Carbon Emissions and Vegetation Dynamics: Assessing the Spatiotemporal Environmental Impacts of Hydropower Dams in the Lancang River Basin

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript submitted for review, "Spatio-Temporal Environmental Impacts of hydropower dams construction in the Lancang River Basin" by Yu Liu and co-authors evaluated the environmental impacts of hydropower dams construction in the Lancang River Basin over a multi-year time horizon. The authors used advanced spatial and temporal analytical models supported by an integrated approach to multivariate data. Satellite remote sensing data were used to examine spatial and temporal changes in vegetation cover and carbon emissions. A large amount of data was analyzed using modern statistical methods. The manuscript contains a sufficient number of relevant literature sources.

The authors have obtained interesting data indicating the critical role of hydropower in contributing to regional environmental restoration and development. Earlier studies have largely noted only the deleterious effects of dams on the environment, but have largely been based on and reflected only short-term effects. This study emphasizes the importance of considering broader geographical and contextual factors when assessing the environmental impacts of large-scale hydropower dams.

Undoubtedly, this work is of interest to a wide audience of readers and is an important area of research for hydropower regions.

 

Author Response

Dear prof,

 

    Thank you very much for your thorough and constructive review of our manuscript. We greatly appreciate your insightful comments and the positive evaluation.

    We are particularly grateful for your recognition of the novel aspects of our research, including our integrated approach and the use of advanced spatial and temporal analytical models. Your acknowledgment of the importance of considering broader geographical and contextual factors in our study encourages us further.

    To further enhance our manuscript and better meet your requirements, we have addressed problematic conclusions within the text, incorporated quantified results into the abstract, provided an overview of methodologies in the introduction, and added a detailed description of the physical environment of the Lancang River basin and a specific table outlining each dam in the study area section. Additionally, we conducted supplementary experiments, introducing changes in agricultural land use from land classification data to comprehensively discuss both natural and anthropogenic factors influencing vegetation recovery.

    We are pleased to hear that our work has contributed to the understanding of the long-term environmental impacts of hydropower dams and is deemed of interest to a broad audience. This motivates us to continue our research and disseminate our findings within the scientific community.

    Thank you once again for your encouraging feedback and valuable suggestions. We look forward to the possibility of further enriching our work based on your insights.

 

Best regards.

Yu Liu

Reviewer 2 Report

Comments and Suggestions for Authors

Review report of the article forests-2973411-peer-review-v1

The work done in this article is quite interesting. Therefore, major remarks should first be addressed before possible publication.

 

Introduction

Consult the journal's Author guide to see how authors are cited in the text. Your authors are sometimes misquoted.

Avoid the use of numbering in the text in this section and elsewhere in the manuscript. Simply go to the line after developing an idea.

Present the novelty of your work in the methodological approach. This may be what leads you to a different result from previous studies.

Clearly state the objective of your study at the end of the introduction. What appears at the moment and which seems to correspond to the introduction is very vague.

 

Study area

In this section, you say nothing about the physical environment (climate, soil, etc.). Before you do all the description you do, start by introducing the physical environment.

 

Discussion

At no point in your discussion do you compare your results with those of previous studies on the issue? In a scientific study, it is essential to discuss your results by comparing them to those of others.

 

 

Finally, consult the guide for authors to improve your document in terms of form (presentation of references, citation of authors in the text, citation of figures and tables, etc.).

Author Response

Dear prof.

     Thank you very much for taking the time to review my manuscript and for providing valuable feedback. Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. In response to your comments, I have made the following adjustments:

 

    Comments 1: Related issues in the Introduction section.

    Response 1: Thank you for pointing this out. We agree with this comment. Firstly，we have updated the citation style for author references in our manuscript. Meanwhile, We have updated the final paragraph of the citations to list the main methods used in the article and their purposes. This update is intended to provide readers with a preliminary understanding of the methodology employed in our study. Please refer to the seventh paragraph of the citations section on page three of the manuscript."

 

    Comments 2: Related issues in the Study area section.

    Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we have revised the manuscript to include detailed information on the Lancang River basin's location, climate, and soil characteristics, drawing on relevant literature. Additionally, we have added a table outlining the construction timelines and reservoir capacities of the dams within the basin. We have also updated Figure 2 to include latitude and longitude coordinates. Please refer to the second paragraph of the study area section on page 4 for these updates.

 

    Comments 3: Related issues in the Discussion section.

    Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we have updated the discussion section of our manuscript to correct conclusions that were problematic and conducted additional experiments. These experiments involved incorporating changes in agricultural land use from land classification data to comprehensively discuss both natural and anthropogenic factors affecting vegetation recovery.

