Challenges of Sustainable Water Management in a Heavily Industrialized Urban Basin, Case of Bytomka River, Poland

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors focus on sustainable water resources management and adopts a series of methods for analysis, such as geospatial analysis, WQI analysis, hydrological data analysis, case comparison, and policy and legal analysis. I suggest some revisions. Some points are listed below.

1. The Abstract section should not only cover the current situation of the research field, but also include the research purpose, solutions and important results.
2. Some state of art wastewater treatment methods could be introduced, e.g. J Environ Chem Eng, 2024, 12: 114446. ACS ES&T Eng, 2024, 4: 2642-2656. NPJ Clean Water. 2024, 7: 38. J Environ Manage. 2024, 359, 120938. Sep Purif Technol. 2024, 341: 126938. Chem Eng J. 2024, 479: 147320. Chem Eng J. 2022, 430: 133166.
3. The structure of Results should be optimized. It is recommended to adjust the numbering hierarchy, e.g., no 3.1?
4. In the Results section, it is better to unify the research duration data in Changes of river flows, Changes of quality pattertns in surface waters of Bytomka river basin and Identification of prevailed impacts on waters in river basin.
5. In the section of constructing the WQI formula, the basis for parameter selection and weight distribution was not clearly defined. It is suggested to appropriately supplement the method details to improve the accuracy.
6. In the final part of the introduction, a summary of the research methods and innovation points of this study should be listed.
7. In the Results section, the article introduces a large amount of climate data, but does not consider its association with flow changes, such as whether the reduction in precipitation leads to an intensification of low flow.
8. In the Discussion section, the limitations of the research were not clearly stated, such as the problems caused by data gaps and model simplification.
9. The topographic map in the figures of the article should indicate the scale and direction.
10. In the discussion section of the response plan, there is a lack of detailed economic cost calculation. It is suggested to refer to the cost-benefit analysis of similar projects to estimate the implementation budget.

Author Response

Authors would like to kindly thank for revision, comments and valuable remarks on the paper. All comments have helped to improve the presentation and depth of our study. Below we have addressed all reviewer’s comments with relevant clarifications.

Reviewer 1

1. The Abstract section should not only cover the current situation of the research field, but also include the research purpose, solutions and important results.

Abstract is now improved and according to reviewer’s comments research purpose, solutions and important results were emphasised as well as abstract was restructured.

2. Some state of art wastewater treatment methods could be introduced, e.g. J Environ Chem Eng, 2024, 12: 114446. ACS ES&T Eng, 2024, 4: 2642-2656. NPJ Clean Water. 2024, 7: 38. J Environ Manage. 2024, 359, 120938. Sep Purif Technol. 2024, 341: 126938. Chem Eng J. 2024, 479: 147320. Chem Eng J. 2022, 430: 133166.

Thank you, relevant reference were cited in the text of introduction.

3. The structure of Results should be optimized. It is recommended to adjust the numbering hierarchy, e.g., no 3.1?

Yes, thank you – relevant numbering is added to the manuscript in Results section and as well in the whole text where relevant (Methods section).

4. In the Results section, it is better to unify the research duration data in Changes of river flows, Changes of quality patterns in surface waters of Bytomka river basin and Identification of prevailed impacts on waters in river basin.

Periods and research duration in the case of Bytomka river basin is the issue and the unifying of this data is problematic considering uncertainties and  gaps (different periods and changing points of monitoring). Relevant comments were added on limitations and uncertainty of presented data (as reviewer #2 underlined it too).

5. In the section of constructing the WQI formula, the basis for parameter selection and weight distribution was not clearly defined. It is suggested to appropriately supplement the method details to improve the accuracy.

Thank you for this suggestion; more detailed description on WQI calculations (parameters of concern and weights) was provided.

6. In the final part of the introduction, a summary of the research methods and innovation points of this study should be listed.

The final part of the introduction was updated on listed research methods, with point of innovative approach.

7. In the Results section, the article introduces a large amount of climate data, but does not consider its association with flow changes, such as whether the reduction in precipitation leads to an intensification of low flow.

Thank you, it is important aspect – we have added data on annual average precipitation with relevant comment in the text; figure 4 and new figure 5 was updated to present how annual flows corelate with mean precipitation.

8. In the Discussion section, the limitations of the research were not clearly stated, such as the problems caused by data gaps and model simplification.

Thank you, the limitations, data gaps and uncertainties were addressed in additional section (3.5)

9. The topographic map in the figures of the article should indicate the scale and direction.

All figures are accordingly improved.

10. In the discussion section of the response plan, there is a lack of detailed economic cost calculation. It is suggested to refer to the cost-benefit analysis of similar projects to estimate the implementation budget.

