As we watch Houston struggle with the catastrophic flooding associated with Hurricane Harvey’s biblical levels of rainfall, it is easy (from a safe distance, anyway) to get judgmental about the city’s famous lack of land-use planning. Houston legendarily has no zoning. The resulting haphazardness of its patterns of development, we may imagine, make the city a sitting duck for all sorts of disasters.
It’s true that Houston’s sprawl does invite problems, but it’s only partially true that the sprawl is a result of its lack of zoning. Houston actually does have has some actual zoning near its three airports, and also sort of quasi-zoning, much of it imposed by developers and individual neighborhoods. But more important, even comprehensive zoning laws don’t prevent the sort of sprawl that really does make Houston even more prone to the flooding which low elevation and the proximity of a warming ocean makes likely.
One urban planning expert familiar with Houston suggests it’s the ability of developers to bootstrap the infrastructure they need through easy access to tax-exempt financing that has really fed the city’s massive sprawl. And virtually everyone agrees Houston’s highway system, which its multiple concentric ring roads, is a big contributor to the city’s unusually large area of metro development.
But the bigger problem is a lack of regional planning. Development has overwhelmed the city’s World War II–era reservoir system of flood control and consumed the wetlands that absorb excess rainwater.
A prophetic 2016 ProPublica/Texas Tribune article on Houston’s unique vulnerability to flooding noted these changes in great detail:
In Harris County alone, research by Texas A&M scientist John Jacob shows, almost 30 percent of freshwater wetlands were lost between 1992 and 2010, a figure he calls “unconscionable.”
As wetlands have been lost, the amount of impervious surface in Harris County increased by 25 percent from 1996 to 2011, Brody said. And there’s no way that engineering projects or flood control regulations have made up for that change, he said.
But even if there wasn’t so much sprawl, and there were more wetlands and sufficient drainage, no one in Houston could have anticipated how frequent previously unusual flooding events would become. There are 140,000 homes in the 100-year floodplain in Greater Houston. That’s bad enough, since Houston has had eight once-in-a-century storms since 1989. But Houston has now had “500-year-floods” — which means the kind there should only be a 1-in-a-500 chance of occurring in any one year — for three straight years now. No city is prepared for that, much less a city with as limited a planning process as Houston’s.
So unless you want to attribute all the ever-increasing frequency of dangerous flooding to bad luck or statistical noise, there are some pretty clear lessons: Don’t let your flood-prone city grow beyond its capacity to absorb floodwaters, and make planning for a flooding catastrophe a day-in-day-out preoccupation. Oh, and yes: Perhaps we should stop ignoring evidence that climate change is rapidly increasing the likelihood of violent, debilitating storms.
Let’s hope Americans never become entirely accustomed to the sights and sounds of flooded roads and streets; people being rescued from roofs; cities taking years and many billions of dollars to recover. But in places like Houston, it’s not a matter of whether catastrophe will strike. It’s just a matter of when.
