Analysis on the Dynamics of Coastline and Reclamation in Pearl River Estuary in China for Nearly Last Half Century
Round 1
Reviewer 1 Report
All minor comments raised by the reviewer during the previous submission have been successfully addressed now and thus I propose the acceptance for publication of this work.
Accept in its current form
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper describes the dynamics of an important coastline in China. Although the results are interesting, the text, tables, graphs, and maps are repetitive. I suggest to chose one, either a table (2 and 3), Figures 4 and 5, or the map. The interesting result is the interpretation of the coastal use change. I suggest a figure showing the timeline that now is in the text and showing the key issues in the key years.
And most importantly, the authors should add a mention to the sea-level rise, I guess the "reclamation land" now is endangered and will cost plenty of money, people´s migration, coastal use change, etc. to deal with it.
Mention other coastlands worldwide, suffering similar scenarios.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
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 aim of the paper is to analyse the changes in the coastline and reclamation processes in the Pearl River Estuary in the last five decades. This is a very interesting zone as it has been developing very rapidly, which represents a challenge to reach a balance between urban and industrial development and nature protection. Although the paper is not very original form the scientific point of view, it is an interesting contribution to understand the changes ocurred and the associated human activities and interests causing those changes.
To my point, the main weakness of the paper is that the results and the discussion sections are not well structured, with some results in the discussion section and viceversa. In addition, the discussion shoud be improved by shortening some paragraphs that are not real discussion and including more references.
Specific comments:
I suggest using commas to separate thousand in the units (please change this in all the text).
In the study area section, line 98, I do not understand what "the second largest" river in China means. In line 100, change "a complex region accumulated by the sediment..." by "a complex region formed by the deposition of the sediment...". In this paragraph, the names of the protected species must be written properly: Sousa chinensis (Indo-Pacific humpback dolphin) and Bahaba taipingensis (Chinese bahaba). Some references supporting the study area characteristics are recommended.
In line 121, is correct "The East Four Estuaries"? They are located just in the West of the Bay.
In the Results section, the first paragraph should be better allocated in the discussion.
In Figure 4, the variables and units should be put in the x axis (years and periods) and in the y axis (coastline lenght, km; coastline average growth, km/year).
The last paragraph (lines 259-268) are not results and would be better allocated in the discussion.
In Figure 6 the variables and units should be put in the x axis (periods) and in the y axis (cumulative growth area of reclamation, ha). One of the graphs can be removed as they represent the same.
In Figure 7, the variables and units should be put in the x axis (Annual average growth of reclamation area, ha/year) and in the y axis (periods).
In the Discussion section, remove lines 310-315. The paper should not make any value judgement.
Table 3 presents the same information than Figure 8 and, hence, one of them should be removed.
Maybe some information (data) on several indicators of human activities could support the results and improve the discussion: humman population in the different districts or areas, economic indicators of by sectors, etc.
Section 5.3 does not discuss any of the obtained results and it does not provide any reference neither scientific nor regarding management or legislation. This is not acceptable in a discussion section. This section should rewritten or removed.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
water-1562462
Analysis on the Dynamics of Coastline and Reclamation in Pearl River Estuary in China for Nearly Last Half Century
General comments:
The present study presents an analysis of the coastline dynamics and reclamation in the Pearl River estuary, China from 1973 to 2021, using satellite remote sensing data. They concluded that the coastline length and reclamation area in the region presented an increasing trend at first with high growth rate but afterwards this rate has slowed down because of different national development strategies and macro-control measures in different historical periods.
In general, the present paper is well written. However, I think the manuscript have some problems that should be addressed before publication. To improve the manuscript, changes and suggestions are described below in the specific comments for all sections of the paper.
Specific comments:
Abstract
I believe the abstract is too long. I would shorten it to be more appealing for the reader. Also, I would remove de AD from the years.
Introduction
Page 2, Lines 47-56: I would not start with this paragraph. I would start with the next one where you talk about China in general and then incorporate this information that relates to your specific study area.
Page 2, Lines 90-96: I believe this sentence is too long, please try to improve it.
Study Area
Page 3, Lines 105-106: You must put the name of the species in italic and the name of the genera in capital letter: Sousa chinensis and Bahaba taipingensis.
Materials and Methods
Page 6, Line 144: I don’t understand what you mean with this sentence: “The processing method is not elaborated in detail here as it is already very mature (Fig. 3).” I believe you must explain the methodological processing in detail or refer to another previous work that has already done it.
Results
I believe this part is the one that deserves more attention to try to improve it, as it seems that many parts are not results. Some belong to introduction, methodology or discussion.
Page 6, Lines 158-175: The information given in this paragraph seems more a framework and a justification of the years used in the study. They are not results of your work. Please, try to incorporate it in the methods.
Page 7, Lines 199-206: This part this seems more like an introduction, not results.
Page 8, Line 225: I suggest changing to: “It can be seen from Figure 5 to Figure 7 that in the past half century, the total area of reclamation in this region increased by 28256.06 ha. The most significant…”
Pages 8 and 9, Lines 259- 268: This seems more like a discussion already and not results.
Discussion
Page 10 and 11, Lines 304-310: You must improve this sentence, as it is too long.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript entitled “Analysis on the dynamics of coastline and reclamation in pearl river estuary in China for nearly last half century” by Zhang et al. represents a significant contribution to the coastline and reclamation changes of the Pearl River estuary including marine ecological protection and restoration issues. I found the topic of the manuscript very interesting and possibly of great interest for the Water readers. The manuscript is of great interest, as it examines for the first time such a synthetic view examining all these ecological and sedimentological/paleoceanographic characteristics.
