SHANGHAI—For over three decades
the Chinese government dismissed warnings from scientists and environmentalists
that its Three
Gorges Dam—the world's largest—had the potential of becoming one of
China's biggest environmental nightmares. But last fall, denial suddenly
gave way to reluctant acceptance that the naysayers were right. Chinese
officials staged a sudden about-face, acknowledging for the first time
that the massive hydroelectric dam, sandwiched between breathtaking cliffs
on the Yangtze River in central China, may be triggering landslides, altering
entire ecosystems and causing other serious environmental problems—and,
by extension, endangering the millions who live in its shadow.
Government officials have long defended the
$24-billion project as a major source of renewable power for an energy-hungry
nation and as a way to prevent floods downstream. When complete, the dam
will generate 18,000 megawatts of power—eight times that of the U.S.'s
Hoover
Dam on the Colorado River. But in September, the government official
in charge of the project admitted that Three Gorges held "hidden dangers"
that could breed disaster. "We can't lower our guard," Wang Xiaofeng,
who oversees the project for China's State Council, said during a meeting
of Chinese scientists and government reps in Chongqing, an independent
municipality of around 31 million abutting the dam. "We simply cannot
sacrifice the environment in exchange for temporary economic gain."
The comments appeared to confirm what geologists,
biologists and environmentalists had been warning about for years: building
a massive hydropower dam in an area that is heavily populated, home to
threatened animal and plant species, and crossed by geologic fault lines
is a recipe for disaster.
Among the damage wrought: "There's been
a lot less rain, a lot more drought, and the potential for increased disease,"
says George Davis, a tropical medicine specialist at The George Washington
University (G.W.) Medical Center in Washington, D.C., who has worked in
the Yangtze River Basin and neighboring provinces for 24 years. "When
it comes to environmental change, the implementation of the Three Gorges
dam and reservoir is the great granddaddy of all changes."
Dam Quake
When plans for the dam were first approved
in 1992, human rights activists voiced concern about the people who would
be forced to relocate to make room for it. Inhabited for several millennia,
the Three Gorges region is now a major part of western China's development
boom. To date, the government has ordered some 1.2 million people in two
cities and 116 towns clustered on the banks of the Yangtze to be evacuated
to other areas before construction, promising them plots of land and small
stipends—in some cases as little as 50 yuan, or $7 a month—as compensation.
Chinese and foreign scientists, meanwhile,
warned that the dam could endanger the area's remaining residents. Among
their concerns: landslides caused by increased pressure on the surrounding
land, a rise in waterborne
disease, and a decline in biodiversity. But their words fell on deaf
ears. Harnessing the power of the Yangtze has been a goal since Nationalist
leader Sun Yat-sen first proposed the idea in 1919. Mao Zedong, the father
of China's communist revolution, rhapsodized the dam in a poem. The mega-
project could not be realized in his lifetime, however, because the country's
resources were exhausted by the economic failures of the Great Leap Forward
in the late 1950s and then the social upheaval of the Cultural Revolution
from the mid-1960s a to the early 1970s. Four decades later, the government
resuscitated Mao's plans. The first of the Yangtze's famed gorges—a collection
of steep bluffs at a bend in the river—was determined to be the perfect
site.
In June 2003, nine years after construction
began, the state-owned China Yangtze Three
Gorges Development Corporation (CTGPC) filled the reservoir with 445
feet (135 meters) of water, the first of three increments in achieving
the eventual depth of 575 feet (175 meters). The result is a narrow lake
410 miles (660 kilometers) long—60 miles (97 kilometers) longer than Lake
Superior—and 3,600 feet (1,100 meters) wide, twice the width of the natural
river channel. Scientists' early warnings came true just a month later,
when around 700 million cubic feet (20 million cubic meters) of rock slid
into the Qinggan River, just two miles (three kilometers) from where it
flows into the Yangtze, spawning 65-foot (20-meter) waves that claimed
the lives of 14 people. Despite the devastating results, the corporation
three years later (in September 2006) raised the water level further—to
512 feet (156 meters). Since then, the area has experienced a series of
problems, including dozens of landslides along one 20-mile (32-kilometer)
stretch of riverbank. This past November, the ground gave out near the
entrance to a railway tunnel in Badong County, near a tributary to the
Three Gorges reservoir; 4,000 cubic yards (3,050 cubic meters) of earth
and rock tumbled onto a highway. The landslide buried a bus, killing at
least 30 people.
