Wastewater System Inflow/Infiltration and Residential Pluvial Flood Damage Mitigation in Canada
Round 1
Reviewer 1 Report
- this study tend to review the work on urban flood and I/I issue in wastewater system, but most of the review work did not sufficiently emphasize the association between urban flood and I/I instead of putting too much emphasis on policies content related to I/I (most of the statements were not referring flood background).
- the title of this paper should be I/I in wastewater systems.
- in the abstract, this paper should provide more specific conclusions on their main review purposes.
- lots of references were missing in this paper, showing ‘error! Reference source not found’.
- in section 1, the authors should provide more support information on why they should conduct a review work on I/I issue in urban flooding management. The only sentence was mentioned in line 60, this is too weak.
- line 70-72, This part of the summary does not correspond to the actual content of the paper.
- line 100, this statement has been mentioned twice.
- section 3 and 4 had little information related to urban flood. There are not enough experimental papers or quantitative analyses in this review work to support the critical role of I/I for urban flooding management.
Author Response
Comment 1: this study tend to review the work on urban flood and I/I issue in wastewater system, but most of the review work did not sufficiently emphasize the association between urban flood and I/I instead of putting too much emphasis on policies content related to I/I (most of the statements were not referring flood background).
Response 1: Thank you for this comment.
We have re-worded the article to emphasize that our focus is on urban pluvial flooding, rather than urban flood in general. The revisions include a new title for the paper.
Further to this, we have added significant new text outlining urban drainage mechanisms in Canada, with the purpose of emphasizing the role of wastewater systems and I/I in urban pluvial flood occurrence. Specifically, see Lines 171-254, and lines 391-490. Throughout the paper we have also provided clearer linkages between the issue of pluvial urban flood and wastewater system inflow & infiltration.
Comment 2: the title of this paper should be I/I in wastewater systems.
Response 2: Thank you – we have revised the title to emphasize our focus on urban pluvial flooding in Canada
Comment 3: in the abstract, this paper should provide more specific conclusions on their main review purposes.
Response 3: Thank you – we have revised the abstract to highlight the paper’s purpose and conclusions.
Comment 4: lots of references were missing in this paper, showing ‘error! Reference source not found’.
Response 4: Thank you – as submitted, all of the in-line references should be working now.
Comment 5: in section 1, the authors should provide more support information on why they should conduct a review work on I/I issue in urban flooding management. The only sentence was mentioned in line 60, this is too weak.
Response 5: Thank you. We have added significant new content on this issue, including new sections outlining examples of urban flood events and urban pluvial flood vulnerability (specifically, Sections 2 and 3.1).
Comment 6: line 70-72, This part of the summary does not correspond to the actual content of the paper.
Response 6: Thank you – we have removed the sentence.
Comment 7: line 100, this statement has been mentioned twice.
Response 7: Thank you – we have removed the repeat mention of $2 billion in losses.
Comment 8: section 3 and 4 had little information related to urban flood. There are not enough experimental papers or quantitative analyses in this review work to support the critical role of I/I for urban flooding management.
Response 8: Thank you for the comment.
We have re-worded the article to emphasize that our focus is on urban pluvial flooding, rather than urban flood in general.
Further to this, we have added significant new text outlining urban drainage mechanisms in Canada, with the purpose of emphasizing the role of wastewater systems and I/I in urban pluvial flood occurrence (specifically, Sections 2 and 3.1).
We believe that we have now clarified the relationship between wastewater systems and urban/pluvial flood hazards in section 2. Thus, sections 3 and 4 deal more specifically with key issues in wastewater systems that relate to urban pluvial flood.
Reviewer 2 Report
This paper review common drivers of the overflow of wastewater systems in Canada during the period of flood, and puts forward specific management implications from the aspects of urban planning, design, construction and inspection. The main comments/doubts are as follows:
(1)Line191. Extensive consultation with municipalities across Canada have indicated that excessive I/I in new sewer construction is an issue experienced nationally.
