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Flood, the Routine Disaster



Flood at El Morro National Monument

US Fish & Wildlife Service image by Gary Stolz
Floods struck Venezuela in December 1999, after weeks of rain. Overflowing rivers and mudslides down the overpopulated mountain slopes killed tens of thousands of people, wiping out whole towns. The new president, Hugo Chavez, quickly blamed the previous adminstration: "There were governments violating the laws of nature. Nature has its own laws." He was right, but what he didn't say was that all governments violate the laws of nature.

Look back a few months earlier in 1999. It was a typical year: Floods killed hundreds of people in Vietnam and in Mexico during October. Flooding caused by Hurricane Floyd killed 70 North Americans in September. Flooding killed hundreds in East Asia in August. Between 1980 and 2003, billion-dollar natural disasters struck the United States 58 times, and 30 of them involved flooding. Floods are disasters, but they happen all the time. They're routine disasters.

Traditional peoples have always known that floods do good. Floods deliver new sediment to the bottomlands around rivers, and that renews the soil. They clear years of brush and dead vegetation from streambeds, making it easy to travel on the river. Flooding leaves clear waters and refreshed habitats behind. But modern people use riversides for other things, like commerce and residences, and the routine flooding that comes with riverside living ruins their livelihood. Governments that try to fight the natural order inevitably lose the war, no matter how many battles they win in one particular decade or century.

The geologist shares part of the ancient traditional outlook—anything that happens all the time, even if it's a disaster, is part of what makes the natural landscape. It happens that floods do almost all of a river's work in moving sediment, clearing out blockages and changing river courses—not the years of "normal" erosion. Normal weather is no more than down time between floods, and the river is basically sleeping. Rivers don't stay healthy unless they can wake up and burst out of their banks now and then.

Levees, those banks of sediment that line the sides of large rivers, are the product of flooding. Deep river channels, suitable for boats, will fill up with silt without a regular flushing by floodwater. And farther downstream, ocean beaches will be eaten away by the surf until fresh sand arrives from flooding rivers. The natural process is a disaster for humans only when they're standing in the way.

An impressive demonstration of the geologist's philosophy took place in the Grand Canyon in March 1996. Ever since the Colorado River was dammed in 1963, the ecosystem at the canyon's bottom has suffered—native fish found less quiet water for spawning, the sandy banks were eroding and being overgrown. So the government, after careful study, decided to let loose an artificial flood from the Glen Canyon Dam. After that successful trial, it was done again in late 2004.

One hope for better ways to deal with flood is modeling a flood before it happens. Consider these two technical articles from Eos, one on improvements in flood forecasting and the other on the potential for satellite-based measurements to assess the state of a rivershed with a snapshot. Maybe this kind of knowledge will keep people out of dangerous floodlands—if governments stop violating the laws of nature.

PS: The United Nations' ReliefWeb coordinates relief efforts for disasters everywhere.

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