    Furthermore, in the introduction, we have cited previous studies that discuss the negative environmental impacts of dam construction. In the updated sections, we have enriched our literature review by adding references that discuss reductions in vegetation, ecological invasions, and damage to native vegetation caused by dam construction, enhancing the comparative depth of our analysis.

     For details, please refer to the second paragraph of the results section on page 20, paragraphs 3, 4, and 5 of the discussion section on page 21, and the first paragraph of the conclusion.

 

    Comments 4: Related issues in the References section.

    Response 4: Thank you for pointing this out. We agree with this comment. Therefore, we have updated the citation style for author references in our manuscript. Meanwhile, we have updated some of the references in our manuscript, removing those that are outdated and of limited relevance. Additionally, all newly added references have been correctly cited.

 

    The details of these adjustments are reflected in the manuscript that I have resubmitted.

    Thank you once again for your effort and insightful comments.

    Best regards.

Reviewer 3 Report

Comments and Suggestions for Authors

Strengths:

1. Utilization of high-precision satellite data for analysis.
2. Integration of data-driven time series and spatial analysis models.
3. Significant findings indicating vegetation restoration and carbon emissions reduction post-dam construction.
4. Use of deep learning models for accurate time series prediction.
5. Contribution to revising and supplementing previous research on hydraulic engineering's environmental impact.
6. Insights provided for construction management and policy formulation in similar river basins globally.

Weaknesses:

1. Lack of detailed methodology explanation.
2. Limited exploration of potential negative environmental impacts.
3. Insufficient exploration of causality between dam construction and observed changes.
4. Short timeframe for analysis may not capture long-term consequences adequately.

Recommendations:

1. Provide detailed methodology explanation for transparency and reproducibility.
2. Address potential negative environmental impacts comprehensively.
3. Explore causal relationships between dam construction and environmental changes more thoroughly.
4. Extend analysis timeframe to capture long-term ecological consequences.

           

Author Response

Dear prof,

    Thank you very much for your thorough and constructive review of our manuscript. We greatly appreciate your insightful comments and the positive evaluation.We are particularly grateful for your recognition of the novel aspects of our research, including our integrated approach and the use of advanced spatial and temporal analytical models. Your acknowledgment of the importance of Construction management and policy formulation of similar river basins worldwide in our study encourages us further.

     Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. In response to your comments, I have made the following adjustments:

 

    Comments1: Provide detailed methodology explanation for transparency and  reproducibility.

    Response 1: Thank you for pointing this out. We have updated the methodology section of our manuscript to provide a more detailed description of all methods employed. We have included a comprehensive introduction to the Global Moran's I index and made corrections to the experimental procedures outlined in the methodology. At the same time, we have updated the detailed process of basic raster data processing in the Data and Methods section on page6, including the tools and related code packages used.

 

    Comments 2: Address potential negative environmental impacts comprehensively.

    Response 2: Thank you for pointing this out. We have updated the discussion section of our manuscript, correcting previously problematic conclusions and conducting additional experiments. These experiments introduce changes in agricultural land use from land classification data to comprehensively discuss both natural and anthropogenic factors in vegetation recovery. For details, please refer to the results section on page 20, paragraph 2, the discussion section on page 21, paragraphs 3, 4, and 5, and the first paragraph of the conclusion on page 22.

 

    Comments 3: Explore causal relationships between dam construction and environmental changes more thoroughly.

    Response 3: Thank you for pointing this out. We have quantified the intensity of vegetation expansion and carbon emissions in the results section. Additionally, we supplemented the manuscript with experiments incorporating historical changes in agricultural land use over the study period. This enhancement allows for a more accurate assessment of whether increases in vegetation are due to natural or anthropogenic factors. For details, please refer to section 4.3 and the discussion section.

 

    Comments4: Extend analysis timeframe to capture long-term ecological consequences.

    Response 4: Thank you for pointing this out. We appreciate the reviewers' insights regarding the extension of the analysis time frame to capture long-term consequences. We acknowledge the importance of assessing long-term impacts, which could indeed add significant value to our findings. However, after a thorough review of the available data and considering the scope of our current analysis, we are constrained by several factors:

    Data Availability and Quality: The data required to extend the time frame beyond our current analysis period are either not available or do not meet the quality standards necessary for robust statistical analysis. Ensuring data integrity and accuracy is paramount in our study, and extending the analysis with the available data could compromise the reliability of our findings.

