Why Miami Beach isn’t planning for epic rain like Emily’s

All of Miami-Dade seems to have one big question after Tuesday night’s floods: Why did this happen when we’ve spent millions on raising roads and installing pumps?

As the Internet outrage built up Tuesday, fueled by commuters furious about wading and driving through knee-high water and residents seeing their garages and cars swamped, Miami Beach government sent out a frantic explanation of what was going on:

We have mobilized flood teams throughout the city, but we are currently experiencing an unprecedented amount of rainfall with a rate of over 7 inches per hour due to the remnants of Tropical Storm Emily. This amount of rainfall is twice our design criteria for our storm water infrastructure. …

There are also reports of power outages and traffic lights throughout the city. These power outages have caused some pump station electrical systems to be temporarily down, and the city is deploying emergency generators as needed.

The public response seemed to be “Why would they design for less than yesterday’s rainfall? It wasn’t even a tropical storm anymore when it hit us, and we get hurricanes.”

Fair question, because this 👇


So we asked Susanne Torriente, the chief resilience officer for Miami Beach, to explain. Here’s what she said in an email:

Cities don’t design for extreme events. That would be very costly, rather unattractive due to size and, quite frankly, we are a seven square mile built-out island – not much space left.  Yesterday was an extreme event with a rainfall rate of more than nine inches an hour and a total of 6 ½ inches from 2 PM to 5 PM.  [Brickell, which got the most rain on the mainland, got 5.5 inches of rain in the same time frame, according to Jane Gilbert, their CRO. Editor’s note: This sentence has been edited to correctly reflect the rainfall total.]

Our system can handle three inches an hour, hour after hour.  When you hear it is designed to the five-year storm, that means it can handle seven inches in 24 hours and the expectation and plan is that within 24 hours you are dry. We design for the high end of the five year storm. So, that is where patience and planning comes in – delay your drive, don’t walk in flood waters.

The point is this: Miami and Miami Beach aren’t trying to keep the cities dry during a hurricane, a tropical storm – or even a crazy strong storm like yesterday (which coincided with an approaching high tide and followed days of heavy rain, making it even worse, according to Jane Gilbert, the City of Miami CRO).

Those events are just not frequent enough to justify the cost, they said.

Governments are trying to keep the city dry during the normal storms and sunny day flooding we experience on the regular. And we’re getting better at that – ask anyone who was living on South Beach before the pumps were installed. (Gilbert says City of Miami will install a permanent pump near Mary Brickell Village, which got slammed Tuesday, by the end of the year.)

But most people don’t notice when something works the way it’s supposed to, they notice the moment when something doesn’t work – no matter how extra the circumstances are.

And that’s a big perception problem, because while local governments are trying to keep above the water on a daily basis, what will be on everyone’s minds are extreme moments like Tuesday, when cars were lifted off the ground. Which means when the city spends hundreds of millions of dollars on resilience efforts and says they’re working, in the worst moments they look a whole lot like they’re not.

That’s only going to make it seem like sea level rise is more and more out of our control, even as we get better at handling the day-to-day stressors.

It’s TBD if any level of innovation will ultimately keep the Magic City livable. We’ve still got a long way to go, and climate change is going to constantly raise the bar.