Spatiotemporal changes in river network connectivity in the Nile River Basin due to hydropower dams

Anthony Basooma; Astrid Schmidt-Kloiber; Rose Basooma; Herbert Nakiyende; Johannes Kowal; Andrea Funk; Thomas Hein; Florian Borgwardt

doi:10.1371/journal.pone.0322338

Peer Review History

Original SubmissionMay 17, 2024
17 May 2024 Author Response https://doi.org/10.1371/journal.pone.0322338.r001
6 Aug 2024 Decision Letter - AL MAHFOODH, Editor PONE-D-24-20020Spatiotemporal changes in river network connectivity in the Nile River Basin due to hydropower damsPLOS ONE Dear Dr. Basooma, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Sep 20 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Partly ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: No Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: General considerations: The authors assessed the impacts of hydropower dams on the network connectivity of two Nile River sub-basins. Additionally, they try to identify the dams to be prioritized to improve river network connectivity. This work is rather ambitious since it deals with a large and complex area, with high fragmentation. Besides, the period considered in the evaluation of the progressive loss of connectivity is quite long. For this purpose, the authors used a common connectivity index (RCI) and network centrality measures to assess temporal and spatial variation in longitudinal connectivity. This seems to be an adequate methodology and the work is interesting and with innovative contribution. However, the authors seem to have considered only hydropower plants, whereas other types of transversal structures, namely for irrigation, or water supply, were not included. This option was not conveniently explained. I also think that Information about the loss of biodiversity and protected habitats is very scarce and it should be more developed. Conclusions are more or less obvious respecting the new proposed dams since the number of impassible barriers is already very high. It would be much more convenient for the authors to focus their work on the dams already built where they could be installed (or improved) the fish passes. But this is an important gap (the authors just assigned downstream and upstream passability values, but far from reality), this is, the absence of information about the observed passability of each dam or the existence of environmental flows. Probably, this information is difficult to obtain (the authors state that is unavailable), but it should be considered in the future towards the management process (and mitigation). Probably these aspects are more realistic in terms of catchment management than barrier removal _especially the big structures, like the authors conclude… Anyway, the results obtained about the individual contribution of each dam are useful if we consider the focus on the passability improvement in those sections, which do not implicate necessarily their removal. .Of course, the authors only consider connectivity, mainly directed to fish populations, but other social and economic criteria should be included as well (many authors consider multicriteria models with this objective). Please, consider these aspects for the discussion to become more complete. Moreover, the 1st hypothesis is obvious and it should be discarded an increase in the number of dams constructed along the river network has significantly reduced the longitudinal connectivity of both basins over time). I believe that the 1st part of 4.1 could be moved to the introduction since it deals with the historical temporal trends in hydropower dam construction. Other aspects: How far it was important to include low-stream orders? Please mention it in the discussion. Line 152: Please explain the acronyms li and L in the formula. Line 198. Explain better what is RCIstart. Line 205 This correlation was obtained between which type of variables? Line 288. Which period? Reviewer #2: Writing Quality Page 1, Abstract: The abstract is wide, and lacks focus on key findings Line 46: Unnecessary use of "river networks”. Suggested: “The growing demand for energy and flood control has led to increased construction of barriers along rivers." Line 55-56: Redundancy and lack of specificity. One-time abbreviations of the BNB and NRB at the beginning are enough. Methods Line 112-118: Lack of detail on data sources and processing. Line 113-119: Insufficient detail on dam data collection. Also figures at the end have not numbers as captions. Line 135: Lack of detail on the alignment of dams to river networks. (in Arcmap? Which version) Line 152-160: Incomplete explanation for variables in the equations 2.1-2.3 Results Repetitive use of the word “passability” Line 204- 205: Statement on dam numbers is not clear. Line 208: Lack of emphasis on significance of results. You can say “scenarios indicate a significant decrease in RCI….” Line 243 Figure 2 Caption: Insufficient detail in figure caption. You can explain more the figure in the caption Discussion The discussion section provides a good interpretation but lacks depth in addressing limitations and actionable recommendations. Line 296-298: Repetitive and lacks depth. Suggestion: "We thoroughly examined the temporal and spatial patterns in the river network connectivity of the Equatorial Nile and Blue Nile, focusing on individual dam contributions to overall river network fragmentation." Line 340-346: you can add: "One limitation of this study is the potential inaccuracies in dam location data, which were cross verified using available literature and datasets." Figures The figures are located at the end of the manuscript and are well-designed but need higher resolution and detailed captions. For example, for Figure 2: Improve resolution: Detailed suggested Caption: "Figure 2. Trends in dam construction from 1925 to 2035 for the Blue Nile Basin (BNB) and Equatorial Nile Basin (ENB). The figure illustrates the increase in dam numbers over time, with a noticeable surge post-2010." Figure 5 and 6 the grids latitude and longitude are not readable. Also yellow is not a good choice for the Figure 7. Science Question The research question is well-defined but needs explicit discussion on how the results validate the hypotheses stated. At the end of discussion or In conclusion it can be added: "Future research should focus on developing detailed fish migration models to validate the effectiveness of proposed fish passes and migratory corridors." Literature Missing recent studies: Incorporate more recent studies to (after 2022) provide an updated perspective on the impacts of dam construction on river connectivity. