To What Extent Have Nature-Based Solutions Mitigated Flood Loss at a Regional Scale in the Philadelphia Metropolitan Area?

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This is a well-written and innovative article that discusses a framework properly. I believe this article has scientific merit and I have no reason to oppose its publication in Urban Science. I appreciate the text and believe it is the result of sound and rigorous research.
A few minor suggestions to improve the paper:

-          I do not understand the research question.
The application of NBS quantity and quality has not properly discussed before the question and formulation of the question could be clearer.
There is more clear use of this term in other parts of the paper (for example line 152)

-          Section 2 can be summarized and more to the point.

-          I would expect more justification on county level analysis. The floodplain planning are usually done in different levels. How does this impact the research hypothesis?

 

Author Response

- Thanks so much for reviewing the article and providing useful comments for the publication of my article. Given the first point, I tried to use NBS structure as the main phrase in the Introduction part and then elaborate on its two main components including composition (quantity) and configuration (quality and spatial factors), and remove the "quantity" and "quality" words from the main question. I've also provided a brief explanation about the research gap in lines 68-85. 

 - I rewrote and summarized section 2 to be more to the point. 

- I tried to re-arrange and add more justifications in lines 71-77 and in lines 93-96. 

Reviewer 2 Report

Comments and Suggestions for Authors

1.      Line 6 mentions urban floods (same as line 202 mentioning pluvial flooding) while line 80 refers to riverine flooding. It understood that the author is analyzing flood loss mitigation, where flooding can be both pluvial and fluvial. It is recommended that the author use a general term flooding, encapsulating the different types of flooding in the study area.

 

2.      Line 60-61 refers to NbS as “effective adaptation to increased flood risk”. However, it has not been stated how NbS helps adapt to mitigate flood risk. The author could mention that NbS helps restore the natural hydrology of a region, which has been altered by urbanization.

 

3.      Line 47, author should stick with either “%” or write percent.

 

4.      Line 178, replace needed with need.

 

5.      Line 142, the author mentions the quality of NbS. The term quantity with respect to NbS is understood but quality of NbS should also be explained concisely.

 

6.      Line 133, stick with the abbreviation of NbS.

 

7.       Line 100-101, the author can mention examples of dam failure leading to flooding in urban areas.

 

8.      Line 183, “The study will be conducted” means that the study is yet to be completed. However, the complete manuscript suggests otherwise. Please change accordingly.

 

9.      Lines 197 and 214 mention the growth rate of population but nowhere is any number given to imply the high growth rate of population in the region.

 

10.  Line 205, how does one flood event due to Hurricane Irene make Norristown “most flood-prone cities in the area”. What about other cities? The statement can be supported by some parameter like impervious area or annual flood hazard layer (if any).

 

11.   Line 242 mentions the landcover map but the landcover map is not present in the manuscript. The landcover map can be included in the manuscript as part of figure 2 or elsewhere, to better represent the area. Further the author can also mark the important cities on the map. What is represented by numbers in brackets in lines 248-249.

 

12.  Some figures lack the north arrow. Also, legends in figure 2 are not clear. The quality of figures can be improved.

 

13.  The word tract is written as “Tract” until line 263, after which it has been written as “tract”.

 

14.  The use of the word “we” in line 266 of manuscript should be resisted.

 

15.  Line 299, OLS should be expanded when first used and later abbreviated.

 

16.  Line 380, R2 instead of R².

 

17.  The results of tests like Jarque-Bera statistics, Breusch-Pagan (heteroscedasticity), and Global Moran's I are discussed but presented in the manuscript in form of table.

 

18.  Lines 397-398, shouldn’t a higher amount of NbS within floodplains reduce the expected loss of flooding, as NbS are primarily employed to reduce the flood risk? Lines 455 onwards

 

19.  Lines 445-448, a study of the impact of imperviousness on flood property damage at a national scale is not suitable for a local or urban level analysis. An urban area is primarily characterized by dense builtup while this is generally not the case on a national scale. The sentence needs to be removed as the research is focused on a county and discussion at a national scale does not fit here.

 

20.  The paper concludes that NBS in floodplains reduce the total damage from flooding (contrary to lines 397-388). Has the author quantified the extend of flood loss mitigation as suggested by the title of the article?

Comments on the Quality of English Language

Can be improved. 

Author Response

Thanks so much for reviewing the article and providing positive feedback and comments on my paper. To address your comments: 

• I  used the general term "flooding" in all the text to be consistent.
• I added "NbS helps restore the natural hydrology of a region, which has been altered by urbanization" in line 62. 
• In Line 47, I replaced percent with “%”.
• Line 178, section 2 was totally rewritten based on another reviewer's comments. 

•  In line 142, the author mentions the quality of NbS. The term quantity with respect to NbS is understood but the quality of NbS should also be explained concisely: section 2 was totally rewritten and I elaborated in more detail about these terms in the intro and section 2 parts.

•   Line 133, stick with the abbreviation of NbS. I revised this issue in the whole text, replacing "nature-based solutions" with NBS.

•  An example of dam failure was added in lines 116-119 with a new citation

• Line 183, “The study will be conducted” ... it was totally changed and corrected

•  Lines 197 and 214 mention the growth rate of population but nowhere is any number given to imply the high growth rate of population in the region: in line 188 a rate was added. 
•  Line 205, how does one flood event due to Hurricane Irene make Norristown the “most flood-prone cities in the area”. What about other cities? The statement can be supported by some parameters like impervious area or annual flood hazard layer (if any): some revisions were made in line 178-180 to address the concern. 
• Line 242 mentions the land cover map but the ...: I added the land cover map as figure 2h.
• Some figures lack the north arrow. ... I added the north arrow. I changed the legends of the figures. 
• The word tract is written as “Tract” ...: I changed all terms to a lowercase.\ to be consistent in all the paper.
•  The use of the word “we” in line 266 of manuscript should be resisted: Revised
•  Line 299, OLS should be expanded when first used and later abbreviated: revised.
•   Line 380, R2 instead of R².: revised
• The results of tests like Jarque-Bera statistics, Breusch-Pagan (heteroscedasticity), and Global Moran's I are discussed but presented in the manuscript in form of a table.: Unfortunately, I did not understand what is the meaning of the comment. These metrics have been presented in tables. 
• shouldn’t a higher amount of NbS within floodplains reduce the expected loss of flooding, as NbS are primarily employed to reduce the flood risk? : This is one of the surprising findings of the article that is further explained in the discussion part. 

•  Lines 445-448, a study of the impact of imperviousness on flood property damage at a national scale is not suitable for a local or urban level analysis. An urban area is primarily characterized by dense builtup while this is generally not the case on a national scale. The sentence needs to be removed as the research is focused on a county and discussion at a national scale does not fit here: revised

• The paper concludes that NBS in floodplains reduce the total damage from flooding (contrary to lines 397-388). Has the author quantified the extend of flood loss mitigation as suggested by the title of the article? : I changed and revised the text in line 470-471 to be more precise and consistent with the findings of the paper. 

• Has the author quantified the extend of flood loss mitigation as suggested by the title of the article? Since the type of dependent variable's values are on a score basis and are not tangible, the quantifications of scores and their changes regarding the existing NBS have not been reported in the paper. 

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

NA

Comments on the Quality of English Language

NA