Cities that soak up water like sponges are more climate-resilient

These in-their-own-words pieces are told to Patricia Lane and co-edited with input from the interviewee for the purpose of brevity.

Usman Khan wants spongier cities. This associate professor at the Lassonde School of Engineering at York University works with communities to design and build urban landscapes to make them more resilient to flooding, cooler in summer and healthier for our minds and bodies.

Tell us about spongier cities.

I love city life and most people live in urban areas. As frequent flooding and global heating threaten our well-being, we have wonderful opportunities to rethink urban infrastructure to improve city life, especially in lower-income communities.

Engineers must design with the risk of flooding in mind. But my research shows that if we also design with the concept of rain as a precious resource and plan to soak it up, floods will do less damage. These design ideas bring many co-benefits including cooling spaces in hot summers, cleaner air and healthier bodies, resilient food and flower gardens and access to more green space, which is accepted as beneficial for our mental health.

This is well understood in wealthy communities where the natural environment is part of the plan to soak up rain and keep residents cool. But climate change-induced flooding and heating are now imperilling the lives and well-being of people who live in communities that have not had this kind of consideration. As we rebuild some of this infrastructure, either after major weather events or hopefully in anticipation of them, thinking about rain and nature differently can do much to keep people safe and improve the quality of their lives.

How did you get interested in this work?

Ten years ago, I was living in Calgary when a major flood of the Bow River destroyed many lovely homes along its banks. I wondered if the care that went into the restoration would have been present if the homes had not been so expensive.

Where are cities getting spongier?

Berlin and Vienna have had major retrofits. Toronto now requires all new buildings of a certain size to have a green roof and new parking lot surfaces must be permeable. I see municipalities replacing concrete traffic-calming blocks with tree boxes and Vancouver and Montreal are embracing rain gardens.

What makes it hard?

Civil engineering is an old profession and many things have been done a certain way for a long time. It is hard to hear people say these things have not been proven to work when the evidence is clear, or to dismiss long-term improvements in health and well-being in favour of cutting costs in the short term, especially when the old approaches are creating tragic and expensive disasters. I feel impatient with misplaced priorities when we could improve our cities.

How did the way you were raised affect your thinking?

When I was a small child, we lived in the United Arab Emirates where it rarely rains. One day it did. My sister and I ran outside to feel it. I was so curious when I came to Canada and saw how differently rain is experienced here.

Perhaps it is not that surprising that, as an undergraduate, I designed a net-zero water-use building. I am also very interested in using big data to improve water quality and am very proud of the work my team has done in that regard in large refugee camps by developing the Safe Water Optimization Tool.

What gives you hope?

In a perverse way, the number of climate events we have suffered this year may have been the attention-getting mechanism we need.

What do you see if we get this right?

More happiness that comes from trees and greenery on every city block everywhere.

What would you like to say to young people?

I have mixed feelings. I have the privilege to design my life so that it has low emissions, but personal responsibility can only take us so far. It must not become a distraction from creating the political will to make the changes we need fast enough.

What about older readers?

Encourage the young people in your life to pursue their ideas. Your support matters more than you know.