Assessing the Effectiveness and Cost Efficiency of Green Infrastructure Practices on Surface Runoff Reduction at an Urban Watershed in China

Round 1

Reviewer 1 Report

Assessing the Effectiveness and Cost Efficiency of Green Infrastructure Practices on Surface Runoff Reduction at an Urban Watershed in China

The paper entitled Assessing the Effectiveness and Cost Efficiency of Green Infrastructure Practices on Surface Runoff Reduction at an Urban Watershed in China reports on the application of the Long-Term Hydrologic Impact Assessment – Low Impact Development (L-THIA-LID) 2.1 model, in order to evaluate the effectiveness and cost efficiency of Green Infrastructures on reducing the surface runoff volume in the Hexi urban watershed, located in Nanking City, in China.

The results obtained from the model seem to have been well perceived and constitute a particularly interesting and innovative topic. The introduction is very well written and noteworthy, and it displays many examples of different Green Infrastructures, as well as several Low Impact Development and Best Management Practices examples. The introduction also mentions the lack of relevant studies in the area, in particular in Chinese cities – as they display very specific populational characteristics –, which, once again, states the innovative character of the article.

The paper is well organized and very well written – presenting the methodology in numerous chapters, detailing every procedure and decision made. Despite being very well written, a few corrections and annotations were still made, which were identified throughout the attached pdf file. An additional small number of points also need to be clarified/notes:

• Overall: I think the introduction is a little bit confusing. It lacks cohesiveness and should be more focused on the actual topic of the research. It seems that the authors talked about various topics without connecting everything.
• Line 39: Why is China a Keyword? I understand the study was developed in China, but since the purpose of the study was not evaluate practices in China or a literature review of GI in China, for example, I don’t know if the word “China” is suitable for a keyword.
• Line 45: Source???
• Line 135 – 150: I’m not sure if this paragraph in suitable for the introduction. It seems much The paper entitled Assessing the Effectiveness and Cost Efficiency of Green Infrastructure Practices on Surface Runoff Reduction at an Urban Watershed in China reports on the application of the Long-Term Hydrologic Impact Assessment – Low Impact Development (L-THIA-LID) 2.1 model, in order to evaluate the effectiveness and cost efficiency of Green Infrastructures on reducing the surface runoff volume in the Hexi urban watershed, located in Nanking City, in China.
• Line 183 - “Maintenance costs were assessed as a percentage of construction costs” what is the scientific source of each maintenance costs. The source must be indicated whenever it is mentioned in the text or the table. If the source is the same, indicate in the table’s legend. The construction costs’ source must be indicated as well.
• In the introduction (last paragraph), it the structure of the article should be specified. It is important to understand how the article is structured/divided, in order to better grasp the contents of the study.
• Although the use of acronyms throughout the article is understandable – as to avoid constant repetitions of certain words –, it can get a bit confusing trying to remember/memorize the meaning of all the different acronyms.
• Maybe include just an introductory sentence in the beginning of chapter 2.3. (Input data).
• When using the referencing style proposed by MDPI, it is not necessary to include the year date in citations, e.g.: “As stated by Li et al. (2009) [2], (…)” should be substituted by “As stated by Li et al. [2], (…)”. Attention to line 337.

Methods

Overall: the methods section needs serious rewriting. It is extremely confusing and lacks clarity.

Section 2.1.1 – Something is missing to explain the model. Maybe the previous paragraph from the introduction?

Figure 1 – this figure needs to be more perceptible. To hard to read.

Line 187 – I would suggest the study area to appear before the 2.1 section. It appears to me it makes more sense to start with the study area, than talk about the model used, and then the data input that you used in the model.

Section 2.3 – The section needs rewriting!! It is not perceptible what these data are. Where was it used? And for what? Was it used in the model? The authors simply put the data they used here and did not explain the context of it.

Section 2.4 – I do not understand this section at all. I think the authors meant to present which are the GI practices that are the most suitable for their study area. Am I wrong?? However, I don’t think this was achieved at all. Not to mention table 2 appears out of nowhere. Where does that data come from?? This section needs rewriting as well.

Section 2.5 – lacks evidences about the areas chosen for the implementation of each GI.

