Assessing the Retention Capacity of an Experimental Green Roof Prototype

Round 1

Reviewer 1 Report

please see attachment

Comments for author File: Comments.pdf

Author Response

-Reviewer 1

Original Submission

1.1. Recommendation

Major Revision

Comments to Author: Ref. No.: water-663801

Title: Assessing the Retention Capacity of an Experimental Green Roof Prototype Authors: Mariana Silva, Mohammad K. Najjar, Ahmed W. A. Hammad, Assed Haddad, Elaine Vazquez

Response: Thanks for your time in reviewing our manuscript.

Overview and general recommendation:

The aim of the present work is to assess the hydrological behavior in response to very heavy rainfall events of an experimental green roof located at Experimental Center for Environmental Sanitation of UFRJ. According to the authors, the novelty of the research is the analysis of ability of a green roof prototype in rainwater retention and in the reduction of peak flow during rainfall events with high intensities which should encourage the adoption of this technology in urban areas to prevent the risk of flooding. In my opinion, several concerns can be raised about the novelty of the work:

 

The results of the present work where an experimental green roof with an area of 1.78 m² has proved to effectively contribute to the control of stormwater runoff, are not enough to assert that these green infrastructures help to mitigate the negative impact of urban flooding at basin scale because it depends on the case. Indeed, at basin scale, the hydrological performance of green roofs is significantly lower and at most the 35% of runoff reduction can be reached when all the green roofing potential in the basin is covered. Versini, P. A., Ramier, D., Berthier, E., & De Gouvello, B. (2015). Assessment of the hydrological impacts of green roof: From building scale to basin scale. Journal of hydrology, 524, 562-575.

Response: Thanks for this comment. The authors have justified this comment by incorporating the following paragraphs in the Abstract, Introduction and Conclusions in order to delimit the study on the scale of buildings, and emphasize its applicability to the basin scale, considering its reductions. However, the suggested reference has been incorporated into the text.

The added paragraph in the Abstract:

“Thus, the present work aims to analyze the efficiency of the use of the green roof technique in reducing the peak of the flow and the retention capacity, when subjected to heavy rains, at the building scale, and also explores their effects in tropical climatic zones with measurements during the summer and fall.”

The added paragraph in the Introduction:

“At building scale green roof can reduce the hydrological impact of stormwater, these consequences for basin-scale are conditioned by intrinsic properties. Results show that impacts estimated at the roof scale can globally approximate those expected at basin scale for a large set of rainfall events by using a reduction coefficient. At both scales (building and basin), the hydrological impact of the green roof seems also to be related to the specific characteristics of the rainfall event [13].”

And: 

“The work presented herein highlights positive impacts on urban runoff at the building scale, with the use of the green roof. However, green roofs only cannot provide full basin-scale stormwater management, but can be integrated with LID practices using conventional micro drainage structures to increase rainfall-runoff at the source where it is generated.”

The added texts in the conclusion:

 “These results reflect the efficiency of the green roof, at building scale, in the quantitative control of runoff. Whether at the scale of building or basin, green roof appears to significantly impact urban runoff in terms of peak discharge and volume and reinforce the need for incentives by public policies for its use in urban centers, considering as a compensatory drainage technique and the low impact development optics. Indeed, at the basin scale, the hydrological performance of green roofs is significantly lower and at most, 35% of runoff reduction can be reached when all the green roofing potential in the basin is covered [13].”

2.Many authors in time have investigated the capacity of green roof system in reducing the stormwater runoff depending on the characteristics of the rainfall events such as cumulative rainfall, duration and peak intensity. In some of these studies, events with higher intensity than those considered in this study (i.e. 158, 181 and 194 mm/h) have been selected.

Palla, A., Gnecco, I., & Lanza, L. G. (2010). Hydrologic restoration in the urban environment using green roofs. Water, 2(2), 140-154. Stovin, V., Vesuviano, G., & Kasmin, H. (2012). The hydrological performance of a green roof test bed under UK climatic conditions. Journal of hydrology, 414, 148-161.

Response: Thanks for this comment. The authors have removed the issues of rainfall, in the introduction and novelty, with great intensity to avoid the conflict with other publications that present higher intensities on these issues. The added references by the reviewer have been already used in this work, as follows: However, the choice of intensities is justified in Subsection 4.1:

“The adopted precipitations were 110 mm/h and 150 mm/h for tests lasting (30 min). The intensity of 110 mm/h was chosen considering the maximum hourly rainfall recorded by Alert Rio in 2018 [71]. The intensity of 150 mm/h was adopted considering the standard ABNT / NBR 10844 (1989). According to this standard, the duration time and the return period determine the precipitation intensity to be adopted. For terraces and roofs, this same standard recommends the return time (T) of five years and presents the rainfall intensity for several municipalities according to this return time. For Rio de Janeiro, there is also this information for seven different neighborhoods. This work took the values ​​of the two neighborhoods closest to the Ilha do Fundão and made an average, with the resulting =value being 156.5 mm/h.”

3.The prototype itself doesn’t represent an aspect of innovation since expanded clay, sand, peat are commonly used in some commercial solutions. In addition, the kind of vegetation is a discriminating factor only for long-tem analysis.

