内容简介

The Three Gorges Project（TGP）is a key backbone project for the flood control，navigation and water resources development of the Yangtze River．The TGP iS located atSandouping，near Yichang City of Hubei Province，in the Xiling Gorge of the Three Gorgesreach on the trunk of the Yangtze River．It is 40 km upstream of the Gezhouba Dam．TheThree Gorges Reservoir is designed to have a normal pool level of 1 75 m above sea levelwith a corresponding aggregated storage capacity of 39．3 billion m3，and a flood control levelof 145 m with a flood control capacity of 22．15 billion m3．It will be of great significance tothe flood control efforts in the middle reaches of the Yangtze River．The total installedcapacity of the TGP will be 1 8．2 GW and the average annual output will be 84．7 billion kW·h．　　Thenavigationconditionswillbeimprovedintheentire600kmlongchannelinthe reservoirarea．
The construction of the TGP began in 1 993，and the first stage cofferdam was closed in1 997 which cut out the Yangtze River and made it flow through a diversion channelexcavated earlier around the dam site．The TGP began its impoundment on June 1，2003，withthe main dam and the cofferdam on the right-bank．On June 10，2003，the water level at thedam was raised from the original 70 m（approx．）to 1 35 m above sea level．In the samemonth；the five-step shiplock began trial operation．In July the same year，the output from thefirst turbine unit was synchronized to the national power grid．From then on，the ThreeGorges Reservoir was operated for power generation and navigation．The upstream part of thethird stage cofferdam was removed in June，2006．Since then，the reservoir water has beenretained by the TGP Dam on its own．On September 20，the pool level began to rise andfinally reached 1 55．68 m above sea level on October 28，with a corresponding aggregatedstorage capacity of 23．3 billion m3．The period between June，2003 and August，2006 isreferred to as the COfierdam impoundment period．