Results

Overall: I’m not sure if this section is presented in the best possible way. First, there is not a Discussion section in this paper, so I assume this section is Results and Discussion. Am I wrong? If so, the title should be changed to “Results and Discussion”. However, only in section 3.4 a discussion is made, where the authors (gladly) discussed their results and compared them with other researches. Although the content of this section in not bad at all, it arises concerns regarding its organization.

Section 3.1. – This is not the result! This section should be in the methods section.

Section 3.2 – I’m not sure if that is the right way to present the results. If in the table the authors experiment with different scenarios, why not present the results by scenario instead of GI practice? Another issue with this section is that the authors decide only to present the results already presented in table 5. Where is the discussion? What do these results mean In practice???

Conclusions

Overall: They are good, however, a question arises: What do these results mean for sponge city planning? And for future decision-making processes in China? It was important to mention the real contributions of this study for future GI planning.

The results obtained from the model seem to have been well perceived and constitute a particularly interesting and innovative topic. The introduction is very well written and noteworthy, and it displays many examples of different Green Infrastructures, as well as several Low Impact Development and Best Management Practices examples. The introduction also mentions the lack of relevant studies in the area, in particular in Chinese cities – as they display very specific populational characteristics –, which, once again, states the innovative character of the article.

I suggest the authors carefully revise this small list of points and, after that, the paper can be published without any further review – as it is a very complete article, with a very thorough and interesting methodology.

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thanks for your review and your suggestions. The following content is the response to your suggestions. Looking forward to your further suggestions.

Best wishes.

Overall: I think the introduction is a little bit confusing. It lacks cohesiveness and should be more focused on the actual topic of the research. It seems that the authors talked about various topics without connecting everything.

Response: In former version, the introduction included some content about the background of the L-THIA-LID 2.1 model, in this version, this part content was moved to “2.2.1” section.

Line 39: Why is China a Keyword? I understand the study was developed in China, but since the purpose of the study was not evaluate practices in China or a literature review of GI in China, for example, I don’t know if the word “China” is suitable for a keyword.

Response: As you mentioned, the word “China” is not suitable for a keyword. We deleted it in this version.

Line 45: Source???

Response: We added references to this sentence.

Line 135 – 150: I’m not sure if this paragraph in suitable for the introduction. It seems much The paper entitled Assessing the Effectiveness and Cost Efficiency of Green Infrastructure Practices on Surface Runoff Reduction at an Urban Watershed in China reports on the application of the Long-Term Hydrologic Impact Assessment – Low Impact Development (L-THIA-LID) 2.1 model, in order to evaluate the effectiveness and cost efficiency of Green Infrastructures on reducing the surface runoff volume in the Hexi urban watershed, located in Nanking City, in China.

Response: This paragraph was moved to the “2.2.1 Principle and framework for GI practices simulation”. (L163)

Line 183 - “Maintenance costs were assessed as a percentage of construction costs” what is the scientific source of each maintenance costs. The source must be indicated whenever it is mentioned in the text or the table. If the source is the same, indicate in the table’s legend. The construction costs’ source must be indicated as well.

Response: The percentage of maintenance costs in construction costs were default setting parameters in the model, which were empirical values based numerous researches. We added reference to this sentence and table1. (L209)

In the introduction (last paragraph), it the structure of the article should be specified. It is important to understand how the article is structured/divided, in order to better grasp the contents of the study.

Response: A new paragraph was added to introduce the structure of this article. (P134-137)

Although the use of acronyms throughout the article is understandable – as to avoid constant repetitions of certain words –, it can get a bit confusing trying to remember/memorize the meaning of all the different acronyms.

Response: As you say, acronyms were used widespread in this paper. However, this was inevitable because there were too many terminologies, so we summarized them in Figure 1 to make it easy distinguish.

Maybe include just an introductory sentence in the beginning of chapter 2.3. (Input data).

Response: Combining your suggestions below, the “input data” was rewritten to introduce how was the data used.

When using the referencing style proposed by MDPI, it is not necessary to include the year date in citations, e.g.: “As stated by Li et al. (2009) [2], (…)” should be substituted by “As stated by Li et al. [2], (…)”. Attention to line 337.

Response: We revised the whole manuscript as your suggestion.