In conclusion, the manuscript requires significant revision to improve the quality and I’d suggest the authors more stressing the climate condition which represents the real aspect of innovation. A section with the characterization of climate including rainfall and air temperature patterns, should be included in the text.

Response: Thanks for your comment. A description of weather conditions as a relevant factor in this research has been included in the abstract and introduction and has been linked to green roof retention performance, as follows:

The added paragraph in the Abstract:

“Thus, the present work aims to analyze the efficiency of the use of the green roof technique in reducing the peak of the flow and the retention capacity, when subjected to heavy rains, at the building scale, and also explores their effects in tropical climatic zones with measurements during the summer and fall.”

The added and edited paragraphs in the Introduction:

“The use of green roofs, in the context of sustainable urban drainage, still lacks more accurate information on its operation for project design. According to Poë et al [36], the use of this technique has been limited by the lack of a predictive model or a consensus on the expectations of its performance. These variations reflect the particularities of each trial, in which various types of configurations can be established for the prototypes, for example the vegetation type, as well as the different climatic conditions of the places that will influence the retention capacity, the regime of rain and the process of water loss system (evapotranspiration) {37].

Regarding the vegetation layer, the hydrological behavior of the green roof depends on the interception, retention and transpiration capacity of the plant [38, 39]. Collischonn and Dornelles [40] Collischonn and Dornelles [40] indicate that the estimated values for interception losses are from 5% to 10% of annual precipitation for meadows and about 25% of annual precipitation for thick forests.. Cogliatti-Carvalho [41] present water accumulation values for bromeliads with a range between 15 to 20% and the estimated maximum water volume for tank bromeliads varies between species due to differences in shape and size.

Regarding the regional climatic conditions, they could strongly alter the stormwater performance of green roofs [42]. Kohler [43-45] shows the relationship between climate difference and the retention capacity of green roofs in temperate climates (Berlin, Germany). The percentage of water retained ranges from 50-75% of total annual precipitation, whereas in tropical climates (Rio de Janeiro, Brazil) this percentage is 65%, mainly due to the high rate of evapotranspiration. This variation of retention percentage deserves special attention, according to the authors cited, mainly due to local climate conditions.

Regarding the intensity and duration of rainfall studies show that the ability to retain rainwater by green cover decreases with increasing rainfall intensity and duration [16,46,47]. A typically higher percentage of retention is indeed observed in climate situations characterized by sporadic rains of moderate cumulative volume [48–51]. According to research by Lee et al [26], in the USA, the green roof has a high retention capacity for precipitation with intensities below 20 mm / h. Carter and Rasmussen [52] point out that retention at 32 rainfall events in Greece ranged from 39% to 100%, averaging 78%. Almost all events below 12 mm showed retention above 90%. The literature review revealed the predominance of studies on rainwater retention and runoff studies in the Northern Hemisphere, when green roofs are subject to a temperate climate. In Brazil, the tropical climate predominates and the behavior of green roofs is expected to be differentiated. Considering also that rainfall intensities are higher in the Southern Hemisphere, it is then expected that in tropical countries during heavy rains and recurring summer, the ability to retain rainwater on rooftops will be lower.

In relation to evapotranspiration, the meteorological factors of temperature and wind speed have a great influence and end up affecting the storage capacity of the system [53]. Warm climates have high evapotranspiration rates, so retention capacity can be restored faster, resulting in better storage availability at the start of a rain event. These relationships are complex, making the interpolation of research carried out in other climate regions hard work [35, 54].

In this context, it is observed that the retention performance of green roofs is being affected by multiple variables that can basically be divided into two categories: Climate variables [55,56] and design variables [57,58].

The novelty of this work is in conducting the investigation on a green roof with bromeliad's performance on retention capacity and also explore their effects in tropical climatic zones with measurements during the summer and fall, taking into consideration the rainfall intensities 110 mm/h and 150 mm/h. The work presented herein highlights positive impacts on urban runoff at the building scale, with the use of the green roof. However, only with green roofs cannot provide full basin-scale stormwater management but can be integrated with LID practices with conventional micro drainage structures to increase rainfall-runoff at the source where it is generated.”

Major comments:

One of the weaknesses of the work is the overall structure that seems not very well organized and pretty confusing.

Response: Thanks for this important comment. First, the structure of the introduction has been reorganized to better illustrate the context and relevance of the research. This way the text is clearer so that the reader can understand the objectives and the innovation of this work. Second, the methods and results have been discussed deeply, where Tables have been modified to better illustrate the aims and objectives of this study.

-Page 1, table 1: Write the same information for each reference. For some references, the authors write the kind of roof (intensive or extensive), for some others they reported the measures of the green roofs. Please uniform the table. Which is the meaning of “w” in the sentences “Extensive 16 platforms w”? Can you clarify?

Response: Thanks for your comment. We have edited Table 1, as follows:

Table 1. Average water retention percentages

Reference	Green roof type	Retention range
Metsellar (2012) [20]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong e Jim 2014 [21]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [22]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1,0 m2 with 20cm)	44%
Stovin (2013) [23]	Extensive (20cm)	3,2 to 23%
Ohnuma et al (2014) [24]	Extensive (5cm)	30 to 57%
Lee et al (2015) [25]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [26]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [27]	Extensive (prototype with 12cm)	Average of 51%

-Page 2, table 1: replace {20] with [20]

Response: Sorry for this technical issue. We have corrected in the whole manuscript.

