Flood of evidence


Furious floods

Too many floods

Fewer trees = more floods?

Wetlands and floods

Flood prevention: the earthmover approach

 
Short of sandbags? Try this human-wave approach to levees, photographed in China.

Courtesy USC-UCLA Hope Primary School.


 

A man holds his son with rippled sand beneath their feet. A farmer surveys the six-foot layer of sand that destroyed a farm field behind a levee break near St. Louis.

Copyright David Tenenbaum.



 


Cincinnati looks even more humid than usual in the 1997 flood.

(Ernest Coleman photo). Courtesy The Cincinnati Enquirer.


Men up to their chests in river water. A flood of floods
There have been plenty of catastrophic floods over the past few years:

  • 1993 - Mississippi and Missouri Rivers, United States. Hundreds of levee breaks flood low-lying towns and fields, leaving enormous scour holes and deep deposits. The cost is estimated at $16 billion. These rivers, draining one of the largest watersheds in the world (3.2 million square kilometers) have been extensively altered for barge traffic and flood control, and encased between thousands of miles of levees.

  • 1997 -- The Red River, North Dakota and Minnesota, United States. The river floods parts of two states for several months.

  • 1998 -- Yangtze River, China. More than 4,000 die and 223 million are dislocated. Twenty-five million hectares of farmland are inundated, and the overall cost exceeds $36 billion.

  • 1998 -- Central America. After an astonishing rainfall from a stalled Hurricane Mitch, half the population of Honduras lose their homes or are evacuated. The flood costs Honduras about $4 billion -- and Nicaragua about $1.5 billion -- roughly equal to each nation's gross domestic product. The deadliest Atlantic storm in 200 years kills 10,000, leaving profound ecological devastation, with erosion, siltation and loss of farmland.

  • 1999 -- North Carolina, United States. The Neuse and Cape Fear Rivers overflow their banks during Hurricane Floyd, spilling 100 million gallons of filth from hog manure storage tanks and municipal sewage systems (see "Hell in High Water" in the bibliography). The storm kills 77 and causes about $6 billion in damages.

Cincinnati looks even more humid than usual in the 1997 flood. A pattern in the wave of disasters?
There's also evidence that disasters are becoming more common. According to historic records, centuries ago the Yangtze flooded Hunan province roughly once every 20 years, now it floods nine years out of 10. The Rhine at Karlsruhe, Germany, rose 7.6 meters above flood stage only four times between 1900 and 1977. Between 1978 and 1996, it reached that point 10 times (see "Imperiled Waters..." in the bibliography). The hand of humans is evident in a lot of these disasters. They are unnatural disasters.

As we've mentioned, natural disasters in 1998 alone were more costly than they were during the entire 1980s. Munich Re, a German insurer, has estimated that the overall cost of natural catastrophes has increased nine-fold since the 1960s. Floods are the major contributor to this sum.

To Abramovitz, the evidence is clear: "A lot of people say [floods] are natural disasters -- the hand of God. I say the hand of man is really evident in a lot of these, and that makes them unnatural disasters."

One mechanism, clearly, is greenhouse gases and global warming, which, many scientists suspect, is changing the climate and increasing the number and intensity of storms. But more localized -- yet still important -- changes are also leading to epic floods from non-epic rainfall.

What is the role of deforestation in floods?



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