Round 1

Reviewer 1 Report

I have read through the paper “Opportunities and challenges for the sustainability of lakes and

reservoirs in relation to the Sustainable Development Goals (SDGs)”. It can be seen that the authors have done many methodological and analytical works on the topic. It is recommended for publication after some minor revisions:

1. Opportunities in Section 3 should be improved further.

2. Management and policy in Section 3.2 had better be improved further.

3. Limitations do exist in every research and therefore, the authors should provide some limitations to their study. Also, they should provide some potential steps that can be taken by future authors to deal with these limitations and suggest possible further studies.

Thank you for giving me this opportunity to review your article and I hope there are some suggestions that may be useful for you.

Author Response

Author's note to reviewer 1:

1. Opportunities in Section 3 should be improved further.

Authors’ response:

The authors realize that the methodology of the bibliometric analysis should be more transparent. However, to avoid a lengthy manuscript and since only section 3.2 uses the information of the bibliometric analysis, we put the methodology into the supplementary materials as follows.

-          To illustrate the whole picture of publications related to the sustainable development of lakes and reservoirs, three research lines were made, including (1) Status; (2) Ecosystem services; (3) Management and Policy (Figure 1). These three research lines cover 18 major research topics, which play important roles in their sustainable development. The details of the topics and their search query in the Web of Science can be found in Table S1. We identified the keyword queries for each research topic based on our expertise and previous bibliometric analyses whose topics are comparable [38,53-68]. (lines 251-255 in the revised manuscript)

-          Figure 1. The number of publications in three research lines with topics related to the sustainable development of lakes and reservoirs from 2009 to 2018. The data were extracted from the online database of the Science Citation Index Expanded (SCI-Expanded) in the Web of Science on January 24, 2019. More information on the methodology of the bibliometric analysis can be found in the Supplementary Material A. (lines 274-278)

-          1. Supplementary Material A: Methodology of the bibliometric analysis

Data were extracted from the online database of the Science Citation Index Expanded (SCI-Expanded) which covers 11,655 outstanding journals across 234 research categories and 80 countries according to Journal Citation Reports 2018 (JCR). The data were collected on January 24, 2019, in the Web of Science from Clarivate Analytics. 65,000 document types were collected from 2009 to 2018. Since publications with topics on the sustainable development of lakes and reservoirs are very interdisciplinary and evolving, hence it is a matter of debate as to what should be included. We categorized these publications on three research lines, in which we further divided into 18 major research topics, which play important roles in the sustainable development of lakes and reservoirs. The details of the topics and their search query in the Web of Science can be found in Table S1. We identified the keyword queries for each research topic based on our expertise and previous bibliometric analyses whose topics are comparable [1-17]. Moreover, different keywords queries were applied for lakes and reservoirs to distinguish the studies on lakes from the studies on reservoirs and small lakes. (lines 9-21 in the revised supplementary materials)

Moreover, the details of the queries can be found in Table S1 in the revised supplementary materials.

2. Management and policy in Section 3.2 had better be improved further.

Authors’ response:

The authors modify and add more information in Section 3.2 to improve its quality as follows.

-          All freshwater basins exploited by human activities demand management. This may involve regular monitoring to maintain and include efforts to enhance and protect the system as well as restore the impaired systems. In the case of lakes and reservoirs, due to their substantial economic benefits, there is an increasing requirement for management and policy for the sustainable exploitation of lakes and reservoirs, to sustain their beneficial uses over the long-term and more specifically meet the objectives related to the Sustainable Development Goals. From that point of view, the multifaceted factors of different stakeholders should be incorporated into the optimization and decision-making process. Consequently, large numbers of conflicting views are governing these systems and more transparent procedures are required to inform and convince stakeholders and authorities. As such, multicriteria decision analysis and computer-based decision support systems can provide a structured way to elicit and communicate individual preferences in a systems’ context [40].