-Page 2, lines from 45 to 47: The sentence in not clear, I suggest to rephrase

Response: Thanks for this comment. We have rephrased this sentence as follows:

 “Green roofs may be able to reduce the generation of runoff from the resumption of hydrological cycle processes (plant interception, evapotranspiration, infiltration and eventually substrate retention) [14, 15].”

- Page 2, lines from 65 to 66: maybe you mean that the hydrological behavior of green roof depends on the interception

Response: Thanks for this comment. We have rephrased this sentence as follows:

“Regarding the vegetation layer, the hydrological behavior of the green roof depends on the interception, retention and transpiration capacity of the plant [38, 39].”

- Page 2, lines 67, 68: Rephrase the sentence. It is confusing and not well presented. I suggest to say: from 5% to 10% of annual precipitation for meadows, about 25% for thick forests...

Response: Thanks for this comment. We have corrected according to the suggestion of the reviewer, as follows:

“Collischonn and Dornelles [40] Collischonn and Dornelles [40] indicate that the estimated values for interception losses are from 5% to 10% of annual precipitation for meadows and about 25% of annual precipitation for thick forests.”

-Page 3, line 94: “obtained via the…and discussion” Missing word?

Response: Thanks for this comment. We have rephrased this sentence as follows:

 “Section 4 presents the experimental testing method on green roof prototype while Section 5 illustrates an analysis of the results and discussions to validate the methodology of this work.”

-Page 4, lines from 114 to 116: The performances of a green roof are affected by many other parameters like characteristics of growing media and of the drainage layer.

Yio, M. H., Stovin, V., Werdin, J., & Vesuviano, G. (2013). Experimental analysis of green roof substrate detention characteristics. Water Science and Technology, 68(7), 1477-1486. Baryła, A., Karczmarczyk, A., & Bus, A. (2018). Role of substrates used for green roofs in limiting rainwater runoff. Journal of Ecological Engineering, 19(5).

Response: Thanks for this comment. We have corrected this sentence according to the reviewer and added the suggested references, as follows:

“The hydrological response of roofs is also influenced by the function of its configuration, with the substrate – or growing media [64] and with the combination of drainage and vegetation layers [65].”

-Page 6 line 170: Here the authors write Equation (1) while at line 181 Eq. (1). Please uniform

Response: Sorry for this technical mistake. We have corrected now in the manuscript.

-Sometimes in the text, the authors express the unit of measurement in “m” and other times in “cm”. Please uniform the text

Response: Thanks for this comment. We have corrected this issue in the whole manuscript using “cm”.

-Page 12, line 376: would you like to say from 08/02/2017 to 07/11/2017? Here you write 07/11/2017 and in Table 4 11/07/2017. Correct the wrong data in the whole text (i.e. page 17, line 518)

Response: Thanks for your comment. We have corrected the dates in the whole manuscript as follows:

In Section 5:

“The campaign of experimental trials that this research deals with was carried out from 02/08/2017 to 07/11/2017”

In Table 5:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
1	06/06/17	116,9	105,2	42,3	0,0585	0,0271	0,41	0,46
2	06/13/17	116,4	104,8	27,2	0,0582	0,0255	0,27	0,44
3	06/20/17	115,4	103,9	23,3	0,0577	0,0280	0,23	0,49
4	06/27/17	113,3	102,0	34,2	0,0567	0,0197	0,34	0,35
5	07/04/17	111,7	100,5	30,9	0,0559	0,0181	0,31	0,32
6	07/11/17	120,8	108,7	36,4	0,0604	0,0222	0,34	0,37
Medium	-	115,8	104,2	32,4	0,0579	0,0234	0,32	0,41

In Table 6:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
7	06/06/17	144,7	130,2	16,8	0,0724	0,0099	0,13	0,14
8	06/13/17	147,0	132,3	28,2	0,0720	0,0148	0,22	0,21
9	06/20/17	147,8	133,0	26,6	0,0739	0,0148	0,20	0,20
10	06/27/17	142,5	128,3	17,9	0,0713	0,0107	0,14	0,15
11	07/04/17	148,0	133,2	23,8	0,0740	0,0132	0,18	0,18
12	07/11/17	142,3	128,1	22,8	0,0712	0,0164	0,18	0,23
Medium	-	145,4	130,9	22,7	0,0725	0,0133	0,18	0,19

In Section 6:

“The experimental trials campaign that this research deals with was carried out from 02/08/2017 to 07/11/2017”

-Page 12, line 380: What means (x)?

Response: Sorry for this technical mistake. We have corrected now in the manuscript as follows:

“Direct measurements - rain intensity, number of days without rain, accumulated Precipitation in 24 h (mm) and in 96 h (mm) and runoff time;”

 

- Sometimes in the text, the authors use the comma as decimal separator and other times the dot.

Response: Sorry for this technical mistake. Correction was made throughout the text using the default of “,” for decimal separator of numeric values.

Please uniform the text -Table 3: 08/12/2017 or 08/02/2017?

