Scale dynamics of extensive green roofs: Quantifying the effect of drainage area and rainfall characteristics on observed and modeled green roof hydrologic performance

2014 ◽  
Vol 73 ◽  
pp. 494-508 ◽  
Author(s):  
Raha Hakimdavar ◽  
Patricia J. Culligan ◽  
Marco Finazzi ◽  
Stefano Barontini ◽  
Roberto Ranzi
Keyword(s):  
Green Roof ◽  
Green Roofs ◽  
Drainage Area ◽  
Rainfall Characteristics ◽  
Extensive Green Roofs ◽  
Hydrologic Performance

scholarly journals Hydrologic Performance of an Extensive Green Roof under Intensive Rain Events: Results from a Rain-Chamber Simulation

2021 ◽  
Vol 13 (6) ◽  
pp. 3078
Author(s):  
Elena Giacomello ◽  
Jacopo Gaspari
Keyword(s):  
Water Retention ◽  
Green Roof ◽  
Green Roofs ◽  
International Standards ◽  
Dimensionless Number ◽  
Runoff Coefficient ◽  
Retention Performance ◽  
Extensive Green Roof ◽  
Rain Events ◽  
Hydrologic Performance

The water storage capacity of a green roof generates several benefits for the building conterminous environment. The hydrologic performance is conventionally expressed by the runoff coefficient, according to international standards and guidelines. The runoff coefficient is a dimensionless number and defines the water retention performance over a long period. At the scale of single rain events, characterized by varying intensity and duration, the reaction of the green roof is scarcely investigated. The purpose of this study is to highlight how an extensive green roof—having a supposed minimum water performance, compared to an intensive one—responds to real and repetitive rain events, simulated in a rain chamber with controlled rain and runoff data. The experiment provides, through cumulative curve graphs, the behavior of the green roof sample during four rainy days. The simulated rain events are based on a statistical study (summarized in the paper) of 25 years of rain data for a specific location in North Italy characterized by an average rain/year of 1100 mm. The results prove the active response of the substrate, although thin and mineral, and quick draining, in terms of water retention and detention during intense rain events. The study raises questions about how to better express the water performance of green roofs.

scholarly journals A laboratory study to determine the use of polluted river sediment as a substrate for extensive green roofs

2018 ◽  
Vol 78 (11) ◽  
pp. 2247-2255 ◽  
Author(s):  
Wei Zhang ◽  
Xing Zhong ◽  
Wu Che ◽  
Huichao Sun ◽  
Hailong Zhang
Keyword(s):  
River Sediment ◽  
Peat Soil ◽  
River Sediments ◽  
Green Roof ◽  
Oxygen Demand ◽  
Green Roofs ◽  
Polluted River ◽  
Artificial Rainfall ◽  
Study Laboratory ◽  
Extensive Green Roofs

Abstract In this study, laboratory-scale green (e.g. living) roof platforms were established to assess the potential use of polluted river sediment in their substrate mixture. The mean runoff retention of the green roof platforms, which contained peat and/or river sediment, after 11 artificial rainfall events was >72%, significantly higher than traditional roofs. However, green roof platforms that had been filled with peat soil showed chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) leaching. Green roofs that had used river sediment showed good leaching control for COD, TN and TP. The cumulative leaching masses from the green roofs contained 30% (COD), 42% (TN) and 47% (TP) as much as the total leaching mass from traditional roofs, and the Cu, Zn, Cd and Pb leaching risk from green roofs when river sediments are used as part of a substrate mixture was relatively low. Despite some nutrient leaching in the initial phase of runoff from the green roofs, river sediment has the potential to be used as a substrate for extensive green roofs.

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.

