Hydrology of an extensive living roof under sub-tropical climate conditions in Auckland, New Zealand

Voyde, Emily; Fassman, Elizabeth A.; Simcock, Robyn

doi:10.1016/j.jhydrol.2010.09.013

Cited by 198 publications

(125 citation statements)

References 14 publications

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“…The same relationship between the runoff and rainfall depth-frequency curves is also evident in the New Zealand field data set presented by Voyde et al (2010b), although in that case the largest rainfall event observed was less than 60 mm.…”

Section: Per-event Retentionsupporting

confidence: 70%

A modelling study of long term green roof retention performance

Stovin

Poë

Berretta

2013

Journal of Environmental Management

194

143

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This paper outlines the development of a conceptual hydrological flux model for the long term continuous simulation of runoff and drought risk for green roof systems. A green roof s retention capacity depends upon its physical configuration, but it is also strongly influenced by local climatic controls, including the rainfall characteristics and the restoration of retention capacity associated with evapotranspiration during dry weather periods. The model includes a function that links evapotranspiration rates to substrate moisture content, and is validated against observed runoff data.to typical extensive green roof configurations is demonstrated with reference to four UK locations characterised by contrasting climatic regimes, using 30-year rainfall time-series inputs at hourly simulation time steps. It is shown that retention performance is dependent upon local climatic conditions. Volumetric retention ranges from 0.19 (cool, wet climate) to 0.59 (warm, dry climate). Per event retention is also considered, and it is demonstrated that retention performance decreases significantly when high return period events are considered in isolation. For example, in Sheffield the median per-event retention is 1.00 (many small events), but the median retention for events exceeding a 1 in 1 yr return period threshold is only 0.10. The simulation tool also provides useful information about the likelihood of drought periods, for which irrigation may be required. A sensitivity study suggests that green roofs with reduced moisture-holding capacity and/or low evapotranspiration rates will tend to offer reduced levels of retention, whilst high moisture-holding capacity and low evapotranspiration rates offer the strongest drought resistance.

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Section: Per-event Retentionsupporting

confidence: 70%

A modelling study of long term green roof retention performance

Stovin

Poë

Berretta

2013

Journal of Environmental Management

194

143

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“…As previously mentioned, literature studies have shown that green roofs have a positive effect on the reduction of stormwater runoff [12,15,16,[19][20][21][22][23]. The water retention capacity mainly depends on the physical features of the green roof (number of layers and materials, soil type and thickness, type of vegetation and percentage of roof covered, roof geometry), and the weather conditions (length of antecedent dry weather period, season/climate, characteristics of rain event like intensity and duration) [14].…”

Section: Factors Influencing the Hydrological-hydraulic Behavior Of Amentioning

confidence: 93%

“…Voyde et al [15] considered 91 events with a minimum rainfall depth of 2 mm and an inter-event time of 6 h, in an area with sub-tropical climate and found that the water retention efficiency of an extensive GR in Auckland, New Zealand, was about 66% on average, with a subsurface runoff coefficient of 0.34.…”

Section: The Subsurface Runoff Coefficient Of An Extensive Green Roofmentioning

confidence: 99%

“…From an energy prospective, green roofs also promote evaporative cooling, thereby offsetting the energy requirements associated with air conditioning systems and reducing urban heat island effects [6,7]. From a hydraulic perspective, several studies have shown that green roofs have significant effects on retaining rainfall volumes [8][9][10][11], delaying the peak flow rate [12,13] and reducing the runoff volume discharged into the combined sewer systems (CSSs) [14][15][16]. Many literature studies have, indeed, investigated the hydraulic efficiency of green roofs, but only few have focused on the performance of such systems under Mediterranean climate condition.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Hydrologic Parameters on the Hydraulic Efficiency of an Extensive Green Roof in Mediterranean Area

Garofalo

Palermo

Principato

et al. 2016

Water

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Abstract:In an urban environment, green roofs represent a sustainable solution for mitigating stormwater volumes and hydrograph peaks. So far, many literature studies have investigated the hydraulic efficiency and the subsurface runoff coefficient of green roofs, showing their strong variability according to several factors, including the characteristics of storm events. Furthermore, only few studies have focused on the hydraulic efficiency of green roofs under Mediterranean climate conditions and defined the influencing hydrological parameters on the subsurface runoff coefficient. Nevertheless, for designing purposes, it is crucial to properly assess the subsurface runoff coefficient of a given green roof under specific climate conditions and its influencing factors. This study intends to, firstly, evaluate the subsurface runoff coefficient at daily and event-time scales for a given green roof, through a conceptual model implemented in SWMM. The model was loaded with both daily and 1-min rainfall data from two Mediterranean climate sites, one in Thessaloniki, Greece and one in Cosenza, Italy, respectively. Then, the most influencing hydrological parameters were examined through a statistical regression analysis. The findings show that the daily subsurface runoff coefficient is 0.70 for both sites, while the event-based one is 0.79 with a standard deviation of 0.23 for the site in Cosenza, Italy. The multiple linear regression analysis revealed that the influencing parameters are the rainfall intensity and antecedent dry weather period with a confidence level of 95%. This study demonstrated that, due to the high variability of the subsurface runoff coefficient, the use of a unique value for design purposes is inappropriate and that a preliminary estimation could be obtained as a function of the total rainfall depth and the antecedent dry weather period by using the validated multi-regression relationship which is site specific.

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“…For example, Voyde et al (2010) reported 66% 1003 retention from of a full-scale extensive green roof in Auckland, New Zealand. The 1004 green roof used in the study had a slope of 1.2% and over 60% plant coverage, akin to 1005 the green roof investigated in this study (Voyde et al, 2010). primarily due to various characteristics of individual rainfall events (Berndtsson, 2010).…”

mentioning

confidence: 99%