Response: Thanks for your comment. We have corrected this issue in Table 3 and Table 4 considering the format as month / day / year, as follows:

In Table 3:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
1	02/08/17	116,9	0	6,2	6,2	7
2	02/15/17	116,4	7	0,0	0,0	8
3	02/21/17	115,4	6	0,0	0,0	8
4	03/07/17	113,3	0	4,6	7,2	4
5	03/14/17	111,7	0	17,2	17,2	5
6	03/20/17	120,8	0	26,8	40,4	5
Medium Value	-	115,8	-	-	-	6,2

 

In Table 4:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
7	06/06/17	144,7	14	0,0	0,0	6
8	06/13/17	147,0	4	0,0	3,0	3
9	06/20/17	147,8	0	4,2	4,2	6
10	06/27/17	142,5	4	0,0	4,0	5
11	07/04/17	148,0	1	0,4	10,6	4
12	07/11/17	142,3	7	0,0	0,0	6
Medium Value	-	145,4	-	-	-	5

 

- Sometimes in the text, the authors use “at al.” and other times ”at al”. Please uniform the text

Response: Sorry for this technical mistake. We have corrected now in the new manuscript.

-Page 14: In captions of Figures 8 and 9 the authors write “Test 04” and “Test 07” while in the headings of the Figure they respectively write “test 05” and “test 010”.

Response: Thank you for your comment. We have corrected this technical mistake in Figure 8 and Figure 9 in the new manuscript, as follows:

“The value of the maximum prototype output flow ( ), measured in the Rain Box, was obtained from the analysis of the response hydrograms obtained for each test performed, being in these examples the values of 0,0197 for the Test E- 05 - I = 111,7 mm/h and 0,0099 for Test E-010 - I = 142.5 mm/h.

Figure 8. Measured and calculated hydrogram - Test E 05 - I = 111.7 mm/h.

 

Figure 9. Measured and calculated hydrogram - test E 10 - I = 142.5 mm/h.”

I recommend using an English Language Editing Service. I have detected some errors in the text, i.e.:

Response: Thanks for this important comment. We have used an English Language Editing Service to answer the errors detected by the reviewer as follows:

-Page 1, table 1: “55 a 75%” or “55 to 75%”?

We have corrected this issue in Table 1:

Reference	Green roof type	Retention range
Metsellar 2012 [21]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong e Jim 2014 [22]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [23]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1,0 m2 with 20cm)	44%
Stovin (2013) [24]	Extensive (20cm)	3,2 to 23%
Ohnuma et al (2014) [25]	Extensive (5cm)	30 to 57%
Lee et al (2015) [26]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [27]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [28]	Extensive (prototype with 12cm)	Average of 51%

-Page 3, line 69: replace “in the range of 15 to 20%” with “range between 15 and 20%”

Response: This sentence has been corrected in the new manuscript according to the suggestion of the reviewer:

“Cogliatti-Carvalho [41] present water accumulation values for bromeliads with a range between 15 and 20%”

- Page 3, line 102: associate or associated?

Response: The sentence has been corrected now as follows:

“the most common classification of green roofs is that associated with a kind of “size””

-Page 10, line 301: “wide” and “long” or “width” and “length”?

Response: The sentence has been corrected now as follows:

“The area of ​​the experimental plot, which receives the precipitation, is delimited by two rectangular metallic plates of 90 cm width and 100 cm length each, totaling 18000 cm² of usable area (collected area).”

-Page 13, line 396: “provided” or “had”?

Response: The sentence has been corrected now as follows:

“where it was raining for less than six days, the roof provided an initial flow delay of 8 minutes.”

-Page 13, line 395: “tests 2 and 3” or “in the tests 2 and 3”?

Response: The sentence has been corrected now as follows:

“It can be realized in Table 3 that in tests 2 and 3, where it was raining for less than six days,”

Furthermore, a general review has been done through the whole manuscript and some minor corrections were conducted in order to enhance the English Language.

Minor comments:

Response: Thanks for these comments. We have answered as follows:

-Page 2, table 1: Please replace Metsellar 2012 with Metsellar (2012)

Response: done.

-Page 2, table2: here the authors write “Gregoire” while in the references “Greogorie”; please replace 2011 with (2011)

Response: done.

-Page 5, lines from 141 to 146: the line spacing is different from the rest of the text

Response: done.

- Page 6, line 155: remove “)”

Response: done.

- Page 7, line 199: “oncircular” or “on circular”?

Response: done.

- Page 8, line 222: revove “(” corrigido

Response: done.

- Page 10, lines 301, 311 and 312: Remove the brackets from 0.90m ,1.0m, 1.80 m2 , 19.2 l, 27.0 l

Response: done.

-Page 11, lines 343, 344: write “i” and “f” as subscripts

Response: done.

-Page 11, line 357: write precipitated as subscript

Response: done.

-Page 16, line 491: delete the dot in “20 min.”

Response: done.

-Pag 16, line 492: Write “Lee at al.”

Response: corrected for the whole manuscript.

-pag 17, line 520: delete “.January”

Response: done.

