Stormwater Management by Green Roof (original) (raw)
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STORMWATER RUNOFF MITIGATION ON EXTENSIVE GREEN ROOF: A REVIEW ON TRENDS AND FACTORS
South East Asian Technical Universities Consortium (SEATUC), 2012
This paper aims to provide a broad overview on research trend and factors contributing towards green roof performance in mitigating urban stormwater runoff. Nineteen papers were selected and examined for trends on research concern and factors attributing towards stormwater runoff mitigation. The factors are then discussed based on stormwater runoff measurements reported and existing literatures in the field. The research trend on green roof stormwater mitigation has evolved around the factors that could delay peak water runoff and increase retention period. Researchers have identified substrate depth, slope, climate, vegetation and green roof age as the significant factors attributing stormwater runoff mitigation. Wide research gap have been identified on the role of vegetation hydrology management and green roof performance on regions other than temperate climate providing opportunity for further research and experiments.
Evaluation of green roof performances for stormwater quantity and quality controls
Rapid urbanization in the recent decades has quickly fuelled up the process of global warming. Many mitigation measures have been formulated and implemented in order to tackle the effect of global warming. Green roofs (roof with vegetated cover) have been proposed and implemented by various countries as one of the new environmentally friendly innovation. This paper evaluates the qualitative and quantitative performances of an extensive green roof system under tropical climate. Simulations showed that the peak discharge of stormwater run-off was reduced up to 26% in relation to concrete tile roof. Its reduction ability was decreased for storms with intense rainfall. Increment of pH was observed for the green roof run-off, and the runoff quality ranged between class I and II under Malaysia National Water Quality Index (WQI). High concentrations of phosphate were observed in the run-off samples, which showed that substrates (fertilized planting soil) might be the potential contributor. Findings indicated that there was a reduction up to around 5% for indoor temperature of the building after installation of the extensive green roof system.
Evaluation of Green Roof as Green Technology for Urban Stormwater Quantity and Quality Controls
Nowadays, people mutually recognise that global warming is actually a fact rather just a scientific theory and it has been fuelled up quickly as resulted from rapid urbanisations. Driven by environmental needs, green building index (GBI) was established in Malaysia to drive the initiative to lead the property industry towards becoming more environmental friendly. Green roofs (roof with vegetated cover), as one of the assessment criteria of GBI, are gaining attention in the Malaysian society as a versatile new environmental friendly mitigation technology. This paper evaluates the qualitative and quantitative performances of extensive green roof at Humid Tropics Center under local tropical climate. Simulations showed that the peak discharge was reduced up to 26% in relation to impervious brown roof. Its reduction ability decreased for storms with intense rainfall. Increment of pH was observed for the green roof runoff and the runoff water quality ranged between class I and II under WQI. High concentrations of phosphate were noticed in the runoff samples and substrates (fertilised planting soil) might be the potential contributor. Findings indicate that there was a reduction of approximately 1.5°C for indoor temperature of the building after installation of the extensive green roof.
GREEN ROOFS FOR SUSTAINABLE WATER MANAGEMENT IN URBAN AREAS
Environmental Engineering and Management Journal - Gheorghe Asachi” Technical University of Iasi, Romania, 2013
This paper presents the description of a pilot green roof on the engineering laboratories of University of Bologna, Italy. The first results of the monitoring and simulation phase of the green roofs project that has been carried out by University of Bologna in collaboration with the Columbia University of New York aim at providing more evidence on green roof stormwater performance. This project is the first green roof in the city of Bologna as no green roofs have been monitored for annual stormwater retention in this area. Only one green roof in City of Genova, belonging to north Italian climate (the specific climatic context of the Mediterranean region: areas with this climate receive almost all of their precipitation during their winter season, and may go anywhere from 4 to 6 months during the summer without having any significant precipitation.) has been monitored and gave a 70 percent result in retention of the annual runoff (Palla et al., 2009). The main objective was to compare this result to the Bologna pilot green roof and see how it differs from the other climatic area results.
