Combined Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain
Round 1
Reviewer 1 Report (New Reviewer)
See the file
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 1 Comments
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Water-1834637)
The authors appreciate the reviewer and the editor for their constructive comments and suggestions. Please see our point-by-point response to the comments. The changes in the manuscript are shown in red text.
Point 1: Some repetitions must be checked. Check also the spelling (e.g. line 103: constructeds; 114 platfoams) and the English
Response 1: The authors appriciate the reviewer’s through review. As the reviewer pointed out by the reviewer, English grammar and spelling errors have been corrected throughout the manuscript.
Point 2: There are several scientific concepts related to Engineering, Soil Science and other that are not clear at all. Examples:
Response 2: We would like to thank the reviewer for insightful comments. The scientific concept of this study has been revised to clearly reflect the contents as follows.
- About the “real world relation” of the idea: is it necessary to reinforce the building structure to support the extra weight?
→ Green roofs usually conducted on a roof surfaces or on green roof platform. In this study, the green roof platform simulated roof surface. Unlike the existing roof surface, the bottom of the roof surface is open to the atmosphere, so the same assembly as a full-scale vegetation roof is possible [35, 46]. (lines 113-116)
→ The weight-loading of green roofs is one of the biggest barriers to widespread absorption and reduces the possibility of retrofitting existing buildings. Increasing the substrate depth increases the weight of the green roof, reducing its applicability to low load-bearing buildings [49]. Thus, a light-weight material was selected as a growth material in consideration of its bearing capacity. (lines 125-129)
- What about the evapotranspiration?
→ Although evapotranspiration is a key parameter influening stormwater retention capacity [32], the percentage of runoff reduction is generally defined as the percentage of the total rainfall control associated with retention and the evapotranspiration effect of substrate and vegetation [14]. (lines 140-143)
- The vegetation metabolizes the acid rain?
→ Acid rain pollution is caused by the emission of numerous precursor such as acid anions (SO42- and NO3- ) from fossil fuel combustion, agricultural productions and vehicle traffic [43]. The addition of acids to the soil promotes the mineralization of nutrients (such as Mg2+, K+, and Ca2+), which expands the available pool in soil, which in turn improves soil neutralization efficiency and plant physiology [44]. (lines 280-284)
Line
21: Vegetated plots
→ ‘Vegetation plots’ has been changed to ‘Vegetated plots’ (line 21)
37: Reference for % of surface? Of course, depends on the type of neighbourhood
→ In particular, roofs generally account for approximately 20 ~ 25% of the total urban surface area [6] or 40 ~ 50% of the total impervious surface area [7, 14, 25]. (line 38-39)
45: Thermal environment?
→ The term ‘Thermal environment’ has instead been changed to ‘temperature’. (line 52)
46: mid-2000s? Around 2050?
→ The sentence including the term ‘mid-2000s’ has been omitted.
50: “a green roof”
→ ‘green roof’ has been modified to ‘a green roof’. (line 60)
56-58: better explanation, it is not so simple. Stored in the vegetation? Is it a remarkable amount?
→ Rainwater is initially stored on a green roof (vegetation + substrate), and the extra water is carried over to the nearby ground and then the excess water flows into the sewage system, which usually helps reduce the maximum flow and volume compared to conventional roofs [14]. Green roof substrates account for 80 ~ 90% of a green roof water storage capacity and 80 ~ 90% of the total system weight [49]. (lines 67-71)
61-63: syntax and meaning
→ Green roofs can reduce nutrient and pollutant runoff by absorbing and filtering pollutants because green roofs are typically composed of multiple layers of components including vegetation, substrate, filter fabric, drainage material, root barrier and insulation [31, 38, 42]. (lines 74-77)
71: eutrophication in green roofs
→ The term ‘eutrophication’ has instead been changed to ‘eutrophication in green roofs’ (line 87)
75-76: difference among extensive and intensive?