 

-Reviewer 2

The study “Assessing the Retention Capacity of an Experimental Green Roof Prototype ” focused Experimental analysis of green roof prototype at CESA-UFRJ  and use in Brazil tropical climate with native species Bromeliads. The topic of the manuscript is very up to date and the authors had a good idea for a research project. The subject is relevant, the analytical methodologies are adequate and the volume of data seems to be enough for publication. Methodology is mostly well explained. I have no hesitation in recommending publication following minor revision.

Response: Thanks for your time in reviewing our manuscript.

Specific comments follow:

Unify units, Line 155,

Response: Thanks for this comment. We have corrected and unified the units in the whole manuscript.

Table 1 Use metric units throughout manuscript.

Response: Thanks for your comment. We have corrected this issue in Table 1 as follows:

Reference	Green roof type	Retention range
Metsellar 2012 [21]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong e Jim 2014 [22]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [23]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1,0 m2 with 20cm)	44%
Stovin (2013) [24]	Extensive (20cm)	3,2 to 23%
Ohnuma et al (2014) [25]	Extensive (5cm)	30 to 57%
Lee et al (2015) [26]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [27]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [28]	Extensive (prototype with 12cm)	Average of 51%

Correct 0.0,

Response: Sorry for this mistake. We have corrected this issue in Table 3 and Table 4 as follows:

Table 3. Direct results of experiments for rainfall of I (average) = 115,8 mm/h.

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
1	02/08/17	116,9	0	6,2	6,2	7
2	02/15/17	116,4	7	0,0	0,0	8
3	02/21/17	115,4	6	0,0	0,0	8
4	03/07/17	113,3	0	4,6	7,2	4
5	03/14/17	111,7	0	17,2	17,2	5
6	03/20/17	120,8	0	26,8	40,4	5
Medium Value	-	115,8	-	-	-	6,2

Table 4. Direct results for rainfall of I (average) = 145,4 mm/h.

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
7	06/06/17	144,7	14	0,0	0,0	6
8	06/13/17	147,0	4	0,0	3,0	3
9	06/20/17	147,8	0	4,2	4,2	6
10	06/27/17	142,5	4	0,0	4,0	5
11	07/04/17	148,0	1	0,4	10,6	4
12	07/11/17	142,3	7	0,0	0,0	6
Medium Value	-	145,4	-	-	-	5

Table: 3, 4, 5, 6. If the campaign of experimental trials was carried out from 08/12/2017 to 07/11/2017 (Page: 376, 518) incorrect date in Table 3.

Response: Thanks for this comment. We have corrected the date in the whole manuscript, considering the format as month / day / year, and confirming that the experimental trials campaign that this research deals with was carried out from 02/08/2017 to 07/11/2017.

Correction of date in Table 3:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
1	02/08/17	116,9	0	6,2	6,2	7
2	02/15/17	116,4	7	0,0	0,0	8
3	02/21/17	115,4	6	0,0	0,0	8
4	03/07/17	113,3	0	4,6	7,2	4
5	03/14/17	111,7	0	17,2	17,2	5
6	03/20/17	120,8	0	26,8	40,4	5
Medium Value	-	115,8	-	-	-	6,2

Correction of date in Table 4:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
7	06/06/17	144,7	14	0,0	0,0	6
8	06/13/17	147,0	4	0,0	3,0	3
9	06/20/17	147,8	0	4,2	4,2	6
10	06/27/17	142,5	4	0,0	4,0	5
11	07/04/17	148,0	1	0,4	10,6	4
12	07/11/17	142,3	7	0,0	0,0	6
Medium Value	-	145,4	-	-	-	5

Correction of date in Table 5:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
1	06/06/17	116,9	105,2	42,3	0,0585	0,0271	0,41	0,46
2	06/13/17	116,4	104,8	27,2	0,0582	0,0255	0,27	0,44
3	06/20/17	115,4	103,9	23,3	0,0577	0,0280	0,23	0,49
4	06/27/17	113,3	102,0	34,2	0,0567	0,0197	0,34	0,35
5	07/04/17	111,7	100,5	30,9	0,0559	0,0181	0,31	0,32
6	07/11/17	120,8	108,7	36,4	0,0604	0,0222	0,34	0,37
Medium	-	115,8	104,2	32,4	0,0579	0,0234	0,32	0,41

Correction of date in Table 6:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
7	06/06/17	144,7	130,2	16,8	0,0724	0,0099	0,13	0,14
8	06/13/17	147,0	132,3	28,2	0,0720	0,0148	0,22	0,21
9	06/20/17	147,8	133,0	26,6	0,0739	0,0148	0,20	0,20
10	06/27/17	142,5	128,3	17,9	0,0713	0,0107	0,14	0,15
11	07/04/17	148,0	133,2	23,8	0,0740	0,0132	0,18	0,18
12	07/11/17	142,3	128,1	22,8	0,0712	0,0164	0,18	0,23
Medium	-	145,4	130,9	22,7	0,0725	0,0133	0,18	0,19

The aim, range and results were clearly defined and demonstrate a good scientific knowledge of the issues being discussed. The work contains appropriate testing methods and analyses of results.

Response: Thank you again for reviewing our manuscript.