Methods

Section 2.1.1 – Something is missing to explain the model. Maybe the previous paragraph from the introduction?

Response: The previous paragraph was moved to this part.

Figure 1 – this figure needs to be more perceptible. To hard to read.

Response: In Figure 1, the whole figure represented a hydrological unit, in this unit, each GI practice treated runoff generated form suitable locations and runoff coming from other locations. We add some explanation both in the text and the figure.

Line 187 – I would suggest the study area to appear before the 2.1 section. It appears to me it makes more sense to start with the study area, than talk about the model used, and then the data input that you used in the model.

Response: Revised as the reviewer’s suggestion.(L139-157)

Section 2.3 – The section needs rewriting!! It is not perceptible what these data are. Where was it used? And for what? Was it used in the model? The authors simply put the data they used here and did not explain the context of it.

Response: Revised as the reviewer’s suggestion. We added some contents to introduce was these data used in the model. (line214-244)

Section 2.4 – I do not understand this section at all. I think the authors meant to present which are the GI practices that are the most suitable for their study area. Am I wrong?? However, I don’t think this was achieved at all. Not to mention table 2 appears out of nowhere. Where does that data come from?? This section needs rewriting as well.

Response: There are many kinds of GI practices in sponge city construction, but not all the GI practices are suitable for this area. So, we introduce the reason to chose part kinds of GI practices in this part. The table 2 should been listed in “2.5 Suitable locations of GI practices”, we revised it in this version of manuscript. (L333)

Section 2.5 – lacks evidences about the areas chosen for the implementation of each GI.

Response: Content in Table 2 is the criteria for the selection of suitable locations. (L333)

Results

Overall: I’m not sure if this section is presented in the best possible way. First, there is not a Discussion section in this paper, so I assume this section is Results and Discussion. Am I wrong? If so, the title should be changed to “Results and Discussion”. However, only in section 3.4 a discussion is made, where the authors (gladly) discussed their results and compared them with other researches. Although the content of this section in not bad at all, it arises concerns regarding its organization.

Response: We change the tile to “Results and Discussion” to make it clearer. In the new version of manuscript, 3.1 section and 3.2 section were results, 3.3 section was discussion. (L368)

Section 3.1. – This is not the result! This section should be in the methods section.

Response: This section was moved to the methods section. (L349)

Section 3.2 – I’m not sure if that is the right way to present the results. If in the table the authors experiment with different scenarios, why not present the results by scenario instead of GI practice? Another issue with this section is that the authors decide only to present the results already presented in table 5. Where is the discussion? What do these results mean In practice???

Response: Table 5 shows that it’s the same to present the results by scenario or GI practice, however, we didn’t present it clearly in the former manuscript. In this version, we did some revision based on the reviewer’s suggestion. (L372-469)

Conclusions

Overall: They are good, however, a question arises: What do these results mean for sponge city planning? And for future decision-making processes in China? It was important to mention the real contributions of this study for future GI planning.

Response: We added some content in this part to introduce the contributions of this study. (L533-536).

Author Response File: Author Response.docx

Reviewer 2 Report

the work deals with an interesting topic and seems to be very current. Research on green infrastructure used in urban areas is obviously necessary. Sustainable rainwater management is of key importance for smart development. To achieve this, it is necessary to implement alternative solutions. This study demonstrated the feasibility of the L-THIA-LID (Long-Term Hydrologic Impact Assessment-Low Impact Development) model for the evaluation of green infrastructure practice implementation effects and cost efficiency on urban runoff in sponge city construction in China. Various scenarios were explored to assess the cost efficiency of individual objects on annual runoff volume reduction and the implementation impact of green infrastructure practice combinations on surface runoff. In my opinion, such research is not novelty but the outcomes can be beneficial for designing local strategies of rainwater management.  

The paper is well-organized, containing all of the expected components. The methodology is effective in attaining the object of this work. In the Introduction, the authors provided a brief research background discussing the current state of green infrastructure practices. Discussion and Conclusions are based on actual facts. Conclusion is supported by the information, discussed inside the manuscript.

The text requires a small editorial correction. Please, format the article and references according to the journal's guidelines.

Author Response

Dear reviewer,

Thanks for your review. We did some revision in this version of manuscript, and we look forward to your further suggestion.

Best wishes.