Fan Xiao, a geologist at the Bureau of Geological
Exploration and Exploitation of Mineral Resources in Sichuan province,
near several Yangtze tributaries, says the landslides are directly linked
to filling the reservoir. Water first seeps into the loose soil at the
base of the area's rocky cliffs, destabilizing the land and making it prone
to slides. Then the reservoir water level fluctuates—engineers partially
drain the reservoir in summer to accommodate flood waters and raise it
again at the end of flood season to generate power—and the abrupt change
in water pressure further disturbs the land. In a study published in the
Chinese journal Tropical Geography in 2003, scholars at Guangzhou's South
China Normal University predicted that such tinkering with the water
level could trigger activity in 283 landslide-prone areas.
That is apparently what happened to the 99
villagers of Miaohe, 10 miles (17 kilometers) upstream of the Yangtze,
who saw the land behind their homes split into a 655-foot- (200-meter-)
wide crack last year, soon after the reservoir water level was lowered
for the summer floods. Officials evacuated them to a mountain tunnel where
they camped for three months.
One of the greatest fears is that the dam
may trigger severe earthquakes, because the reservoir sits on two major
faults: the Jiuwanxi and the Zigui–Badong. According to Fan, changing the
water level strains them. "When you alter the fault line's mechanical state,"
he says, "it can cause fault activity to intensify and induce earthquakes."
Many scientists believe this link between
temblors and dams—called reservoir-induced seismicity—may have been what
happened at California's Oroville Dam, in the foothills of the Sierra Nevada.
The largest earthen dam in the U.S., it was constructed on an active fault
line in the 1950s and filled in 1968. Seven years later, when the reservoir's
water supply was restored to full capacity—after engineers lowered it 130
feet (40 meters) for maintenance—the area experienced an unusual series
of earthquakes. U.S. Geological Survey seismologists subsequently found
a strong link between the quakes and the refilling of the reservoir.
The Oroville area was sparsely populated,
so little damage was done. But earthquakes have also been connected to
past hydropower projects in China, where dams are often located in densely
populated and seismically active river basins. Engineers in China blame
dams for at least 19 earthquakes over the past five decades, ranging from
small tremors to one near Guangdong province's Xinfengjiang Dam in 1962
that registered magnitude 6.1 on the Richter scale—severe enough to topple
houses.
Surveys show that the Three Gorges region
may be next. Chinese Academy of Engineering scholar Li Wangping reports
on the CTGPC's Web site that the area registered 822 tremors in the seven
months after the September 2006 reservoir-level increase. So far, none
have been severe enough to cause serious damage. But by 2009, the dam's
water level is set to be raised to its full 575-foot capacity and then
lowered about 100 feet (30 meters) during flood season. That increase in
water pressure, in water fluctuation and in land covered by the reservoir,
Fan says, makes for a "very large possibility" that the situation
will worsen.
Local news media report that whole villages
of people relocated to make room for the dam will have to move a second
time because of the landslides and tremors, indicating that officials failed
to foresee the full magnitude of the dam's effects. Guangzhou's Southern
Weekend late last year reported that villagers in Kaixian County were eager
to move again, citing landslides, mudslides and ominous cracks that had
appeared in the ground behind their homes. They also hoped that moving
might resolve land allocation issues: Some said they received only half
of the acreage they had been promised.
Water Displacement
The dam is also taking a toll on China's animals
and plants. The nation—which sprawls 3.7 million square miles (9.6 million
square kilometers)—is home to 10% of the world's vascular plants (those
with stems, roots and leaves) and biologists estimate that half of China's
animal and plant species, including the beloved giant
panda and the Chinese sturgeon, are found no where else in the world.