→ Green roofs are generally divided into the main engineering categories of intensive and extensive, based on the depth of the substrate. Extensive green roofs consist of substrate layers with a maximum depth of about 150 mm, whereas intensive green roofs are established with deeper soil layers than the extensive ones [27]. Depending on the weight of the load, an extensive or intensive green roof is often added to an existing roof [42]. (lines 54-59)
78: BMP for what?
→ ‘BMP’ has been changed to ‘stormwater management solution’. (line 95)
87: survival of the vegetation during dry-climate periods?
→ Indeed, outside of this period, low temperatures and dry winds often severely limit viable vegetation in South Korea. (lines 106-108)
93: 9, 14 and 17 what?
→ The monthly rainfall intensity in June, July, and August was approximately 63.3, 92.6, and 284.3 mm/h, respectively, and the rainfall for each event was 9, 14, and 17, respectively. (lines 109-111)
134-138: meaning of the sentence?
→ All green roofs were more effective in precipitation retention than the control (hard roofs). However, there was a difference in the amount of runoff in June, July, and August (24 ~ 78, 23 ~ 80, and 24 ~ 48 %, respectively), and the amount of runoff reduction decreased as the rain intensity. (lines 162-165)
143: least?
→ ‘least’ has been changed to ‘lowest’. (line 169)
145: performed in what?
→ At the same substrate depth, the vegetated system performed better at reducing runoff than the non-vegetated system (Table 1). (lines 170-172)
146: Title?
→ Table 1. Runoff reduction from different substrate depths and vegetation plots based on rainfall intensity. (lines 173-174)
202: the roots hold heavy metals?
→ These changes may be due to the removal or fixation of contaminants in soil and water through absorption, volatile decomposition, and stabilization by plants to purify the environment [45]. (lines 320-322)
256: subsided?
→ Vijayaraghavan et al. (2012) observed that concentrations of most chemical compounds in runoff from green roofs were the highest at the beginning of rain events, and gradually decreased over time [31]. (lines 297-299)
263: comparison with wastewater reuse standards?
→ The sentence has been omitted.
279: plants can metabolize pollutants?
→ Plants need mineral nutrients to grown. After plant uptake, the substrate binding site becomes empty, allowing the substrate to adsorb additional elements from the incoming contaminated water [35]. From the standpoint of runoff water quality, green roofs can be considered as potential to control air quality of air pollutants by filtration and adsorption through vegetation and substrates. In particular, vegetation has shown the potential to continuously absorb and immobilize various contaminants [42]. (lines 328-334)
281: sinks with or without a limit?
→ Although green roofs are recognized as a source of various nutrients [27, 29, 30], the extent of nutrient loss is closely controlled by runoff reduction [47]. Green roofs with vegetation also improve runoff quality [22]. Therefore, vegetated-green roofs have the potential to be used as pollutant sinks related to phytoremediation in urban environments (lines 343-338)
Author Response File: 
Author Response.docx
Reviewer 2 Report (New Reviewer)
The manuscript " Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain“ addresses a interesting topic, and the authors investigated effects of substrate depth and vegetation of a green roof on runoff reduction and airborne pollutant purification based on rainfall intensity. I have appreciated the cycling investigation. However, the purpose and mechanism of this paper must be declared. After minor revision this contribution could be accepted.
1. Introduction should be added some sections about the purpose of this article.
2. The authors should strengthen the correlation analysis of experimental results. Comparative study between those related studies should be provided, it could be used to provide more evidence of the mechanism.
Author Response
Response to Reviewer 2 Comments
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Water-1834637)
The authors appreciate the reviewer and the editor for their constructive comments and suggestions. Please see our point-by-point response to the comments. The changes in the manuscript are shown in red text.
The manuscript " Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain“ addresses a interesting topic, and the authors investigated effects of substrate depth and vegetation of a green roof on runoff reduction and airborne pollutant purification based on rainfall intensity. I have appreciated the cycling investigation. However, the purpose and mechanism of this paper must be declared. After minor revision this contribution could be accepted.
Point 1: Introduction should be added some sections about the purpose of this article.
