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Management of the Three Gorges Dam

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  • Management of the Three Gorges Dam

    Zhao-Yin WangProfessor, Tsinghua University

    Chairman, Advisory Council of IRTCESVice President of IAHR

    Chief Editor International Journal of Sediment Research

  • Outline1 Construction of the Three Gorges

    Dam2 Sedimentation and Management

    strategies3 Emigration and Resettlement4 Environmental and Ecological

    Impacts and management strategies

  • 1. Construction of the Three Gorges Dam

  • The Yangtz River 6300 km long ,1.8million km2, Total annual runoff (Datong) 1000 billion m3 (37%)The Three Gorges 192 km (Qutan, Wuxia and XilingGorges).Dam site Sandouping 38 km upstream from the Gezhouba dam. Project consists of dam, power stations and navigation structures.

  • Beautiful three gorges

  • TGP(CHINA)

    Itaipu(BRAZIL)

    Grand Coulee(USA)

    Guri(VENUZUELA)

    Tucurui(BRAZIL)

    Aswan(EGYPT)

    MW

    Comparison Between TGP and World Power Comparison Between TGP and World Power stations stations

    Instalation Capacity MW

    18200

    12600

    10830

    10300

    8000

    2100

  • Main Purposes of the Project Flood Defense Power generation 18200 MW - 85 billion

    kwh/a=50mton coal; Shipping - Yichang-Chongqing 660 km with

    120 m drop, 130 dangerous shoals and 46 one-way sections

    With TGP 10000 tons towboats to ChongqingShipping capacity from 10 mt to 50 mt (2005:

    795 mt; 2008 1.2 bt)

  • Flood disasters

    214 disastrous floods / 2000 years 1931 - 3.4 mha, 145000 lives 1935 -1.5 mha, 142000 lives 1954 - 3.17 mha, 33000lives, $10 billion 1998 - 0.33 mha, 2292 lives, $20 billion,

    1.6 m were evacuated, 6 m houses damaged,

  • FLOOD IN WUHAN 1935FLOOD IN WUHAN 1935

  • Floods in 1998Floods in 1998

    The floods (The floods (dischagedischage at the3 at the3

    dam site was 67000 m3/s) dam site was 67000 m3/s)

    caused a direct loss of about caused a direct loss of about

    100 billion Yuan 100 billion Yuan about 12 about 12

    billion $billion $ in 1998.in 1998.

  • The JingJiang Grand LeveeThe JingJiang Grand Levee

  • Flood defense capacity before TGP

    3600 km grand levees along the Yangtze River

    30000 km levees on the tributaries and riparian lakes

    Tongting lake clip peak by 10000 m3/s Several flood diversion basins Gezhouba Dam with no flood control

    capacity Capacity- control 20 years flood

  • Wuhan

    ChenglingjiYeyang

    Jianli

    Shishou

    Zhicheng

    Songzikou

    Shashi

    Gezhouba Project

    Three Gorges project

    Yichang

    Major City

    County Town

    Levee

    Flood-diversion Area

    Lake

    Hanjiang R.

    Lishui

    Qingjiang R.

    Tong ting Lake

    Yangt

    ze R.

    Yangtze R.

    River0 50km

    Flood defense system of the middle and lower reaches

  • Model of the Gezhouba dam

  • 1993-1997

  • 1998-2003

  • 2004-2009

  • 1993

  • 1995

  • June 1997

  • The TGP in 1997The TGP in 1997

  • Nov. 1997

  • The TGP in 1998The TGP in 1998

  • The TGP in 1999The TGP in 1999

  • The TGP in 2001The TGP in 2001

  • Oct. 2002

  • Closure of the open channel Nov. 2002

  • The TGP in 2002The TGP in 2002

  • TGP in 2003TGP in 2003

  • The TGP in 2004The TGP in 2004

  • Oct. 2004

  • 2004

  • Oct. 2004

  • 2000

  • 2002

  • Power house 2002

  • 2002

  • Flood control with TGP

    Management of flood: The dam stores flood water if the discharge is exceeds 56,000 cms to guarantee the stage at Shashi can not exceed 45 m

    The food discharge in 2010 was 70000 m3/s, higher than the 1998 flood. The reservoir was operated to store water and released flood discharge was between 40000-45000 m3/s, which successfully controlled the flood and reduced the flood loss to the minimum

  • 2 Sedimentation and Management strategies

  • The main sedimentation problems are:

    1) Reservoir sedimentation and permanent use of the reservoir capacity for flood control;

    2) Sedimentation in the navigation channel in the fluctuating backwater zone;

    3) Sedimentation in the vicinity of the dam; 4) Degradation in the downstream reaches;

  • 1) Permanent Use of the ReservoirSedimentation in the reservoir depends on the operation scheme and pool levels The main sedimentation control strategies isStoring the clear and releasing the turbid During the flood season (June-Sept), when the river carries 90% of the annual sediment load and 61% of the annual runoff, the pool level is drawn down to flood season pool level to create a condition in favor of sediment sluicing. After the flood the sediment concentration is low and the reservoir store water for power generation during winter and spring and the pool level rises to the normal pool level.Normal pool level (NPL) is set at 175 m. Flood season pool level (FCL) is 145 m.