It only indicates that there is excessive I/I in the new sewer, but it does not indicate there is problem in the old pipeline. Is it that has existed long time or only the new ones have problems? If the old ones don't have problems, what's the reason?
(2)Line 400. Protecting sewer systems from I/I aligns directly with protecting buildings from urban flood impacts.Line120. It has been reported that roughly half of all wastewater volume may be attributed to I/I. Negative consequences of I/I include increased risk of sewer backup flood, multiple risks to the environment, and risks public health and safety.
The relationship is controversial between flood and sewer overflow. Sewer networks can overflow during heavy rains, but it wasn't the main cause of the flood. On the other hand, it can also divert flood water to reduce flood inundation losses. It is mentioned that sanitary pipe overflow is very harmful. But the damage caused by flooding here is hard to define, especially because of the dual role of sewer networks.
(3)Table 6. Direct new sewer construction away from surface flood risks, groundwater, or areas with site conditions that exacerbate I/I risk, including stormwater infiltration features.
It is recommended to avoid constructing new sewer in low-lying places where prone to water accumulation, but such places are precisely where pipeline drainage is most needed. More consideration should be given to preventing pipe leakage.
(4)Table 7. New buildings should not be located in areas exposed to surface flood risks, groundwater, or areas with site conditions that exacerbate I/I risk, including stormwater infiltration features.
Building in flood-prone areas should be avoided, but there is usually an objective need to build in low-lying areas. As stated in line 55 of this paper, vulnerable residents live in basements that are susceptible to flooding. Banning low-lying buildings will creates other social problems. More consideration should be given to preventing pipe leakage.
Author Response
Comment 1: This paper review common drivers of the overflow of wastewater systems in Canada during the period of flood, and puts forward specific management implications from the aspects of urban planning, design, construction and inspection. The main comments/doubts are as follows:
Response 1: Thank you for your considered comments.
Comment 2: (1)Line191. Extensive consultation with municipalities across Canada have indicated that excessive I/I in new sewer construction is an issue experienced nationally.
It only indicates that there is excessive I/I in the new sewer, but it does not indicate there is problem in the old pipeline. Is it that has existed long time or only the new ones have problems? If the old ones don't have problems, what's the reason?
Response 2: Thank you for the comment. We have included a new section covering the issue of I/I as it has contributed to pluvial flooding in existing/older areas (see Section 3.1).
Older systems are certainly vulnerable to I/I. We have clarified this point with the new discussion on I/I in pluvial flood events in Canada and have clarified reference to “existing/older” systems throughout the paper.
Comment 3: (2)Line 400. Protecting sewer systems from I/I aligns directly with protecting buildings from urban flood impacts.Line120. It has been reported that roughly half of all wastewater volume may be attributed to I/I. Negative consequences of I/I include increased risk of sewer backup flood, multiple risks to the environment, and risks public health and safety.
The relationship is controversial between flood and sewer overflow. Sewer networks can overflow during heavy rains, but it wasn't the main cause of the flood. On the other hand, it can also divert flood water to reduce flood inundation losses. It is mentioned that sanitary pipe overflow is very harmful. But the damage caused by flooding here is hard to define, especially because of the dual role of sewer networks.
Response 3: Thank you for the comment. We have added significant new content to outline the role of I/I in damaging pluvial flood events, including section 3.1 and new/additional context throughout the paper. We have also discussed limitations of our review paper in Section 6.5, including limited information on the relative impacts of different drivers of I/I and how they directly contribute to flood damage (an area requiring further work).
Comment 4: (3)Table 6. Direct new sewer construction away from surface flood risks, groundwater, or areas with site conditions that exacerbate I/I risk, including stormwater infiltration features.
It is recommended to avoid constructing new sewer in low-lying places where prone to water accumulation, but such places are precisely where pipeline drainage is most needed. More consideration should be given to preventing pipe leakage.
