From nuisance floods to severe storms, most communities aren’t at all prepared for extreme weather. The climate is changing. It’s absurd to politicize it, because the climate always has been and always will be changing and humans can’t control it. Not even Al Gore-type humans. But with the vast majority of 7.5 billion humans living in cities that depend on centralized water infrastructure, the effects of extreme weather can be devastating.
Climate resilience was a fancy buzz-phrase ten years ago. It actually means something today, as 2019 marked the fifth consecutive year that the U.S. endured 10 or more extreme weather events causing greater than $1 Billion in damage each. And while the storm events that cause the most damage are newsworthy, we rarely hear about the smaller events that are occuring much more commonly. Smaller scale flooding is happening all the time in cities across the country, causing property damage and threatening the security of urban water systems.
Stormwater management is the policy, planning, engineering, implementation, and maintenance of urban water systems. It is a critical component of any city’s water infrastructure. But since these systems are conceived within the limits of expected behavior, it should come as no surprise that they are continually overwhelmed by larger storm events. From New York to Minnesota, a common theme endures: in the face of extreme weather, our nation’s stormwater infrastructure is failing.
Communities across the U.S. are responding on very different ends of the spectrum. In some cases, towns are trying to buy out flood-prone neighborhoods and turn them into wetlands. On the other end of the spectrum, officials keep their heads in the sand and do nothing. The majority of U.S. cities, however, recognize serious vulnerabilities within current infrastructure. Unfortunately, upgrading mammoth assemblages of underground plumbing and conveyance isn’t cheap, and a one-size-fits-all approach to stormwater management isn’t practical.
Remember how I mentioned that existing stormwater infrastructure in this country was conceived within the limits of what used to be expected? Federal rainfall estimates are continually being adjusted upward. As an example, a 100-year storm event in Minnesota, over the course of 24 hours, used to produce 6 inches of rain. Today that same storm is expected to produce 8 inches. In Austin, a 24 hour, 100-year rainfall event has increased by an average of 3 inches, and in Houston it’s increased by 5 inches!
Cities that commit to an evolving stormwater design philosophy will be most prepared for this type of sudden weather event. A shift from grey infrastructure - the pipes and conveyance system that moves runoff someplace else - to a more natural approach that manages stormwater right where it falls, will be critical to the future resilience of urban water systems.