Urban Design in the Time of Climate Change: Making a Friend of Floods

How do you design a flood-proof city? You don’t. How do you prepare for extreme weather in the era of climate change? You let the water come.

That’s the approach that landscape architects and other designers are taking to address the threat of flooding in urban areas: designing cityscapes that are designed to absorb water; and riverfronts and lakefronts that are meant to get wet.

Last week’s funding announcement in Toronto of the Port Lands Flood Protection Project, to which Prime Minister Justin Trudeau and his Ontario and Toronto counterparts committed nearly $1.2-billion, reflects a big bet on this model.

That project, based on a design led by landscape architects Michael Van Valkenburgh Associates and urban designer Ken Greenberg, is not based on heroic engineering. It reshapes the mouth of the Don River in downtown Toronto; where the river once meandered into a marshland at Lake Ontario, it has been shaped into a concrete channel for more than a century. The new project will reverse some of those changes. “Rather than building high dikes,” Greenberg says, “it creates a broad expanse of parkland that would be flooded in times of severe events – but would also set up a new neighbourhood.”

The Don River runs south to Lake Ontario, but makes a last-minute right turn in the concrete-lined Keating Channel. The new design will keep that in place but add a second outlet, this one broad and lined by a bowl-shaped park. This green space will be the heart of new neighbourhoods, housing tens of thousands of people, that can only be built because the risk of flooding has been reduced.

The adjacent Villiers Island, a 54-acre chunk of city, is already being master-planned. This scheme is urban design and landscape architecture, linked with flood protection and adaptation to climate change – the effects of which are already showing themselves in more frequent floods such as those on the Ottawa River this year. “This is a problem that requires lateral thinking, stepping out of the individual silos,” Greenberg says.

It also demands a new conceptual approach to the problem: “Allowing the river to shape the city, rather than the city to subvert the river,” says Nina-Marie Lister, a planner and ecologist at Ryerson University. The planning of Corktown Common, a nearby Toronto park that also provides flood protection, is a good example of such flexible thinking, says Lister, who is also a member of the Ryerson Urban Water Centre. This is “a smarter way to design,” she says. “But we’re just not very good at it, institutionally.”

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