How a Sponge Approach Can Help Build More Climate-resilient Cities

More greenery and green roofs mean better flood protection as well as cleaner air and cooler temperatures.

Heat domes, wildfires, droughts—Canadians have firsthand experience of the effects of climate change on our weather. And from British Columbia to the Atlantic provinces this also includes heavier and more frequent rains, which are flooding communities across the country.

Meanwhile, our cities and water-management infrastructure were designed for an era where powerful rainstorms were considered a once-in-a-century event.

“We’re building larger buildings and leaving less landscaping around buildings because we’re going for maximum density,” says Ron Schwenger, president of Architek, a design-build company that’s been on the leading edge of living architecture for 15 years. “That also means more surrounding hardscape—pavement and concrete.”

When it rains, it pours

In the past, lawns, gardens, parks and meadows did some of the heavy lifting after a downpour, absorbing water into the ground. But as concrete jungles expand, excess water has nowhere to go. “All the rain gets deflected into the storm sewer system, which can only take so much water,” Schwenger says.

With more forceful rainstorms happening more often, these systems become overwhelmed, putting a high imperative on creative new solutions to reduce the deluge.

For Schwenger, stemming this rising tide means making building surfaces more absorptive. “The spongier a city is, the more capable it is of managing water during a heavy rain event,” he says.

Creating a sponge effect

The so-called sponge city approach doesn’t mean incorporating dishwashing aids into urban design. Rather, it builds on another climate change-fighting tactic—the green roof—to absorb and utilize rain waters, essentially turning hard surfaces into sponges.

“Planted materials can percolate and hold water just like miniature sponges,” Schwenger says. “When rains come down, green roofs and green spaces absorb water rather than deflecting it to the storm sewer system.”

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