Analysis of stormwater retention on green roofs
Archives of Environmental Protection, 2012
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 infl uence the reduction of the maximum runoff intensity, and thus may limit the impact of stormwater on the stormwater drainage and combined sewage systems.
Nowadays, Green Building index (GBI) has became a hot issue in society of Malaysia especially for the field of construction and infrastructure works. Government has promoted this index intensively by launching city developments projects which emphases on environmental friendly buildings and infrastructures. Green Building Index is Malaysia first comprehensive rating system for evaluating the environment design and performance of Malaysian buildings. Green roof system is one of the assessment criteria of this rating system which is under category of sustainable site planning and management. Green roof also serves as one of the components of application of Water Sensitive Urban Design (WSUD) in Humid Tropic Center (HTC). This paper portrays evaluations of the performance of extensive green roof at Humid Tropic Center (HTC) on reducing peak discharge for tropical climate. This study also reviews thermal performance of vegetated rooftop in reducing temperature of the building which enables the building consumes less energy. On-site experiments would be carried out to determine the ability of water retention of green roof in HTC by measuring the runoff produced by the green roof. The total amount of runoff measured was compared with standard peak discharge for Kuala Lumpur calculated from Rational Method with referring to Mesra Alam Saliran Manual (MASMA) chapter 13. The temperature of the building was measured by a thermometer which was attached to the inner wall of the surau. Indoor temperature was recorded every 15 minutes daily. Mean maximum temperature recorded before and after installation of green roof was compared. The results indicate that green roof at HTC can reduce peak discharge up to 44% and it is able to induce cooler indoor environment.
GREEN ROOF PERFORMANCE FOR STORMWATER MANAGEMENT IN MALAYSIA
PhD Thesis, 2020
In managing stormwater, Sustainable Urban Drainage Systems (SUDS) has promoted the control-at-source concept. This concept focuses equally on quantity, quality of stormwater and amenity as an integrated approach. Many components in SUDS have different purposes depending on design and location to implement. One of these components is green roof. There are two types of green roof namely extensive and intensive green roof. Many studies overseas have shown that green roof can help not only in slowing down the rainwater to reach the ground and sinking numerous pollutants in its substrate, but also leaching pollutants from the substrate. Notably, the rainfall characteristics in those countries are different compared to the conditions in Malaysia. Malaysia receives high rainfall depth throughout the year from low to severe intensity (1->60mm/hr). High and severe intensity rainfall may cause flash flood in Malaysia particularly in urban and dense areas. Due to the limitation of space, the performance of green roof towards high-intensity rainfall needs to be further studied in Malaysian conditions. It is to determine the performance of this SUDS component in combating flash flood issues and become an alternative for stormwater management in Malaysia. Other than that, the application of green roof can also be considered for a major system in Urban Stormwater Management Manual for Malaysia 2nd Edition (MSMA 2nd Edition) since it is still not included in the manual. This research was carried out in River Engineering and Urban Drainage Research Centre (REDAC), Universiti Sains Malaysia (USM). Through simulated and real rainfall events, the performance of intensive green roof in terms of flow attenuation, volume retention, and green roof outflow water quality were studied. The result showed that green roof testbeds managed to attenuate the inflow and volume retention. Runoff was delayed in the range of 20 to 65 minutes. Green roof was found to successfully reduce peak discharge of rainfall in the range of 68.8% to 95.6% with moderate influence by rainfall depth and rainfall duration with R2=0.5. In simulated high-intensity rainfall (52mm/hr – 1040mm/hr), the green roof managed to retain rainwater from 0.02m3 to 1.22m3. Volume retention was calculated and found to have a significant correlation with rainfall depth, intensity and rainfall duration with R2=0.8. Based on the Water Quality Index of Malaysia (WQI), the quality of green roof outflow was studied and it was found that pH and COD fell in Class I, BOD5 and TSS in Class I-II, AN in Class I-III, and depletion of DO fell in Class I-V. No significant difference was found in green roof vegetation performance in treating these WQI parameters except for TSS (p<0.05). It was confirmed that green roof discharge would not cause a nuisance to water bodies. To conclude, this study believes that the implementation of green roof in Malaysia is very promising.