Response 4: Thank you for the comment. We agree and we have added content in the discussion section to address this point. See Tables 8 and 9, and lines 1026 to 1044.
Comment 5: (4)Table 7. New buildings should not be located in areas exposed to surface flood risks, groundwater, or areas with site conditions that exacerbate I/I risk, including stormwater infiltration features.
Building in flood-prone areas should be avoided, but there is usually an objective need to build in low-lying areas. As stated in line 55 of this paper, vulnerable residents live in basements that are susceptible to flooding. Banning low-lying buildings will creates other social problems. More consideration should be given to preventing pipe leakage.
Response 5: Thank you for the comment – we have added content in the discussion section to address this point. See Tables 8 and 9, and lines 1026 to 1044.
Reviewer 3 Report
Plz find the attached file
Comments for author File: 
Comments.pdf
Author Response
Comment 1: Manuscript ID# water-1717178, Review of “Managing Urban Flood Risk in Canada: Addressing Wastewater Systems and Inflow/Infiltration” for Water.
Thanks for opportunity to review this critical review paper. This paper addresses flooding in urban areas associated with short-duration, high intensity (SDHI) rainfall events, the most significant drivers of disaster loss in Canada.
Although paper is short, this review focused on managing underlying factors contributing to urban and basement flood risk. Only major comments are provided for the authors to consider.
Response 1: Thank you very much for your considered comments on our manuscript. We’d like to highlight that this paper is submitted as a “review” manuscript.
Comment 2: Title - Title is mismatching the content of the paper. Title should be changed
Response 2: Thank you – we have updated the title to reflect reviewer comments.
Comment 3: Abstract • Clearly state the objective of the study • What is the new knowledge, missing in this section • In the end of abstract, needs one line policy formulations. • A table of content is required for better reader understand after abstract
Response 3: Thank you – we have revised the introduction to address each of the points raised here.
An outline of the structure of the paper is now provided in the introduction section.
Comment 4: Introduction
What is the framework/ hypothesis of the study?
There are several publications regarding urban flood risk in literature. What is the contribution in the study to scientific knowledge?
It is suggested that authors should be properly addressed the hypothesis in the revised MS, especially the relevant literature is not fully presented here.
I suggest to add these papers for international audience • 10.1007/s12665-022-10269-0; 10.1016/j.gsf.2020.09.006
There are lots of error in referencing.
Response 4: Thank you for the questions and comments. The primary contribution offered here is the role of the wastewater system in pluvial flood risk: A review of the problem, and ongoing work to mitigate the hazard. We have clarified this in the introduction, and have generally clarified our focus on pluvial flood specifically.
We have expanded the review of literature, bringing more perspectives in from the pluvial urban flood literature.
Thank you for the referring us to these papers. We have included additional reference to publications concerning pluvial flooding in urban areas. In the discussion (section 6.5), we discuss how we have not comprehensively addressed “urban flooding,” but have focussed on the role of I/I & wastewater systems in pluvial urban flooding.
Thank you – as submitted, all of the in-line references in the Word file should be working now.
Comment 5: Discussion
The more scholarly discussions are required to justify the uniqueness of this review.
What are the limitations of the study?
How this study aids to policy formulation?
-What is the future research trend in the field?.
These issues should be discussed here.
Response 5: Thank you very much for these helpful comments.
We have included new text in the discussion section to identify limitations of the review.
We have clarified how we are contributing policy formulation in the discussion section of the paper – see lines 940 through 955.
Discussion concerning future research has been added to the discussion section (see Section 6.5).
Comment 6: Conclusion
The conclusions should be concise and clear. It is suggested to add novelty, main findings with the policy implication of the study.
Response 6: Thank you for the comment. We have re-written the conclusion to clarity.
Round 2
Reviewer 1 Report
this paper has been well revised
Reviewer 2 Report
The authors has revised the manuscript addressing to reviewer's comments. It's acceptable now.
Reviewer 3 Report
accept in current form
