Chicago, once a swamp, also could be walloped by a catastrophic flood

The catastrophic flooding in Houston has been called “biblical” in scale, but unlike the Great Flood, it was widely predicted. The combination of low-lying terrain, latticework of bayous, a harbor prone to tidal surges, lack of zoning, and location on the hurricane-prone Gulf coast, put Houston on everybody’s map of next great disasters.

Chicago of course is not on Hurricane Alley. We have an elaborate structure of zoning laws, a Deep Tunnel to collect storm water — some of it now deposited in Thornton Quarry — and a lake without tides. Though Lake Michigan has been known to overflow its banks, its waters are unlikely to travel far inland. And we have political leaders who accept the reality of climate change.

But yes, the Chicago region, too, could experience catastrophic floods.

We already have had such floods, but they have been localized. They have been catastrophes for neighborhoods and suburbs such as Albany Park, Chatham, Robbins, Riverdale, Calumet City, Blue Island and Midlothian.

In 2014, a team of researchers led by my colleague Harriet Festing, published a study called “The Prevalence and Cost of Urban Flooding.” It revealed that over a four-year period from 2007-11, more than 180,000 insurance claims were filed across 97 percent of Cook County zip codes. Most of these claims were small, averaging under $5,000, but the greatest flood damage occurred in the most economically disadvantaged communities. Many of the areas, especially on the West and South sides of Chicago, already suffer from high levels of violence, unemployment, and urban decay.

Flooding only makes a bad situation worse. Even a wet basement — with its sewer backup, damage to electrical wiring, and growth of mold — can make a home uninhabitable. And only a small number of Chicago area homeowners carry flood insurance. (It’s available only through the National Flood Insurance Program.)

The prospects are for greater and more widespread flooding. Chicago was famously built on a swamp, and rather than adapt to that environment, we have mostly paved it over. Highways, parking lots, rooftops and other impermeable surfaces mean water has no place to go and simply collects on streets and in homes or flows into sewers. Our combined sewer and storm-runoff system means that water treatment facilities are deluged during heavy rains and often release untreated sewage into Lake Michigan.

The latest National Climate Assessment, prepared by experts from four government agencies, predicts that climate change will lead to an approximately 20 percent increase in “extreme rainfall events” in the Midwest over the next few decades, on top of the 20 percent increase during the previous three decades. This will result in more flooding, soil erosion, declining water quality and damage to homes and infrastructure.

So should we expect Houston-style flooding events in Chicago? Probably not on the same scale. But we are already experiencing major flooding and significant harms to homes, businesses and communities.

In addition, climate change and the city’s stalled embrace of easily available green solutions are certain to make matters worse in coming years. We need to adapt now by embracing simple and inexpensive technologies such as permeable paving, green roofs, tree planting, development of bioswales and disconnection of downspouts to prevent the overfilling of sewers.

By taking preventative measures like these — and of course by challenging the climate change deniers in Washington — we can prevent climate disaster here.

Stephen F. Eisenman is co-founder of the Anthropocene Alliance and Flood Forum USA.

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