Investigating the Plant Species and Rainfall Factors on  Stormwater Retention Performance of Extensive Green Roofs in  Malaysia

Information on the influences of native plant species and rainfall characteristics on the stormwater retention performance of extensive green roofs in Malaysia is still scarce. More local data is still required because rainfall and runoff generation processes in tropical environment are very different from the temperate regions. This study is aimed to investigate the stormwater retention performance of native plant species in extensive green roofs with respect to different rainfall characteristics in Malaysia. Two test beds consist of pro-mixing potting soil were vegetated each with different native plant species (Axonopus Compressus (cow grass), Portulaca Grandiflora (sedum) and one test bed with no vegetation (bare ground) was prepared as a control. A total of 22 significant storm events were collected over a 3-month period from March 2016 to May 2016. The rainfall depths for monitored storm events were ranged from 4.5 mm to 63.2 mm and rainfall intensities ranged from 0.5mm/hr to 58.5 mm/hr. The results showed that sedum exhibited higher mean runoff retention percentage than grass which is 75.8% and 70.9%, respectively. Bare soil was the least effective for reducing water runoff with retention percentage of 62.6%. Overall, sedum and grass species provided 90.6% and 88.2% of cumulative rainfall retention in this study. The rainfall depth and intensity are correlated negatively with stormwater retention performance of green roofs. Meanwhile, longer dry weather period are likely to increase the water retention capacity of green roof.

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Factors Affecting Runoff Retention Performance of Extensive Green Roofs

Water ◽

10.3390/w10091217 ◽

2018 ◽

Vol 10 (9) ◽

pp. 1217 ◽

Cited By ~ 11

Author(s):

Yongwei Gong ◽

Dingkun Yin ◽

Xing Fang ◽

Junqi Li

Keyword(s):

Hydraulic Conductivity ◽

Retention Rate ◽

Green Roofs ◽

Retention Performance ◽

Dry Period ◽

Rainfall Events ◽

Rainfall Characteristics ◽

Drainage Layer ◽

Factors Affecting ◽

Extensive Green Roofs

The runoff retention effectiveness of 10 extensive green roof (EGR) modules (100 mm substrate planted Sedum lineare Thunb.) were analyzed in Beijing for 22 rainfall events (2.4–46.4 mm) from 1 July to 30 September 2017. Differences between minimum inter-event dry periods, module scales, substrate hydraulic conductivity and depths, drainage layer types and rainfall characteristics were examined to study their correlation to the retention performance of EGRs. In general, EGRs with lower substrate hydraulic conductivity, deeper substrate and lower rainfall depth had higher runoff retention performance. By comparsion, no siginificant correlation was found between rainfall duration, prior dry period, average rainfall intensity, drainage layer type and EGR runoff retention rate. Analyses of variance (ANOVA) and Tukey tests supported these results. Low or moderate rainfall (<15 mm) may or may not have an effect, but heavy rainfall (>25 mm) definitely affects the EGR retention performance of the next rainfall event.

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Amount of water runoff from different vegetation types on extensive green roofs: Effects of plant species, diversity and plant structure

Landscape and Urban Planning ◽

10.1016/j.landurbplan.2011.11.001 ◽

2012 ◽

Vol 104 (3-4) ◽

pp. 356-363 ◽

Cited By ~ 116

Author(s):

Ayako Nagase ◽

Nigel Dunnett

Keyword(s):

Species Diversity ◽

Plant Species ◽

Green Roofs ◽

Plant Species Diversity ◽

Water Runoff ◽

Vegetation Types ◽

Plant Structure ◽

Extensive Green Roofs

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Introduced and native plant species composition of vacant unmanaged green roofs in New York City

Urban Ecosystems ◽

10.1007/s11252-020-00992-6 ◽

2020 ◽

Vol 23 (6) ◽

pp. 1227-1238

Author(s):

Jason M. Aloisio ◽

Matthew I. Palmer ◽

Amy R. Tuininga ◽

J. D. Lewis

Keyword(s):

New York ◽

New York City ◽

Species Composition ◽

Plant Species ◽

York City ◽

Green Roofs ◽

Plant Species Composition ◽

Native Plant ◽

Native Plant Species

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Performance of Three Different Native Plant Mixtures for Extensive Green Roofs in a Humid Subtropical Climate Context

Water ◽

10.3390/w12123484 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3484 ◽

Cited By ~ 1

Author(s):

Giampaolo Zanin ◽

Lucia Bortolini

Keyword(s):

Canopy Cover ◽

Crop Coefficient ◽

Green Roofs ◽

Subtropical Climate ◽

Native Plant ◽

Mineral Layer ◽

Climate Conditions ◽

Extensive Green Roofs ◽

Stormwater Retention ◽

Vegetation Layer

Most of the services and benefits of green roofs are related to the substrate as well as the vegetation layer. Although plant selection should be made on the basis of green roof typology, morphology, and climate conditions, very often, Sedum species only are used worldwide. However, they do not always guarantee the best performances; hence, it is important to investigate different plant species and their performance in different climate contexts. Herein, an experiment was conducted using three plant mixes (i.e., a Sedum mix, a perennial herbaceous mix, and a suffruticose mix), grown in boxes containing two substrates (a volcanic substrate or a recycled crushed brick substrate) and two drainage/storage layers (a preformed layer or a mineral layer), in factorial combination. The Sedum mix showed a high canopy cover, comparable to or even higher than that of the other mixes, particularly when supplemental irrigation was stopped. However, the actual crop coefficient (Kcact) of the herbaceous and suffruticose mixes was often higher than that of the Sedum mix. The results also showed that both the substrate and the drainage/storage layer may improve Kcact values as a consequence of their capacity for stormwater retention.

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Evapotranspiration Measurement and Estimation of Crop Coefficient for Native Plant Species of Green Roof in the Tropics

Water ◽

10.3390/w13121669 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1669

Author(s):

Ming Fai Chow ◽

Muhammad Fadhlullah Abu Bakar ◽

Jee Khai Wong ◽

Lloyd Ling

Keyword(s):

Soil Moisture ◽

Plant Species ◽

Green Roof ◽

Crop Coefficient ◽

Green Roofs ◽

P Value ◽

Water Retention Capacity ◽

Native Plant ◽

Retention Capacity ◽

Native Plant Species

Extensive green roof is one of the sustainable urban stormwater management alternatives to manage and mitigate the urban surface runoff. In order to implement green roofs more effectively, suitable plant species and substrate components for tropical climate must be identified. The aim of this study is to investigate the evapotranspiration (ET) behaviors in extensive green roofs based on different substrate types and local native plant species. Four green roof test beds containing pro-mixing pot and burn soils were each vegetated with Axonopus Compressus (grass) and Portulaca Grandiflora (sedum). A weather station with soil moisture sensors was installed to measure the weather and soil moisture data. The results showed that the mean ET rates for grass-pot soil, sedum-pot soil, grass-burn soil and sedum-burn soil were 1.32 ± 0.41 mm/day, 2.31 ± 0.72 mm/day, 1.47 ± 0.39 mm/day and 2.31 ± 0.43 mm/day, respectively. It is noted that environmental parameters such as ambient temperature, solar radiation and wind speed showed significantly positive relationship (p value < 0.01) with ET rates of green roofs except relative humidity. The crop coefficients (Ks) for the studied green roof plant species are estimated based on actual and reference evapotranspiration rates. The sedum planted in burn soil showed the highest crop coefficient (0.64), followed by sedum in pot soil (0.62), grass in burn soil (0.39) and grass in pot soils (0.37), respectively. The findings in this study also showed that substrate with better water retention capacity generally improved the Ks values.

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