The flash flood that swept over New York City last week, sending water sloshing through the subway system, is a reminder of how lousy North American cities are at dealing with storms. The water only had one place to go: the sewers, which were often blocked. Ordinary people throughout Brooklyn, which was hit particularly hard, trudged out into the water-filled street, past floating cars, to scoop fallen leaves and debris off sewer grates.
It doesn’t have to be this way. Usman T. Khan, who teaches civil engineering at York University, is obsessed with stormwater management and is an evangelist for the idea of “sponge cities,” which have permeable surfaces that can absorb huge amounts of water when the deluge comes. In Toronto, we’ve started building public parking lots with asphalt that looks just like regular asphalt, but collects rainfall underground so it seeps back into the environment. In his opinion piece for Maclean’s, he describes how materials like this, along with green roofs, rain gardens and other surfaces that can absorb rainwater, should be major city-planning priorities from now on.
—Sarah Fulford, editor-in-chief