 

Author Response File: Author Response.docx

Reviewer 2 Report

The study “Assessing the Retention Capacity of an Experimental Green Roof Prototype ” focused Experimental analysis of green roof prototype at CESA-UFRJ  and use in Brazil tropical climate with native species Bromeliads. The topic of the manuscript is very up to date and the authors had a good idea for a research project. The subject is relevant, the analytical methodologies are adequate and the volume of data seems to be enough for publication. Methodology is mostly well explained. I have no hesitation in recommending publication following minor revision.

Specific comments follow:

Unify units, Line 155, Table 1 Use metric units throughout manuscript. Correct 0.0, Table: 3, 4, 5, 6. If the campaign of experimental trials was carried out from 08/12/2017 to 07/11/2017 (Page: 376, 518) incorrect date in Table 3.

The aim, range and results were clearly defined and demonstrate a good scientific knowledge of the issues being discussed. The work contains appropriate testing methods and analyses of results.

Author Response

-Reviewer 2

The study “Assessing the Retention Capacity of an Experimental Green Roof Prototype ” focused Experimental analysis of green roof prototype at CESA-UFRJ  and use in Brazil tropical climate with native species Bromeliads. The topic of the manuscript is very up to date and the authors had a good idea for a research project. The subject is relevant, the analytical methodologies are adequate and the volume of data seems to be enough for publication. Methodology is mostly well explained. I have no hesitation in recommending publication following minor revision.

Response: Thanks for your time in reviewing our manuscript.

Specific comments follow:

Unify units, Line 155,

Response: Thanks for this comment. We have corrected and unified the units in the whole manuscript.

Table 1 Use metric units throughout manuscript.

Response: Thanks for your comment. We have corrected this issue in Table 1 as follows:

Reference	Green roof type	Retention range
Metsellar 2012 [21]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong e Jim 2014 [22]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [23]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1,0 m2 with 20cm)	44%
Stovin (2013) [24]	Extensive (20cm)	3,2 to 23%
Ohnuma et al (2014) [25]	Extensive (5cm)	30 to 57%
Lee et al (2015) [26]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [27]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [28]	Extensive (prototype with 12cm)	Average of 51%

Correct 0.0,

Response: Sorry for this mistake. We have corrected this issue in Table 3 and Table 4 as follows:

Table 3. Direct results of experiments for rainfall of I (average) = 115,8 mm/h.

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
1	02/08/17	116,9	0	6,2	6,2	7
2	02/15/17	116,4	7	0,0	0,0	8
3	02/21/17	115,4	6	0,0	0,0	8
4	03/07/17	113,3	0	4,6	7,2	4
5	03/14/17	111,7	0	17,2	17,2	5
6	03/20/17	120,8	0	26,8	40,4	5
Medium Value	-	115,8	-	-	-	6,2

Table 4. Direct results for rainfall of I (average) = 145,4 mm/h.

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
7	06/06/17	144,7	14	0,0	0,0	6
8	06/13/17	147,0	4	0,0	3,0	3
9	06/20/17	147,8	0	4,2	4,2	6
10	06/27/17	142,5	4	0,0	4,0	5
11	07/04/17	148,0	1	0,4	10,6	4
12	07/11/17	142,3	7	0,0	0,0	6
Medium Value	-	145,4	-	-	-	5

Table: 3, 4, 5, 6. If the campaign of experimental trials was carried out from 08/12/2017 to 07/11/2017 (Page: 376, 518) incorrect date in Table 3.

Response: Thanks for this comment. We have corrected the date in the whole manuscript, considering the format as month / day / year, and confirming that the experimental trials campaign that this research deals with was carried out from 02/08/2017 to 07/11/2017.

Correction of date in Table 3:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
1	02/08/17	116,9	0	6,2	6,2	7
2	02/15/17	116,4	7	0,0	0,0	8
3	02/21/17	115,4	6	0,0	0,0	8
4	03/07/17	113,3	0	4,6	7,2	4
5	03/14/17	111,7	0	17,2	17,2	5
6	03/20/17	120,8	0	26,8	40,4	5
Medium Value	-	115,8	-	-	-	6,2

Correction of date in Table 4:

Test	Date	I (m/h)	days without rain	Accumulated Precipitation. 24 h (mm)	Accumulated Precipitation. 96 h (mm)	T (min) before the outflow begins
7	06/06/17	144,7	14	0,0	0,0	6
8	06/13/17	147,0	4	0,0	3,0	3
9	06/20/17	147,8	0	4,2	4,2	6
10	06/27/17	142,5	4	0,0	4,0	5
11	07/04/17	148,0	1	0,4	10,6	4
12	07/11/17	142,3	7	0,0	0,0	6
Medium Value	-	145,4	-	-	-	5

Correction of date in Table 5:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
1	06/06/17	116,9	105,2	42,3	0,0585	0,0271	0,41	0,46
2	06/13/17	116,4	104,8	27,2	0,0582	0,0255	0,27	0,44
3	06/20/17	115,4	103,9	23,3	0,0577	0,0280	0,23	0,49
4	06/27/17	113,3	102,0	34,2	0,0567	0,0197	0,34	0,35
5	07/04/17	111,7	100,5	30,9	0,0559	0,0181	0,31	0,32
6	07/11/17	120,8	108,7	36,4	0,0604	0,0222	0,34	0,37
Medium	-	115,8	104,2	32,4	0,0579	0,0234	0,32	0,41

