scholarly journals Factors Affecting Runoff Retention Performance of Extensive Green Roofs

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1217 ◽  
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.

scholarly journals Nutrient Leaching in Extensive Green Roof Substrate Layers With Different Configurations

2021 ◽  
Author(s):  
Chen Xu ◽  
Zaohong Liu ◽  
Guanjun Cai ◽  
Jian Zhan
Keyword(s):  
Green Roofs ◽  
Pollution Source ◽  
Nutrient Leaching ◽  
Rainfall Runoff ◽  
Rainfall Events ◽  
Rainfall Characteristics ◽  
Substrate Layer ◽  
Rainwater Runoff ◽  
The Impact ◽  
Extensive Green Roofs

Abstract Due to substrate layers with different substrate configurations, extensive green roofs (EGRs) exhibit different rainfall runoff retention and pollution interception effects. In the rainfall runoff scouring process, nutrient leaching often occurs in the substrate layer, which becomes a pollution source for rainwater runoff. In this study, six EGR devices with different substrate layer configurations were fabricated. Then, the cumulative leaching quantity (CLQ) and total leaching rate (TLR) of NH4+, TN and TP in the outflow of nine different depth simulated rainfall events under local rainfall characteristics were evaluated and recorded. Furthermore, the impact of different substrate configurations on the pollution interception effects of EGRs for rainfall runoff was studied. Results show that a mixed adsorption substrate in the EGR substrate layer has a more significant rainfall runoff pollution interception capacity than a single adsorption substrate. PVL and PVGL, as EGRs with layered configuration substrate layers, exhibited good NH4+-N interception capacity. The CLQ and TLR of NH4+-N for PVL and PVGL were -114.613 mg and -63.43%, -121.364 mg and -67.16%, respectively. Further, the addition of biochar as a modifier significantly slowed down the substrate layer TP leaching effect and improved the interception effect of NH4+-N and TN. Moreover, although polyacrylamide addition in the substrate layer aggravated the nitrogen leaching phenomenon in the EGRs outflow, but the granular structure substrate layer constructed by it exhibited a significantly inhibited TP leaching effect.

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

2018 ◽  
Vol 7 (3.9) ◽  
pp. 71
Author(s):  
Chow Ming Fai ◽  
Muhammad Fadhlullah Abu Bakar ◽  
Lariyah Mohd Sidek1 Wong Jee Khai
Keyword(s):  
Plant Species ◽  
Green Roofs ◽  
Water Runoff ◽  
Storm Events ◽  
Native Plant ◽  
Retention Performance ◽  
Rainfall Characteristics ◽  
Native Plant Species ◽  
Extensive Green Roofs ◽  
Stormwater Retention

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.  

scholarly journals Vegetation Survival in Green Roofs without Irrigation

2020 ◽  
Author(s):  
Anita Raimondi ◽  
Mariana Marchioni ◽  
Umberto Sanfilippo ◽  
Gianfranco Becciu
Keyword(s):  
Probabilistic Approach ◽  
Green Roofs ◽  
Design Parameters ◽  
Dry Period ◽  
Rainfall Events ◽  
Average Return ◽  
Growing Medium ◽  
A Chain ◽  
Proper Values ◽  
Stormwater Control

The implementation of green roofs as sustainable urban drainage systems provides benefits for stormwater control and the environment and is always more encouraged. In this paper, the estimation of the probability of vegetation survival without irrigation has been proposed as a guide to choose the proper values for the design parameters; in particular the growing medium thickness has been related to the average return interval of the water content at the end of the dry period. Moreover the study represents an improvement of the analytical probabilistic approach since a chain of consecutive rainfall events has been considered, in order to take into account the possibility that the storage capacity is not completely available at the beginning of each event because of the pre-filling from more than one previous rainfall as typically happens for green roofs. Finally, developed equations have been validated by means of their application to two case studies, respectively in northern and southern Italy.

