Author(s): Aung Naing Soe; Asaad Y. Shamseldin; Kilisimasi Latu; Conrad Zorn; Rachel Devine; Robyn Simcock; Zoe Avery
Linked Author(s): Conrad Zorn
Keywords: Green roofs urban stormwater management hydrological performance nature-based solutions
Abstract: With the intensifying of urbanization and climate-induced shifts in precipitation patterns in New Zealand, green roofs may become a pivotal element within urban stormwater management. A green roof research facility has been set up to monitor the hydrological performances of green roofs at the University of Auckland in collaboration with the Auckland Council. Seven experimental green roof trays have been installed and monitored for one year. These include unplanted ballast stone over bark mulch tray (a control, one tray replicating 4 m2 of Auckland Library green roof) and six planted trays, two ‘Eco-pillow’ trays (a proprietary, lightweight system of pre-grown pillows over moisture retention materials replicating 4 m2 of Auckland Library green roof), two trays with ~150 mm depth of conventional green roof media and drainage mat (Daltons living roof mix), and two trays with ~150 mm depth of an experimental green roof media (Daltons pine grow mix). The conventional media met the Auckland Council specifications for green roof media for stormwater management, TR2013/045). Native Plant species selected by the local Iwi, Ngāti Whātua Ōrākei, include one succulent (Disphyma australe) but are mostly herbs, sedges, rushes, and woody shrubs up to 1 m height with no sedums established. Hydrology monitoring measures runoff and peak discharge reduction in rainfall events by comparing actual precipitation depth and runoff depth usingCalibrated pressure transducers and customed orifice tubes. This paper discusses preliminary results that suggest all trays have comparable performance in runoff volume while peak discharge reduction ranged between 84% and 94% under a daily irrigation regime. The insights from this study may foster technical innovations and support policy transformations.
Year: 2025