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy . Reviewer #1: Yes: Rui Manuel Vitor Cortes Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0322338.r002
Revision 1
29 Oct 2024 Author Response Response to reviewers We are very grateful for the tremendous effort by the reviewers and the editor for the comments provided to improve our work. We have accordingly addressed the comments and hope the study will be impactful but, most importantly, aid in managing the Nile River Basin in general. Editor comments 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf Response: the manuscript has been fully updated based on the required formatting 2. In your Methods section, please provide additional information regarding the permits you obtained for the work. Please ensure you have included the full name of the authority that approved the field site access and, if no permits were required, a brief statement explaining why. Response: Since the study was not field-based, we did not require any research permit for this work. 3. We note that the grant information you provided in the ‘Funding Information’ and ‘Financial Disclosure’ sections do not match. When you resubmit, please ensure that you provide the correct grant numbers for the awards you received for your study in the ‘Funding Information’ section. Thank you for stating the following financial disclosure: "Anthony Basooma acknowledges funding from AquaINFRA (agreement ID: 101094434) and DANUBE4All (grant agreement no. 101093985) projects funded by the European Commission. The financial support by the HR21 Doctoral School of the University of Natural Resources and Life Sciences, Vienna, Austria, the Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology, and Development, and the Christian Doppler Research Association is gratefully acknowledged." Response: The funding information has been updated in the system, and the manuscript is on lines 458 to 463. 4. Please state what role the funders took in the study. If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." If this statement is not correct you must amend it as needed. Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf. Response: the statement “The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript” has been incorporated on lines 464 and 465. 5. We note that [Figures 1,5 and 6] in your submission contain [map/satellite] images which may be copyrighted. All PLOS content is published under the Creative Commons Attribution License (CC BY 4.0), which means that the manuscript, images, and Supporting Information files will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution. For these reasons, we cannot publish previously copyrighted maps or satellite images created using proprietary data, such as Google software (Google Maps, Street View, and Earth). For more information, see our copyright guidelines: http://journals.plos.org/plosone/s/licenses-and-copyright. We require you to either (1) present written permission from the copyright holder to publish these figures specifically under the CC BY 4.0 license, or (2) remove the figures from your submission: a. You may seek permission from the original copyright holder of Figures 1,5 and 6 to publish the content specifically under the CC BY 4.0 license. We recommend that you contact the original copyright holder with the Content Permission Form (http://journals.plos.org/plosone/s/file?id=7c09/content-permission-form.pdf) and the following text: “I request permission for the open-access journal PLOS ONE to publish XXX under the Creative Commons Attribution License (CCAL) CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). Please be aware that this license allows unrestricted use and distribution, even commercially, by third parties. Please reply and provide explicit written permission to publish XXX under a CC BY license and complete the attached form.” Please upload the completed Content Permission Form or other proof of granted permissions as an "Other" file with your submission. In the figure caption of the copyrighted figure, please include the following text: “Reprinted from [ref] under a CC BY license, with permission from [name of publisher], original copyright [original copyright year].” b. If you are unable to obtain permission from the original copyright holder to publish these figures under the CC BY 4.0 license or if the copyright holder’s requirements are incompatible with the CC BY 4.0 license, please either i) remove the figure or ii) supply a replacement figure that complies with the CC BY 4.0 license. Please check copyright information on all replacement figures and update the figure caption with source information. If applicable, please specify in the figure caption text when a figure is similar but not identical to the original image and is therefore for illustrative purposes only. The following resources for replacing copyrighted map figures may be helpful: USGS National Map Viewer (public domain): http://viewer.nationalmap.gov/viewer/ The Gateway to Astronaut Photography of Earth (public domain): http://eol.jsc.nasa.gov/sseop/clickmap/ Maps at the CIA (public