-          Noteworthy is that in contrast to substantial knowledge and understanding of water quality management in natural lakes as a result of long historical research, there is a shortage of insights into the characteristics of artificial reservoirs [1]. Despite the little distinctions between these two freshwater bodies in terms of limnology, their functions can be very different. Neglecting these differences can lead to inappropriate and unsustainable developments. In fact, a management policy should be site-specific for lakes and reservoirs, since they also serve different purposes leading to different priorities corresponding to different optimization methods in their management plans. However, there are certain aspects that need to address in the management policy. These aspects include aquatic species management with invasive species control, wildlife and fisheries management, nutrient budget, shore protection, water quality management, recreational and watershed management. Depending on the prioritized purposes and problems of the inland water body systems, site-specific actions, which put economic and time factors in their agenda, can be proposed.

-          Many efforts have been made for the restoration of lakes and reservoirs, in which there are many successful restoration projects, while several are reported as a failure [41]. One of the solutions for habitat disconnection is the use of fish bypasses, however in case of severe physical degradation at river basin level, undamming might be considered, as is reflected in its current controversial debate. In a short-term period, dam removal can increase the amount of sediment load leading to abrasion and toxicity to biota and habitats. However, it was also reported that restoration of unregulated flow regimes improved significantly the biotic diversity due to the enrichment of free movement and spawning grounds [42]. Regarding eutrophication, due to the resilience of lake biochemical conditions, solely reduction of the external nutrient loading often led to unsuccessful restoration project [43]. To reinforce recovery, numerous biomanipulation methods have been integrated with physicochemical methods. Fish removal becomes popular for a restoration project in Denmark and the Netherlands, which resulted in improvement of visibility and less abundance of algae. However, the high concentration of mobile phosphorus in lake sediment can lead to the return of turbid conditions [41]. Moreover, the multifunctional exploitations of these stagnant waters challenge the determination of specific operation and restoration action and need multidisciplinary research and multi-stakeholder approaches [44]. (lines 185-224)

3. Limitations do exist in every research and therefore, the authors should provide some limitations to their study. Also, they should provide some potential steps that can be taken by future authors to deal with these limitations and suggest possible further studies.

Authors’ response:

The limitations on our proposed indicators which are based on the 232 indicators that are still undergoing methodological development by the United Nations are added in the revised manuscript with the suggested actions to deal with them as follows.

-          As mentioned in the SDGs that their indicators should be implemented as an ‘indivisible whole’, the same principle is applied to the proposed indicators for the sustainable development of lakes and reservoirs. Noteworthy is that the situation of individual countries/regions may vary significantly, hence one should pay extra attention to the aggregated data despite its convenient way to track the progress of sustainable development. Besides, since the proposed indicators based on the 232 indicators that are still undergoing methodological development by the United Nations, updating information is necessary to keep track of the progress on SDG implementation. (lines 369-374)

4. Thank you for giving me this opportunity to review your article and I hope there are some suggestions that may be useful for you.

Authors’ response:

The authors would like to give sincere gratitude to the reviewer for her/his constructive remarks. We acknowledge that these remarks lead to necessary modifications that definitely improve the quality of our manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

The strength of the article is a cross-cutting view on the challenges and opportunities of lakes and reservoirs management, taking into account a broad evidences delivered by bibliographic analysis.

At the same time, the paper in its current form has important shortcomings, which I think should be addressed to provide a significant contribution to the field:

·         manuscript should be reorganized – all chapter 2 and subchapter 3.1 should be integrated with subchapter 4.4.  Currently, the information presented in 2 and 3.1 does not provide a novelty; but, it can provides if it will serve as arguments for the discussion of tab.1 in subchapter 4.2.

·         the separate section Methods should be introduce. Currently, the methodology is unclear for readers. How did you perform the search in the database to find ‘around 65,000 publications related 78 to lakes and reservoirs from 2009 to 2018 is implemented’? What settings did you use? What criteria did you use to do bibliographic analysis these publication? How did you distinguish the research topics presented in Fig. 1? And, what criteria did you use when assigning publications to specific topics?

·         Table 1 should be shortened, i.e. the content from columns 2 and 3 should be presented in the summary form, using shorter entries. Arguments and scientific underpinnings for individual interlinkages should be included in the subchapter 4.2 as a text that justifies the nature of the links presented in the table.

·         Avoid unnecessary repetitions of information between table 1 and previous chapters. E.g. information in table about ‘around 900,000 cases of illnesses and 900 deaths occurred each year in the US due to microbial contamination’ is already know from chapter 2.1.

