Video of Flood-Swept Debris Is Terrifying and Mesmerizing

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Aug. 15 2013 11:00 AM

Staying Ahead of the Flood

flash flood
The dark advance of a debris-choked flash flood.

Photo by David Rankin, from the video

I can’t help thinking that this is an astoundingly foolish thing to do, yet at the same time being mesmerized by this: Photographer David Rankin catches the front wave of a flash flood in Utah which is carrying a huge amount of debris.

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Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death from the Skies! Follow him on Twitter.

If you are wondering just how dangerous this is to do, start watching at about 2:50 in, when the water is pushing a large and presumably very heavy boulder downstream. A human caught in that flood wouldn’t have a chance. They’d be dead.

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I strongly urge people not to do this! Getting video of a flood in this manner is incredibly dangerous; if the water is moving faster than you expect it might be hard to get out of the way. A slight miscalculation—like, say, slipping in the soft, loose bank soil, or tripping over a rock on the uneven surface—and under you go. That amount of debris moving at even at a slow pace packs a helluva wallop. And if you’re distracted holding a camera, and trotting backwards, well, you’re just asking for a Darwin Award.

But this is still fascinating. Years ago I was in New Orleans about a year after hurricane Katrina tore the town apart. I was driving in one section, and noticed all the street and stop signs were bent in the same direction, like they had been hit with a sledgehammer one after another by someone in a passing car. I realized the flood waters did this… but it wasn’t the water, it was the debris being carried by the water. Branches, trees, even cars must have floated down the streets, slamming one by one, over and again, into the signposts, bending them over.

That’s when I learned that although floods are dangerous, the debris they carry is even more dangerous. As Rankin points out on his web page, these kinds of floods kill more people every year on average than hurricanes, tornadoes, or lightning. Surprise is a big factor, of course, but the debris sweeping down must be a significant factor as well.

If there is one thing this video does for me, it reinforces just how sudden and disastrous nature can be. My hometown of Boulder doesn’t suffer from earthquakes or hurricanes, but we do get the occasional tornado and, every few decades, a pretty big flood. The wildfires we’ve been experiencing amplify flooding as well, since plants burn away that would otherwise soak up rainwater and help retain loose soil. That means floods can turn into debris flows, which can do even more damage.

It’s chilling, but useful, to be reminded every now and again that nature remains largely untamed.

Tip o’ the lens cap to Fark.