South Australian Study Reveals New Way To Keep Streets Cooler & Greener!

Image: City Of Holdfast Bay Council

This Simple Device Can Boost Tree Growth In Suburban Areas! 

A team at Flinders University, have discovered an innovative way to boost tree canopy in urban environments. Their new study, published in Frontiers of Climate, assesses the ability of a stormwater harvesting device to provide passive irrigation directly into street tree root zones. 

The ‘TREENET Inlet’ device works by intercepting stormwater runoff from the streets and diverting it to the soil around street trees. Over a three-year period, the researchers noticed some extraordinary developments! The study shows that the TREENET Inlet device provides significant benefits to white cedar trees growing in suburban areas of Adelaide. Thanks to the device, the cedar saplings grew 65% more in height and 60% more in diameter than the saplings without the stormwater harvesting.

Image: Magdevski / Canva

Harvesting Stormwater For Urban Greening Projects

Lately, we’ve seen more people talking about the rising temperatures in our cities and suburban areas, alongside the decline of street trees. According to the lead researcher of the study —  Xanthia Gleeson — the reason is simple.

“Increased land surface sealing due to urbanisation and building homes and infrastructure has decreased rainfall infiltration to the soil, decreased vegetation cover and has increased demand on mains water resources,” she said.

“As a result, city water management projects using stormwater harvesting and infiltration are increasingly combined with urban greening to support adaptation and resilience to the changing climate,” she says. Harvesting stormwater for urban greening projects is growing in popularity as a form of WSUD.

How Does The TREENET Inlet Work?

So, how does the TREENET Inlet work? Well, the device was designed to repurpose a ‘waste’ resource into something valuable by collecting stormwater runoff and diverting it into the soil as a passive form of irrigation.

According to Flinders University researcher Associate Professor Huade Guan, “it makes sense, because increased stormwater discharge presents risks to marine and other ecosystems, and infiltration in-situ is a low-cost and sustainable alternative”. 

Harvesting stormwater and diverting it into nature strips prevents storm water from entering our waterways and allows trees to grow and thrive in warm suburban areas! In the study, the Inlets provided 20% more water to the white cedar trees in Summer, and assisted root zone moisture at night.

Image: Belle Co / Canva

Our Streets Could Reach 50C By 2050, Which Is Why We Need More Trees!

Sufficient tree cover is essential to keeping our neighbourhoods cool and shady. A single tree can transpire (release water into the atmosphere from their leaves) hundreds of litres of water per day, which provides natural cooling. 

Managing our changing climate is going to be incredibly difficult in Australian cities. Western Sydney, for example, has endured sweltering conditions due to the growth in population and decline in urban greenery. 

Huade Guan recognises this growing challenge. “Quick urban drainage exacerbates the heat island effects which is raising the stakes on the health and lifestyle risks of extreme climate events under climate change. As it stands, summer temperatures are likely to reach 50C by 2050.