This article appeared in the March-April 2004 issue of Science & Spirit.
A River Runs Through It
by Barbara Stahura
At the tail end of the summer monsoon, a storm deluged the far-east side of Tucson. A driving rain pelted the bare, desert soil for more than an hour, accompanied by marble-sized hail that hit the ground and bounced. I walked through the house, opening windows with enough overhang to keep out the wet, delighting in the feel of the moist air and the sound of pattering rain. A rainstorm feels more of a miracle in the desert than it does near the southern tip of Lake Michigan, where I grew up.
With hard-packed sand substituting for lawns here, there is nothing to soak up a long, drenching rain. As the rain tapered off, I heard rushing water: The storm had transformed the normally dry wash winding through our neighborhood into a fierce torrent. The fast-running water, no higher than my ankles, became dirty-beige wavelets as it sped through our backyard.
Hundreds of washes gouge this region, hardtack-dry most of the time. But during a heavy rain, many of them roil with unstoppable water: Even when it’s only a foot deep, fast-moving water can float a vehicle and carry it away. Thus, many streets throughout this sprawling city display yellow signs warning, “Do Not Enter When Flooded.” It’s surprising how many people ignore them; local fire departments rescue the swept-away during nearly every significant downpour. This is such a common occurrence that Arizona has a “Stupid Motorist Law,” stating that people who drive around barricades into a flooded roadway can be liable for the cost of their rescue, up to $2,000.
Within an hour of the storm’s end, the empty, damp bed of my backyard wash was the only trace of its brief life as a small river. But the surprise of the earlier flow started me thinking about the inherent paradox: Sometimes, there can be too much water in the desert.
Flash floods occur every monsoon season and every winter, occasionally drowning people caught unaware. At lower elevations, floods can explode under blue skies, rain having let loose over the mountains surrounding the city. This past August, the National Weather Service reported 1.8 inches of rainfall in twenty-five minutes in the nearby Oracle area one afternoon. A man died when a flood from that storm swept down Bonito Canyon and through his home, possibly hurtling him through the downstream corner, then nearly a mile further. The floodwaters also rammed his Toyota 4Runner into the next house, 100 feet away.
