Two years ago this Sunday, the Chicago region was declared a federal disaster area due to widespread flooding that paralyzed the region and large swaths of northeastern Illinois. The flooding resulted from storms of such intensity that thousands of homes were flooded, streets and viaducts were closed, and people suddenly found themselves unable to get their children to school or themselves to work for days afterwards. Five-and-a-half inches of rain fell in less than 24 hours.
Alot of the flooding was not caused by a river leaping its banks, which we typically associate with flooding, but from our stormwater sewers being overwhelmed. Too much water in too little time exposed a system unable to cope with the storm. The result was more than a billion dollars in damages and associated losses.
What's truly scary is how much more frequent storms like these will be in the future thanks to the effects of climate change. Over the last 50 years the number of storms that dump in excess of three inches of rainfall has nearly doubled. And Chicago can expect two to three times more extreme storms like these in the future.
Urban flooding doesn't just affect people's basements, it affects thousands of homes and living spaces that are at or below grade, devaluing property, and causing public health problems from exposure to raw sewage and from the risk of toxic mold growing in walls and floors. In Chicago what we flush from our toilets and put down our sinks ends up in the same place as what goes down the storm grate.
These issues are symptomatic of a larger water infrastructure problem that needs solutions. For much of Chicago's history, we've applied brute force techniques to solve our city's water problems. But each problem that a massive public works project was designed to solve has been overtaken by changing land use, changing development patterns, and (now) by a rapidly changing climate that produces severe storms more frequently with each passing year.
It's time to for a new approach.
The solutions need to be closer to the source of the problem, right where the rain hits the ground. Excessive runoff from streets, parking lots, and buildings is a major reason why our stormwater systems are overloaded. But we can more thoughtfully design our streets, parking lots, parks, and public spaces to be a bigger part of the solution and a smaller part of the problem. By capturing, retaining, and slowing down stormwater we can minimize how much runoff reaches the sewers -- or your home.
These "green infrastructure" techniques can be put in place throughout a neighborhood -- and throughout the city. They may look like a new flower bed along a slightly narrower street or a shallow swale around the edge of a parking lot. They may look just like your typical city street, sidewalk or alley, except the surface allows rainwater to percolate through the pavement, instead of shunting it all to the nearest sewer grate. What they all have in common is they decrease the amount of runoff that can reach our sewers -- and people's homes and basements.
Chicago currently lags behind other cities like Seattle, Philadelphia, and Milwaukee in the use of green infrastructure techniques. But the time is ripe for Chicago to take its efforts from a series of demonstration projects to making green infrastructure an integral part of how we build things. Mayor Emmanuel has committed $50 million to a green infrastructure initiative. Now we need to build on this effort, at a more ambitious scale that is more in line with our current needs and the increasing future risks of flooding.