    We acknowledge the importance of these aspects and suggest them as potential avenues for future research. In subsequent studies, with improved data collection and advancements in modeling approaches, we aim to address these limitations. This will potentially allow us to extend our analysis and provide a comprehensive understanding of the long-term consequences.

    The details of these adjustments are reflected in the manuscript that I have resubmitted.

    Thank you once again for your effort and insightful comments.

    Best regards.

Reviewer 4 Report

Comments and Suggestions for Authors

 In this article some of the conclusions does not seem logical, for example: Several issues have been mentioned in justifying the increase in vegetation, such as; changing the regional climate patterns - creating job opportunities and preventing the destruction of vegetation - changing the pattern of using fossil fuels to clean energy and GDP and some other cases. These are mostly expert opinion and speculation Therefore, in order to prove this claim, the contribution of each variable must be determined in increasing the intensity of vegetation cover. Especially because the results of this research are contrary to many researches conducted on the effects of dams, it is necessary to provide scientific (not expert) documentation about this claim.

To determine the contribution of climate and dam in the increase of vegetation cover, the climatic conditions of the region should be investigated during the study period in the dam and non-dam areas.

It is need to quantitatively examine and calculate changes in GDP and calculate population changes in the same study periods.

In this review, you have discussion about clean weather while, there is no mention of industries and vehicles, as well as the labor market and agriculture.

Questions and suggestions are highlighted on pages 2-9-11-12-13-14-15-16-18-19.

Do you know the effects of building these dams in the downstream of the river? No special events can be seen in the downstream ecosystem. because the natural regime of the river and the entire ecosystem has changed. These dams may be good for one region but not good for another region. Therefore, the implications of dam constructions should be examined in the ecosystem of the watershed.

 

Comments for author File: Comments.pdf

Author Response

Dear prof.

    Thank you very much for taking the time to review my manuscript and for providing valuable feedback. Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. We have addressed each point with thorough explanations and revisions. Due to the extensive nature of the content, I have compiled all responses into a document and uploaded it for your review.

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

Dear authors and editors.

The article “Spatio-Temporal Environmental Impacts of hydropower dams construction in the Lancang River Basin” is devoted to the analysis of changes in vegetation cover (through NDVI analysis), carbon sequestration through analysis of the intensity of construction of hydroelectric dams. The article has some interesting findings! However, some sections are written rather poorly: Study area, Discussion, Conclusion. Therefore, I propose to return it to the authors for revision and re-review.

1) There are no line numbers, which makes it very inconvenient to review!!!

2) Section 2 -Study area

1. “Our  research  meticulously  delineates  the  geographical  scope  to  counties  within  the

Lancang  River  Basin  directly  affected  by  hydropower  dams  and  those  in  the  periphery

impacted   by   these   hydrological   developments”. – I don't understand what you mean by this?

2. «Our inquiry spans two decades, from 2001 to 2020, a period marked by significant hydroelectric

infrastructure  development,  including  the  completion  and  near-completion  of  hydropower

dams» - this needs to be moved into the introduction.

3. The section is called “Study area”!!! Here you need to write about the area of ​​the study region, what the climate is (precipitation, temperature), relief, soil, plowing, etc. Figure 2 needs to be redone; it does not allow us to understand where the study site is located within China; there is no coordinate grid, scale bar, etc. All this is gone now.

4.It would be nice to provide a table for hydroelectric power plants that would show: the catchment area of ​​each hydroelectric power station and its power!

Section 3 - Data and Method

1. Why MODIS data was used, since there are more detailed Landsat data, needs to be justified here.

2. GDP -?? All abbreviations in the article need to be explained.

3. How does the methodology reflect the fact that the impact that the construction of each specific dam has does not extend to your entire study area; accordingly, to assess the impact of the dam, it is necessary to analyze factors that are located close to the dam? Have you taken into account the boundaries of hydroelectric power catchment areas?

4. «In  the  GTWR  model,  each  county  within  our  study  is  represented  by  its  centroid

coordinates, allowing a single sample point to represent each county area.  The fundamental

formula for GTWR is» - As I understand it, for spatial modeling of changes in the state of vegetation, spatial units with administrative boundaries(counties) are used, how justified is this? In my opinion, you need to use either a raster grid or spatial units with natural boundaries.

5. «We  employed  the  GTWR  model  to  dissect  the  complex  array  of  factors  contributing  to total  carbon  emissions  in  various  counties». Why do you need to spatial model of emissions of total carbon emissions ? After all, you download them ready-made from the website (https://db.cger.nies.go.jp/dataset/ODIAC/DL_odiac2022.html) (раздел 3.1 п.2)

Section 4-  Results

1. In paragraph 4.1.1 it is not clear what is meant by “first category of vegetation”, since there are no numbers in Table 1.