Thank you for this suggestion. Some studies have been carried out for Bytomka river, with estimation of possible cost of revitalisation. We have added relevant reference and estimated cost value of proposed revitalization plan with relevant comment on long time planning several legislative and management basis on governmental level.

Reviewer 2 Report

Comments and Suggestions for Authors

1. The abstract feels messy—it tries to say too much at once. I'd suggest breaking it into clearer sections: what was done, why it matters, and what was found.
2. There are quite a few grammar issues throughout the manuscript. I recommend a full language check—it would help readability a lot.
3. The methodology section doesn't explain how the WQI was calculated in enough detail. For instance, how were the weights for each parameter chosen?
4. The historical land use map from 1883 is interesting, but the reliability of that data isn't addressed. There should be some discussion of its accuracy and limitations.
5. The land use analysis is a bit thin—it would help to connect specific land cover types (e.g., industrial zones, roads) to their water impact rather than just giving percentages.
6. GIS tools are mentioned, but we don’t get any details on what kind of spatial analysis was done. A few sentences on that would really strengthen the methods section.
7. The water quality trends are described, but there’s no statistical analysis to support those trends. A basic trend test or ANOVA would help.
8. There’s no section discussing uncertainties or limitations. Given the data gaps and changing monitoring points, this really needs to be addressed.
9. The discussion mostly repeats results and talks broadly about policy. It would be stronger if it tied the findings back to concepts like environmental flows or integrated water management.
10. Environmental flow is brought up, but never quantified. Could the authors try to estimate it, even roughly?
11. The conclusion is very general and doesn’t say much that wasn’t already said in the introduction. Try summarizing the actual findings more clearly.

Overall, the topic is interesting and timely, but the manuscript needs tighter structure, more detail in the methods, and clearer messaging to meet journal standards.

Author Response

Authors would like to kindly thank for revision, comments and valuable remarks on the paper. All comments have helped to improve the presentation and depth of our study. Below we have addressed all reviewer’s comments with relevant clarifications.

1. The abstract feels messy—it tries to say too much at once. I'd suggest breaking it into clearer sections: what was done, why it matters, and what was found.

Abstract is now improved and according to reviewer’s comments research purpose, solutions and important results were emphasised as well as abstract was restructured.

 

2. There are quite a few grammar issues throughout the manuscript. I recommend a full language check—it would help readability a lot.

Thank you, language check was performed – we hope that readability is improved

3. The methodology section doesn't explain how the WQI was calculated in enough detail. For instance, how were the weights for each parameter chosen?

In the method sections more detailed description on WQI calculations (parameters of concern and weights) was provided.

 

4. The historical land use map from 1883 is interesting, but the reliability of that data isn't addressed. There should be some discussion of its accuracy and limitations.

 

Thank you, very important remark. Relevant comments on the source of the map, accuracy and limitations were added in the manuscript.

 

5. The land use analysis is a bit thin—it would help to connect specific land cover types (e.g., industrial zones, roads) to their water impact rather than just giving percentages.

Land use analysis was part of the project related to post industrial zones development, where only limited analysis of possible impact on surface water was performed. However, we have added reference to literature accordingly to this comment to connect specific land cover types with possible contamination generated in surface water.

6. GIS tools are mentioned, but we don’t get any details on what kind of spatial analysis was done. A few sentences on that would really strengthen the methods section.

Additional comments on spatial analysis were added in the text.

 

7. The water quality trends are described, but there’s no statistical analysis to support those trends. A basic trend test or ANOVA would help.

We have added additional analysis of quality trends based on available data, which substantially improved the research value of this study, thank you for this comment.

8. There’s no section discussing uncertainties or limitations. Given the data gaps and changing monitoring points, this really needs to be addressed.

Thank you, very important issue – we have added relevant section in the manuscript.

9. The discussion mostly repeats results and talks broadly about policy. It would be stronger if it tied the findings back to concepts like environmental flows or integrated water management.

Thank you for this valuable comment – we have improved discussion and as well conclusions not only related to policy but as well on water management concept including environmental flow

 

10. Environmental flow is brought up, but never quantified. Could the authors try to estimate it, even roughly?

We have added this aspect in the section on water quantity in Bytomka river

 

11. The conclusion is very general and doesn’t say much that wasn’t already said in the introduction. Try summarizing the actual findings more clearly.

Thank you, we have improved conclusions according to this remark.

 

Overall, the topic is interesting and timely, but the manuscript needs tighter structure, more detail in the methods, and clearer messaging to meet journal standards

Thank you, all remarks and necessary corrections were done, thanks to valuable comments of reviewers.