Response 1: The authors appriciate the reviewer’s insightful comments. As suggested by the reviewer, the Introduction section has been modified throughout to account for gaps in knowledge about green roofs runoff and to better reflect the main objective of the current study. (lines 38-40, 42-45, 48-50, 54-59, 67-71, 74-77, 89-91)
Point 2: The authors should strengthen the correlation analysis of experimental results. Comparative study between those related studies should be provided, it could be used to provide more evidence of the mechanism.
Response 2: Based on the comments of the reviewer, the results of the current study have been discussed in comparison with previous related studies in the Disucssion setion (lines 254-256, 261-262, 266-269, 279-284, 286-291, 295-298, 305-309, 320-326, 327-336), and relevant references have been added. (Refs # 42, 43, 44, 45, 46, 47, 48, and 49)
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report (New Reviewer)
The comments on the previous version remain the same, but some improvements can be found
Author Response
Response to Reviewer 1 Comments
(Round 2)
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Water-1834637)
The authors would like to thank the reviewer for taking the time to review this paper once again. We have carefully revised the manuscript once again to reflect the reviewers last comments. Please see the changes in red in the manuscript.
Point 1: The comments on the previous version remain the same, but some improvements can be found
Response 1: We have revised the manuscript to account for gaps in knowledge about green roof runoff and to better reflect the main objective of the current study as follow. In addition relevant references have been added. (Refs # 50, 51, 52, and 53)
→ This type is thickest and heaviest green roof (usual weight > 300 kg/m2), which requires additional structural support due to increasing roof loads. On the other hand, extensive green roofs (usual weight 50 ~ 150 kg/m2) do not required addition support because the soil layer is shallow and light, and can be easily installed during new construction and renovation of buildings. However, an extensive green roof can only accommodate a limited range of plants [50, 51]. Thus, the selection of the most suitable system must take into account building characteristics and local climate conditions [42, 53]. (lines 58-65)
→ Although evapotranspiration is a key parameter influening stormwater retention capacity [32], runoff reduction is generally defined as the percentage of total rainfall control associated with retention and evapotranspiration effect of substrate and vegetation [14]. In other words, the retained water in green roof is equivalent to evapotranspirtation over several wet/dry cycles [51]. Therefore, evapotranspiration was not independently considered in this study. As a result, the runoff reduction was calculated using the following equation [15, 46]: (lines 146-152)
→ Neutralization is an important environmental benefit that contributes to lowering the degree of acidification of natural water [27]. Green roof structure, as a filter layer, reduces acid rain damage by raising the pH levels [52], which meet the standard V (pH 6 ~ 9) of Environmental Quality Standards for Surface Water [24]. (lines 286-290)
→ Acid rain pollution is caused by the release of numerous precursors such as acid anions (SO42- and NO3- ) from road traffic and industrial emissions [43]. Depending on their shape and size, plant species can sequester air pollutants and consume carbon dioxide to develop their vital function [53]. In general, improved nutrient availability, due to acid rain in the soil promotes mineralization of nutrients (such as Mg2+, K+, and Ca2+) and expands available pool in the soil. While these mechanisms improve soil neutralization efficiency and plant physiology, acid rain in direct contact with leaves can negatively affect leaf performance and chemical composition [44]. (lines 291-299)
→ Green roofs also contribute to the quality of runoff by reducing the amount of dust, pollutants and nutrients that would be sent to the sewage systems and waterways [53]. If the substrate of green roofs is saturated and the atmospheric humidity rises, it can become a source of pollution [27, 29, 30, 51]. However, the extent of loss is closely controlled by the runoff reduction [47]. In other words, high water retention capacity, green roofs limit pollution exports for most storm events [51]. (lines 348-353)
Author Response File: Author Response.docx
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
The paper describes experimental research that is performed and described adequately. The results are mainly in line with the general expectations and do not deliver new insights. So the novelty and originality is rather as well as the contribution to scientific development. In this form I am not able to advise acceptance of the paper. I would like to offer some suggestions to the authors in which way the paper could be improved.