2.RM, XW and NZD -??? What are these abbreviations? Where are these dams in the overall cascade of hydroelectric power stations?

3. It is better to move the beginning of section 4.1.2 to the “Study area” section, since it is not the results.

4. What is represented on the Y axis in Figures 5?

5.«1608701.67», «138770.33», in what units of measurement is the area presented here?.

6. Figure 6 In what units of measurement are the figures presented? And by the way, it is signed “Figure 1”

7. Section 4.3, what the Moran index is, how it is calculated, this needs to be transferred to the methodology and given a detailed description!

8. Parts a, b, c and d, e, f of Figures 6 and 7, representing the change in some parameter over time, cannot be compared, since they are made using different numerical and color scales; they must be represented using the same scale!!!

9. Figure 7 – units of measurement

10.«The  completion  of  several  local  hydropower  projects  and  the

advancement   of   China's   environmental   policies   heralded   the   rapid   development   of

hydropower and other clean energy sources. This transition facilitated the replacement of the

traditional  fossil  fuel-based  economic  system  with  a  more  sustainable  and  eco-friendly

model.» - this does not apply to the results of your research.

Section 5 - Discussion

Needs to be rewritten, since in its current form there is no comparison of the results of your research with the results of other similar studies both within China and in the world.

Section 6 - Conclusion

 You need to rewrite it, shortening the general words and briefly show the results obtained specifically in your study. Provide more numbers from your article. For example: provide the year-over-year figures for the increase in NDVI during the construction of dams in the considered districts. Let it be small, but very clear and specific.

Author Response

Dear prof.

    Thank you very much for taking the time to review my manuscript and for providing valuable feedback. Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. We have addressed each point with thorough explanations and revisions. Due to the extensive nature of the content, I have compiled all responses into a document and uploaded it for your review.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Review report of the article forests-2973411-peer-review-v2

The manuscript has been partially improved. Some of my comments have been taken into account. All the following remarks had already been made in the previous review. I maintain that authors should consult the journal's guide to authors. The authors are always misquoted in the text, particularly in the introduction (lines 19, 22, 25, etc.).

The location map is not good. Your thumbnails are difficult to understand. The vignettes allow you to understand the situation in the region studied (continent, country, etc.). This is not the case with yours. Also, your map does not have a scale.

We always find numbering in the text whose objective we do not understand (subsection 3.1 for example).

In your document, you do not compare your results with those of studies already published, yet this is fundamental in scientific work.

 

 

Author Response

Dear prof.

       Thank you very much for taking the time to review my manuscript and for providing valuable feedback. Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. We have addressed each point with thorough explanations and revisions. Due to the extensive nature of the content, I have compiled all responses into a document and uploaded it for your review.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

Thank you. Almost, most of my suggestions in this article have been corrected and in some cases have been answered and I am satisfied.
Please correct in line 482 , Figure 6. NDVI is correct No NDIV

Comments for author File: Comments.pdf

Author Response

Dear prof.

 

   Your attention to detail has not only improved our manuscript but also contributed significantly to our understanding of the subject. We appreciate your thorough analysis and constructive criticism, which have undoubtedly enriched our work.

   Thank you once again for your valuable contribution to our manuscript.

 

Sincerely

Reviewer 5 Report

Comments and Suggestions for Authors

Dear authors and editors.
The text of the article has been significantly revised. Most of my comments have been taken into account and eliminated. The article contains interesting results.  
After some minor revision, it can be recommended for publication!
However, I have some  recommendations for authors!
1.Still, include the catchment area in Table 1, I did not find the this areas in the text.
2.Why were counties used at all, and not some natural boundaries or raster grid? It is necessary to provide a rationale for the choice of counties in the article!!
3.Parts a, b, c and d, e, f of Figures 6 and 7, representing the change in some parameter over time, cannot be compared, since they are made using different numerical and color scales; they must be represented using the same number and color scale!!!

Author Response

Dear prof.

      Thank you very much for taking the time to review my manuscript and for providing valuable feedback. Your expert advice has been instrumental in enhancing the quality of my paper. I apologize for any confusion caused by the issues present in the manuscript. We have addressed each point with thorough explanations and revisions. Due to the extensive nature of the content, I have compiled all responses into a document and uploaded it for your review.

Author Response File: Author Response.pdf