Quantifying Spatio-Temporal River Morphological Change and Its Consequences in the Vietnamese Mekong River Delta Using Remote Sensing and Geographical Information System Techniques

Round 1

Reviewer 1 Report

Reviewer's Comments:

Literature Review: The paper lacks a comprehensive literature review on the subject matter. It is advisable to include relevant studies that provide context and background to the research, showcasing the existing knowledge gaps.

Maps: The labels on the maps are noted to be messy, and the absence of lat-long coordinates on the maps hinders precise location identification. Recommendations include repositioning labels for clarity and incorporating lat-long information.

Graphical Representation: The graphical representation of figures and maps is criticized for its inadequacy. Enhanced visualization techniques and clarity in graphical elements are suggested to improve the overall quality of the visuals.

Methodology: The methodology is deemed weak, repetitive, and lacks innovation. The reviewer recommends strengthening the methodology section by introducing innovative approaches, ensuring it is both robust and distinct.

Abstract and Conclusion: Both the abstract and conclusion sections require improvement. They should be revised for clarity, coherence, and conciseness, ensuring that readers can easily comprehend the research objectives and findings.

References: A significant number of references are outdated. It is strongly advised to incorporate recent literature to ensure the inclusion of the latest developments and research in the field.

Language and Grammar: The language throughout the manuscript is identified as weak, with several grammatical mistakes. A thorough proofreading and language refinement are necessary to enhance the overall readability and professionalism of the paper.

Paper Length: The manuscript is considered lengthy. A concise summary is recommended, eliminating unnecessary text, figures, and maps. This will streamline the paper, making it more focused and reader friendly.

Overall Evaluation: The paper has potential, but substantial improvements are needed in the literature review, map labeling, graphical representation, methodology, abstract, conclusion, references, and language. Addressing these issues will significantly enhance the quality and impact of the research.

The authors are encouraged to carefully consider these suggestions for the refinement of their manuscript.

Reviewer's Comments:

Literature Review: The paper lacks a comprehensive literature review on the subject matter. It is advisable to include relevant studies that provide context and background to the research, showcasing the existing knowledge gaps.

Maps: The labels on the maps are noted to be messy, and the absence of lat-long coordinates on the maps hinders precise location identification. Recommendations include repositioning labels for clarity and incorporating lat-long information.

Graphical Representation: The graphical representation of figures and maps is criticized for its inadequacy. Enhanced visualization techniques and clarity in graphical elements are suggested to improve the overall quality of the visuals.

Methodology: The methodology is deemed weak, repetitive, and lacks innovation. The reviewer recommends strengthening the methodology section by introducing innovative approaches, ensuring it is both robust and distinct.

Abstract and Conclusion: Both the abstract and conclusion sections require improvement. They should be revised for clarity, coherence, and conciseness, ensuring that readers can easily comprehend the research objectives and findings.

References: A significant number of references are outdated. It is strongly advised to incorporate recent literature to ensure the inclusion of the latest developments and research in the field.

Language and Grammar: The language throughout the manuscript is identified as weak, with several grammatical mistakes. A thorough proofreading and language refinement are necessary to enhance the overall readability and professionalism of the paper.

Paper Length: The manuscript is considered lengthy. A concise summary is recommended, eliminating unnecessary text, figures, and maps. This will streamline the paper, making it more focused and reader friendly.

Overall Evaluation: The paper has potential, but substantial improvements are needed in the literature review, map labeling, graphical representation, methodology, abstract, conclusion, references, and language. Addressing these issues will significantly enhance the quality and impact of the research.

The authors are encouraged to carefully consider these suggestions for the refinement of their manuscript.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Brief summary:

The study analyzes morphological changes and their impacts in the Vietnamese Mekong Delta (VMD) from 1988 to 2020 using remote sensing and GIS techniques. The findings reveal a shift from dominant accretion to dominant erosion in the last period of the study, increased exposure of riverbank erosion to local economic, and significant economic damages caused by land loss.

General concept comments:

A potential weakness of the study is the limited analysis of the potential causes of riverbank erosion in the VMD. While the authors briefly mention factors such as dam construction and sand mining, a more in-depth analysis of their influence on the observed morphological changes, and the impacts of hydrological and sediment alterations from the upstream VMD on the river morphology would strengthen the study.

The most important specific comments:

- Lines 22/23 and whenever it is repeated afterwards: Island (It is better to use islet term in a riverine  environment).

- Line 220: the ArcGIS 10.8 processing tool was used (It is better to be more specific).

- Line 271: highly accurate (When Kappa is less than 80% it is better to use: substantial).

- Line 300: around 2008 (between 2015 and 2020): Because the accretion width is still more than erosion width in 2008-2015.

- Line 403/404: Elaborate on the criteria used to classify the population density groups (It is better to use equal interval classification method).

- Lines 434 to 441: it is better to add an illustrative map of all provinces and the economic loss in each of them.

Overall assessment:

The study provides a valuable contribution to the understanding of morphological changes and their impacts in the VMD, offering insights for effective planning and management of this region.

The study is well-structured, and presents its findings in a clear manner. The cited references are mostly recent publications within the last 5 years, supporting the relevance of the manuscript.

The identified areas of weakness and specific comments provide constructive feedback for the authors to further improve the manuscript.