domain): https://www.cia.gov/library/publications/the-world-factbook/index.html and https://www.cia.gov/library/publications/cia-maps-publications/index.html NASA Earth Observatory (public domain): http://earthobservatory.nasa.gov/ Landsat: http://landsat.visibleearth.nasa.gov/ USGS EROS (Earth Resources Observatory and Science (EROS) Center) (public domain): http://eros.usgs.gov/# Natural Earth (public domain): http://www.naturalearthdata.com/ Response: Figures 1, 5, and 6 were regenerated from HydroATLAS, which forms a Collective Database, i.e., a collection of information from independent datasets, and as a whole is licensed under a Creative Commons Attribution 4.0 International License (CC-BY 4.0) (https://data.hydrosheds.org/file/technical-documentation/HydroATLAS_TechDoc_v10.pdf). Reviewers Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Partly ________________________________________ 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ________________________________________ 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: No Response: We have provided links for all the data used and supplementary table S1 for the dataset for the dams. We created a Figshare account to archive the river network data and develop the maps on lines 480 to 485. Reviewer #2: Yes ________________________________________ 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ________________________________________ 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: General considerations: The authors assessed the impacts of hydropower dams on the network connectivity of two Nile River sub-basins. Additionally, they try to identify the dams to be prioritized to improve river network connectivity. This work is rather ambitious since it deals with a large and complex area, with high fragmentation. Besides, the period considered in the evaluation of the progressive loss of connectivity is quite long. For this purpose, the authors used a common connectivity index (RCI) and network centrality measures to assess temporal and spatial variation in longitudinal connectivity. This seems to be an adequate methodology and the work is interesting and with innovative contribution. However, the authors seem to have considered only hydropower plants, whereas other types of transversal structures, namely for irrigation, or water supply, were not included. This option was not conveniently explained. Response: Due to data availability, the current study focused on hydropower plants, especially confirming the dam's location and the commissioning time. Unfortunately, obtaining the necessary information for small barriers was difficult. This was provided on lines 137 to 138. I also think that Information about the loss of biodiversity and protected habitats is very scarce and it should be more developed. Response: we have created a section in the discussion to briefly highlight the likely and already existing impacts on biodiversity, mostly fish, due to dams in both basins on lines 352 to 377. Conclusions are more or less obvious respecting the new proposed dams since the number of impassible barriers is already very high. It would be much more convenient for the authors to focus their work on the dams already built where they could be installed (or improved) the fish passes. But this is an important gap (the authors just assigned downstream and upstream passability values, but far from reality), this is, the absence of information about the observed passability of each dam or the existence of environmental flows. Probably, this information is difficult to obtain (the authors state that is unavailable), but it should be considered in the future towards the management process (and mitigation). Response: We agree with the reviewer and have included the statement recommending further research on fish migration models to validate the available fish passes. Also, the need to evaluate the passability of the barriers for fish needs to be conducted on lines 452 to 456. Probably these aspects are more realistic in terms of catchment management than barrier removal _especially the big structures, like the authors conclude… Anyway, the results obtained about the individual contribution of each dam are useful if we consider the focus on the passability improvement in those sections, which do not implicate necessarily their removal. Of course, the authors only consider connectivity, mainly directed to fish populations, but other social and economic criteria should be included as well (many authors consider multicriteria models with this objective). Please, consider these aspects for the discussion to become more complete. Response: we have included a section on the other criteria of barrier removal in the discussion on lines 427 to 436. Moreover, the 1st hypothesis is obvious and it should be discarded an increase in the number of dams constructed along the river network has significantly reduced the longitudinal connectivity of both basins over time). Response: We acknowledge that the first hypothesis, regarding the reduction in longitudinal connectivity due to increased dams, may seem obvious. However, we included this hypothesis to establish a foundational understanding of the impact of dam construction over time. This baseline is crucial for contextualizing our subsequent analyses and comparing the extent of connectivity loss across different sections of the river network. We have restructured it on lines 101 to 102 I believe that the 1st part of 4.1 could be moved to the introduction since it deals with the historical temporal trends in hydropower dam construction. Response: Although the section deals with a historical perspective of dam construction, it was brought up to discuss the temporal change in dam construction and why changes occurred over those times. Other aspects: How far it was important to include low-stream orders? Please