·         Figure 1 – there is ‘the number of publications’ in the figure title; please provide information on number, now there is no information that allows reader to learn about it.

·         Table 2 – for users from which spatial scale are the suggested indicators designed? E.g. for national authorities or can some of them be used on local, regional scale?

·         Table 2 - indicators should be measurable. Please comment how ‘Progress towards sustainable lake management’ can be measured.

·         Finally, it is interesting how do you understand the ‘sustainability’ of lakes and reservoirs? As you proved by bibliographic and SDGs analysis, there can be many synergies, but also many trade-off between different goal and action. So, in the light of your results, how should we understand this sustainability?

Author Response

1. Manuscript should be reorganized – all chapter 2 and subchapter 3.1 should be integrated with subchapter 4.4. Currently, the information presented in 2 and 3.1 does not provide a novelty; but, it can provides if it will serve as arguments for the discussion of tab.1 in subchapter 4.2.

Authors’ response:

The main focus of the study is the interlinkages between the necessary implementation for achieving a better and more sustainable future of lakes and reservoirs and the actions in the framework of the Sustainable Development Goals (SDGs). As such, a major portion of the manuscript is spent on analyzing the interlinkage in section 4. However, from the authors’ point of view, it is also important to deliver a necessary background of the development of lakes and reservoirs. This overview is based on a multi-disciplinary review of the recent literature in three different perspectives of the lake development, i.e. status, ecosystem services, and management and policy. This categorization is also relevant and necessary for the understanding of the information in section 3. Specifically, by understanding the current situation, the readers can straightforwardly comprehend the emerging challenges and opportunities of lakes and reservoirs’ development that are written in section 3.

Furthermore, as mentioned by the reviewer as the information in sections 2 and 3.1 can support section 4.2, their position locates before section 4.2 is reasonable.

2. The separate section Methods should be introduce. Currently, the methodology is unclear for readers. How did you perform the search in the database to find ‘around 65,000 publications related 78 to lakes and reservoirs from 2009 to 2018 is implemented’? What settings did you use? What criteria did you use to do bibliographic analysis these publication? How did you distinguish the research topics presented in Fig. 1? And, what criteria did you use when assigning publications to specific topics?

Authors’ response:

Indeed, the authors agree that the methodology of the bibliometric analysis should be more transparent. However, to avoid a lengthy manuscript and since only section 3.2 uses the information of the bibliometric analysis, we put the methodology into the supplementary materials as follows.

-          To illustrate the whole picture of publications related to the sustainable development of lakes and reservoirs, three research lines were made, including (1) Status; (2) Ecosystem services; (3) Management and Policy (Figure 1). These three research lines cover 18 major research topics, which play important roles in their sustainable development. The details of the topics and their search query in the Web of Science can be found in Table S1. We identified the keyword queries for each research topic based on our expertise and previous bibliometric analyses whose topics are comparable [38,53-68]. (lines 262-268 in the revised manuscript)

-          Figure 1. The number of publications in three research lines with topics related to the sustainable development of lakes and reservoirs from 2009 to 2018. The data were extracted from the online database of the Science Citation Index Expanded (SCI-Expanded) in the Web of Science on January 24, 2019. More information on the methodology of the bibliometric analysis can be found in Supplementary Material A. (lines 287-291)

-          1. Supplementary Material A: Methodology of the bibliometric analysis

Data were extracted from the online database of the Science Citation Index Expanded (SCI-Expanded) which covers 11,655 outstanding journals across 234 research categories and 80 countries according to Journal Citation Reports 2018 (JCR). The data were collected on January 24, 2019, in the Web of Science from Clarivate Analytics. 65,000 document types were collected from 2009 to 2018. Since publications with topics on the sustainable development of lakes and reservoirs are very interdisciplinary and evolving, hence it is a matter of debate as to what should be included. We categorized these publications on three research lines, in which we further divided into 18 major research topics, which play important roles in the sustainable development of lakes and reservoirs. The details of the topics and their search query in the Web of Science can be found in Table S1. We identified the keyword queries for each research topic based on our expertise and previous bibliometric analyses whose topics are comparable [1-17]. Moreover, different keywords queries were applied for lakes and reservoirs to distinguish the studies on lakes from the studies on reservoirs and small lakes. (lines 9-21 in the revised supplementary materials)

Moreover, the details of the queries can be found in Table S1 in the revised supplementary materials.

