When the Dam Breaks
Millions of people are potentially just hours away from seeing their homes inundated. How do you prepare for that?
Image: Wikimedia Commons
Dubai, the fabulous desert city in the United Arab Emirates, just experienced a mind-boggling flood event. Dubai’s airport on average receives 3.73 inches of rain per year. This week it got 5.59 inches in a single 24 hour period. Other parts of the UAE saw as much as 10 inches.
This is not normal. That amount of rain more than doubles the region’s 1-in-100 year storm probability. Some climate change skeptics tried to blame it on cloud seeding flights, but the storm was already forecasted several days earlier.
We don’t know exactly how climate change may have affected this. We do know global warming is about more than heat. Warmer air holds more moisture, which then travels via clouds. More water caught up in transit means drought in some places and the opposite in others: short periods of intense rainfall, causing more floods.
Humans have become pretty skilled at controlling floods with dams, levees, and reservoirs. Often these help farmers and supply water to cities. All good… except most were designed for conditions that no longer exist.
Just this month, for example, workers in Utah noticed an ice sheet floating on unusually high water had caused a 60-foot crack in the Panguitch Lake Dam, about 10 miles upstream of a town. Had the dam broke, the town would have been washed away within hours, along with any of the 1,800 residents who didn’t evacuate fast enough.
Fortunately, local authorities moved fast, piling giant boulders over the crack and opening floodgate to relieve pressure on the dam. What would have been a major disaster became a minor news footnote.
But these close calls are happening more often. Last year a huge rainstorm in Libya collapsed the two Wadi Derna dams, unleashing floodwaters that killed more than 10,000 people downstream.
Those dams appear not to have been well maintained. But unstable dams aren’t unique to unstable developing countries. The US has over 2,200 of them, according to a recent Associated Press analysis. Many were built 50 or more years ago. Since then, a lot of development has happened in the flood zones below these dams.
This means flooding isn’t just a coastal problem. Millions of people are potentially just hours away from seeing their homes inundated. How do you prepare for that?
First, know the threat. It’s highly specific to your local topography. But if you live near any kind of lake, river or stream, think about how high that water could rise in an extreme rainstorm. Assume it will go significantly higher than ever before.
Second, if your location is vulnerable, have an evacuation plan. Where will you go and what will you take with you? Thinking ahead pays off.
Third, if you’re a homeowner, look into protecting your property. You might be able to do some landscaping that looks nice and holds back the water, too. Small fixes to your plumbing can help keep water (and worse, sewage) out of the house, too.
Watch this fascinating Japanese TV show about how flooding happens. It’s only 15 minutes, with English dubbing and subtitles.
Video: NHK World Japan
In the video, you’ll see an amazing test of a Japanese home designed to actually float above flood waters. I’m not sure US building codes would allow that here, but the concept still makes a good point.
We aren’t powerless against these increasingly common disasters. We have options. We just have to use them.