The goal of the paper is not defined explicitly. The authors state "The goal of these green roof field experiments was to quantify the contribution of the design components of a green roof system to the quantity and quality of stormwater runoff during the rainy season." But considering the conclusion (the last line of the abstract) " These results suggest that green roofs may be installed to enhance stormwater runoff quantity and quality. " we do not see a quantitative conclusion derived from the experiment.
So my first suggestion would be to define explicitly a clear research goal or research hypothesis and to validate this based on the experiments.
Defining the research goal the authors should consider explicitly its originality and its potential contribution to the expansion of scientific knowledge. The present conclusion seems to be fully in line with the present insights and does not really contribute to an increase of scientific understanding.
A potential increase of understanding could be found in the analysis dynamic quantitative behaviour of green roof systems. The experimental findings could be used fruitfully to gain more insight in the dynamic behaviour. Understanding the dynamic behavior is important to consider applications of green roofs under several climatological conditions.
The study is performed under Korean conditions. The authors should discuss the representativeness of a Korean case study for general applicability of the conclusions of the study.
Author Response
Response to Reviewer 1 Comments
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Sustainability-1714643)
The authors appreciate the reviewers, and the editor for their constructive comments and suggestions. Please see our point-by-point response to the comments. The changes in the manuscript are shown in red text.
Point 1: The paper describes experimental research that is performed and described adequately. The results are mainly in line with the general expectations and do not deliver new insights. So the novelty and originality is rather as well as the contribution to scientific development. In this form I am not able to advise acceptance of the paper. I would like to offer some suggestions to the authors in which way the paper could be improved. The goal of the paper is not defined explicitly. The authors state "The goal of these green roof field experiments was to quantify the contribution of the design components of a green roof system to the quantity and quality of stormwater runoff during the rainy season." But considering the conclusion (the last line of the abstract) " These results suggest that green roofs may be installed to enhance stormwater runoff quantity and quality. " we do not see a quantitative conclusion derived from the experiment. So my first suggestion would be to define explicitly a clear research goal or research hypothesis and to validate this based on the experiments. Defining the research goal the authors should consider explicitly its originality and its potential contribution to the expansion of scientific knowledge. The present conclusion seems to be fully in line with the present insights and does not really contribute to an increase of scientific understanding.
Response 1: The authors appriciate the reviewer’s insights. Following the reviewer’s comments, the title and abstract (lines 12-18) have been modified to clarify the main purpose of the current study. This study was conducted to determine the effct of substrate depth and vegetation of green roofs on runoff and phytoremediation under heavy rain. In addition, Introduction section (lines 70-79) has also been added to reflect this main purpose. We hope that our revised paper is improved by responding to the reviewer’s comments.
Point 2: A potential increase of understanding could be found in the analysis dynamic quantitative behaviour of green roof systems. The experimental findings could be used fruitfully to gain more insight in the dynamic behaviour. Understanding the dynamic behavior is important to consider applications of green roofs under several climatological conditions. The study is performed under Korean conditions. The authors should discuss the representativeness of a Korean case study for general applicability of the conclusions of the study.
Response 2: We would like to thank the reviewer for insightful comments. To indicate the represetativeness and general applicability of this study, the relevant climatic conditions of the current study have been discussed in the Introduction section (lines 75-79) and Conclusions section (lines 292-301).
