Carbon Accounting and Carbon Emission Reduction Potential Analysis of Sponge Cities Based on Life Cycle Assessment

Round 1

Reviewer 1 Report (Previous Reviewer 1)

The changes to the manuscript and the explanation provided by authors is acceptable. 

No additional comments

Author Response

It's my honor to receive your recognition and thank you for your recognition.

Reviewer 2 Report (Previous Reviewer 2)

The topic of this article is current and interesting. Unfortunately, it is not clear what the authors of this study aimed to achieve. Whether it is a case study of a "Sponge city" or if they are comparing "Sponge city" and "Integrated urban drainage system (IUDS)" with each other. It is not clear why the authors chose CO₂ in the case of "Sponge city," which is based on water management. The authors do not adhere to the basic formal rules.

Specific comments:

Introduction:

• The topic of "Sponge city" deserves a broader introduction (positives/negatives).

• Lines 35–52 are not cited, even though they contain information that is not the authors’ thoughts and work.

• Missing comparison of methods for assessing the carbon footprint of construction activities and city operations.

• Scientific hypotheses and specific objectives are not defined.

Materials and Methods:

The use of Intergovernmental Panel on Climate Change (IPCC) guidelines and life cycle assessment (LCA) is mentioned, but the specific parameters, assumptions, and limitations of these models are left unaddressed. This omission undermines the robustness of the method and raises questions about the validity of the results.

• Missing GPS coordinates, construction and renovation dates, description of the water cycle, population count, etc.

• Figure 1. The scale is missing.

• Define the "interest 50 years."

• Is IUDS not part of the Sponge city?

3.4.1. Plant maintenance carbon emissions:

• If the research does not include an evaluation of the species composition of vegetation, it is better not to mention this.

Results and Discussion:

• Line 284: The amount of CO₂ is only estimated (calculated) and not measured

• Lines 366–369: Does not the amount of rainfall have the biggest impact?

• Lack of discussion of the calculated results.

Conclusions:

• Structure conclusions according to specific objectives and hypotheses.

The conclusion attempts to offer recommendations for reducing carbon emissions in Sponge city construction. However, these recommendations are general and lack specificity, making it difficult for policymakers and practitioners to translate them into actionable steps.

The article aims to contribute to the development of sustainable urban planning through Sponge city construction, it falls short in several crucial aspects. The lack of a clear research question, the absence of comprehensive methodological explanations, and the shallow presentation of results hinder the impact of the study. To enhance its value, the article should provide a clearer research framework, address methodological limitations, and offer more specific and actionable recommendations for real-world application.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (Previous Reviewer 2)

The article aims to contribute to the development of sustainable urban planning through Sponge city construction, it falls short in several crucial aspects.

Specific comments:

 • The authors do not adhere to the basic formal rules.

• Scientific hypotheses are not defined.

• Figure 1 (b,c,d). The scale is missing.

• Lack of discussion of the calculated results.

• The use of verb tenses is inconsistent in the text, making it unclear what has already happened and what is currently happening.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Authors present a comprehensive analysis based on carbon emissions factors for "sponge cities". But the presentation, structure, and the language can be improved. 

For example, before a concept is described it should be clearly defined. 

A lot of the equations can go in supporting equation

Tables need to be properly formatted. 

Introduction says a framework is presented, but rest of the study seems like a case study. 

Description of results and key findings need to be more comprehensible. Authors can use bullet points to clear state their findings 

Should be improved

Reviewer 2 Report

The paper's subject is both engaging and highly current. Unfortunately, it is unclear what the authors aim to achieve with this study, whether it is developing and adapting the methodology for "Carbon accounting" or a case study of the "Sponge city" project.

Specific comments:

Abstract:

·         The main conclusions of the study should be emphasized.

·         Lines 29-32: These details are not essential for this study.

 Introduction

 

·         Individual topics lack continuity.

·         The definition of "Sponge city" is missing.

·         It is not clear whether you will be evaluating "Carbon accounting" models or the "Sponge City project in Beijing," or assessing CO₂ reduction possibilities.

·         The scientific hypothesis and sub-goals are not defined.

 Materials and Methods

 

·         Provide a more detailed description of the "Sponge City project in Beijing," including GPS coordinates, construction and renovation dates, the water cycle, urban greenery, population count, etc.

·         Define the 50-year period of interest in the context of the study

·         Explain how the need for indoor air conditioning is incorporated into the calculations (over 50 years).

·         Describe how the amount of rainfall is accounted for in the calculations (over 50 years).

 

3.4.1. Plant maintenance carbon emissions

·         Line 258: I do not understand the sentence "Grass was transformed into trees and shrubs in a common green space."

Results and Discussion

 

·         Line 284: The amount of CO₂ is only estimated (calculated), not measured!

·         Lines 352-353: I do not understand the sentence "The analysis was not carried out because of the low carbon emission during the process of disassembly and recycling."

·         Lines 366-369: "The construction of the sponge city had a positive effect on the carbon emission reduction of IUDS, which reduced carbon emissions by 87.08% on average. Rainwater purification had the largest contribution rate of carbon emission reduction (CRCR), which was 46.77% in the sponge city." Doesn't the amount of rainfall have the most significant impact?

·         Lines 420-421: I do not understand the sentence "Biological carbon can not only relieve stormwater run-off but also reduce carbon emissions in the production of the material."

·         Lines 426-427: I do not understand the sentence „The analysis was not conducted due to its low significance.“

 Conclusions

 

·         Formulate the conclusions according to the sub-goals and hypothesis

 

English errors:
Line 451: Morris global analysis method was used to analyze the sensitivity of LCA results and obtained that the influence factors on carbon emissions in the life cycle waswere in the order of annual rainfall…

Reviewer 3 Report

The study and paper have merit, but revisions are necessary:

Line 51. The runoff will not be unchanged. It might have improved quality, but any construction will change the runoff, at least to some extent.

Line 98. Sludge treatment and disposal should not be capitalized. Other lines have words that are capitalized but should not be capitalized.

Lines 128 to 134 (and others). I don’t believe it is worth carrying areas in square meters out to the hundredth place. It makes more sense to me to round to the nearest square meter.

Line 153. Why was the IPCC method selected? Justify this selection. What other methods were considered and why were they not selected?

Line 205. Please provide a complete list of the types of plants used in this study. The list provided ends with etc., which suggests there are other plant types. In order to reproduce your study, this manuscript should provide a complete list.

Line 226. What are the units on catchment area, it is listed as (h m²)

Line 266. Permeable pavement typically does not require daily maintenance. What is meant by daily cleaning? Maintenance activities for permeable pavement include pressure washing and vacuuming but these do not occur daily. To avoid confusion, please explain in detail what daily cleaning activities were performed. Also, typically there is routing maintenance that needs to occur and then there is non-routine maintenance. Non-routine maintenance includes things like damaged pavement repair, etc. Dis your study include non-routine maintenance? It should have but it was not discussed.

Line 276. Tables should be on a single page, if possible (and it is possible), not split between two pages.

Line 284-316. This is a very long paragraph that should be broken into two or more paragraphs.

General comments: There are locations throughout the manuscript that need to be addressed due to grammar issues. Most are subtle, but some are not.

Please see General comments.