  • 145

    150

    155

    160

    165

    170

    175

    Jan April July Oct. Dec.

    Jan April July Oct. Dec.

    Reservoir pool level

    E (m

    )0

    2

    4

    6

    S (k

    g/m

    3 )

    Sediment concentration at Yichang

    Storing the clear and releasing the turbid - During the flood season, when the river carries 90% of the annual sediment load and 61% of the annual runoff, the pool level is drawn down to 145 m to create a condition in favor of sediment flushing.

  • Annual runoff at the dam site = 450 bi m3Annual sediment load = 532 mi tons (0.8 mi tons gravel bed load). Median diameter = 0.033 mm (24 mm for bed load)

  • Five operation schemes have been simulated and the accumulated sedimentation volume is a function of the pool levels:

    Calculation results with the YVPO model

  • 1-D numerical model calculations for 106 years:

    As the recurrence period of the 1954 flood is approximately 40 years, the stream record of 1954 was inserted into the hydrological series in such a manner that it appears three times in 106 years:

    2 cycles of 1961-1970 plus 1954, 1955; 2 cycles of 1961-1970 plus 1954, 1955 4 cycles of 1961-1970 plus 1954, 1955; 2 cycles of 1961-1970

  • 1-D model: River bed profile after 100 years operation and the original river bed profile.

  • Sedimentation volume from 2003-2012 In the first 10 years operation of the TGP Dam

    the sedimentation volume was only 40% of the modeling results.

    In the upstream the construction of the Xiangjiaba and Xiluodu dams trap sediment and reduce the sediment load into the TGP reservoir.

    It is estimated that about 30 million tons of fine and coarse sand and gravel are mined for building materials per year, which has reduced the sedimentation in the reservoir.

  • XiangjiabaXiangjiaba Dam Dam 1020 km upstream of the TGP dam with a capacity of 5.06 billion m3 and power instalation capacity of 6000MW

  • XiluoduXiluodu Dam Dam 1180 km from TGP dam with a storage of 11.6 billion m3 and power instalation capacity of 12600 MW

  • 0

    20

    40

    60

    80

    100

    120

    140

    160

    180

    0 10 20 30 40 50 60 70 80 90 100Year of operation

    Sedi

    men

    tatio

    n vo

    lum

    e (1

    08m

    3 )

    Scheme 1

    Scheme 2

    Scheme 3

    Calculated sedimentation volume in the TGP reservoir for the three scenarios: Scheme 1 = without upstream dams; Scheme 2 = with Xiangjiaba Reservoir; Scheme 3 = with Xiangjiaba and Xiluodu Dams

  • Gravel mining in the upper Yangtze basin

  • Sediment mining

  • 2) Sedimentation in the Fluctuating Backwater zoon

    The fluctuating backwater zoon is the river reach with flood stage between 145 and 175m.

    There is a passenger ship harbor-Chaotianmen harbor, and a freight ship harbor-Jiulongpo Harbor (602 km).

    Sedimentation in the zoon affect the navigation channel

  • Permanently preserved storageNPL

    FCL

    Dam

    Sediment depositionFluctuating backwater region

  • Two major problem are to be addressed :1) whether sedimentation would affect the navigation channel suitable for the navigation of 10000 ton tows, and

    2) whether sedimentation would affect the Chaotianmen and Jiulongpo Harbors in Chongqing.

    The problems were studied with physical models.

    The results showed that the sedimentation in the channel and harbors can be minimized by constructing groyins.

  • Five selected sections of physical model experiments on the influence of sedimentation on the navigation in the fluctuating backwater region of the TGP reservoir.

  • Sedimentation in the Chongqing reach after 80 years operation of TGP. The shadowed areas indicate the places where cumulative sedimentation would occur (Wang et al. 1986)

  • 3) Sedimentation in the Vicinity of the Dam

    Sedimentation occurs by the right bank in the vicinity of the dam.

    Sedimentation occurs in the upper approaching channel connecting the five step ship locks, which is segregated by a protecting dike.

    Sedimentation in the approaching channel can be controlled with a long dyke separating the approaching channel and the main reservoir water.

  • Long dykes separating t