scholarly journals Analysis of the retention capacity of green roofs

2012 ◽  
Vol 16 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Ewa Burszta-Adamiak
Keyword(s):  
Urban Areas ◽  
Soil Surface ◽  
Green Roofs ◽  
Retention Capacity ◽  
Local Conditions ◽  
Rainfall Events ◽  
Runoff Reduction ◽  
Education Centre ◽  
Peak Runoff ◽  
Rain Events

Abstract Green roofs are one of the modern solutions used to achieve sustainable stormwater management in urban areas. These structures are still more often designed for newly constructed buildings in Poland, based on the observations of changes in urban areas that result in the increased sealing of soil surface and thus in the limitation of natural stormwater infiltration and retention sites. In spite of a growing interest in green roofs, the data related to their retention capacity in Polish conditions is still insufficient. This study presents the results of the author’s tests, conducted in the years 2009-2010 on experimental sites located on the roof of the Science and Education Centre building of the University of Environmental and Life Sciences in Wrocław. The aim of these tests was to determine the retention capabilities of green roofs and the runoff delay and peak runoff reduction during rainfall events recorded in local conditions. The results show that green roofs can play a significant role in the reduction of total outflow volume of stormwater falling on their surface. Multi-layered structure of green roofs contribute also to a slowdown in the outflow of stormwater and to reduction in the peak runoff volume in comparison to the maximum recorded intensity of rainfall. Mean retention for 153 analysed rainfall events amounted from 82.5% to 85.7% for green roofs. In the case of rain events up to 1 mm a day, the retention for green roofs reached nearly 100%.

scholarly journals Analysis of Stormwater Retention on Green Roofs / Badania Retencji Wód Opadowych Na Dachach Zielonych

2012 ◽  
Vol 38 (4) ◽  
pp. 3-13 ◽  
Author(s):  
Ewa Burszta-Adamiak
Keyword(s):  
Life Sciences ◽  
Green Roofs ◽  
Retention Capacity ◽  
Runoff Reduction ◽  
Science And Education ◽  
Peak Runoff ◽  
The Impact ◽  
Stormwater Retention ◽  
Maximum Runoff ◽  
Sewage Systems

Abstract This study presents the results of tests conducted in 2009 and 2010 on experimental sites installed on the roof of the Science and Education Building of the Wroclaw University of Environmental and Life Sciences. The aim of the analysis was to determine the retention capacity of green roofs and the runoff delays and peak runoff reduction during rainfall recorded in Wroclaw conditions. The research shows that green roofs allow to reduce the volume of runoff stormwater in comparison to conventional roofs, that they delay the runoff in time and influence the reduction of the maximum runoff intensity, and thus may limit the impact of stormwater on the stormwater drainage and combined sewage systems.

scholarly journals Rainwater retention effect of extensive green roofs monitored under natural rainfall events – a case study in Beijing

2018 ◽  
Vol 49 (6) ◽  
pp. 1773-1787 ◽  
Author(s):  
Yongwei Gong ◽  
Dingkun Yin ◽  
Xing Fang ◽  
Dandan Zhai ◽  
Junqi Li
Keyword(s):  
Green Roofs ◽  
Northern China ◽  
Regression Equations ◽  
Peak Reduction ◽  
Retention Capacity ◽  
Rainfall Events ◽  
Natural Rainfall ◽  
Rainfall Depth ◽  
Reduction Effect ◽  
Peak Runoff

