Three Gorges Probe

Severe floods expected to put new dam to the test

Kelly Haggart
May 27, 2003

Abnormally heavy flooding on the Yangtze River this summer is expected to put the newly built Three Gorges dam to its first major test.

Chinese weather experts are predicting more rainfall than usual this
year, which could cause severe floods in the Yangtze Valley. The
Beijing-based State Meteorological Bureau says precipitation in the
Dongting and Poyang lake areas downstream of the dam is likely to be
20-per-cent greater than normal this summer.People’s Daily ascribed the “high possibility of massive rainfall in
the Yangtze’s middle and lower reaches … mainly to the influence of
El Nino.”

One of the worst Yangtze flood years of the past century occurred in
1998, when more than 3,000 people died. Officials are keeping an
anxious eye on water levels this year, which in some areas have been
similar to those recorded in 1998. Scores of people have already died
in storms and floods that have hit southern China since mid-May.

Li Yongan, vice-manager of the Three Gorges Project Development
Corp., has stressed the importance of being well prepared for the
coming floods, which will put immense pressure on the dam for the first
time. Meeting the flood-management challenge will help ensure that the
goal of generating 5.5 billion kWh of hydropower this year is met, he
added.

Since the temporary shiplock at the Three Gorges project was taken
out of operation on April 10, the flow of water through the dam has
relied entirely on 23 outlets at the bottom of the dam and 22 surface
sluice gates. If things go according to plan, these structures will be
closed June 1, and the reservoir water level will rise by less than
five metres a day, until the 135-metre level is reached on June 15. But
if floodwater coming from upstream areas is more abundant than usual,
the 135-metre level will be reached sooner than planned and the sluice
gates will be pressed into service to discharge the excess water.

Meanwhile, the World Health Organization has warned that the summer
floods could cause sewage systems to overflow, complicating China’s
fight against severe acute respiratory syndrome (SARS).

“We see this as a potential threat, something to beware of,” said
Bob Dietz, a WHO spokesman in Beijing. “SARS could rear up again.”

Mr. Dietz saw no way of preventing the problem. “You can’t stop
flooding and there’s nothing that can be done to improve sewage systems
at such a short order,” he said.

While the SARS virus is not thought to be transmitted by water, it
does appear to survive for days in human waste. Hundreds of residents
of the Amoy Gardens apartment complex in Hong Kong contracted SARS in
March and April after a malfunctioning sewage system spread the virus
around the building.

Thousands of rural residents could face a similar threat during
China’s flood season, when water laced with sewage can inundate homes
and contaminate drinking water.

The WHO warning, which referred to natural, annual floods, also
raises an unanticipated concern about the imminent manmade flooding of
the Three Gorges area.

Thousands of public toilets were among the areas that had to be
cleaned up before the huge reservoir begins to form behind the Three
Gorges dam. According to a survey
conducted in the early 1990s by Chongqing’s Centre for Disease Control
and Prevention, the reservoir area contains 300,000 square metres of
public toilets and 1,500 slaughterhouses.

With China’s SARS crisis underscoring the importance of a thorough scrubbing of the reservoir bed, the South China Morning Post
reported in March that the cleanup campaign was faltering. The Hong
Kong newspaper quoted State Environmental Protection Administration
(SEPA) official Xie Zhenhua as saying that water pollution in the dam
region was higher than expected, that many industrial wastewater
treatment projects were not meeting targets, and efforts to remove
garbage from the area were moving slowly.

And just two weeks ago, SEPA issued a directive
calling on officials in the Three Gorges area to redouble their efforts
to remove all possible sources of infectious disease, including SARS,
before the reservoir begins storing water this Sunday.

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