3. Table 1 should be shortened, i.e. the content from columns 2 and 3 should be presented in the summary form, using shorter entries. Arguments and scientific underpinnings for individual interlinkages should be included in the subchapter 4.2 as a text that justifies the nature of the links presented in the table.

Authors’ response:

The authors are aware that it is inevitable to have a lengthy table covering the interlinkages between the sustainable future of lakes and reservoirs and the 169 targets of the 17 SDGs in the framework of the SDGs. As such, to avoid exhaustive description, Table 1 shows an overview of only direct interlinkages, meaning only the interlinkages including the SDGs that refer explicitly to inland water bodies or perceptions involved directly to lakes and reservoirs. The indirect interlinkages are located in the Supplementary Material B. The authors improve the readability of the table by highlighting the important points in bold. Moreover, we don’t want to deliver an empty list of targets whose achievements are contributed by the development of lakes and reservoirs but also the scientific reasons behind that. As such, we chose using paragraphs instead of bulleted text.

4. Avoid unnecessary repetitions of information between table 1 and previous chapters. E.g. information in table about ‘around 900,000 cases of illnesses and 900 deaths occurred each year in the US due to microbial contamination’ is already know from chapter 2.1.

Authors’ response:

The authors agree to remove this sentence in Table 1. Another fact to support the current situation of the spreading of water-borne diseases in small inland water bodies as follows.

-          In fact, lakes and ponds are the locations that have the second-highest number of outbreaks of water-borne diseases, occupying around 40% of the total number of outbreaks occurring between 1951 and 2006 [83]. (in the SDG 3 in Table 1 in the revised manuscript)

5. Figure 1 – there is ‘the number of publications’ in the figure title; please provide information on number, now there is no information that allows reader to learn about it.

Authors’ response:

As mentioned in the previous comment, more details on the methodology of the bibliometric analysis are added in the revised supplementary materials.

-          Figure 1. The number of publications in three research lines with topics related to the sustainable development of lakes and reservoirs from 2009 to 2018. The data were extracted from the online database of the Science Citation Index Expanded (SCI-Expanded) in the Web of Science on January 24, 2019. More information on the methodology of the bibliometric analysis can be found in Supplementary Material A. (lines 287-291)

6. Table 2 – for users from which spatial scale are the suggested indicators designed? E.g. for national authorities or can some of them be used on local, regional scale?

Authors’ response:

The list of our proposed indicators is based on the 232 indicators developed by Inter-Agency and Expert Group on Sustainable Development Goal Indicators and adopted by the General Assembly at its seventy-first session in July 2017. In the report on Progress towards the Sustainable Development Goals of Secretary-General's annual, these indicators are calculated from data from national statistical systems, compiled by international agencies. This means that the data are available on the national level as such the national authorities can be used as a convenient way to track progress towards the SDGs. However, it is important to keep in mind that the situation of individual countries/regions may vary significantly.

These arguments are added in the revised manuscript as follows

-          After the assessment of the interlinkages between the SDGs and the sustainable development of lakes and reservoirs, we propose a list of indicators to monitor the sustainable development of lakes and reservoirs. The list is built, based on their strong synergies with the abovementioned SDGs with the main focus on the environmental dimensions, i.e. SDG 6, 13, 14, and 15, and SDG 7 with regards to renewable energy from hydropower reservoirs. 22 proposed indicators were based on the 232 indicators developed by Inter-Agency and Expert Group on Sustainable Development Goal Indicators and adopted by the General Assembly at its seventy-first session in July 2017. These indicators are measurable with their values that can represent global, regional and subregional aggregates (Table 2). According to the Secretary-General's annual report on "Progress towards the Sustainable Development Goals", these indicators are calculated from data from national statistical systems, compiled by international agencies which are vital for evidence-based decision-making and the full implementation of the 2030 Agenda. As such, our proposed indicators scaled up to lake and reservoir systems can be used to monitor the sustainable development of lakes and reservoirs. Particularly, these indicators focus on urgent topics, i.e. water quality, eutrophication and (micro) plastics, fisheries, biodiversity, biological invasions, eco-friendly dams, and (inter) national and local management. As mentioned in the SDGs that their indicators should be implemented as an ‘indivisible whole’, the same principle is applied to the proposed indicators for the sustainable development of lakes and reservoirs. Noteworthy is that the situation of individual countries/regions may vary significantly, hence one should pay extra attention to the aggregated data despite its convenient way to track the progress of sustainable development. Besides, since the proposed indicators based on the 232 indicators that are still undergoing methodological development by the United Nations, updating information is necessary to keep track of the progress on SDG implementation. (lines 350-374)

