We've documented here and on our social media feeds our belief that more zoning and regulation would not have changed the devastation from Hurricane Harvey in any meaningful way ("Piling on Houston" and "Houston isn't flooded becuase of its land use planning"). Even still, many of you are insistent that there is a valuable lesson to learn here, that the "wild west" attitude of Houston/Texas is dangerous and, if karma is to have any meaning, there must be consequences. Specifically, Houston needs proper zoning that would, at a minimum, keep all new construction out of floodplain areas, require additional stormwater management and reduce the amount of impervious surfaces.

We agree there is a lesson to learn here, but that's not it—not in this instance. Here's a thoughtful and credible piece of feedback we received last week challenging our assertions:

I'm a flood modeler, and I will tell you straight up that pretty standard modern landscape planning standards absolutely would have prevented some (by no means all, or perhaps even most) of the misery in Houston. But this is when people are paying attention, and it makes all the sense in the world to say we can and must do better. Climate change science informs us that these seemingly improbable, outlier events are becoming more common and likely. Throwing up our hands and saying nothing at all would have ever made this better is basically negligence when something similar happens again and nothing was done to mitigate because "no one plans for outliers."

No one plans for outliers

Later this week I plan to outline what it would take to accommodate a Hurricane Harvey level of event (hint: it's ridiculous) but for now, let's hone in on the notion of what an outlier is because, contrary to the assertion of many, we can plan for outliers. We just don't plan for outliers the same way we plan for routine or even rare events.

There has been a lot of talk about repeated flooding events in Houston. The notion is, we see this over and over and Harvey is simply another in a long list. The first part of that reaction is true — Houston has seen a lot of flooding — but the second part is not. The website FiveThirtyEight.com has the best graphic on just how much of an outlier Harvey is (I'm jealous; I wish we had that kind of research and graphics capability). Scroll down to the third chart and you'll see a plot of events by inches of rainfall. Harvey is alone in the upper right corner. No other event comes close.

The two recent Houston events that many people yelled at me about were the Memorial Day Flood of 2015 (11 inches) and the Tax Day Flood of 2016 (7.75 inches). FiveThirtyEight suggests Harvey dropped 52 inches of rain on Houston.

There is an assumption — and I think it is debatable at the margins, but that debate is not real important for this conversation — that rainfall amounts follow a normal distribution. In other words, we can plot of the number of events of different intensity levels and there will be far more routine events (trace levels of rain, 1/4 inch of rain, etc...) than outlier events (2 inches, 4 inches, etc...). The more intense the rainfall, the less frequent the events become. Such a distribution would look like this.


Let me be explicit here and repeat something I've said multiple times over the past week: If we're discussing frequently occurring or even rare events, I think the people being critical of Houston for not having good stormwater management have a valid point. If you buy a home with a 30-year mortgage and that home is in the 100-year floodplain, assuming that designation is accurate (it's likely underestimating your risk), you have a 25% chance of being flooded before your home is paid off. That's the simple math of taking a 1% risk every year for three decades in a row. Those are not odds I like, and I find it rather insane that Houston would facilitate people to build — and that the federal government would then offer insurance — within such an area.

With Harvey, we're not talking about that. The people in the 100-year floodplain flooded. So did everyone else. Harvey was, in my chart above, an Extreme Event. It was off the charts. Not absolutely unpredictible, but not something that can reasonably be anticipated and planned for. Not something we'll build a cultural consensus around mobilizing resources.

If we took the most progressive set of planners and public officials and transplanted them in Houston a generation ago and instructed them to do what it took to properly manage stormwater, all of their mitigation systems would have been overwhelmed in the first few hours of Harvey and then everything would have flooded just as it did.

I realize many of you don't care about this nuance. As the commentor said, "This is when people are paying attention, and it makes all the sense in the world to say we can and must do better." To quote Rahm Emanuel from his days as President Obama's chief of staff, never let a crisis go to waste. Let's use this extreme event to mobilize action so Houston — and cities tempted to emulate them — cleans up their act and won't suffer in the more-frequent rare events.

If that's your political stance, fine. Whatever. But if you're here at Strong Towns attempting to understand the world a little better, that kind of simple, linear thinking is not good enough.

Complex Systems during Extreme Events

Cities are complex, adaptive systems. That means a city emerges from a collection of interacting objects, each of which experience their own feedback, are free to adapt their strategies based on their experiences and are influenced by their environment. Such systems have unique characteristics. They often function in ways that are seemingly predictable, until they don't. Complex systems also respond to extreme events in fascinating ways.

As an analogy, I'd like to focus on a complex, adaptive system we are all familiar with: the human body. Under normal circumstances, our bodies are a collection of interacting objects — white blood cells, bacteria, protiens and hormones to name a few — that operate in mostly predictible ways. I've been diagnosed with hypothyroidism, a condition where my thyroid doesn't produce enough hormones. It causes my body to want to store fat and sleep as if I were trying to hibernate. A small pill each day replaces those lost hormones and tricks my body into working fine. It's genius and I'm intensely grateful to the brilliant people who figured this out.