mention it in the discussion. Response (lines 347 to 351): A section on including low-stream orders has been incorporated in the discussion, and a supplementary figure, Fig S1 (lines 710 to 712), expounds on the aspect. Line 152: Please explain the acronyms li and L in the formula. Response: We have included the meaning of the acronyms on line 160 Line 198. Explain better what is RCIstart. Response: we renamed the RCIstart to CCIstart to indicate the initial catchment when all barriers are considered on the river network noted on line 204. Line 205 This correlation was obtained between which type of variables? Response: the statement has been removed and maintained as a description of the steady dam increase over time. Line 288. Which period? Response: REVIEWER #2: WRITING QUALITY Page 1, Abstract: The abstract is wide, and lacks focus on key findings Response: We have revised the abstract to provide a clearer and more focused summary of the key findings. We believe these changes enhance the clarity and impact of the abstract, and we hope it now better reflects the core contributions of our study. Line 46: Unnecessary use of "river networks”. Suggested: “The growing demand for energy and flood control has led to increased construction of barriers along rivers." Response: We agree with the reviewers and changed the text accordingly on line 50 Line 55-56: Redundancy and lack of specificity. Response: removed One-time abbreviations of the BNB and NRB at the beginning are enough. Response: We agree with the reviewer and changed the abbreviation with the full names left in Figure captions and first mentions. Methods Line 112-118: Lack of detail on data sources and processing. Response: This was addressed by providing the reference, data links, and supplementary material for updated data for hydropower dams on lines 112 to 124. Line 113-119: Insufficient detail on dam data collection. Also figures at the end have not numbers as captions. Response: The dams used were obtained from the RePP, an open-access dataset. We have archived the extracted reviewed dataset used in this analysis, accessible at https://doi.org/10.6084/m9.figshare.26886409.v1. This has been indicated in lines 120 to 123. Line 135: Lack of detail on the alignment of dams to river networks. (in Arcmap? Which version) Response: we used Q-GIS ver 3.28.4 addressed on lines 114. Line 152-160: Incomplete explanation for variables in the equations 2.1-2.3 Response: the variables have been well described on lines 160 to 165 Results Repetitive use of the word “passability” Response: addressed – rephrased the text. Line 204- 205: Statement on dam numbers is not clear. Response: the statement has been rephrased on lines 209 to 210. Line 208: Lack of emphasis on significance of results. You can say “scenarios indicate a significant decrease in RCI….” Response: The text changed accordingly on lines 212 to 213 Line 2 https://doi.org/10.1371/journal.pone.0322338.r003
26 Feb 2025 Decision Letter - Halil Ibrahimi, Editor PONE-D-24-20020R1Spatiotemporal changes in river network connectivity in the Nile River Basin due to hydropower damsPLOS ONE Dear Dr. Basooma, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by Apr 12 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols . We look forward to receiving your revised manuscript. Kind regards, Halil Ibrahimi Academic Editor PLOS ONE Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Additional Editor Comments: Please check comments of the reviewers and proceed with the corrected version of manuscript. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: (No Response) Reviewer #3: (No Response) ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #3: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #3: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #3: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #3: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This is, in fact, an ambitious work, covering a vast catchment, facing the difficulties of scarce available (and detailed) data about the transversal structures that impose a loss of connectivity. The hypotheses tested are more or less obvious (as well as the impact of the new structures to be built), especially the 1st hypothesis testing if there is a significant temporal increase in the number of dams constructed …? I think that this hypothesis could be discarded. However, the authors obtained some interesting conclusions, like the importance of the contribution of the dam in the river reach to the global network fragmentation. I acknowledge that the authors improved substantially the original paper following the indications of both reviewers. However, some questions remain, some of them that were already pointed out by the reviewer(s). For instance, it was identified the dams that were prioritized to improve connectivity. But how to mitigate, for these specific dams the effects of fragmentation? The idea that effective fish passes for migratory fish species should be built represents a nice intention but is that feasible considering the respective dam heights? What are the most convenient fish passes for each case? Were installed in this catchment any fish passes (and defined environmental flows) and is it possible to know their relative success?. I believe that the removal option to improve connectivity is not a real possibility in this catchment (except for small weirs with low relevance in the connectivity). The authors should introduce these aspects in the discussion, following also previous considerations by the reviewers. Reviewer #3: The authors present a good research paper on the impacts of hydroelectric dams on the connectivity of two sub-basins of the Nile River. In previous revisions, they added the suggestions and comments made by the reviewers, strengthening their study. My comments are basically directed at two recommendations related to the two most significant weaknesses that the authors make in their conclusions. Regarding the need to create a systematic inventory of barriers for both basins, he recommended that the authors read, and if they wish, the bibliographical citation of this article. https://doi.org/10.1038/s41586-020-3005-2 And on the need to raise awareness by including basin-wide river assessments, examples from other parts of the world could be helpful. To this end, I suggest that the authors read, and if they wish, cite the bibliography of these two articles: https://doi.org/10.1007/s11273-022-09864-6 https://doi.org/10.1038/s41598-022-10170-7 ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy . Reviewer #1: No Reviewer #3: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0322338.r004