The work fits the scope of the journal after minor revision, as it demonstrates the application of remote sensing techniques to analyze morphological changes and their impacts.

Author Response

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Reviewer 3 Report

You need to describe the four parameters used to assess the accuracy of water extraction.

I think the Economic damages and loss is irrelevant in this context.

Author Response

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Reviewer 4 Report

It is meaningful to use the remotely sensed data and GIS tools to detect the long-term change of the riverbank. However, the title is not so suitable for the contents. Morphological change includes not only the river channel migration but also the soil erosion, landslide, and the construction of terrace fields. It is suggested to revise the title of the manuscript to more focusing on the topic. The detailed comments are shown as follows:

1、 In the abstract section, it is recommended to begin with an introduction to the impact of delta changes and riverbank erosion, rather than placing specific methods at the forefront.

2、  There are many problems in the cited references such as P3L108, P4L128, P5L145, L158, P7L 230, P9L144, P10L305-306, P13L326, L331, P14L340, P16 L356 L359, and  P21 L474 Please check the paper completely and correct them.

3、 It is suggested to review the more original reference about the remotely sensed analysis of riverbank change with the consideration of water level fluctuation and add some important references such as “Remotely Sensed Trajectory Analysis of Channel Migration in Lower Jingjiang Reach during the Period of 1983–2013”.

4、 It is necessary to highlight the Tan Chau and Chau Doc hydrological stations in Fig.1 to understand the possible impact of water level fluctuation. Please give out the datum information of the water level observations as important information for hydrology applications.

5、 P6L187-189 Please clarify the sentence “ A normalized difference vegetation index (NDVI) of 0.2 and a modified normalized difference water index (MNDWI) of 0 were set for dense riparian vegetation and the water body, respectively [72]. “. Are the 0.2 and 0 set as thresholds for distinguishing the water and dense riparian or not? Are there other land cover types that need to be considered to extract the riverbank in VMD such as sand or muddy beach?  

6、 P8L248-249 It seems that no need to vectorize the raster data to estimate the population and land price affected by the erosion if using the zonal statistics tool. Please clarify the reason why doing such a processing.

7、 P8L260-261 Please explain how to separate the built-up land in the rural or urban areas in the LULC maps.

8、 It lacks an explanation for subfigur. B and C in Fig.9. Moreover, the subfig. A in the Fig.9 and Fig11 seem to be the same. It is suggested to merge or simplify the two figures. Additionally, the annotations in Figure 14 are not clear, please provide a better version of the figure.

9、 In the results section, erosion in length was analyzed in different periods, yet there was no explanation provided regarding the method used for calculating the length. Please clarify the calculation approach or give out the reference.

10、In section 4.3.1, the description of the percentage of land types affected is not well-aligned with the table. The calculation of percentages should be explicitly shown in the table, or the text should provide specific statements about the percentages related to the types of land affected.

The title of the manuscript is not suitable to the content.

Author Response

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Reviewer 5 Report

The manuscript, entitled “Quantifying Spatio-Temporal Morphological Change and Its Consequences in the Vietnamese Mekong River Delta Using Remote Sensing and GIS Techniques " (by T.H. Vu et al.) identified the morphological changes in the social conditions in the Vietnamese Mekong Delta using satellite data from between 1988 and 2020. We further determined the exposure of riverbank and island erosion on land use/cover (LULC) and population along the VMD was also determined. Moreover, economic damages due to land loss were estimated.

General remarks

The manuscript deals with a topic of high interest. The applied methodology and its output results are certainly valuable. In general, I find some issues regarding the content of the manuscript. Hence, just a few comments and suggestions as minor revisions are provided below so that the authors take them under consideration.

Minor comments

Line 37: Since the format of journal supports the number-based citations and reference list, you cannot start from 22th citation. Re-order this citation as first one, and subsequently consider that all your citations. A re-ordering is required.

Line 63: Regarding “low-cost”, only the open-source GIS tools, not generally.

Line 67: With "cloud" you mean cloud (computing) of satellite data, or cloud-free (weather) satellite data. Clarify or rephrase it.

Line 104: "(Error! Reference....B)"? Present in many parts of body text. Consider about it.

No severe issues detected.

Author Response

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Round 2

Reviewer 1 Report

Comments to the Authors:

English Language: The authors have made commendable efforts to improve the English language throughout the manuscript. However, I recommend a final round of proofreading to ensure consistency and accuracy in language usage.

Manuscript Length: The manuscript length remains a concern, potentially impacting reader engagement. I suggest the authors consider summarizing the main findings and conclusions in a concise manner to enhance readability and maintain reader interest.

Summary of Findings: While the authors have made improvements to the manuscript, there is still room for further summarization of the main findings. A clear and succinct summary will help readers grasp the key points without delving into the entire manuscript.

Response to Reviewer Comments: The authors have adequately addressed the reviewer's comments and incorporated suggested revisions into the manuscript. I commend their responsiveness and thoroughness in this regard.

Recommendation:

Based on the improvements made and the minor revisions required, I recommend accepting the manuscript for publication in its current form after the authors address the remaining comments. With the suggested revisions implemented, the manuscript will make a valuable contribution to the field.

The authors have made commendable efforts to improve the English language throughout the manuscript. However, I recommend a final round of proofreading to ensure consistency and accuracy in language usage.

Author Response

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