The biodiversity of temperate extensive green roofs – a review of research and practice

2016 ◽  
Vol 62 (1-2) ◽  
pp. 44-57 ◽  
Author(s):  
Christine Thuring ◽  
Gary Grant
Keyword(s):  
Green Roof ◽  
Green Roofs ◽  
Ecological Design ◽  
Ecological Research ◽  
Extensive Green Roof ◽  
Research And Practice ◽  
Climatic Regions ◽  
History Of ◽  
Research To Policy ◽  
Extensive Green Roofs

From its beginnings in Germany in the twentieth century, a thriving extensive green roof industry has become established in many countries in temperate climates. Based upon the success of the industry, and with an expectation that this technology will be adopted in other climates, this review of the ecological research of extensive green roofs aims to evaluate the application of this knowledge. The modern extensive green roof is the product of research in the 1970s by German green roof pioneers; the selection of suitable species from analogue habitats led to green roof vegetation dominated by drought tolerant taxa. The commercial success of extensive green roof systems can be attributed to engineering and horticultural research, to policy mechanisms in some places, and to a market that encourages innovation, and the origins in ecological design are now easily overlooked. Some of the work reviewed here, including the classification of spontaneous roof vegetation into plant communities, is not widely known due to its confinement to the German literature. By re-visiting the history of the extensive green roof and reviewing the ecological research that has contributed to our understanding of it, the intention is, for this paper, to inform those considering green roofs in other climatic regions, to apply an ecologically informed approach in using local knowledge for developing installations that are suited to the bioregion in which they occur. Finally the paper considers some future directions for research and practice.

scholarly journals Evaluating different machine learning methods to simulate runoff from extensive green roofs

2021 ◽  
Vol 25 (11) ◽  
pp. 5917-5935
Author(s):  
Elhadi Mohsen Hassan Abdalla ◽  
Vincent Pons ◽  
Virginia Stovin ◽  
Simon De-Ville ◽  
Elizabeth Fassman-Beck ◽  
...  
Keyword(s):  
Machine Learning ◽  
Green Roof ◽  
Green Roofs ◽  
Storm Water ◽  
Water Runoff ◽  
Learning Methods ◽  
Retention Model ◽  
Machine Learning Methods ◽  
Storm Water Runoff ◽  
Extensive Green Roofs

Abstract. Green roofs are increasingly popular measures to permanently reduce or delay storm-water runoff. The main objective of the study was to examine the potential of using machine learning (ML) to simulate runoff from green roofs to estimate their hydrological performance. Four machine learning methods, artificial neural network (ANN), M5 model tree, long short-term memory (LSTM) and k nearest neighbour (kNN), were applied to simulate storm-water runoff from 16 extensive green roofs located in four Norwegian cities across different climatic zones. The potential of these ML methods for estimating green roof retention was assessed by comparing their simulations with a proven conceptual retention model. Furthermore, the transferability of ML models between the different green roofs in the study was tested to investigate the potential of using ML models as a tool for planning and design purposes. The ML models yielded low volumetric errors that were comparable with the conceptual retention models, which indicates good performance in estimating annual retention. The ML models yielded satisfactory modelling results (NSE >0.5) in most of the roofs, which indicates an ability to estimate green roof detention. The variations in ML models' performance between the cities was larger than between the different configurations, which was attributed to the different climatic characteristics between the four cities. Transferred ML models between cities with similar rainfall events characteristics (Bergen–Sandnes, Trondheim–Oslo) could yield satisfactory modelling performance (Nash–Sutcliffe efficiency NSE >0.5 and percentage bias |PBIAS| <25 %) in most cases. However, we recommend the use of the conceptual retention model over the transferred ML models, to estimate the retention of new green roofs, as it gives more accurate volume estimates. Follow-up studies are needed to explore the potential of ML models in estimating detention from higher temporal resolution datasets.

scholarly journals An Evaluation of Plant Selections and Irrigation Requirements for Extensive Green Roofs in the Pacific Northwestern United States

