other published research), since the selected studied area has 2 sandy beaches. Still, we revised the introduction to include a few more references published in Ocean Engineering (Elsevier). Please check the revised version of the manuscript, which includes tracking changes.

 

 

 

Comment 3: The research in this article is mainly qualitative description of phenomena, lacking  quantitative comparison or description.

 

Response 3: Thank you very much for the comment. We revised the text to highlight more quantitative comparisons and descriptions of the model results from 9 m cell size [ref 16] and 3 m cell size (this study). Please check the revised version of the manuscript, which includes tracking changes.

Comment 4: In the conclusion part, although some conclusions are obtained. Readers are also interested in the implications of these conclusions for practical projects/coastal protections. So, it would be better to summarize a few implications to guide for practical projects/coastal protections.

 

Response 4: Thank you very much for the comment. We revised the conclusion, by summarizing the highlights of our findings: the use of LIDAR data to improve the local coastal Digital Elevation Model and the use of tsunami numerical models allow the calculations of tsunami travel times and inundation areas. Furthermore, based on field surveys conducted on several coastal areas in Portugal and Japan, we propose the construction of more sea walls at the beaches and the margins of Barcarena Stream. Finally, we propose the construction of a new bridge for pedestrians that would serve as a tsunami gate to divert the incoming sea waves. Please check the revised version of the manuscript, which includes tracking changes.

 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

This version can be accepted.

Comments on the Quality of English Language

Moderate editing of English language is required.