Long-Term Change of Coastline Length along Selected Coastal Countries of Eurasia and African Continents

Round 1

Reviewer 1 Report (Previous Reviewer 1)

No further comments 

Author Response

Thanks a lot for your comments!

Reviewer 2 Report (Previous Reviewer 2)

Paper describes well the method to determine the coastline length, but fails in the interpretation of this information. The length scale is too big for good moprhological conclusions. The amount of erosion/accretion on a length scale equal to a morphological unit is relevant. Especially with archipelago countries this is essential. This is fully missing.

 

Author Response

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Reviewer 3 Report (Previous Reviewer 3)

Authors should match the text with the title:

It is recommended to change the title to be:

Long-term Change of Coastline Length along Selected Coastal Countries of Eurasia and African Continents

Figure 1, 2. Too small to read, it is recommend to increase the accuracy to display contents.

Methods flow chart is required to summarize the applied techniques.

Table 1. The description of coasts types need to support with references.

In figure 4. The cartographic display is bad, color contrast is needed.

Author Response

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Round 2

Reviewer 2 Report (Previous Reviewer 2)

After this last change in title of the paper and the small changes I do no longer object publication.

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 authors submitted a well written and an interesting manuscript focusing on the Long-term Coastline Change analysis along the Maritime Silk Road using multi-temporal Landsat data. However, the authors need to improve the manuscript, especially by providing sufficient description of the methodology and additional references, before it could be considered for publication. Below are some comments and suggestions to improve the overall quality of the manuscript:

Line 119: On the Figure 1, it could be interesting to include the legend with explanation of the colors represented on this Figure.

Lines 106-119: The section of Study area, should be included in the section of Material and Methods. And after you could continue this section of Material and Methods with its subsection of Methodology where the authors could include the section presented on lines 121-186.

Lines 124-126: Please provide more recent studies conducted in coastal areas mainly focusing on the definition of coastline and coastline indicators. Please refer to (1) Boak, E.H.; Turner, I.L. Shoreline definition and detection: A review. J. Coast. Res. 2005, 21, 688–703, (2) McAllister, E.; Payo, A.; Novellino, A.; Dolphin, T.; Medina-Lopez, E. Multispectral satellite imagery and machine learning for the extraction of shoreline indicators. Coast. Eng. 2022, 174, 104102, (3) Cadier, C.; Bayraktarov, E.; Piccolo, R.; Adame, M.F. Indicators of Coastal Wetlands Restoration Success: A Systematic Review. Front. Mar. Sci. 2020, 7, 600220.

Lines 58-59: Please provide more recent studies conducted in coastal areas mainly focusing on coastline degradation. Please refer to (1) Petrişor, A.-I.; Hamma, W.; Nguyen, H.D.; Randazzo, G.; Muzirafuti, A.; Stan, M.-I.; Tran, V.T.; Aştefănoaiei, R.; Bui, Q.-T.; Vintilă, D.-F.; Truong, Q.H.; Lixăndroiu, C.; Ţenea, D.-D.; Sîrodoev, I.; Ianoş, I. Degradation of Coastlines under the Pressure of Urbanization and Tourism: Evidence on the Change of Land Systems from Europe, Asia and Africa. Land 2020, 9, 275. https://doi.org/10.3390/land9080275, (2) Nicholls, R.J.; Woodroffe, C.; Burkett, V. Chapter 20—Coastline Degradation as an Indicator of Global Change. In Climate Change, 2nd ed.; Letcher, T.M., Ed.; Elsevier: Boston, MA, USA, 2016; pp. 309–324

Lines 140-143: The description of the dataset provided is not sufficient for some readers. The authors should provide the names and the spatial resolutions of the bands they selected to conduct this study. It is also important to provide the exact date of acquisition of each image.

Lines 145-147: Please provide more recent studies conducted in coastal areas mainly focusing on the methods of coastline extraction using remote sensing images.

Lines 146-152: The authors should provide the name of the software used and the steps followed to extract the coastline from this dataset.

Line 156: The authors should indicate how the total coastline length was computed by indicating the limits, the parameters considered during this process.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Title is confusing.  As explained in the abstract and in the intro it states:  “Starting from East Asia, the Maritime Silk Road (MSR) connects dozens  of countries and regions in Asia, Africa and Europe, making it one of the longest and most flourishing maritime transport routes in the world. “ Apart from the fact that the name “Maritime Silk Road” is more a political approach, and as such not really fitted for a Journal like Remote Sensing, it also gives a wrong impression. The MSR is a maritime connection, so elements of it are the ports and harbours in this region, as well as approach channels towards these ports (e.g. the Suez Canal , but also the more than 100 km long seaway over the Hooghly River to Kolkota. With this title I expect a paper on the de sedimentation problems in the access to these ports and in the navigation channels. But this paper does not deal with this item at all, it deals with the coastal erosion (and accretion) of the coastlines of the countries which (according to China) are part of the MSR. (Note that many countries mentioned in the paper do not consider themselves as part of the Chinese MSR).  Also on many places in the paper it is suggested that the MSR is a physical entity, e.g. in lin 202-204 where is mentioned that “ the overall length of the coastline of the Maritime Silk Road began to decrease slowly after reaching a maximum in 2010.”

So, in any case the title should be something like “Long term coastline change in countries considered by China as part of the Maritime Silk Road”.