Overall, all data are sufficient, and the treatment of the data are appropriated. The figures are appropriated as both quantity and quality. The length of this review paper is appropriated for this journal, with all interpretations and conclusions to be in general very well justified. The text is very well organized, and this makes the manuscript easily readable and understandable. However, there are repetitive phrases that should be eliminated. The bibliography is accurate too, but some additions are needed. The English is in relatively good shape, but some places need some improvements (please see my comments about rephrasing below). However, there are some critical points that need to be clarified and/or better discussed before acceptance. Therefore, I propose several points to be addressed before it can be considered for publication (minor revision). Both the minor comments and suggestions are presented in the attached pdf file. I hope seen this work published soon.
Minor comments/ suggestions:
L72: What is the meaning of “natural ecology”? Rephrase it or briefly explain it
L90-95: Split it into 2 different sentences
L101-104: Reference is missing here
L178: Here and throughout the manuscript: Replace the symbol “&” with “and” into the text
L181-196: I propose all this information to be evident into a Table. In such way the text will flow easier for the potential reader
L205: …provide views and spaces… what the authors mean with this phrase? Briefly explain it
L213-214: What is biological coastline?
L334-337: This part is unclear. Please rephrase it
L376-378: Several references should be added here for describing all these processes. For instance, the citation of Zarkogiannis et al., 2018 in Coastal Engineering
Zarkogiannis S.D., Kontakiotis G., Vousdoukas M.I., Velegrakis A.F., Collins M.B., Antonarakou A., 2018. Scarping of artificially-nourished mixed sand and gravel beaches: Sedimentological characteristics of Hayling Island beach, Southern England. Coastal Engineering, 133, 1-12, https://doi.org/10.1016/j.coastaleng.2017.12.003.
L397: Again, a reference should be added here
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear Authors:
My comments are as follows:
- The abstract is too long. An abstract should be a total of 150-250 words. Please revise the abstract and make sure your abstract contains a clear background, brief description of methods, results, and conclusions.
- It is not clear to me what is the objective of this study. Please state clearly what is the objective of this study in the Introduction section?
- Table 1: The authors used images with various spatial resolutions, how did the authors overcome this issue?
- Table 1: It is unclear whether the images are taken at the same tide condition. The difference in tides will result in very different coastline positions. Given the wide time span of each image, I am afraid the changes in the coastline position were caused more by tidal differences than by the dynamics of the coastline itself!
- It is not clear what is the proxy when generating those various coastlines. The author mentioned in line 148 that “..the location can be inferred to by using common geographical knowledge in combination with the images’ seasonal and ground feature distribution characteristics….”: what does it mean? Please explain clearly in the method section how the authors delineate these coastlines?
- Line 152 “…conducted an in-depth analysis of the coastline changes and the reclamation of the Pearl River Estuary in light of local socio-economic development…” could the author improve this sentence and describe more clearly what actually did the author do in analyzing the changes?
- Figure 3: “comprehensive judgment analysis”, please explain briefly in the text what did the authors mean by this?
- Figure 3: “background information of economic and social development” please explain in the text (maybe in the method section) what other information was used in explaining the changes in coastline position?
- The study area should also describe the hydro-oceanographic conditions that can help in explaining the dynamics of the coastline!
- Line 185: what does “inner coastline” mean?
- How did the authors differentiate natural coastline from the artificial coastline by using remote sensing images? Please explain briefly in the method section!
- Lines 236-237: “…from 1987 when the national policy of "centering on economic development was proposed to 1994..” This sentence requires citation!
- Lines 240-241” “…Since the sustainable development strategy was determined in 1994 to 2002,..” This sentence requires citation!
- Table 3 should be part of the results section
- Lines 279-282: This sentence is too long, please revise it!
- Lines 293-299: what is the benefit of knowing this information? what suggestions can the authors give to decision-makers?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
After the revision and corrections to the first version, I consider the manuscript ready for publication in Water.
Reviewer 2 Report
water-1562462
Analysis on the Dynamics of Coastline and Reclamation in Pearl River Estuary in China for Nearly Last Half Century
General comments:
The manuscript has been revised following the reviewers’ suggestions and answering the questions posed to clarify some aspects. I appreciate the changes that the authors have made throughout the manuscript. It was a huge improve and I believe the manuscript is almost ready for publication. However, I still think there are a few things that can still be improved:
Specific comments:
Abstract
Page 1, Line 38: I suggest changing to: “…which makes the average annual growth rate of the coastline length and the reclamation area in the region show a significant downward trend.”
Study Area
Page 3, Lines 105-106: Remove the italic from the name of the animals in brackets: “The national first-class protected animal Sousa chinensis (Indo-Pacific humpback dolphin) and second-class protected animal Bahaba taipingensis (Chinese bahaba) are distributed here [36-37].”
Materials and Methods
Page 7, Line 204: I suggest changing to: “…socio-economic development (e.g. sea area and land ownership information, coastline renovation and restoration projects, relevant planning, etc.)”
Results
Page 8, Lines 236: I suggest changing to: “Tables 2, 3 and Figure 4 show…”
Reviewer 4 Report
Dear Authors,
My comments are as the following:
- The slope of the coast will affect the position of the coastline, that’s why images at the same tide condition are important. On a sloping beach, a slight change in the tide will cause a change in the position of the coastline. And it's not impossible to get images in the same tidal situation.
- For the proxy when generating the coastline, the method contains a lot of uncertainty. For steep beaches, it may be easy to delineate water and land boundaries but what about gently sloping sandy or silt areas, how did the author decide which part to be delineated?
- The author mentioned using 7 images for this study and combining them with other factors to determine the coastline position (including expert judgment); however, it was still not clear how the authors developed those coastlines for this study. The author must explain the method in detail to make sure that the method is reproducible.