Factors affecting the ability of extensive green roofs to reduce nutrient pollutants in rainfall runoff

2020 ◽  
Vol 732 ◽  
pp. 139248 ◽  
Author(s):  
Yongwei Gong ◽  
Xianwei Zhang ◽  
Junqi Li ◽  
Xing Fang ◽  
Dingkun Yin ◽  
...  
Keyword(s):  
Green Roofs ◽  
Rainfall Runoff ◽  
Factors Affecting ◽  
Extensive Green Roofs

scholarly journals Probabilistic assessment of hydrologic retention performance of green roof considering aleatory and epistemic uncertainties

2020 ◽  
Vol 51 (6) ◽  
pp. 1377-1396
Author(s):  
Lingwan You ◽  
Yeou-Koung Tung ◽  
Chulsang Yoo
Keyword(s):  
Stormwater Management ◽  
Epistemic Uncertainty ◽  
Green Roofs ◽  
Source Control ◽  
Retention Performance ◽  
Rainfall Characteristics ◽  
Retention Ratio ◽  
Urban Stormwater Management ◽  
Substrate Depth ◽  
Unique Relationship

Abstract Green roofs (GRs) are well known for source control of runoff quantity in sustainable urban stormwater management. By considering the inherent randomness of rainfall characteristics, this study derives the probability distribution of rainfall retention ratio and its statistical moments. The distribution function of can be used to establish a unique relationship between target retention ratio , achievable reliability AR, and substrate depth h for the aleatory-based probabilistic (AP) GR design. However, uncertainties of epistemic nature also exist in the AP GR model that makes AR uncertain. In the paper, the treatment of epistemic uncertainty in the AP GR model is presented and implemented for the uncertainty quantification of AR. It is shown that design without considering epistemic uncertainties by the AP GR model yields about 50% confidence of meeting . A procedure is presented to determine the design substrate depth having the stipulated confidence to satisfy and target achievable reliability .

scholarly journals Temperatures and precipitation affect vegetation dynamics on Scandinavian extensive green roofs

2020 ◽  
Author(s):  
Joel Lönnqvist ◽  
Hans Martin Hanslin ◽  
Birgitte Gisvold Johannessen ◽  
Tone Merete Muthanna ◽  
Maria Viklander ◽  
...  
Keyword(s):  
Green Roofs ◽  
Species Traits ◽  
Annual Precipitation ◽  
Weather Data ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Dry Period ◽  
Spontaneous Vegetation ◽  
Successional Stages ◽  
Extensive Green Roofs

AbstractStandard succulent vegetation mixes developed mostly in temperate climates are being increasingly used on green roofs in different climate zones with uncertain outcome regarding vegetation survival and cover. We investigated vegetation on green roofs at nine temperate, cold, and/or wet locations in Norway and Sweden covering wide ranges of latitude, mean annual temperature, annual precipitation, frequencies of freeze-thaw cycles, and longest annual dry period. The vegetation on the roofs were surveyed in two consecutive years, and weather data were compiled from meteorological databases. At all sites we detected a significant decline in species compared to originally intended (planted/sown) species. Both the survival rate and cover of the intended vegetation were positively related to the mean annual temperature. Contrary to a hypothesis, we found that intended vegetation cover was negatively rather than positively related to mean annual precipitation. Conversely, the unintended (spontaneous) vegetation was favoured by high mean annual precipitation and low mean annual temperature, possibly by enabling it to colonize bare patches and outcompete the intended vegetation. When there is high mortality and variation in cover of the intended vegetation, predicting the strength of ecosystem services the vegetation provides on green roofs is difficult. The results highlight the needs for further investigation on species traits and the local factors driving extinction and colonizations in order to improve survivability and ensure a dense vegetation throughout the successional stages of a green roof.

Decoupling factors affecting plant diversity and cover on extensive green roofs

2013 ◽  
Vol 130 ◽  
pp. 297-305 ◽  
Author(s):  
J. Scott MacIvor ◽  
Liat Margolis ◽  
Curtis L. Puncher ◽  
Benjamin J. Carver Matthews
Keyword(s):  
Plant Diversity ◽  
Green Roofs ◽  
Factors Affecting ◽  
Extensive Green Roofs
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