Correction of date in Table 6:

Test	Date	I (mm/h)	(l)		(l/s)	(l/s)
7	06/06/17	144,7	130,2	16,8	0,0724	0,0099	0,13	0,14
8	06/13/17	147,0	132,3	28,2	0,0720	0,0148	0,22	0,21
9	06/20/17	147,8	133,0	26,6	0,0739	0,0148	0,20	0,20
10	06/27/17	142,5	128,3	17,9	0,0713	0,0107	0,14	0,15
11	07/04/17	148,0	133,2	23,8	0,0740	0,0132	0,18	0,18
12	07/11/17	142,3	128,1	22,8	0,0712	0,0164	0,18	0,23
Medium	-	145,4	130,9	22,7	0,0725	0,0133	0,18	0,19

The aim, range and results were clearly defined and demonstrate a good scientific knowledge of the issues being discussed. The work contains appropriate testing methods and analyses of results.

Response: Thank you again for reviewing our manuscript.

 

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

see attached file

Comments for author File: Comments.pdf

Author Response

Ms. Cici Hu

Assistant Editor

Journal Water

December 21, 2019

 

Dear Ms. Cici Hu,

 

Manuscript ID: water-663801

Please find attached a revised version of our manuscript, “Assessing the Retention Capacity of an Experimental Green Roof Prototype”, submitted as an Article in Journal Water, after we perform the requested reviews.

The comments on the review form were highly insightful and enabled us to greatly improve the quality of our manuscript. In the following pages are our point-by-point responses to each of the comments of the reviewer. Revisions in the text, below, are shown using yellow highlight for additions. In accordance with the suggestions of the reviewer, we edited Table 1 and Table 2, described the weather data, and added the Figure 8.

We hope that the revisions in the manuscript and our accompanying responses will be sufficient to make our manuscript suitable for publication in Journal Water.

We shall look forward to hearing from you at your earliest convenience.

Yours sincerely,

Mariana Silva, Mohammad K Najjar, Ahmed W A Hammad, Assed Haddad, and Elaine Vazquez

 

 

 

 

 

 

 

 

Responses to the comments from the reviewers on the Review Form:

 

-Reviewer 1

I'm satisfied with the authors corrections, but I still have little suggestion:

Response: Thanks for your time in reviewing our manuscript.

Table1 and Table2: Still missing brackets, Replace Metsellar 2012, Wong e Jim 2014, Gregoire; Clausen 2011 with Metsellar (2012), Wong e Jim (2014), Gregoire; Clausen (2011).

Response: thanks for this comment. We have corrected this issue in Table 1 and Table 2 as follows:

Table 1. Average water retention percentages

Reference	Green roof type	Retention range
Metselaar (2012) [21]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong and Jim (2014) [22]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [23]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1.0 m2 with 20cm)	44%
Stovin (2013) [24]	Extensive (20cm)	3.2 to 23%
Ohnuma et al (2014) [25]	Extensive (5cm)	30 to 57%
Lee et al (2015) [26]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [27]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [28]	Extensive (prototype with 12cm)	Average of 51%
Longobardi et al (2010) [29]	Extensive (two prototypes with 15cm)	above 75% Between 50% 100%
Palla et al (2008) [30]	Extensive (20cm)	Average of 85%

 

Table 2. Runoff reduction percentages

References	Extensive Green Roof	Intensive Green Roof
Oberndorfer et al (2007) [31]	66 to 69%	26 to 100%
Gerardi et al (2014) [20]	57 to 71.7%	-
Rowe (2011) [32]	50 to 60%	-
Gregoire; Clausen (2011) [33]	34 to 69%	-
Mentens et al (2006) [34]	27 to 81%	54%
Hathaway et al (2008) [35]	77 to 88%	54%
Galarza- Molina et al (2014) [36]	38 to 100%	54%
Palla et al (2008) [30]	95%	-

Table 1: replace “Metsellar” with “Metselaar”

Response: Sorry for this technical error. We have corrected now in Table 1.

Table 1: replace “Wong e Jim” with “Wong and Jim”

Response: Sorry for this technical error. We have corrected now in Table 1.

In international documents, i suggest to use dot as decimal separator and not comma

Response: Thanks for this comment. We have followed the suggestion of the reviewer and used dot as decimal separator instead of comma in the whole manuscript.

What about the section with the long term characterization of climate including rainfall and air temperature patterns using figures? As the innovative aspect of the work is the climate too, it is highly recommended.

Response: Thank you for this important comment. We have highlighted the relevance of weather conditions, especially temperature and rainfall information, during the trial period as follows:

The added paragraph in the Introduction:

“According to Kasmin et al [37], full-scale green roof studies show varying levels of rainwater retention as a function of local weather conditions (temperature, previous drought periods and rainfall patterns, rainfall intensity).”