→ We believe the current study provides useful data to determine the rainfall performance of extensive or intensive green roofs in temperate and monsoon climates, where heavy rainfall is concentrated in a specific season. This study results encourage the adoption of green roofs as a best management practices (BMP), including improving the urban environment. (lines 75-79)
→ These results underscore the importance of substrate depth in improving runoff retention over vegetation. Additionally, our research has shown that vegetated green roofs neutralize acid rain to stabilizing pH, and effectively reducing heavy metals in runoff. In particular, the heavy metal removal capability of the vegetated green roofs can be implemented to pollutant sinks in cities with a temperate and monsoon climate, where heavy rainfall is concentrated in a specific season. Nevertheless, these results are not sufficient to explain the dynamic quantitative behavior of green roofs systems under several climatological and hydrological application of green roofs. Therefore, further investigation of long-term monitoring field experiments on substrate moisture dynamics, evapotranspiration and runoff processes of green roofs is needed. (lines 292-301)
In addition, we have described detailed informantion on Korean climate in the Materials and Methods section. (lines 85-89)
→ The climate of Korea is generally a humid continental climate (hot-humid summers, cool-dry winters). The annual precipitation is 1,100 ~ 1,360 mm, and 50% of the total rainfall is concentrated in summer from June to August, and a rather dry climate in spring, autumn and winter from September to May [14]. (lines 85-89)
Reviewer 2 Report
Dear authors,
Congratulations for sharing with us the results of your research. The paper is original and well documented, the methodology used is proper and the results are clearly presented.
Although, I suggest using as references only articles indexed in SCOPUS and WoS/CA/ISI in the last 1-3 years. Also, some of the data used in the research are pretty old and it must be updated. Please, try as much as you can to cite papers already published in this journal, because they are very interesting and well done.
I wish you to continue your research in this field, with many great results.
Best regards,
EG
Author Response
Response to Reviewer 2 Comments
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Sustainability-1714643)
The authors appreciate the reviewers, and the editor for their constructive comments and suggestions. Please see our point-by-point response to the comments. The changes in the manuscript are shown in red text.
Point 1: Congratulations for sharing with us the results of your research. The paper is original and well documented, the methodology used is proper and the results are clearly presented. Although, I suggest using as references only articles indexed in SCOPUS and WoS/CA/ISI in the last 1-3 years. Also, some of the data used in the research are pretty old and it must be updated. Please, try as much as you can to cite papers already published in this journal, because they are very interesting and well done. I wish you to continue your research in this field, with many great results.
Response 1: The authors appreciate the reviewer’s guide. As recommended by the reviewer, references from the last 1-3 years have been discussed in the Introduction and Discussion section and cited along with relevant references (now Refs# 14, 37, 38, 39, and 40).
Reviewer 3 Report
· The English language is not adequate with plenty of grammatical mistakes, including the title and abstract
· Abstract needs rewriting. The authors mention the rainy season. When is precisely the rainy season, and in which region or part of the world?
· The concluding sentence in the abstract does not align with the findings.
· Major grammatical mistakes in the introduction section (difficult to read). I would suggest the paper be rewritten by a native English speaker or someone who has previous publications in English.
· The authors talk about water harvesting through green roofs. This is a different environmental service from stormwater management. It is important not to mix terminology.
· The introduction is too short – at least two more paragraphs are needed.
· While the authors do highlight some factual information about what would affect green roof performance, they do not give examples from the literature. Any percentages of retention or pollutant concentrations in the previous studies?
· The objective of the research is mentioned in the introduction. However, the rainy season is a vague term. Where was the study performed? What was the monitoring period (in month-year)?
· The rainy season is referred to (June, July, and August) in the methodology. Is this really the rainy season in the region? Why not continue the monitoring in September, October and November and observe any seasonal trends? Since the paper looks at the influence of design variables (substrate depth and vegetation), these two are subjected to seasonal variations.
· Line 115: Equations used should be outlined and numbered appropriately as per the journal’s requirements. They cannot be included within the paragraph.
· Line 134: the authors classify the results based on the early, mid, and late rainy season. I understand that these are referred to as June, July, and August. I find it unnecessary to view the results through this lens. It is unlikely that you will observe significant differences between these months since they follow each other with minimal climatic differences. However, what would be helpful, is to talk about the different precipitation trends received each month. This will allow you to justify the obtained results better.
· Figure 3b is adequate and makes sense, but Figure 3a is not meaningful
· Studying stormwater quantity of green roofs cannot be understood by only investigating the precipitation and discharge quantities. That being said, precipitation intensity is a major influencing factor. The antecedent dry period is another important factor since retention is restored during long ADP. I suggest you talk about these when describing the hydrologic performance and aim to discuss the result on a per-event basis.
