As the threats of climate change loom large and extreme rainfall events become more frequent, Canadian municipalities from Vancouver to Toronto are turning to innovative “sponge” solutions to bolster their resilience.
The Rise of the Sponge City
Inspired by initiatives from cities like those in China, the concept of a sponge city involves creating infrastructure that can absorb, rather than repel, excess rainwater. This is in stark contrast to the decades-long trend of building impermeable infrastructures such as roads and parking lots which redirect water to underground sewers.
Melanie Glorieux, a sustainable landscape planner with Rousseau Lefebvre, emphasized the growing appeal of the sponge city model. “While the concept of building a ‘sponge city’ isn’t new,” she said, “it’s an idea that more and more municipalities are embracing as they cope with extreme weather.”
Montreal Paves the Way
Mayor Valérie Plante of Montreal recently announced plans to introduce 30 “sponge parks” and an additional 400 “sponge sidewalks.” These innovative infrastructures, combined with vegetation squares, are designed to catch and absorb rainwater, thereby reducing the stress on the city’s sewage systems. According to a news release from the city, these measures will help Montreal retain water equivalent to three Olympic swimming pools at “half the cost of underground works.”
Reversing Decades of Damage
A large part of the sponge city strategy aims to address and reverse the challenges posed by car-oriented urban development over the past 40 to 50 years. “The goal is to reverse some of the harm done,” Glorieux said. The approach is to “limit run-off and maximize infiltration.”
Emily Amon, the director of green infrastructure at Green Communities Canada, shed light on the matter, mentioning, “real losses on the landscape in terms of our ability to absorb that stormwater we receive.”
More Than Just Water Management
While the primary focus is on stormwater management, the Sponge City model has numerous added benefits. It promises increased biodiversity, reduced heat island effects, more attractive public spaces, and increased exposure to nature which is known to contribute positively to mental health.
Guillaume Grégoire, an assistant professor at Université Laval, remarked that green infrastructure holds a vast potential for cities. He acknowledged the initial expenses and increased maintenance compared to traditional methods, but said, “comparative studies have shown that the cost over time is the same or even less.”
A Pan-Canadian Initiative
Cities across Canada seem eager to implement these green measures. Toronto, for instance, has been lauded for its bylaw mandating new developments larger than 2,000 square meters to include green roofs. Vancouver has also been proactive with its rain city strategy which aims to incorporate green infrastructure throughout its planning decisions.
Amon further highlighted how green infrastructure could foster more equitable neighborhoods. “It can be transformative in so many different ways,” she expressed, noting the benefits of adding food-bearing trees, and culturally significant plants, and increasing overall greenery in urban settings.