Influences of Four Extensive Green Roof Design Variables on Stormwater Hydrology

Hill, Jenny C.; Drake, Jennifer; Sleep, Brent E.; Margolis, Liat

doi:10.1061/(asce)he.1943-5584.0001534

Cited by 34 publications

(13 citation statements)

References 33 publications

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“…Modeling approaches have advanced in number and sophistication since 2007, when Elliot and Trowsdale [26] reported that only one model (e.g., Water Balance Model) could be used to model green roof hydrology explicitly. Recent modeling efforts represent green roof storm water attenuation using runoff coefficients or curve numbers [27][28][29][30] and use more elaborate physically-based models such as HYDRUS-1D (Prague, Czech Republic) [31][32][33] to represent saturated and unsaturated flow patterns.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and Modeling the Long-Term Rainfall-Runoff Response of the Jacob K. Javits Center Green Roof

Abualfaraj

Cataldo

Elborolosy

et al. 2018

Water

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Drainage from the 27,316-m2 Jacob K. Javits Convention Center (JJCC) green roof was investigated in the field to quantify the system’s long-term rainfall-runoff response. The JJCC hosts one of the largest extensive green roofs in the United States. Utilizing four years of rooftop monitoring data collected using a weather station, custom designed and built drainage systems, three Parshall flumes equipped with pressure transducers, and weighing lysimeters, this study quantified the 25.4-mm-deep green roof’s ability to decrease the volume and peak rate of runoff. With parameters derived from the site, the Environmental Protection Agency Stormwater Management Model (EPA-SWMM) predicted event total runoff volume and event peak runoff rates to within +10% to −20% and +25% to −15% of the observations, respectively. The analysis further indicated that approximately 55% of the cumulative precipitation that fell on the JJCC extensive green roof during the monitoring period (warm weather months, June 2014–November 2017) was captured and retained. The average percent retained on an event-basis was 77%, and average event runoff coefficient was 0.7, implying a substantial reduction in the volume and rate of runoff generated from the roof compared to the pre-green roof condition, when most, if not all, of the precipitated water would have immediately resulted in runoff. Our research suggests that, on average, 96% of rainfall events 6.35 mm or less were retained within the green roof, whereas 27% of the total event volume was retained for events greater than 12.7 mm in depth. A sensitivity analysis suggests if the substrate depth were increased, better stormwater capture performance would be achieved, but only up 127 mm, whereas increased precipitation coupled with warmer temperatures as a result of climate change could decrease the performance by up to 5%, regardless of substrate depth. An equivalency analysis suggested that even shallow green roofs can significantly reduce the required stormwater detention volume that New York City requires on new development. This particular green roof appears to be more than 18 times as cost-effective as a subsurface cistern would be for managing an equivalent volume of stormwater in Midtown Manhattan.

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Section: Introductionmentioning

confidence: 99%

Monitoring and Modeling the Long-Term Rainfall-Runoff Response of the Jacob K. Javits Center Green Roof

Abualfaraj

Cataldo

Elborolosy

et al. 2018

Water

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“…Green roofs help reduce peak storm flows and volumes discharged to storm and combined sewer systems (Nawaz et al, 2015). On an annual basis, extensive green roofs can capture, store, and evapotranspire 40 to 70% of the total precipitation (Fassman‐Beck et al, 2016; Hill et al, 2017). Extensive green roofs comprise a layer of lightweight, typically soilless, planting medium, to a maximum depth of 15 cm, that is used to support the growth of plants (Czemiel Berndtsson, 2010).…”

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confidence: 99%

The Effect of Intraparticle Porosity and Interparticle Voids on the Hydraulic Properties of Soilless Media

Hill

Sleep

Drake

et al. 2019

Vadose Zone Journal

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Core Ideas Green roofs comprise a soilless medium over an atmospheric equilibrated space. Green roofs represent microcosms of capillary fringe and vadose zone hydraulics. Bulk properties come from the interparticle voids and the intraparticle pores. Capillary retention is fundamental for water storage in a green roof system. Design specifications for green roofs should focus on using a well‐graded medium. An essential component of a building‐integrated vegetation system, such as an extensive green roof, is the layer of lightweight planting medium that supports rooting and stores water. Predicting and describing the stormwater management performance of green roofs requires reliable data regarding the water retention properties of the planting medium. Ten materials proposed for use on green roofs, including four mineral components, three biological components, and three commercial blends, were characterized through measurement of their water release curves (WRCs). In combination with the particle size distributions, the resultant data demonstrate that some of the materials contain measurable intraparticle pore networks in addition to the interparticle void spaces described in classical soil hydrology. The WRCs were also used to model the maximum water storage under static equilibrium conditions throughout a 15‐cm profile of each material. In freely draining, unsaturated green roof systems, the role of the intraparticle pores may be limited to increasing microscale roughness of particle surfaces, thereby reducing film flow under drier conditions. The highly organic, biologically derived materials—screened compost, bark fines, and shredded wood—demonstrated hydrophobicity when air dried, but wetting occurred within <30 min on all occasions, which would be within the time frame of many rainstorms. As with natural soils, the saturated hydraulic conductivity was lower in materials with a higher proportion of fines (<106 μm).

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“…In biochar-amended columns, FIB removal was not affected by the presence of an IWS or duration of anteceident dry days (3 versus 7). However, both Afrooz and Boehm (2017) (Hill, Drake et al, 2017). Of the parameters studied, the use of timed-irrigation had the largest negative impact on the greenroof stormwater retention rates.…”

Section: Field Laboratory and Modeling Performancementioning

confidence: 95%

Urban Stormwater Characterization, Control and Treatment

Moore

Rodak

Ahmed

et al. 2018

Water Environment Research

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A review of literature related to stormwater runoff characterization and its subsequent management and treatment from 2017 was conducted. The 250 articles summarized herein are organized along three central themes: (1) stormwater quality and quantity characteristics, (2) site-scale stormwater management practices, with a focus on low impact development (LID) and green infrastructure (GI), and (3) watershed-scale performance of stormwater controls. Within each section, common research themes and future work are highlighted.

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Influences of Four Extensive Green Roof Design Variables on Stormwater Hydrology

Cited by 34 publications

References 33 publications

Monitoring and Modeling the Long-Term Rainfall-Runoff Response of the Jacob K. Javits Center Green Roof

Monitoring and Modeling the Long-Term Rainfall-Runoff Response of the Jacob K. Javits Center Green Roof

The Effect of Intraparticle Porosity and Interparticle Voids on the Hydraulic Properties of Soilless Media

Urban Stormwater Characterization, Control and Treatment

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