Dr. Scott Somers describes the steps that occur when the body is injured.

Sometimes, however, the human body experiences an extreme event. Once I fell while climbing rocks and another time I was in a serious car crash. Both times I experienced a variation of the body's response, an involuntary set of reactions evolved over tens of thousands — maybe hundreds of thousands — of years. In retrospect, it's an astounding feat.

First, the body goes into shock. It's a preservation mechanism to keep blood flowing to critical places at the expense of the less critical. If you've experienced this, there's also often a shot of adrenaline. I imagine an early version of a sapien attacked be a predator, fighting it off and then fleeing madly only to collapse into a coma as the body shut down to preserve vital functions. That pre-human survived, which is why you have a chance to survive a brush with death today.

Whether or not the body goes into a coma, multiple systems start to kick into a different gear. Metabolism changes. The immune system goes into overdrive. Parts of the body are cheated of normal support so that aid and repairs can be given to injured parts. It's truly remarkable.

Historian and author Rebecca Solnit is the author of A Paradise Built in Hell: The Extraordinary Communities that Arise in DisasterIn listening to the book, it was hard for me not to connect how humans (an evolved species) interact with each other in our cities (our evolved habitat) during times of crisis. As presented in a New York Times review of the book:

“What is this feeling that crops up during so many disasters?” Ms. Solnit asks. She describes it as “an emotion graver than happiness but deeply positive,” worth studying because it provides “an extraordinary window into social desire and possibility.” Our response to disaster gives us nothing less than “a glimpse of who else we ourselves may be and what else our society could become.” Her overarching thesis can probably be boiled down to this sentence: “The recovery of this purpose and closeness without crisis or pressure” — without disaster, that is — “is the great contemporary task of being human.”

Lesson for a Strong Town

You are more likely to survive a traumatic event if you are healthy, not sick. You are most likely to survive it if you are not so young that you're still developing or not so old that you're experiencing decline. You increase your odds if you eat well, exercise and don't live with a lot of stress. In other words, the complex adaptive system that is your body is most likely to carry you through an extreme event the closer to optimal condition you are. You'll get through alive, recover more quickly and then return closer to normal the stronger you are going in.

Of course, by definition, we never know when that extreme event will be. We can't stop aging, but there are a lot of things we can do to help our bodies be stronger and healthier throughout our lives. The great thing is, even if we don't experience that extreme event, the things we do to be stronger and healthier help us in many other ways. There is little downside and lots of upside to healthy living.

This is why it's not good enough to let a myopic reaction to Hurricane Harvey obsessing with stormwater management and regulation dominate our discourse. No reasonable amount of that activity would have mattered for this extreme event, but Houston is a really fragile place. Before this latest disaster, I had the chance to speak with a number of public and private officials, on and off the record, and got a real sense of the impending fiscal disaster that is Houston's city budget. There was no way they were ever going to have the money to fix all the roads, streets, sidewalks, pipes, pumps, etc... that they were obligated to take care of with the tax base they had. This was a pending catastrophe for the people and businesses that depend on those systems. Now that hundreds of billions of that tax base has been destroyed, the desperation is going to ratchet up considerably.

And that is before factoring in pension obligations, staffing levels, current service levels and debt service, all of which depend on aggressive growth from a fragile — now impaired — tax base just to stay even. 

It's not clear to me how Houston will respond to this trauma. Maybe the city will get a lot of federal aid (although the numbers I've seen have underwhelmed), but most of the loss is actually in the private sector. Much of that private loss is uninsured. Maybe this will provide a pretext for Houston to do some community triage and shift their public investments from the unproductive outskirts to their more productive downtown and core neighborhoods. Maybe the reduced emphasis on regulation and taxation will be a driver of the economy and allow them to adapt in novel ways. I'm not predicting Houston's demise, but the poor financial health of their city government has given them little margin for error.

For extreme events, we can't measure risk, but we can measure fragility. Cities that want to protect themselves from extreme events need to become less fragile. They need to adopt a Strong Towns approach.

Later this week I'm going to examine the myopia of the planning profession, "flood modelers" and policy wonks and the psychology that drives them to learn the wrong lessons from events like Harvey. I'm also going to look at what it would take to design a stormwater system for an extreme event like Harvey (it's insane). I'd also like to take a deeper look at complex versus complicated systems (in Nassim Taleb language: the difference between a cat and a washing machine) as a prelude to examining what a policy approach based on stormwater management will look like (see: New Orleans post-Katrina) as well as the tradeoffs involved (funding ditches, not schools). We should also examine how we can use antifragility during frequent events to improve our robustness to extreme events.

Finally, because I was told a number of times how irresponsible I was to not obsess about climate change, we're going to take some lessons from Fooled by Randomness and hopefully find a way to explain rare/extreme events without making everyone ticked off. 

(Top photo from Wikipedia)

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