Revision 2
14 Mar 2025 Author Response Journal Requirements: Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice. Response: We have critically checked the reference list for spellings, consistencies, and doi validity on lines Additional Editor Comments: Please check comments of the reviewers and proceed with the corrected version of manuscript. [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #1: (No Response) Reviewer #3: (No Response) 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #3: Yes Response: We thank the reviewers for acknowledging that our manuscript is technically sound and that data supports the conclusions. 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #3: Yes Response: We thank the reviewers for acknowledging that the statistical analysis was appropriate and rigorously conducted. 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #3: Yes Response: We thank the reviewers for confirming the presence of underlying data that enables the reproducibility of our study. 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #3: Yes Response: We thank the reviewers for agreeing that our manuscript was written in an intelligible manner. 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This is, in fact, an ambitious work, covering a vast catchment, facing the difficulties of scarce available (and detailed) data about the transversal structures that impose a loss of connectivity. The hypotheses tested are more or less obvious (as well as the impact of the new structures to be built), especially the 1st hypothesis testing if there is a significant temporal increase in the number of dams constructed …? I think that this hypothesis could be discarded. However, the authors obtained some interesting conclusions, like the importance of the contribution of the dam in the river reach to the global network fragmentation. Response: we agree with the reviewer that the first objective was quite obvious but vital for the study because it showed that between the two basins, the increase in the number of dams was not the same. For instance, a significant increase was mainly in the Equatorial Nile region. I acknowledge that the authors improved substantially the original paper following the indications of both reviewers. However, some questions remain, some of them that were already pointed out by the reviewer(s). For instance, it was identified the dams that were prioritized to improve connectivity. But how to mitigate, for these specific dams the effects of fragmentation? The idea that effective fish passes for migratory fish species should be built represents a nice intention but is that feasible considering the respective dam heights? What are the most convenient fish passes for each case? Were installed in this catchment any fish passes (and defined environmental flows) and is it possible to know their relative success?. I believe that the removal option to improve connectivity is not a real possibility in this catchment (except for small weirs with low relevance in the connectivity). The authors should introduce these aspects in the discussion, following also previous considerations by the reviewers. Response: we addressed the questions on lines 441 to 455 Reviewer #3: The authors present a good research paper on the impacts of hydroelectric dams on the connectivity of two sub-basins of the Nile River. In previous revisions, they added the suggestions and comments made by the reviewers, strengthening their study. My comments are basically directed at two recommendations related to the two most significant weaknesses that the authors make in their conclusions. Regarding the need to create a systematic inventory of barriers for both basins, he recommended that the authors read, and if they wish, the bibliographical citation of this article. https://doi.org/10.1038/s41586-020-3005-2 Response: Incorporated on L77 and also L470 And on the need to raise awareness by including basin-wide river assessments, examples from other parts of the world could be helpful. To this end, I suggest that the authors read, and if they wish, cite the bibliography of these two articles: https://doi.org/10.1007/s11273-022-09864-6 https://doi.org/10.1038/s41598-022-10170-7 Response: Included in the lines 41 to 45 as a recommendation for environmental monitoring 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #3: No https://doi.org/10.1371/journal.pone.0322338.r005
21 Mar 2025 Decision Letter - Halil Ibrahimi, Editor Spatiotemporal changes in river network connectivity in the Nile River Basin due to hydropower dams PONE-D-24-20020R2 Dear Dr. Basooma, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Halil Ibrahimi Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: https://doi.org/10.1371/journal.pone.0322338.r006
Formally Accepted
Acceptance Letter - Halil Ibrahimi, Editor PONE-D-24-20020R2 PLOS ONE Dear Dr. Basooma, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Professor Halil Ibrahimi Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0322338.r007

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