The Three Gorges area alone accounts for 20% of Chinese seed plants—more
than 6,000 species. Shennongjia, a nature reserve near the dam in Hubei
province, is so undisturbed that it is famous for sightings of yeren, or
"wild man"—the Chinese equivalent of "Big Foot"—as well as
the only slightly more prosaic white monkey. |
That biodiversity is threatened as the dam
floods some habitats, reduces water flow to others, and alters weather
patterns. Economic development has spurred deforestation and pollution
in surrounding provinces in central China, endangering at least 57 plant
species, including the Chinese dove tree and the dawn redwood. The reservoir
created by Three
Gorges dam threatens to flood the habitats of those species along with
over 400 others, says Jianguo Liu, an ecologist at Michigan State University
and guest professor at the Chinese Academy of Sciences who has done extensive
work on biodiversity in China.
The dam further imperils delicate fish populations
in the Yangtze. Downstream, near where the river empties into the East
China Sea, the land around the Yangtze contains some of the densest clusters
of human habitation in the world, and overfishing there has already endangered
25 of the river's 177 unique fish species. According to a 2003 letter to
Science by Wuhan University ecologist Ping Xie, many of these fish evolved
over time with the Yangtze flood plain. As the dam decreases flooding downstream,
it will fragment the network of lakes around the middle as well as lower
the Yangtze's water level, making it difficult for the fish to survive.
The project has already contributed to the decline of the baiji
dolphin, which is so rare that it is considered functionally extinct.
The reservoir could also break up land bridges
into small islands, isolating clusters of animals and plants. In 1986,
Venezuela's Raúl Leoni Dam flooded 1,660 square miles (4,300 square
kilometers) of land, creating the vast Lake Guri, along with a scattering
of nonsubmerged land. The nascent islands lost 75% of their biological
species within 15 years, according to research published in Science.
To determine the true toll, the Three Gorges
Dam is taking on animal and plant species, Liu says, long-term data is
needed, so that decreases in population totals can be compared with natural
species fluctuation. But he cautions that many of the dam's effects may
not be immediately apparent. The project is altering reproduction patterns,
meaning it may already be too late for some plants and animals. "In
the short term, you see the species still there, but in the long term you
could see [them] disappear," Liu says. It is here that State Council
representative Wang's allusion to "hidden dangers" rings especially
true.
Disease and Drought
When officials unveiled plans for the dam,
they touted its ability to prevent floods downstream. Now, the dam seems
to be causing the opposite problem, spurring drought in central and eastern
China. In January, the China Daily (the country's largest English-language
newspaper) reported that the Yangtze had reached its lowest level in 142
years—stranding dozens of ships along the waterway in Hubei and Jiangxi
provinces. An unnamed official with the Yangtze River Water Resources Commission
blamed climate change, even as he acknowledged that the dam had reduced
the flow volume of the river by 50%. To make matters worse, China is now
plowing ahead with a controversial $62-billion scheme to transfer water
from the Yangtze to northern China, which is even more parched, through
a network of tunnels and canals to be completed by 2050.
Meanwhile, at the mouth of the Yangtze residents
of Shanghai, China's largest city, are experiencing water shortages. The
decreased flow of fresh water also means that saltwater from the East China
Sea now creeps farther upstream. This, in turn, seems to be causing a rise
in the number of jellyfish, which compete with river fish for food and
consume their eggs and larvae, thereby threatening native populations that
are already dwindling as a result of overfishing. In 2004, a year after
the dam was partially filled, scientists noted a jellyfish
species in the Yangtze that had previously only reached the South China
Sea.
The effects of the dam's disturbance of whole
ecosystems could reverberate for decades. G.W.'s Davis is part of a project
researching the disease schistosomiasis
(a.k.a. snail fever or swimmer's itch), a blood parasite transmitted to
humans by snails; people can get it by swimming or wading in contaminated
fresh water when infected snails release larvae that can penetrate the
skin. (Symptoms include fever, appetite and weight loss, abdominal pain,
bloody urine, muscle and joint pain, along with nausea, a persistent cough
and diarrhea.) The snails used to breed on small flood plain islands where
annual flooding prevented a population explosion. Now, the decreased flow
downstream from the dam is allowing the snails to breed unchecked, which
has already led to a spike in schistosomiasis cases in some areas.