· The footer of Table 2 is too lengthy. Abbreviations used to describe different plots can be written once at the beginning of the paper, and authors can refer later throughout the article.
· In both paragraphs (water quantity and quality, I did not see any reflection on literature findings. Since this is a research article, a significant component is to reflect on results from previous studies.
· There were some good descriptions of the water quality observations. However, comparing vegetated versus unvegetated plots requires you to talk a little more about your types of vegetation. Indeed, the literature does not show that vegetation has an enormous impact on hydrologic performance, but they affect water quality.
· Figures 4 and 5 are too small to read. Please readjust the figure.
· I can see a reflection on the literature in the Discussion section, but the discussion is too short, given your results.
· The paper needs more thorough discissions and restructuring.
Author Response
Response to Reviewer 3 Comments
Title: Effects of Substrate Depth and Vegetation of Green Roofs on Runoff and Phytoremediation under Heavy Rain (MS ID: Sustainability-1714643)
The authors appreciate the reviewers, and the editor for their constructive comments and suggestions. Please see our point-by-point response to the comments. The changes in the manuscript are shown in red text.
Point 1: The English language is not adequate with plenty of grammatical mistakes, including the title and abstract
Response 1: The authors appriciate the reviewer’s comment. Grammar errors have been corrected throughout the manuscript and edited by a native speaker.
Point 2: Abstract needs rewriting. The authors mention the rainy season. When is precisely the rainy season, and in which region or part of the world?
Response 2: The authors appreciate the reviewer’s insight. To indicate the represetativeness and general applicability of this study, the relevant climatic conditions of the current study have been discussed in the Introduction section (lines 75-79) and Conclusions section (lines 292-301). In addition, we have described detailed informantion on Korean climate to the Materials and Methods section (lines 85-91).
→ We believe the current study provides useful data to determine the rainfall performance of extensive or intensive green roofs in temperate and monsoon climates, where heavy rainfall is concentrated in a specific season. This study results encourage the adoption of green roofs as a best management practices (BMP), including improving the urban environment. (lines 75-79)
→ These results underscore the importance of substrate depth in improving runoff retention over vegetation. Additionally, our research has shown that vegetated green roofs neutralize acid rain to stabilizing pH, and effectively reducing heavy metals in runoff. In particular, the heavy metal removal capability of the vegetated green roofs can be implemented to pollutant sinks in cities with a temperate and monsoon climate, where heavy rainfall is concentrated in a specific season. Nevertheless, these results are not sufficient to explain the dynamic quantitative behavior of green roofs systems under several climatological and hydrological application of green roofs. Therefore, further investigation of long-term monitoring field experiments on substrate moisture dynamics, evapotranspiration and runoff processes of green roofs is needed. (lines 292-301)
→ The climate of Korea is generally a humid continental climate (hot-humid summers, cool-dry winters). The annual precipitation is 1,100 ~ 1,360 mm, and 50% of the total rainfall is concentrated in summer from June to August, and a rather dry climate in spring, autumn and winter from September to May [14]. Although the antecedent dry weather period (ADWP) is also considered a major factor influencing the rainfall performance of the green roofs, this study period was chosen as summer (June ~ August) to facilitate runoff sample collection. (lines 85-91)
Point 3: The concluding sentence in the abstract does not align with the findings.
Response 3: We would like to thank the reviewer for insightful comments. Conclusion based on our findings have been added to the Abstract section (Lines 26-29).
→ These results suggest that as the rainfall intensity increase, the depth of the substrate is more important than vegetation, while the vegetation neutralizes acid rain to stabilize the pH and effectively reduce the heavy metals in the runoff.
Point 4: Major grammatical mistakes in the introduction section (difficult to read). I would suggest the paper be rewritten by a native English speaker or someone who has previous publications in English.