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript presents a case study on sustainable water management in the Bytomka River basin, but it would be benefit from several improvements to enhance clarity, structure, and scientific impact.  Here are detailed suggestions:

1.- Make the title more concise and clear: for example "Challenges and prospects of sustainable water management in a heavily industrialized urban basin: Case of Bytomka River, Poland".

2.- Rewrite the abstract to improve grammar and flow. Include clearer sections: background, aim, methods, key findings, implications. End with a strong concluding sentence summarizing the key message.

3.- The manuscript contains frequent grammar and sintax issues that affect readability. Use consistent tenses.  Many paragraphs shif between past and present witout clear logic.

4.- The article could benefit from tighter structure: Merge or clearly separate results and discussion.  Currently, section 3 is fragmented. Considering splitting into: *Land use and impervious surface trends. *Flow variability and water quantity. *Water quality trends and WQI analysis. *Pollution sources and impacts.  Section 4 should critically analyze findings, relate them to literature, and not simply re-state results.  Conclusions are well-focused but could more explicity suggest policy or managment actions.

5. Acknowledge the limitations of WQI use (e.g. changing sampling points, inconsistent parameters), and suggest improvements.

6. Improve explanations of how sub-indices and wights were assigned in WQI; consider including a table of parameters used and their weights.

7. Some figures (e.g. Figure 3) are mentioned but not described well. Add informative captions and reference them explicitly in the text.

8. Use consistent reference fomatting.

9. Emphasize more clearly how this case offers lessons of frameworks applicable to other industrial river basins in Europe or globally.

Author Response

Authors would like to kindly thank for revision, comments and valuable remarks on the paper. All comments have helped to improve the presentation and depth of our study. Below we have addressed all reviewer’s comments with relevant clarifications.

Reviewer 3: The manuscript presents a case study on sustainable water management in the Bytomka River basin, but it would be benefit from several improvements to enhance clarity, structure, and scientific impact.  Here are detailed suggestions:

1. Make the title more concise and clear: for example "Challenges and prospects of sustainable water management in a heavily industrialized urban basin: Case of Bytomka River, Poland".

Thank you for this suggestion, we proposed the new title of the manuscript.

2. Rewrite the abstract to improve grammar and flow. Include clearer sections: background, aim, methods, key findings, implications. End with a strong concluding sentence summarizing the key message.

Abstract was substantially rewritten, with relevant restructuring as well as language and grammar check.

3. The manuscript contains frequent grammar and sintax issues that affect readability. Use consistent tenses.  Many paragraphs shift between past and present without clear logic.

Full language and grammar check was performed to improve readability, thank you for this remark.

4.The article could benefit from tighter structure: Merge or clearly separate results and discussion.  Currently, section 3 is fragmented. Considering splitting into: *Land use and impervious surface trends. *Flow variability and water quantity. *Water quality trends and WQI analysis. *Pollution sources and impacts.  Section 4 should critically analyze findings, relate them to literature, and not simply re-state results.  Conclusions are well-focused but could more explicity suggest policy or managment actions.

Thank you, very important remark. We have followed your suggestion and improved results and discussion, as well as have split section 2 and 3 accordingly. We have improved section 4 following your remarks and necessary additional text was added.

5. Acknowledge the limitations of WQI use (e.g. changing sampling points, inconsistent parameters), and suggest improvements.

Yes, we agree and we have dedicated accordingly one additional section on uncertainties and data gaps and limitations

6. Improve explanations of how sub-indices and weights were assigned in WQI; consider including a table of parameters used and their weights.

Thank you for this suggestion; detailed description on WQI calculations (parameters of concern and weights) was provided.

7. Some figures (e.g. Figure 3) are mentioned but not described well. Add informative captions and reference them explicitly in the text.

Thank you, relevant references to the text and improvement of captions were included in the text.

8. Use consistent reference formatting

Thank you, formatting of references were improved also according to Editor’s remark - all references were cited in sequential numerical order instead of author plus year.

9. Emphasize more clearly how this case offers lessons of frameworks applicable to other industrial river basins in Europe or globally.

Thank you, this is an important aspect – we have added additional comment in the conclusions.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The response letter was not well written, and the comments were not well replied.

Author Response

Authors would like to kindly thank for revision, comments and valuable remarks on the paper. All comments have helped to improve the presentation and depth of our study. Below we have addressed all reviewer’s comments with relevant clarifications, with additional point by point answers to relevant remarks. 

Reviewer 1

1. The Abstract section should not only cover the current situation of the research field, but also include the research purpose, solutions and important results.