7. Table 2 - indicators should be measurable. Please comment how ‘Progress towards sustainable lake management’ can be measured.

Authors’ response:

The authors totally agree with the comment of the reviewer. As such, for this indicator, we propose two alternative indicators which can be used to measure the ‘Progress towards sustainable lake management’. These two indicators are used to measure the target 15.2.1. Moreover, we also put the unit of the proposed indicators in the revised Table 2. More importantly, we also found new indicators which are also essential for monitoring the sustainable development of lakes and reservoirs. The revised Table 2 can be found as follows.

Table 2. Proposed indicators for monitoring the sustainable development of lakes and reservoirs.

8. Finally, it is interesting how do you understand the ‘sustainability’ of lakes and reservoirs? As you proved by bibliographic and SDGs analysis, there can be many synergies, but also many trade-off between different goal and action. So, in the light of your results, how should we understand this sustainability?

Authors’ response:

The sustainability of lakes and reservoirs simply follows the most well-known definition of sustainability, which is defined in the report of the World Commission on Environment and Development: Our Common Future, that is to “meet the needs of the present without compromising the ability of future generations to meet their own needs”. This means that the holistic point of view that containing not just the development of economy and society but also take into account the negative impacts of this growth on the environment. From that, we need to keep a balance between the three dimensions to reach a sustainable future.

This information is added in the revised manuscript as follows.

-          Emerging global threats, such as biological invasions, climate change, land use intensification, and water depletion, endanger the sustainable future of lakes and reservoirs. To deal with these threats, a multidimensional view on the protection and exploitation of lakes and reservoirs is needed. This holistic needs to contain not just the development of economy and society but also take into account the negative impacts of this growth on the environment, from that the balance between the three dimensions can be sustained to reach a sustainable future.  As such, this paper provides a comprehensive review on future opportunities and challenges for sustainable development of lakes and reservoirs via a critical analysis on their contribution to individual and subsets of Sustainable Development Goals (SDGs). (lines 10 to 15 in the revised abstract)

-          Based on these interlinkages, we proposed 22 indicators that cover five main areas related to five SDGs, i.e. Goals 6, 7, 13, 14, and 15. More specifically, these indicators focus on urgent topics, i.e. water quality, eutrophication and (micro) plastics, fisheries, biodiversity, biological invasions, eco-friendly dams, and (inter) national and local management. With these indicators, policymakers are able to keep track of the development of lakes and reservoirs, hence, have holistic and multidimensional management and policies for the sustainable future of lakes and reservoirs which, following the definition of Brundtland Commission [117] on sustainability, is to “meet the needs of the present without compromising the ability of future generations to meet their own needs”. (lines 396-404)

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

It is suitable for publication.

Author Response

Thank you very much for your final decision!

Reviewer 2 Report

The authors addressed many of my comments. For some other they explained why they hadn't decided apply them.
However I still think that it is important to shorten the table 1. Now it covers six pages; moreover, it contains many repetitions of information that is already included in previous chapters. The authors have removed one repetition, but still there is a few of them. I think that part of information from the table 1 should be removed/moved to the supplementary materials.

Author Response

The authors agree to remove unnecessary parts of Table 1 and put them into a bullet form to facilitate the readiness of the reader. 

The revised Table 1 with the length of four pages can be found in the revised manuscript. 

Likewise, the reviewer can find the same changes in the revised Table S2 showing an overview of indirect interlinkages between the sustainable development of lakes and reservoirs and the SDGs.

Round 3

Reviewer 2 Report

The authors revised Table 1.