China Floods Exacerbated By Man's Impact on Land, Climate

[DisasterRelief, 19 Aug 1998]

Written by Doug Rekenthaler, Managing Editor, DisasterRelief.org

As the world's attention once again is drawn to the massive floods sweeping across large sections of China, a growing chorus of voices is suggesting that mankind is playing an increasingly important role in both the scope and severity of those floods.

Thus far this summer, China's floods have killed at least 2,000 people (although the actual toll is believed to be much higher), driven 14 million people from their homes, and destroyed 11 million acres of croplands in a nation that perpetually struggles to feed its 1.2 billion citizens. Unfortunately, the worst is far from over.

Heavy rains continue to pound large stretches of the country as a succession of low-pressure systems seemingly march in lockstep across China's northern and western reaches. The additional waters pour into already overfed rivers and streams, sending one flood crest after another crashing down the mighty Yangtze as well as other, lesser-known rivers. Sodden levees suffer breaches or simply collapse under the relentless assault, sending hundreds of thousands fleeing for higher ground.

Across the affected flood zones, millions of people have taken up residence on levees, with fears that more floods -- and the diseases that accompany them -- will raise the death toll. At least one-third of the world's largest army, or about one million soldiers, have been drafted into the flood-fighting campaign, which ultimately is expected to cost the country a half-percent or more of its annual gross domestic product.

Human Fingerprints All Over Floods

For decades, the floods -- especially along the Yangtze, the world's third largest river -- have been a way of life for millions of Chinese, an annual scourge that arrives with the summer's monsoon rains. But this year's floods have been among the worst in Chinese history, and they aren't confined solely to the Yangtze. In the northeast and northwest, heavy rains have sent a number of rivers to record levels and chased millions from their homes and businesses.

For its part, the Chinese government blames the floods on Mother Nature and a chronic lack of funds necessary to strengthen an immense string of levees that border nearly half the 6,300-kilometer course of the Yangtze. The government is pouring billions into the construction of the mammoth Three Gorges Dam, which is intended to produce enormous quantities of electricity and put an end to -- or at least partially contain -- the annual floods.

But in recent years, critics increasingly have complained that the Chinese government has practiced policies -- both official and unspoken -- that exacerbate an already devastating situation. Specifically, the government is charged with permitting human encroachment and development in places that heretofore had been ceded to the flood waters. For example, tens of millions of homes and businesses have been built along the Yangtze flood plain, essentially hemming in the river and stealing its high-water outlets.

According to the Worldwatch Institute in Washington, the Yangtze basin is home to 400 million people -- one-third of the Chinese population. ``To understand the population pressure in eastern and southern China,'' says a recent release from Worldwatch, ``imagine squeezing the entire U.S. population into the area east of the Mississippi River and then multiplying it by five.''

Worldwatch President Lester Brown, a co-author of the paper, said development in the basin is taking place at a ``staggering pace.'' In essence, human development increasingly is putting the squeeze on the river, meaning even moderate floods are affecting more and more people.

Additionally, fully 85 percent of the Yangtze's original forest cover has been clear-cut. As a result, heavy run-off from torrential rains is continually pushing massive quantities of silt into the river. This raises water levels which, in turn, force flood control officials to constantly raise the height of the surrounding levees. Besides controlling erosion, the trees also absorbed the heavy rains and controlled their migration into the soil. With the trees largely supplanted by buildings and blacktops, the rains have nowhere to go but directly into increasingly constricted rivers and streams -- a recipe for massive flooding.

Concern also is mounting that climate changes are contributing to heavy rainfall totals. Specifically, Worldwatch and other environmental watchdog groups believe that warmer global temperatures are leading to faster snow melts along the Yangtze headwaters in the Tibetan Plateau, which often kickstarts the flood season. Also, warmer temperatures lead to high evaporation rates, and what goes up eventually must come back down. ``Where it comes down is less predictable,'' says the Worldwatch release. ``But the Yangtze basin may well be one of the areas getting some of the additional rainfall.''

In short, as the burgeoning Chinese population continues to put more and more pressure on the Yangtze and rivers like it, this summer's record floods may become the norm rather than the exception.