Response 4: Grammatical errors were corrected throughout the manuscript and reviewed by a native speaker.
Point 5: The authors talk about water harvesting through green roofs. This is a different environmental service from stormwater management. It is important not to mix terminology.
Response 5: The authors appreciate the reviewer’s thorough comments. Throughout the manuscript, terminology has been revised to clearly reflect the content.
Point 6: The introduction is too short – at least two more paragraphs are needed.
Response 6: In response to the comments of the reviewer, the Introduction section has been modified to account for gaps in knowledge about green roofs runoff and to better reflect the main objective of the current study.
Point 7: While the authors do highlight some factual information about what would affect green roof performance, they do not give examples from the literature. Any percentages of retention or pollutant concentrations in the previous studies?
Response 7: Based on the reviewer’s comments, the results of the previous studies have been described in the Discussion section (lines 212-220, 223-236, 244-261, 268-276) and related references have been added. (Refs # 14, 37, 38, 39, 40, and 41)
Point 8: The objective of the research is mentioned in the introduction. However, the rainy season is a vague term. Where was the study performed? What was the monitoring period (in month-year)? The rainy season is referred to (June, July, and August) in the methodology. Is this really the rainy season in the region? Why not continue the monitoring in September, October and November and observe any seasonal trends? Since the paper looks at the influence of design variables (substrate depth and vegetation), these two are subjected to seasonal variations.
Response 8: The authors appreciate the reviewer’s attentive comments. As suggested by the reviewer, the term ‘the rainy season’ has instead been changed to ‘rainfall intensity’, throughout the manuscript. The monitoring period and rainfall characteristics of this study site has been added in Lines 83-91 as follows:
→ Field experiments were conducted on the rooftop-platform of Konkuk University Complex Practice Building in Chungju, Chungcheongbuk-do, with latitude 35°49'N, and longitude 127°08'E, located in the central part of South Korea. The climate of Korea is generally a humid continental climate (hot-humid summers, cool-dry winters). The annual precipitation is 1,100 ~ 1,360 mm, and 50% of the total rainfall is concentrated in summer from June to August, and a rather dry climate in spring, autumn and winter from September to May [14]. Although the antecedent dry weather period (ADWP) is also considered a major factor influencing the rainfall performance of the green roofs, this study period was chosen as summer (June ~ August) to facilitate runoff sample collection.
Point 9: Line 115: Equations used should be outlined and numbered appropriately as per the journal’s requirements. They cannot be included within the paragraph.
Response 9: As the reviewer pointed out, the equation has been modified according to the requirements of the journal (lines 119-121).
Point 10: Line 134: the authors classify the results based on the early, mid, and late rainy season. I understand that these are referred to as June, July, and August. I find it unnecessary to view the results through this lens. It is unlikely that you will observe significant differences between these months since they follow each other with minimal climatic differences. However, what would be helpful, is to talk about the different precipitation trends received each month. This will allow you to justify the obtained results better.
Response 10: The authors appreciate the reviewer’s thorough review. Per reviewer comments, the term ‘the rainy season’ has been changed to ‘rainfall intensity’, throughout the manuscript. It is now stated “June, July, and August” in manuscript to clearly reflect the different rainfall intensity received each month, and described in the Materials and Methods section (lines 91-94) as follows:
→ During this study period, 40 rainfall events were recorded with a total precipitation of 440.2 mm. The monthly rainfall intensity in June, July, and August was approximately 63.3, 92.6, and 284.3 mm respectively, and 9, 14, and 17, for each event.
Point 11: Figure 3b is adequate and makes sense, but Figure 3a is not meaningful
Response 11: Per the reviewer’s comment, Figure 3a has been omitted.
Point 12: Studying stormwater quantity of green roofs cannot be understood by only investigating the precipitation and discharge quantities. That being said, precipitation intensity is a major influencing factor. The antecedent dry period is another important factor since retention is restored during long ADP. I suggest you talk about these when describing the hydrologic performance and aim to discuss the result on a per-event basis.
