Three Gorges Dam: A Blessing or an Environmental Disaster? 
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 Three Gorges Dam: A Blessing or an Environmental Disaster?
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Three Gorges Dam: A Blessing or an Environmental Disaster?
2 October 2007 | By Ethan Theuerkauf, Flat Hat Science Columnist | The
Flat Hat ? news
The world's largest hydropower dam project could be facing an
environmental disaster in the near future if care is not taken to
address several serious problems.

The Three Gorges Dam located in Southwestern Asia along the Yangtze
River, generates electrical power and protects against flooding of the
Yangtze River during the rainy season.

Environmental concerns caused by the Three Gorges Dam include coastal
erosion, landslides, siltation, agricultural and fisheries degradation
and species loss.

Landslides are one of the biggest threats to the areas surrounding the
Three Gorges Dam because of the steep slopes and degradation of the
land around the dam. Senior engineer for the dam project, Huang
Xuebin, stated that debris that could fall into the dam from a
landslide event could raise the water level by dozens of meters, and
that this water will cause significant flooding to the surrounding
shoreline.

Siltation is another major concern because the dam traps silt that
would normally flow through.

Silt scouring gates are employed to remove silt from within 100 meters
of the dam, but these are not guaranteed to be effective because they
have not been used on a dam the size of the Three Gorges.

The relatively low flow velocity of water moving through the dam may
also cause increased siltation problems because it offers more time
for the silt to settle out and build up.
Agricultural production may also be adversely affected by the Three
Gorges Dam. Silt is one of the main methods of carrying nutrients
downstream to farmland, and if silt flow is stopped by the dam, it is
likely that agricultural production will decrease due to a lack of
nutrients.

Almost all dams create erosional problems for the surrounding
coastline. If erosion occurs at the Three Gorges Dam it could be
devastating for China's coastal towns, but the Chinese government is
not currently projecting that the high rate of siltation will have
this effect.

Species loss in the dam area may be quite drastic. At least three
major species are guaranteed to be negatively affected by the dam
construction - the endangered Siberian crane, the Yangtze sturgeon and
the Yangtze freshwater dolphin. Around one-half of the total
population of Siberian cranes lives in the Three Gorges at the low
stand of the Yangtze River. The cranes eat aquatic weeds that grow on
the bottom, but as the water gets deeper in the Three Gorges area, the
cranes may no longer be able to feed on the weeds.

According to the International Rivers Network, hundreds of factories,
mines and waste dumps were submerged during the construction of the
dam, which is leading to major pollution problems in the Yangtze River
and its tributaries. Massive industrial centers upstream are also
contributing to pollution problems.

During the five-month rainy season, the water levels in the dam are
lowered to prevent flooding, which creates a bog of effluent silt and
industrial pollutants. This bog creates a breeding ground for flies,
mosquitoes, bacteria and parasites, which pose serious risks to human
health.

The East China Sea was also adversely affected by the construction of
the Three Gorges Dam. A decline in freshwater and increase in
sediments reaching the East China Sea may cause total annual catches
to be reduced by approximately one million tons. Sediment losses are
also badly eroding the Yangtze River delta and the tidal wetlands.

The potential for the Three Gorges Dam to create serious environmental
degradation has been addressed by several groups and people, including
Wang Xiaofeng, the director of the administrative office that is in
charge of building the dam.

"We absolutely cannot relax our guard against ecological and
environmental security problems sparked by the Three Gorges Project,"
Xiaofeng said in an interview with the Xinhua news agency.

The Three Gorges Dam demonstrates the tradeoff between creating an
infrastructure that will be able to generate enough electricity to
power China into the 21st century and the environmental and ecological
devastation that can occur as a result of constructing such an
expansive and invasive structure.



Sat, 20 Mar 2010 19:43:25 GMT
 
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