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Introduction |
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It is 75 years since
Dr.SunYat-sen first proposed to launch the Project. Thanks to several
decades of extensive scientific research and international cooperation
by numerous scientists, scholars and experts of several generations,the
extremely complex engineering poser for the construction of the
Three Gorges Project(TGP) was finally resolved. These studies provided
the scientific basis whereby the National People's Congress passed
"The Resolution for the Construction of the Three Gorges Project
on the Yangtze River".
It was during the fifth session of the Seventh National People's
Congress that the examination and debate on the feasibility of the
Project which lasted more than half a century came to an end and
a new era to harness and develop the Yangtze was ushered in. The
project will not only make contributions to the present age but
also benefit the nation and people for centuries to come.
From its source to its estuary, the Yangtze River meanders over
6,300 kilometers. Its annual runoff into the sea amounts to nearly
1,000 billion m3 and its total drop is more than 5,800 meters with
a hydroelectric power potential of up to 268 million kW. In order
to harness the River and develop its resources, extensive efforts
in survey, planning and scientific research have been made since
the founding of the People's Republic of China. After overall planning,
repeated studies and verifications, the conclusion has been reached
that the TGP is the key to the comprehensive control of the floods
and exploitation of the resources of the River.
From Fengjie County to Yichang City, a 200-kilometer-long stretch
of the River, it rushes through the majestic Qutang, Wuxia and Xiling
gorges, after which the Yangtze Three Gorges is so called . The
TGP, which is attracting worldwide attention now, is located at
the town of Sandouping, Yichang, Hubei Province in the middle section
of Xiling Gorge, about 38 km upstream of the Gezhouba Project. The
dam site boasts excellent natural conditions such as a rather wide
valley, sound and intact granite bedrock, an average annual runoff
of about 500 billion m3 and a vast drainage basin of more than 1
million km2. Decades of arduous reconnaissance and studies resulted
in the final approval of Sandouping to be the site of the TGP.
The TGP will be built in accordance with the scheme of "development
in one cascade, construction at one stroke, impoundment at stages
and resettlement in succession". The concrete gravity dam will
be 3,035 m long on the top, with the crest at EL 185 meters. The
designed normal pool level of the reservoir is EL 185 meters, and
the total storage capacity 39.3 billion m3 , of which 22.15 billion
m3 is for flood control. The silt flushing bays are to be arranged
in the concrete gravity dam and at the bottom of the power station,
with a silt flushing capacity
of 2,460 m3 per second. The discharging capacity of the spillway
which constitutes the middle section if the dam is 110,000 m3
per second. The designed two powerhouses to be located on both
sides of the spillway have 26 units of generators of 700,000 kW
each, with a total capacity of 18.2 million kW and an annual
output of nearly 84. 7 billion kWh. The designed one-way shipping
capacity of the navigation facilities (including a twin 5-step shiplocks
and a one-step vertical shiplift) is 50 million tons a year.The
shiplocks can adequately handle tows up to 10 ,000 tons and the
shiplift can provide immediate service for any vessels under 3,000
tons. The major work amounts of the Project are as the principal
indices in Table attached.
It is expected that the preparation work and the main works of the
Project will take 2 years and 15 years respectively. By the ninth
year the permanent shiplocks and the first group of units will be
put into operation. Owing to the construction of the Project, 1.13
million people are expected to be resettled and 28,800 ha. of farmland
inundated.
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