Abstract The rainwater retention and peak flow reduction effect of seven extensive green roof (EGR) modules were studied in Beijing under natural rainfall events from May to September 2015. Monitored EGR modules had a layer of vegetation widely planted in northern China and a substrate layer with a thickness of 20 or 50 or 100 mm. The EGRs effectively retained rainwater, and regression equations of the potential retention capacity as a function of rainfall depth were developed for five EGR modules, which show that generally the capacity decreased as rainfall depth increased. The EGR with Sedum lineare Thunb and 100 mm improved soil had relatively higher average retention capacity (61.8%) than others, but all EGR modules had similar retention for an extraordinary rainfall event of 114.4 mm. For rainfall events less than 15 mm, EGR modules had 100% rainfall retention most of the time. The reduction in peak runoff rate ranged from 30.8% to 85.4%. The EGRs with Sedum lineare Thunb using 20 mm improved soil and 50 mm either pastoral soil or ultra-low weight substrates have similar peak reduction (51.3–58.2%). The EGRs with Sedum lineare Thunb have better rainfall retention and peak reduction than EGRs with Angiospermae or Sedum aizoon L.

scholarly journals Water Resilience by Centipedegrass Green Roof: A Case Study

Buildings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 141 ◽  
Author(s):  
Shuai Hu ◽  
Lijiao Liu ◽  
Junjun Cao ◽  
Nan Chen ◽  
Zhaolong Wang
Keyword(s):  
Soil Moisture ◽  
Green Roof ◽  
Green Roofs ◽  
Saturated Soil ◽  
Water Retention Capacity ◽  
Water Runoff ◽  
Retention Capacity ◽  
Runoff Reduction ◽  
Eremochloa Ophiuroides ◽  
Rain Events

Centipedegrass (Eremochloa ophiuroides) is a low-maintenance turfgrass. The first extensive green roof of centipedegrass was established in TongZhou Civil Squares in 2014. However, storm-water-runoff reduction, water-retention capacity, and plant-water requirements by a centipedegrass green roof has not yet been defined. The soil moisture dynamics, rainwater-retention capacity, runoff reduction, and plant evapotranspiration were investigated by simulated centipedegrass green roof plots, which were constructed in the same manner as the green roofs in TongZhou Civil Squares in 2018. The results showed that the centipedegrass green roof retained 705.54 mm of rainwater, which consisted 47.4% of runoff reduction. The saturated soil moisture was 33.4 ± 0.6%; the excess rainfall over the saturated soil moisture resulted in runoff. The capacity of rainwater retention was negatively related to the soil moisture before rain events and was driven by plant evapotranspiration. Drought symptoms only occurred three times over the course of a year when the soil moisture dropped down to 10.97%. Our results indicate that the rainwater retained in the soil almost met the needs of plant consumption; a further increase of rainwater retention capacity might achieve an irrigation-free design in a centipedegrass green roof.

scholarly journals Addressing the Water–Energy–Food Nexus through Enhanced Green Roof Performance

2021 ◽  
Vol 13 (4) ◽  
pp. 1972
Author(s):  
Jeremy Wright ◽  
Jeremy Lytle ◽  
Devon Santillo ◽  
Luzalen Marcos ◽  
Kristiina Valter Mai
Keyword(s):  
Climate Change ◽  
Performance Optimization ◽  
Urban Areas ◽  
Stormwater Management ◽  
Green Roof ◽  
Green Roofs ◽  
Management Tool ◽  
Contributing Factors ◽  
Rainwater Runoff ◽  
Rain Events

Urban densification and climate change are creating a multitude of issues for cities around the globe. Contributing factors include increased impervious surfaces that result in poor stormwater management, rising urban temperatures, poor air quality, and a lack of available green space. In the context of volatile weather, there are growing concerns regarding the effects of increased intense rainfalls and how they affect highly populated areas. Green roofs are becoming a stormwater management tool, occupying a growing area of urban roof space in many developed cities. In addition to the water-centric approach to the implementation of green roofs, these systems offer a multitude of benefits across the urban water–energy–food nexus. This paper provides insight to green roof systems available that can be utilized as tools to mitigate the effects of climate change in urbanized areas. A new array of green roof testing modules is presented along with research methods employed to address current issues related to food, energy and water performance optimization. Rainwater runoff after three rain events was observed to be reduced commensurate with the presence of a blue roof retention membrane in the testbed, the growing media depth and type, as well as the productive nature of the plants in the testbed. Preliminary observations indicate that more productive green roof systems may have increasingly positive benefits across the water–energy–food nexus in dense urban areas that are vulnerable to climate disruption.