According to Davis, such alterations could
precipitate a rise in other microbial waterborne diseases as well. "Once
you dramatically change the climate and change water patterns, as is now
seen in the Three Gorges region," he says, "you change a lot of
environmental variables. Almost all infectious diseases are up for grabs."
The official recognition of the dam's dangers
suggests that the project's environmental and public health impacts are
starting to sink in. Political analysts speculate that President Hu Jintao
and Premier Wen Jiabao are eager to distance themselves from a project
they inherited. Although halting plans at this point would be an admission
of government error, the openness following the Chongqing meeting raised
the hopes of worried scientists that officials would take action to minimize
the project's environmental and public health fallout.
Government-funded institutions have been quietly
assessing possible recourses. Officials say they've spent more than $1.6
billion on fortifying landslide-prone areas and will spend an additional
$3.2 billion on water cleanup over the next three years. In January the
CTGPC signed a memorandum of understanding with the Nature Conservancy
allowing that organization to consult on species protection and river health
in the dam area. China's Ministry of Health, meanwhile, is trying to control
schistosomiasis infections with a combination of drugs and applications
of molluscicides, pesticides that wipe out the disease's snail carriers.
But these measures may not be sufficient to
avert disaster. In February China's State Environmental Protection Administration
said reservoir water quality targets had not been reached despite a cleanup
effort that had been underway since 2001. And fighting schistosomiasis
requires a more holistic, multi-pronged approach—particularly now that
ecosystems in the Three Gorges region have been altered. To ward off an
outbreak, Davis says, the government would have to prevent the use of night
soil as fertilizer, build cement irrigation ditches, and ensure area villagers
access to clean water. So far, that hasn't happened.
Government Oversight
In the wake of media reports about the government's
concerns, officials began to backpedal. In a November 2007 interview with
state news agency Xinhua, State Council's Wang claimed that "no major geological
disasters or related casualties" had occurred since the reservoir's water
level was raised in 2006; five days later, the earth in Badong crumbled
and the railroad tunnel landslide wiped out the bus and its passengers.
Following a brief period of openness, discussion
of the dam's environmental effects has once again become largely taboo
in China. Government officials fear that continued free discussion of the
project's ramifications could lead to civil unrest. One internationally
published Chinese scientist working in the Yangtze Basin declined to comment
publicly, noting, "This is a very sensitive topic…. I can't give hypotheses."
Despite the Three Gorges dam's growing list
of problems, however, hydropower remains an integral—and ostensibly green—component
of China's energy mix. China still draws 82% of energy from coal, but large
dams are crucial to the country's climate change program, which aims to
increase its proportion of electricity from renewable resources from the
current 7.2% to 15% by 2020. Over one third of that will come from hydropower—more
than from any other source. Twelve new dams are planned for the upper Yangtze
alone.
The logistical and environmental hurdles involved
in executing these dams underscore China's commitment to hydropower. The
Yangtze's newest dams include several smaller projects that are necessary
to alleviate sedimentation caused by the Three Gorges reservoir. In his
2007 report to the National People's Congress, Prime Minister Wen Jiabao
said that China had relocated 22.9 million people to make room for its
large hydroprojects.
China's original goal was to fill the reservoir
to its maximum level by 2013. Despite all the trouble, that target was
moved up to 2009, Fan says, to boost hydropower output by an additional
2.65 billion kilowatt-hours each year.
"For the economic interests and profit
of the Three Gorges Project Development Corporation," he says, "that's
very important. But the function of any river, including the Yangtze, is
not only to produce power. At the very least, [a river] is also important
for shipping, alleviating pollution, sustaining species and ecosystems,
and maintaining a natural evolutionary balance."
"The Yangtze doesn't belong to the Three
Gorges Project Development Corporation," Fan adds. "It belongs to
all of society." |