Abstract is now improved and according to reviewer’s comments research purpose, solutions and important results were emphasised as well as abstract was restructured. Research purpose and the background were described at the beginning of abstract introduction (v11 – 15): Identification of related impacts is particularly important in the aspect of increasing water shortages due to climate change. Overlapping industrial impacts and drought occurrence have resulted in long lasting deterioration of surface water status. Therefore, mitigation of negative impacts is crucial for relevant and sustainable water management in river basins. Research purpose was underlined (v 17 – 19) Mine waters discharged into rivers have induced significant increase of salinity, while urban wastewater have increased biogenic contamination in surface waters. The solutions and key findings were emphasised at the end of abstract (v33 – 40): The presented study reveals key findings that future coal mine closure would result in significant water resources shortage due to reduction of mine water discharges, significant biogenic (N, P) pollution and hazards of harmful algal blooms. Therefore, there is an urgent need to increase the retention potential of watershed and to use of nature -based solutions to mitigate negative impacts of coal mining transition. The increase in treatment capability of industrial wastewater and sewage discharge would help to cope with natural water vulnerability induced by impacts of climate change.

2. Some state of art wastewater treatment methods could be introduced, e.g. J Environ Chem Eng, 2024, 12: 114446. ACS ES&T Eng, 2024, 4: 2642-2656. NPJ Clean Water. 2024, 7: 38. J Environ Manage. 2024, 359, 120938. Sep Purif Technol. 2024, 341: 126938. Chem Eng J. 2024, 479: 147320. Chem Eng J. 2022, 430: 133166.

Thank you, relevant reference were cited in the text of introduction (v 80 – 86) Wastewater treatment plants in densely urbanized areas are capable to remove basic compounds (COD, BOD5, N and P) in conventional sewage sludge technology, while rapid development of modern industry makes the efficient treatment of organic wastewater a critical issue. Therefore, innovative, and high-effective technology solutions i.e., carbon nanotubes [16] which aim at preventing eutrophication, heavy metals reduction and removal of harmful substances from wastewater are crucial for mitigation of negative impacts on water ecosystems.

[16] Yi Yang, Minyi Liu, Shuo Tang, Xintong You, Ying Li, Ying Mei, Yiliang Chen (2024) Investigation of the key mechanisms and optimum conditions of high-effective phosphate removal by bimetallic La-Fe-CNT film. Separation and Purification Technology 341(2024)126938 doi.org/10.10160j.seppur.2024.126938

3. The structure of Results should be optimized. It is recommended to adjust the numbering hierarchy, e.g., no 3.1?

Yes, thank you – relevant numbering is added to the manuscript in Results section and as well in the whole text where relevant (Methods section).

Results section were optimized and now consists of four consecutive subchapters: 3.1. Land use and impervious surface trends.  3.2 Flow variability and water quantity in Bytomka river 1990 – 2022. 3.3 Pollution sources and identification of prevailed impacts on waters in river basin in 1990 – 2024. 3.4. Uncertnainties of analysis, limitations and data gaps identified in the case Bytomka river basin.

4. In the Results section, it is better to unify the research duration data in Changes of river flows, Changes of quality patterns in surface waters of Bytomka river basin and Identification of prevailed impacts on waters in river basin.

Periods and research duration in the case of Bytomka river basin is the issue and the unifying of this data is problematic considering uncertainties and  gaps (different periods and changing points of monitoring). Relevant comments were added on limitations and uncertainty of presented data (as reviewer #2 underlined it too). Therefore, to make it clear that several data gaps and uncertainty were discussed in chapter 3.4: Considering limitations of the research several data gaps and uncertainties should be underlined. Data gaps are mostly related to availability of monitoring results from the period of 1990 – 2024. In this period monitoring requirements, data collection and legal basis have changed to fulfill several regulations related to water policy. Inconsistency in range of parameters as well as simplifications of river model in such complex basin should be treated as estimation to make assessment of water quality and quantity possible. Therefore, WQI was simplified and calculated to present long lasting impact of industrial and urban impact with relevant identification of prevailing factors, which are now mostrly related to mine water and coal industry impacts. Considering coal industry transition in the near future it is highly important to identify appropriate maeasures in water management.

5. In the section of constructing the WQI formula, the basis for parameter selection and weight distribution was not clearly defined. It is suggested to appropriately supplement the method details to improve the accuracy.

Thank you for this suggestion; more detailed description on WQI calculations (parameters of concern and weights) was provided (v275 – 298) - For the purpose of presented study, parameters of concern related to salinity, water temperature, biogenic contamination, dissolved oxygen and total suspended solids were col-lected – all parameters T [^oC], BOD [mgO₂/L], TSS [mg/L], DO [mgO₂/L], and PEW [µS/cm] represent individual index terms with different weighting factors for each parameter.