The added subsection in the Experimental Testing Method on Green Roof Prototype Section:

“4.1. Weather data during the collection period

Rainfall Station 32, located at GEORIO headquarters (Campo de São Cristóvão Street, 268 - São Cristóvão), was chosen because it is the closest station to the experiment, just 4.4km away and has complete weather data [75]. The station is managed by the National Institute of Meteorology (INMET), which makes this information available on the Alert Rio website [77]. Weather data, such as accumulated rain, temperature, humidity and wind speed, are measured daily by Station 32 over a 15-minute interval, generating 96 daily sampling points. In order to analyze the influence of the climate of the region, meteorological data from Station 32 (São Cristóvão) were analyzed during the period in which rainwater samples were collected between February and July 2017, as follows: temperature (oC ), instant rain (mm) and cumulative rainfall over 24h and 96h.

In the first rehearsal campaign, February 2017 was especially atypical, with 17.6 mm, while March was wettest, with 109.6 mm. In the second rehearsal campaign, June had 121.8 mm of rain while July had only 13.0 mm. The maximum temperatures values varied significantly, between 38.4^oC and 30.3^oC, due to the high summer temperature and the occurrence of rainfall, which naturally lowers the temperature. On the other hand, the minimum temperature values reflect the night periods. Figure 8 illustrates a graph with total rainfall intensity information for February, March, June and July, as well as the maximum and minimum temperature values for each of these months, respectively.

 

 

Figure 8. Monthly rainfall (mm), maximum temperature (oC) minimum temperature (oC).”

Since your study mainly focus on the climate condition, i suggest to consider the hydrological performances of green roofs in different climates. The retention performances reported in Tables 1 and 2 mainly refer to green roofs in Temperate, Continental and Tropical climates with very few references to Mediterranean climate where many studies exist, among these one of the most recent is: Longobardi, A., D’Ambrosio, R., & Mobilia, M. (2019). Predicting Stormwater Retention Capacity of Green Roofs: An Experimental Study of the Roles of Climate, Substrate Soil Moisture, and Drainage Layer Properties. Sustainability, 11(24), 6956.

Response: Thank you for this comment. We have included two references from studies that carried out a survey of green roof rainwater retention in Mediterranean climate regions, as yellow highlighted in Table 1 and Table 2:

Table 1. Average water retention percentages

Reference	Green roof type	Retention range
Metselaar (2012) [21]	Extensive and Intensive (5, 10, 20, 40, 60 and 80cm)	55 to 75%
Wong and Jim (2014) [22]	Intensive (16 platforms with 40 and 80cm)	Average from 39 to 43%.
Stovin (2010) [23]	Extensive (prototype with 5cm)	Average of 34%
Graceson et al (2013) [12]	Extensive (36 decks 1.0 m2 with 20cm)	44%
Stovin (2013) [24]	Extensive (20cm)	3.2 to 23%
Ohnuma et al (2014) [25]	Extensive (5cm)	30 to 57%
Lee et al (2015) [26]	Extensive (7 pilots with 15 and 20cm)	13 to 34% (15cm) 43 to 61% (20cm)
Carson et al (2013) [27]	Extensive (3 pilots with 5cm)	21 to 34% for rain> 5cm
Palla et al (2010) [28]	Extensive (prototype with 12cm)	Average of 51%
Longobardi et al (2010) [29]	Extensive (two prototypes with 15cm)	above 75% Between 50% 100%
Palla et al (2008) [30]	Extensive (20cm)	Average of 85%

 

Table 2. Runoff reduction percentages

References	Extensive Green Roof	Intensive Green Roof
Oberndorfer et al (2007) [31]	66 to 69%	26 to 100%
Gerardi et al (2014) [20]	57 to 71.7%	-
Rowe (2011) [32]	50 to 60%	-
Gregoire; Clausen (2011) [33]	34 to 69%	-
Mentens et al (2006) [34]	27 to 81%	54%
Hathaway et al (2008) [35]	77 to 88%	54%
Galarza- Molina et al (2014) [36]	38 to 100%	54%
Palla et al (2008) [30]	95%	-

 

 

 

 

 

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

This study analyses the prototype green roof via a Pluviometer. Experimental design methods are used to assess the efficiency of using green roofing technique to reduce the peak flow and the retention capacity, when subjected to very heavy rains as well as encouraging the adoption of compensatory drainage techniques to reduce the risks and damage caused by floods. It is confirmed that this paper has some academic values. However, in order to make this paper more readable and reference value, the authors can refer to the following review opinions for the editing of the paper.

1.Factors such as the plant type, soil type and rainfall pattern (mm/min) of the green roof have a great influence on the "peak flow". This study was conducted in only one type of experiment, and the academic reference value and application reference value were not high. In addition, in the 12 experimental days of this study, the degree of influence by natural rainfall (days without rain, accumulated precipitation within 24 h and 96 h) was not consistent. Therefore, it may also lead to errors in the research results.

2.The resolution of Figure 1 needs to be improved.

3.The text in Figure 4 should be in English.

4.According to Table 2, "days without rain" has a great influence on "T (min) before start of flow". Please explain the reasons for the selection of the six experimental days and explain the representativeness of these six days.

5.It is suggested that this study refer to the experimental planning method of relevant research, re-adjust the experimental content and sampling times (and frequency) to make the research results more useful.

Reviewer 2 Report

Review in attachment.

Best regards,

Reviewer

Comments for author File: Comments.pdf