Designing a rainwater harvesting system for urban green roof irrigation

Abstract

Green roof systems have been suggested to ease the growing urban environmental problems resulting from rapid urbanization. However, the irrigation of green roofs heavily depends on using precious potable water and consequently generates negative environmental effects. Rainwater has been recommended to address this dilemma, but the design method has not been well developed. In this study, the major design factors of a rainwater harvesting system for green roof irrigation systems are examined, and a simulation-based mathematical model is established to elucidate the correlation between tank volume and system performance. The optimal system design and probability distribution of the potable water replacement rate are also discussed on the basis of a case study of a university building in Keelung, Northern Taiwan. The results show that the optimal tank volume, potable water replacement rate, and probability of exceedance are 9.41 m 3 , 92.72%, and 88.76% (±1SD), respectively. In addition, the economic performance is identified to be feasible. Hence, the design method has been verified to be a useful tool to ease the urban environmental issues.

Multilayer blue-green roofs as nature-based solutions for water and thermal insulation management

“…Besides this potential usage, rainwater harvesting systems are nowadays mainly used to mitigate extreme rainfall events (Boers & Ben-Asher 1982;Zhang & Hu 2014;Teston et al 2018;Freni & Liuzzo 2019;Akter et al 2020;Cristiano et al 2021b). Thanks to their water storage capacity, rainwater harvesting tanks can reduce the pressure on the drainage systems, detaining a fraction of the rainfall during the events and releasing it in a later moment (Bocanegra-Martínez et al 2014;Chao-Hsien et al 2014;Sample & Liu 2014;Akter & Ahmed 2015;Campisano & Modica 2015;Campisano & Lupia 2017;Adugna et al 2018;Cipolla et al 2018;Abas & Mahlia 2019;Palermo et al 2020). If properly stored and treated, this water can be reused for different domestic purposes, such as home-garden irrigation and flushing toilets, potentially reducing potable water consumption.…”

Sustainable green roofs: a comprehensive review of influential factors

“…Chao-Hsien et al ( 2014 ) examined the primary design factors of a rainwater harvesting system for GRs and conducted a case study on a university building in Keelung, Northern Taiwan. For this building and climate, the optimal tank volume was 9.41 and the potable water replacement rate and probability of exceedance were 92.72% and 88.76%, respectively.…”

“…Rainwater harvesting has gained popularity for GRs in some regions (Almeida et al 2021;Burszta-Adamiak and Spychalski 2021). Different studies proposed multiple approaches for rainwater harvesting, such as rainwater cisterns or tanks, treatment trains, and constructed wetlands (Hardin et al 2012;Coutts et al 2013;Chao-Hsien et al 2014;Hafizi Md Lani et al 2018;Kucukkaya et al 2021). For example, Coutts et al (2013) studied the potential of water-sensitive urban design (WSUD) (WSUD is an approach to design urban areas to make use of valuable resources like rainwater).…”

Rainwater Use for Vertical Greenery Systems: Development of a Conceptual Model for a Better Understanding of Processes and Influencing Factors

“…Depending on the scale, rainwater harvesting can include only the roof area as well as the road run-off for bigger applications [20]. While the use of rainwater is already applied for green roofs [21][22][23], studies investigating rainwater use for VGS are scarce [24] or combined with greywater use to overcome long dry periods and secures the water supply for the vegetation [25].…”