Water Temperature Index is particularly important for biological water status and aquatic ecosystems. Water temperature is also important for its influence on water chemistry and self-purification ability. The water temperature index varies from 0 to 1. The temperature index decreases from 1 for every degree that water temperature is greater than 20°C.

Biological Oxygen Demand Index (BOD) indicates a high amount of organic pollution in water, which may be an indication of contamination by sewage or other waste. The BOD index reaches a high of 30 for BOD = 0 mg/L. For BOD values > 12 mg/L, index = 0.

Total suspended solids are a measure of the mass of particles suspended in water (mostly mineral), which is also an indicator of mine water discharges and rainwater outflow from industrial and urban areas. Index TSS reaches a high of 25 for TSS = 0 mg/L. For TSS val-ues > 250 mg/L, ITSS =0.

Dissolved oxygen (DO) parameter related to biological status of surface water for aquatic organisms; the index of DO in this study reaches 25 when dissolved oxygen > 10 mg/L, for DO values = 0 mg/L index is equal 0.

Conductivity (PEW) of surface water is particularly important in the case of identification of saline mine water discharged to the river. Index of PEW reaches a high of 20 when conductivity is 200 μS/cm (conductivity of drinking water). For conductivity values greater than 4000 μS/cm, index value is equal 0.

6. In the final part of the introduction, a summary of the research methods and innovation points of this study should be listed.

The final part of the introduction was updated on listed research methods, with point of innovative approach: v 97 – 106:

Proposed research methods for complex recognition of heavily impacted water basin are complementary and based on integrated approach, considering:

-              water quality measurements from representative monitoring points,

-              flow measurement results as part of quantitative water resources assessment,

-              meteorological data (precipitation) in representative monitoring station,

-              inventory of wastewater discharges with data of quality and quantity.

Innovation in the approach of water management derives from using complex GIS datasets on the area development connected with possible qualitative impact on water, which is related to specific cover types and contamination.

7. In the Results section, the article introduces a large amount of climate data, but does not consider its association with flow changes, such as whether the reduction in precipitation leads to an intensification of low flow.

Thank you, it is important aspect – we have added data on annual average precipitation with relevant comment in the text; figure 4 (Records on mean annual flows of Bytomka River in period 1991 – 2022 (measuring point – flow gauge as presented on  Figure 3) and new figure 5 (Records on mean annual precipitation measured in Katowice – Muchowiec representative meteorological station for Bytomka River Basin in period 1990 – 2022) was updated to present how annual flows corelate with mean precipitation.

8. In the Discussion section, the limitations of the research were not clearly stated, such as the problems caused by data gaps and model simplification.

Thank you, the limitations, data gaps and uncertainties were addressed in additional section (3.4), which was added to the manuscript to make clear all the discussion on the periods of measurements, data gap and accuracy of presents results.

9. The topographic map in the figures of the article should indicate the scale and direction.

All figures are accordingly improved (figures 1, 2, 3 were improved with addition relevant scale and direction)

10. In the discussion section of the response plan, there is a lack of detailed economic cost calculation. It is suggested to refer to the cost-benefit analysis of similar projects to estimate the implementation budget.

Thank you for this suggestion. Some studies have been carried out for Bytomka river, with estimation of possible cost of revitalisation. We have added relevant reference and estimated cost value of proposed revitalization plan with relevant comment on long time planning several legislative and management basis on governmental level (v 528 – 540: Considering the methodology for estimating environmental flows in Poland it is worth to mention that it is the most important problems related to the currently updated water management plans. Overestimating environmental flows may result in a reduction of water resources available to other water users especially industrial and urban wastewater discharges in the river basin.

Detailed plan of water management in highly impacted water basins requires detailed economic cost calculation. The implementation budget for revitalization plan in Bytomka river basin may cost about millions of PLN, spent directly on actions of improvement water status as well as restoration of watershed area. The City of Ruda Śląska has obtained nearly PLN 19.9 million in funding for a project to renaturalization the Bytomka River Valley. The investment, worth over PLN 21 million (5 million USD) in total and financed from the European Union and the State Budget, aims to restore the natural landscape and create an attractive, green space for residents.

 

Reviewer 2 Report

Comments and Suggestions for Authors

The Manuscript can be acceptted now.

Author Response

Authors would like to kindly thank for review and valuable remarks, and the acceptation of the Manuscript.

 

Reviewer 3 Report

Comments and Suggestions for Authors

I consider now the paper ready for publication

Author Response

Authors would like to thank for valuable comments and the acceptation of the manuscript.

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

Accept.