Fractal tools to analyse the spatial variability of Blue Green Solutions in an urban area

2021 ◽  
Author(s):  
Gustavo Otranto-da-Silva
Keyword(s):  
Urban Area ◽  
Urban Areas ◽  
Model Performance ◽  
Green Roofs ◽  
Initial State ◽  
Runoff Reduction ◽  
Build Environment ◽  
Input Variables ◽  
Neighborhood Scale ◽  
Design Options

<div> <p><span>A city's response to a rainfall event depends not only on the rainfall spatial-temporal variability, but also on the spatial distribution and the initial state of its Blue Green Solutions (BGS), such as green roofs. They hold back runoff and may prove being critically important elements of blue-green build environment.</span></p> </div><div> <p><span>The aim of this study was first to adapt the existing hydrological model to the urban area of Melun (France), to validate it and then to assess numerically an optimal configuration of green roofs to mitigate pluvial floods for particularly vulnerable areas. </span><span>The main focus was put on the investigation of interactions between rainfall space-time scales and resulting hydrological response over fine scales, all being controlled by the performance assessment of BGS. </span></p> </div><div> <p><span>This presentation will particularly illustrate how fractal </span><span>tools were used to:</span></p> </div><div> <p><span>- highlight the scale dependency of the input variables and its e</span><span>ff</span><span>ects on gridded model performance;</span></p> </div><div> <p><span>- explore, </span><span>analyse</span><span> and represent the influence of BGS location and configuration on the mitigation of runoff associated with short-duration, high-intensity rainfall at neighborhood scale;</span></p> </div><div> <p><span> - identify the urban design options that maximize the potential for runoff reduction</span><span>. </span></p> </div><div> <p><span>In overall, these </span><span>results may serve as a referential </span><span>for upscaling the optimized implementation of BGS in urban areas, by considering other urban infrastructures and their interactions.</span></p> </div>

scholarly journals Meta-Analysis of Storm Water Impacts in Urbanized Cities Including Runoff Control and Mitigation Strategies

2018 ◽  
Vol 11 (6) ◽  
pp. 27 ◽  
Author(s):  
Pengfei Zhang ◽  
Samuel T. Ariaratnam
Keyword(s):  
Urban Areas ◽  
Meta Analysis ◽  
Mitigation Strategies ◽  
Storm Water ◽  
Water Runoff ◽  
Land Resources ◽  
Drainage Systems ◽  
Runoff Reduction ◽  
Natural Land ◽  
Rain Events

The rate of urbanization has been impacted by global economic growth. A strong economy results in more people moving to already crowded urban centers to take advantage of increased employment opportunities often resulting in sprawling of the urban area. More natural land resources are being exploited to accommodate these anthropogenic activities. Subsequently, numerous natural land resources such as green areas or porous soil, which are less flood-prone and more permeable are being converted into buildings, parking lots, roads and underground utilities that are less permeable to storm water runoff from rain events. With the diminishing of the natural landscape that can drain storm water during a rainfall event, urban underground drainage systems are being designed and built to tackle the excess runoff resulting from urbanization. However, the rapid pace of urbanization has profoundly affected the formation of urban runoff thus resulting in the existing underground drainage system being unable to handle current flow conditions. This paper discusses storm water impacts in urbanized areas globally by reviewing historical storm water events and mitigation strategies accompanied with runoff reduction performance that are considered simultaneously for the purpose of relieving the stress on underground drainage systems. It was found that the stormwater impact on ten selected typical urban areas were enormously destructive followed by billions of direct economy loss, fatalities, damaged properties and residents’ relocations. Furthermore, the meta-analysis of selected six runoff mitigation methods indicated that the average runoff reduction percent ranged from 43% to 61% under different rain events in various installed sites across different event years.