2011 ◽  
Vol 21 (3) ◽  
pp. 314-322 ◽  
Author(s):  
Erin Schroll ◽  
John G. Lambrinos ◽  
David Sandrock
Keyword(s):  
United States ◽  
Green Roof ◽  
Green Roofs ◽  
Wildlife Habitat ◽  
Growth Forms ◽  
Supplemental Irrigation ◽  
Seasonally Dry ◽  
The Pacific ◽  
Survival And Growth ◽  
Extensive Green Roofs

Extensive green roofs are a challenging environment for most plants, and this has typically limited the available plant palette. However, some functional goals for green roofs such as wildlife habitat require a broader spectrum of plant species from which to choose. In addition, pronounced seasonality in rainfall is a common climatic trait throughout much of the world; yet, few studies have evaluated green roof plant selections or the need for supplemental irrigation in a seasonally dry climate. In a field trial conducted in the Pacific northwestern United States, we evaluated the performance of eight taxa during establishment and under three different water management regimes post establishment: 1) non-irrigated; 2) irrigation based on green roof–specific water conservation guidelines for Portland, OR; or 3) the minimum irrigation required to maintain good plant condition. Plants were regionally available and represented a range of growth forms (succulents, shrubs, grasses, bulbs, and rhizomes) and potential functional attributes (habitat quality, aesthetic quality, and stormwater management proficiency). All eight species had generally high survival over the establishment year, although hardy iceplant (Delosperma cooperi) and common woolly sunflower (Eriophyllum lanatum var. lanatum) experienced some overwinter mortality. Species differed in the timing and absolute amount of growth during establishment. However, when the strong effect of initial size on growth was taken into account using analysis of covariance, there were no remaining differences between species in the relative magnitude of growth during establishment. During the summer following establishment, irrigation regime had significant effects on survival and growth, but these varied across taxa. Irrigation had no effect on survival or growth of the succulents hardy iceplant and ‘Cape Blanco’ broadleaf stonecrop (Sedum spathulifolium) and the bulb small camas (Camassia quamash). For the other taxa, plant survival and growth generally decreased with decreasing irrigation and many species did not survive at all without irrigation. Several species, particularly the grass roemer's fescue (Festuca idahoensis var. roemeri) and the shrub ‘Lasithi’ cretan rockrose (Cistus creticus ssp. creticus) suffered aesthetically under low irrigation, partly reflecting adaptive responses to drought stress. Weed pressure was high on bare substrate and was enhanced by irrigation, but weed pressure was negligible following canopy closure across all water regimes. These results suggest that succulents, bulbs, and rhizotomous forbs have potential for use on extensive green roofs in seasonally dry climates even without supplemental irrigation. Designing extensive roofs composed of more diverse growth forms will likely require some amount of supplemental irrigation. This study highlights the need to design context-specific green roofs that match appropriate plant selections with explicit functional goals and management plans. This will improve function and reduce the overall costs associated with maintenance.

scholarly journals Green Roof Plant Suitability Analysis for Northern Climates

2013 ◽  
Vol 23 (5) ◽  
pp. 563-574 ◽  
Author(s):  
Katherine L. Vinson ◽  
Youbin Zheng
Keyword(s):  
Plant Species ◽  
Green Roof ◽  
Green Roofs ◽  
Plant Production ◽  
Suitability Analysis ◽  
Production Growth ◽  
Diverse Plant Species ◽  
Extensive Green Roofs ◽  
Different Levels ◽  
Diverse Plant

To select plant species and species combinations for northern climates, mats with different plant species and species combinations were constructed on a green roof plant production farm and later transported and installed on an urban rooftop. There were three treatments: two different planting combinations, which together consisted of 10 diverse plant species [both stonecrop (Sedum) species and nonstonecrop species], and a control, which consisted of 26 stonecrop species used for standard mat production. Growth measurements and observations were made at both sites and special attention was paid to the performance of species during the harvest, transportation, and installation stages, as well as during recovery postinstallation. All species but false rock cress (Aubrieta cultorum) were found to be suitable for extensive green roof applications in northern climates, although there were variations of suitability among the species. Good, mediocre, and poor interactions formed between numerous species, displaying different levels of compatibility. Finally, all species were considered appropriate for a mat production system; species that failed to germinate, species planted postinstallation, the frequently displaced rolling hens and chicks (Jovibarba sobolifera), and false rock cress were exceptions. Overall, many species in this study displayed successful, well-rounded growth. Based on results, species and species combinations were recommended for extensive green roofs in northern climates.