Effectiveness of Non-monitored Green Roofs for Stormwater Management
IOP Conference Series: Materials Science and Engineering, 2019
A green roof is an alternative roofing system of any building or house that provides a better environment for urban areas. It has the potential to mitigate urban water problems. This study aims to investigate the rainfall runoff performance of two non-monitored green roofs with two different slopes. The experiment uses two types of non-monitored green roofs, namely flat roofs and sloped roofs that were exposed to climatic conditions in Parit Raja. The physical characteristics of the roofs were observed and rainfall runoff data was collected. The results showed that when 4 L of water was manually poured onto the roofs, an average of 60.4% of water was retained on sloped roofs whereas 48.4% was retained on flat roofs. Based on the 5-minute interval data, the retention ranges between 55.6% and 71.2% for both roofs. In terms of daily rainfall for a week, the average percentage was 69.2% for sloped roofs and 70.6% for flat roofs. All three approaches show that the green roofs produced le...
EVALUATING THE PERFORMANCE OF GREEN ROOF FOR STORMWATER MANAGEMENT OPTIONS FOR GREEN TECHNOLOGY
Green roof is reasonably new concept introduced in Malaysia as part of green technology initiatives in the construction industry. It minimizes the degradation of the environment; zero or low green house gas (GHG) emission is safe for use and promotes healthy and improved environment for all forms of life; conserves the use of energy and natural resources; and promotes the use of renewable resources. Nowadays, Green Building index (GBI) has became a hot issue in society of Malaysia especially for the field of construction and infrastructure works. Green Building Index is Malaysia's first comprehensive rating system for evaluating the environment design and performance of Malaysian buildings. Green roof system is one of the assessment criteria of this rating system which is under category of sustainable site planning and management. Green roof was designed to be one of the components of application of Water Sensitive Urban Design (WSUD) in Humid Tropic Center (HTC) study area. This paper portrays evaluations of the performance of extensive green roof at Humid Tropic Center (HTC) on reducing peak discharge for tropical climate. This study also reviews thermal performance of vegetated rooftop in reducing temperature of the building which enables the building consumes less energy. Onsite experiments would be carried out to determine the ability of water retention of green roof in HTC by measuring the runoff produced by the green roof. The total amount of runoff measured was compared with standard peak discharge for Kuala Lumpur calculated based on MSMA Manual. The temperature of the building was measured by a thermometer which was attached to the inner wall of the selected building. Indoor temperature was recorded every 15 minutes daily. Mean maximum temperature recorded before and after installation of green roof was compared. The results indicated that green roof at HTC capable to reduce peak discharge up to 44% and it is able to induce cooler indoor environment to reduce usage of energy.
Green roofs for stormwater mitigation in Hong Kong
2009
Hong Kong often faces stormwater problems during the rainy season. The heavy rainstorm could cause flooding and serious damages to the society. To tackle this, the Government has to make large investment in drainage and flood control projects which have significant socioeconomic implications. The research findings in other countries indicated that green roofs can be an effective tool to help mitigate stormwater problems. The application of green roofs in the buildings can delay the starting time of the stormwater runoff and reduce the magnitude of peak runoff and the total amount of rainwater discharged from the buildings. Also, the roof greening method in urban areas can improve the quality of the built environment and provide useful spaces for community functions. This paper explains the major findings of a research project to study the potential of green roofs for stormwater mitigation in Hong Kong. The rainfall characteristics and stormwater issues in Hong Kong are evaluated. Th...