scholarly journals A Quantity–Quality Model to Assess the Effects of Source Control Stormwater Management on Hydrology and Water Quality at the Catchment Scale

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1415 ◽  
Author(s):  
Abdul Razaq Rezaei ◽  
Zubaidah Ismail ◽  
Mohammad Hossein Niksokhan ◽  
Muhammad Amin Dayarian ◽  
Abu Hanipah Ramli ◽  
...  
Keyword(s):  
Water Quality ◽  
Best Management Practices ◽  
Urban Areas ◽  
Low Impact Development ◽  
Real Field ◽  
Rain Garden ◽  
Quality Model ◽  
Catchment Scale ◽  
Runoff Reduction ◽  
Peak Runoff

The vast development of urban areas has resulted in the increase of stormwater peak runoff and volume. Water quality has also been adversely affected. The best management practices (BMPs) and low impact development (LID) techniques could be applied to urban areas to mitigate these effects. A quantity–quality model was developed to simulate LID practices at the catchment scale using the US Environmental Protection Agency Storm Water Management Model (US EPA SWMM). The purpose of the study was to investigate the impacts of LID techniques on hydrology and water quality. The study was performed in BUNUS catchment in Kuala Lumpur, Malaysia. This study applied vegetated swale and rain garden to assess the model performance at a catchment scale using real field data. The selected LIDs occupied 7% of each subcatchment (of which 40% was swale and 30% was rain garden). The LID removal efficiency was up to 40% and 62% for TN and TSS, respectively. The peak runoff reduction was up to 27% for the rainfall of up to 70 mm, and up to 19% for the rainfall of between 70 and 90 mm, respectively. For the longer storm events of higher than 90 mm the results were not as satisfactory as expected. The model was more effective in peak runoff reduction during the shorter rainfall events. As for the water quality, it was satisfactory in all selected rainfall scenarios.

Modelling of green roofs' hydrologic performance using EPA's SWMM

2013 ◽  
Vol 68 (1) ◽  
pp. 36-42 ◽  
Author(s):  
E. Burszta-Adamiak ◽  
M. Mrowiec
Keyword(s):  
Urban Areas ◽  
Low Impact Development ◽  
Green Roofs ◽  
Storm Water ◽  
Storm Water Management Model ◽  
Measured Flow ◽  
Rain Events ◽  
Few Data

Green roofs significantly affect the increase in water retention and thus the management of rain water in urban areas. In Poland, as in many other European countries, excess rainwater resulting from snowmelt and heavy rainfall contributes to the development of local flooding in urban areas. Opportunities to reduce surface runoff and reduce flood risks are among the reasons why green roofs are more likely to be used also in this country. However, there are relatively few data on their in situ performance. In this study the storm water performance was simulated for the green roofs experimental plots using the Storm Water Management Model (SWMM) with Low Impact Development (LID) Controls module (version 5.0.022). The model consists of many parameters for a particular layer of green roofs but simulation results were unsatisfactory considering the hydrologic response of the green roofs. For the majority of the tested rain events, the Nash coefficient had negative values. It indicates a weak fit between observed and measured flow-rates. Therefore complexity of the LID module does not affect the increase of its accuracy. Further research at a technical scale is needed to determine the role of the green roof slope, vegetation cover and drying process during the inter-event periods.

scholarly journals Experimental study on the selection of common adsorption substrates for extensive green roofs (EGRs)

2021 ◽  
Vol 83 (4) ◽  
pp. 961-974
Author(s):  
Chen Xu ◽  
Zaohong Liu ◽  
Guanjun Cai ◽  
Jian Zhan
Keyword(s):  
Synergistic Effects ◽  
Low Cost ◽  
Reduction Rate ◽  
Green Roofs ◽  
High Porosity ◽  
Retention Capacity ◽  
Factors Affecting ◽  
Runoff Reduction ◽  
Practical Engineering ◽  
Selection Of