scholarly journals Establishment and Persistence of Sedum spp. and Native Taxa for Green Roof Applications

HortScience ◽  
2005 ◽  
Vol 40 (2) ◽  
pp. 391-396 ◽  
Author(s):  
Michael A. Monterusso ◽  
D. Bradley Rowe ◽  
Clayton L. Rugh
Keyword(s):  
Native Species ◽  
Green Roof ◽  
Green Roofs ◽  
Geographic Area ◽  
Michigan State University ◽  
State University ◽  
Native Plant ◽  
Visual Appearance ◽  
Extensive Green Roofs ◽  
The U.S

Although the economic, environmental, and aesthetic benefits of green roofs have been recognized for decades, research quantifying these benefits has been limited—particularly in the U.S. Green roof usage and research is most prevalent in Germany, but can also be seen in several other European countries and Canada. If green roof installations are to be successful in Michigan and the rest of the U.S., then a better understanding of what specific taxa will survive and thrive under harsh rooftop conditions in this geographic area is required. Nine simulated rooftop platforms containing three commercially available drainage systems were installed at Michigan State University. Eighteen Michigan native plants planted as plugs and nine Sedum spp. planted as either seed or plugs were evaluated over three years for growth, survival during both establishment and overwintering, and visual appearance. All Sedum spp. tested were found to be suitable for use on Midwestern green roofs. Of the eighteen native plant taxa tested, Allium cernuum L., Coreopsis lanceolata L., Opuntia humifosa Raf., and Tradescantia ohiensis L. are suitable for use on unirrigated extensive green roofs in Michigan. If irrigation is available, then other native species are potential selections.

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.

EFFECT OF SUBSTRATE DEPTH AND TYPE ON PLANT GROWTH FOR EXTENSIVE GREEN ROOFS IN A MEDITERRANEAN CLIMATE

2019 ◽  
Vol 14 (2) ◽  
pp. 29-44 ◽  
Author(s):  
Mert Eksi ◽  
D. Bradley Rowe
Keyword(s):  
Green Roof ◽  
Green Roofs ◽  
Municipal Compost ◽  
Sedum Acre ◽  
Armeria Maritima ◽  
Survival And Growth ◽  
Roof Design ◽  
Substrate Depth ◽  
Extensive Green Roofs ◽  
Better Than

Although numerous examples of green roofs can be found in Turkey, limited research has been conducted on plant material and substrate type in this climate. Both plants and substrate are very important components in green roof design, it is essential to determine the proper substrates and plants in green roof systems for domestic green roof design. Two types of growing substrates: a commercial substrate consisting of crushed brick and clay (45%), pumice (45%), and organic matter (10%), and a recycled substrate including 90% coarse pumice (10–20 mm) and municipal compost (10%), were tested in three depths of 4, 7 and 10 cm. Tested plant species included Achillea millefolium , Armeria maritima , Sedum acre and Sedum album . Overall, the commercial substrate performed better than the recycled pumice. In addition, deeper substrates promoted greater survival and growth for nearly all species tested. Either A. maritima or A. millefolium survived in the recycled pumice at any depth, whereas they did survive when grown in the commercial substrate in greater than 7 cm and 10 cm, respectively. They both likely would require supplemental irrigation to be acceptable for green roofs in Istanbul or locations with a similar climate. Both Sedum species survived in all substrate types and depths. Information gained can be utilized by green roof professionals in the Istanbul region and in other parts of the world with a similar climate.

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