In this respect that the story regarding the history of the MSR (line 78-105) is not so relevant.

Also relevant to mention is that in the reference-list there is no reference to a studies like Luijendijk et al. (2018) and Murray et al. (2022). This study has done the same as what is done in this paper, only it covers the full world (and not only the so-called MSR-countries), as well in more detail.

The overall figures (fig 2, fig 3, fig 4) do not provide real relevant information. For example the impression that in Greece there is a major increase of the coastline gives a fully wrong impression, especially because most of the Greek coastlines suffer from erosion . See for example https://www.climatechangepost.com/greece/coastal-erosion/ , where is stated “Nearly one-third (28.6%) of the Hellenic coastline is eroding (mostly < 10 m over time periods of 20-30 years). Sediment supply to the coast has decreased strongly due to the construction of dams, river channelization and intense coastal development.”

From a practical point of view fig 6 is confusing, because for all years the countries are ordered by total coast length. Especially for countries with less than 1000 km length this is not clear.

References:

Luijendijk, A., Hagenaars, G., Ranasinghe, R. et al. The State of the World’s Beaches. Sci Rep 8, 6641 (2018). https://doi.org/10.1038/s41598-018-24630-6

Murray, N.J., Phinn, S.P., Fuller, R.A. et al. High-resolution global maps of tidal flat ecosystems from 1984 to 2019. Sci Data 9, 542 (2022). https://doi.org/10.1038/s41597-022-01635-5

Author Response

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Reviewer 3 Report

The overall decision is the manuscript still need to correction. It has analysed coastline change length along very huge spatial area including (three continents), oceans and seas coasts between 1990-2020. The methods of study still not clear, shoreline extraction and analysis techniques need to clarify. The comparative analysis between coasts in different marine environments, driving factors, and human impact assessment still need to more work.

There is some notes to follow:  

Figure 1. Map of study area is not clear. The sink road must be appear in the map. The colours used are not clear.

Page 4: L129-137 there is a generalization in the coastline classification; the classification of the coasts along this huge area is dilemma. Authors must clarify how they classified and mapped coasts over time; maps of the classified coasts should be inserted.

Table 1. References were used to summarize the table should be mentioned.

Page 4. L 142: the total number of the Landsat imagery were used is 3872 scene. How you could analysed and storage these data?

Page 4: Line 146-152 Methods of coastline extraction used in this study is not clear.

Results: The Spatial and Temporal identification of the Natural and Artificial coastlines from Landsat imagery are not clear.

The time interval should be, equal (1990-2000-2010-2015-2020) to simplify analysis and cartographic analysis. How we can assess and judge in these results?

Figure 3: is not representative! It need to other cartographic symbols

Figure 4. Please change the color of the base map other than color of levels to contrast it. Add a caption to describe the size of the grid, how it calculated.

Page 9 line 241: what did you mean with Km/a?

In table 2 – page 9: for Bedrock How the change rate (km/a) is nearly similar? Although the time interval is not equal: between 1990-2000 (10 years) = -275.3 km/a, between 2000 and 2010 (10 years) the length was -276.3 km/a, and from 2010-2015 (5-years) = -265.2 km/a. in the final period 2015-2020 (5-years) the length was only 32.3 km/a ??? Please give an interpretation.

 

Figure 6: The difference between three sub-figure 1990, 2015, and 2020 is too small, you cannot detect it easily!

 

Figure 8. Figure is too small to read, Time should be appear in all scene.

Author Response

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Round 2

Reviewer 2 Report

An important issue with this paper is that the parameter "coastline length" does not really informs about the state of the coast. When the coast is eroding, the total length can increase, but also it can decrease. Also determine values for countries as a whole has no meaning. For example the Atlantic coast of Spain is completely different from the Mediterranean coast of Spain.

In this version many references are given to previous studies in this field, but it is not discussed if the findings are the same or different, neither are differences explained.

Author Response

Thank you for your positive comments! We have revised our manuscript. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The Title of the manuscript is too general; it is not correct. It cannot accepted with selection the coastal countries. Something missing intentionally from the title.

The author should show the importance of the study. An explanation is required for the benefits from this study to the scientific community from this study.

Authors should explain why they choose the selected countries to study.

In page, 4 line 139-140 authors did not clarify the methods used for coastline extraction; digitizing manually, semiautomatic, or automatic!

According to Table 2. It is recommended to check the results accurately for example the Bedrock rate of change rates (Km/a) changed -275.3, -276.3, -265.2, 32.3). In addition, for Biotic coasts (448.3, 168.2, 28.4, and 1021.7). These rates are not consistency, an explanation is required for the dramatically change.

In the figure 7. Although the analysis for all study used the periods 1990,2000,2010,2015, and 2020. In this figure, the 2015 period has been excluded.

The References 43, 45, and 46 have been written in Asian Language, It is recommended to translate it in English.

Comments for author File: Comments.pdf

Author Response

Thank you for your positive comments! We have revised our manuscript. Please see the attachment.

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Round 3

Reviewer 2 Report

Indeed it is now explained that in this reseach only the changes in the overall length of the coast  is studied on a large scale. However, this parameter is not relevant at all for coastal managers.

For world wide scale changes in the coastline position (i.e. erosion and accretion) are relevant and not the change in coastlength.