Abstract Adsorption substrate in the substrate layer of an extensive green roof (EGR) is one of the most important factors affecting rainwater retention and pollution interception capacity. However, the contact time between runoff and adsorption substrate is extremely short in actual rainfall, and adsorption substrate cannot show fully rainwater retention and pollution interception capacity. So, selection of adsorption substrate based on its physical properties and theoretical adsorption capacity is unreliable. In this study, eight commonly-used adsorption substrate experimental devices are constructed with the same configuration. The delayed outflow time and runoff reduction rate of each device, along with event measurement concentration (EMC), average EMC, and cumulative pollutant quantity of SS, ammonium (NH4+), nitrate (NO3−), total nitrogen (TN), and total phosphorus (TP) in each device outflow under nine simulated rainfall events are measured and evaluated. The results indicate that vermiculite has a significant interception effect on NH4+ and TP with the advantages of low bulk density, high porosity, low cost, and a good rainfall runoff retention capacity under torrential rain and downpour events. In future practical engineering and related studies of EGR, attention should be paid to ameliorating the deficiencies of the adsorption substrates and optimizing their synergistic effects when combined with nutrient substrates.

scholarly journals Investigation of the Influence of Hydrogel Amendment on the Retention Capacities of Green Roofs

2018 ◽  
Vol 25 (3) ◽  
pp. 373-382 ◽  
Author(s):  
Iwona Deska ◽  
Maciej Mrowiec ◽  
Ewa Ociepa ◽  
Katarzyna Łacisz
Keyword(s):  
Urban Areas ◽  
Drainage Basin ◽  
Green Roof ◽  
Green Roofs ◽  
Retention Capacity ◽  
Rainwater Infiltration ◽  
Sewer Systems ◽  
Basin Surface ◽  
Drainage Layers ◽  
Antecedent Dry Days

Abstract Progressive economic development as well as urbanisation influence the characteristics of the stormwater runoff. Progressive sealing of drainage basin surface prompts the decrease of rainwater infiltration, thus increasing the runoff intensity. This results in an increase of flood risk. Thus, in urban areas the sustainable urban drainage systems (SUDS) are used in addition to the traditional sewer systems. The examples of SUDS strategy are, inter alia, the roofs covered with vegetation (the green roofs). The paper presents the results of research of retention capacities of 4 diverse green roof models with following growing media: (1) the typical green roof substrate without any additions, (2) the substrate with addition of about 1 % by weight of hydrogel (the cross-linked potassium polyacrylate), (3) the substrate with addition of about 0.25 % by weight of hydrogel, (4) the substrate with addition of expanded clay and perlite. The models did not have the vegetation layers in order to explore only the retention capacities of drainage layers and substrates. The aim of the first part of research was to investigate the retention capacities of green roof models after 1, 2, 6, 8 and 10 antecedent dry days. In the case of 1 and 2 antecedent dry days the best medium retention capacity had green roof model 2 (with substrate with addition of 1 % by weight of hydrogel), and the weakest medium retention capacity had green roof model 1 (without any additions). In the cases of precipitations which occurred after 6 as well as 8 and 10 antecedent dry days the best retention capacity had green roof model 3 (with addition of about 0.25 % by weight of hydrogel). The weakest retention capacity had in these cases green roof model 4 (with addition of expanded clay and perlite). The aim of the second part of research described in the paper was to investigate the retention capacities of green roof models during precipitations that occurred after long antecedent dry periods of time (34, 59 and 106 antecedent dry days). The substrates and drainage layers were air-dry directly before precipitations. The best retention capacity had in this case green roof model 3 (with the substrate with addition of about 0.25 % by weight of hydrogel). The second largest retention capacity had model 2 (with the substrate with addition of about 1 % by weight of hydrogel). The definitely weakest retention capacity had model 4 containing the substrate with addition of expanded clay and perlite. The results may indicate that the efficacy of hydrogel decreased over time probably due to its decay under the influence of solar radiation.

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