Response 12: The authors appreciate the reviewer’s constructive comments, As the reviewer suggested, the hydrologic performance characteristices of the study site has been described in the Materials and Methods section (lines 83-94) and relevant references have been added (Ref # 14)
Point 13: The footer of Table 2 is too lengthy. Abbreviations used to describe different plots can be written once at the beginning of the paper, and authors can refer later throughout the article.
Response 13: Per the reviewer’s comment, the footer of Table 2 and 3 have been changed to ‘z, y See Table 1’.
Point 14: In both paragraphs (water quantity and quality, I did not see any reflection on literature findings. Since this is a research article, a significant component is to reflect on results from previous studies.
Response 14: The authors appreciate the reviewer’s knowledge and detailed expantation. As the reviewer guided, previous studies have been discussed to reflect the main purpose and results of the current study in the Introduction section (lines 58-61, 66-72) and Discussion section (lines 212-220, 223-235, 244-261, 268-276) along with relevant References (Refs # 37, 38, 39, 40, and 41).
Point 15: There were some good descriptions of the water quality observations. However, comparing vegetated versus unvegetated plots requires you to talk a little more about your types of vegetation. Indeed, the literature does not show that vegetation has an enormous impact on hydrologic performance, but they affect water quality.
Response 15: The authors appreciate the reviewer’s insight. As the reviewer suggested, types of vegetation in this study has been described in the Discussion section (lines 268-272, 279-280) and relevant references have been added (Ref # 40, 41)
→ Liu et al. (2021) reported the role of plant uptake on runoff pollutants from green roof would be plant species dependent [40]. In this study, Kentucky bluegrass (Poa pratensis) vegetated plots had significantly lower heavy metal concentrations in runoff than non-vegetated plots and controls, similar to those reported by Vijayaraghavan and Joshi (2014) [41]. (lines 268-272)
→ These results suggest that plants can absorb and metabolize atmospheric pollutants during heavy rain as shown in this study. (lines 279-280)
Point 16: Figures 4 and 5 are too small to read. Please readjust the figure.
Response 16: According toer the reviewr’s comment, the old Figure 4 (now Figure 3) and 5 (now Figure 4) have been modified so that they can be seen clearly.
Point 17: I can see a reflection on the literature in the Discussion section, but the discussion is too short, given your results. The paper needs more thorough discissions and restructuring.
Response 17: As the reviewer suggested, the results of the present study were further discussed more intensively (lines 208-210, 236-239, 241-243, 258-260, 268-272, 276-283), with relevant references (Refs # 37, 38, 39, 40, and 41).
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
No supportive review comments because the paper is not understandable.
Author Response
Point 1: No supportive review comments because the paper is not understandable.
Response 1: We are very sorry for the reviewer’s comment that, despite the best efforts of the authors, the paper is not understandable.
Reviewer 3 Report
The revised manuscript is a significant improvement over the original submissions. Earlier comments have been adequately addressed, with two remaining recommendations: 1) a final proofread to eliminate a few grammatical errors, and 2) a slight expansion of the conclusions to include a brief summary of the paper objectives and procedures.
Author Response
Point 1: The revised manuscript is a significant improvement over the original submissions. Earlier comments have been adequately addressed, with two remaining recommendations: 1) a final proofread to eliminate a few grammatical errors,
Response 1: The paper has been significantly improved thanks to the reviewer’s comments. The authors corrected grammatical errors throughout the paper.
Point 2: and 2) a slight expansion of the conclusions to include a brief summary of the paper objectives and procedures.
Response 2: We would like to thank the reviewer for insightful comments. A brief summary of the paper objectives and procedures has been added to the Conclusion section (Lines 288-291).
→ Efficient green roofs in urban areas that experience heavy rainfall during certain periods of time can help mitigate pollutants. In this study, the effects of green roof vegetation and substrate depths (100, 200, 400 mm) according to rainfall intensity on runoff reduction and air pollutant purification was investigated.
Author Response File: Author Response.docx
