Yangtze River

Geomorphology, Hydrology, and the Three Gorges Dam

Chris Pavlovich, Lauren Ceckowski

Brian Singer, Aveline Cruickshank

Yangtze River: Vital Stats

•Length: 3,915 mi (6,300 km) - third longest•Annual Discharge: 900 km3

year−1 - fifth largest•Peak annual discharge: 110,00 m3/s•Mean annual discharge: 30,166 m3/s•Drainage basin area: 1.8 x106 km2 (largest in SE Asia)•Current average suspended sediment discharge: 480 million tons/year-1

Significance of the Yangtze

•The Yangtze River basin is home to approximately 400 million people

•1/3 of the Chinese population

•Along with the United States, China was overenthusiastic with their dam construction in the post WWII era

•subsequently the Yangtze is home to nearly 50,000 dams

• Yangtze an ideal site for observation of the effects of dams

•particularly on sediment discharge

Geology of the Yangtze

•The Plateau of Tibet marks the area where the Indian and Eurasian tectonic plates collide

•The Northern portion of the Yangtze drains across this plateau

•The Yangtze flows from the Tibetan Plateau through eroded mountainous regions

Hydrology of the Yangtze• Monsoon winds bring significant precipitation to the Yangtze

basin•Floods will begin in early spring and can occur until the end of fall

• Flooding and flood damage are the primary reasons the Three Gorges Dam was built• The water discharge of the Yangtze is incredible (greater than the Huang He) but it has decreased since the completion of the Three Gorges Dam

Hydrograph: Yangtze River

Fishing on the Yangtze

•The Yangtze is home to around 1/3 of the Chinese

population, so many people rely on the river to

support themselves

•Carp and variations of the carp species are of

vital economic importance•Carp rely on the rise in water level during the

monsoons to breed

•The construction of the TGD has prevented

this natural rise from occurring, which has jeopardized the carp population

•There is already a 3-month yearly ban on fishing in

place, to allow fish populations to replenish, but it

has become clear that a longer break will be necessary

Damming along the Yangtze

• Over 700 tributaries

• ~ 50,000 Dams

Damming along the Yangtze

Three Gorges Dam

Sandauping, China

The Three Gorges

Qutang Gorge

Wu Gorge

Xiling Gorge

Three Gorges Dam: Vital Stats

•Height - 181 m (594 ft)

•Length - 2,335 m (7,661 ft)•Spillway capacity - 116,000 m3/s

(4,100,000 cu ft/s)

•Installed capacity - 18,200 MW

•Maximum capacity - 22,500 MW•Annual generation - 80,000 GWh

Three Gorges Dam Reservoir

Three Gorges Dam Reservoir

•Three Gorges Reservoir

Capacity - 39.3 km3

(9.4 cu mi)

•Surface area 1,045 km2

(403 sq mi)

•Catchment Area - 1,000,000

km2 (390,000 sq mi)

•Water level raised 566 ft

Politics

• First proposed in 1919-Supported by leader of the

Chinese Republic

• National Peoples Congress approved TGD in

1992

• Passed by smallest margin in legislature’s history

• Serious controversy over TGD construction –

government found benefits outweighed

negative effects

Construction

• Began on Dec 14th 1994

• 200,000 cu meters of concrete, 463,000 tons of steel

• Completed in 2009

• Estimated cost ~ 22.5 billion dollars

• Costs will be covered after 5 – 8 years of generation

Advantages: Hydropower

• Worlds largest Hydropower plant

• Low operations and maintenance costs

• Renewable resource

• TGD produces energy = 15 nuclear power plants

• Long economic Life (50-100 yrs)

• Reduced Greenhouse gas emissions

• 2003 - 2007, TGD power production = 84 million tons of standard coal, reducing carbon dioxide by 190 million tons

Hydropower

Advantages: Flood Control

• One of the most significant functions of TGD

• Historically population in lower regions suffered great

losses from flooding in human lives and property

• 1931 flood caused 3 million deaths – flooding and

starvation

• TGD reduces seasonal flooding in lower Yangtze

• Flooding reduced from 1 in 10 yrs to 1 in 100 yrs

Advantages: Navigation

• Ship Locks installed for river traffic to bypass the

dam

• Allow raising and lowering of boats between stretches of water of different levels

• Locks made navigation much safer

• Intended to increase shipping from 10 million

tons annually to 100 million tons annually

• Cut transportation costs by 30-37%

Disadvantages: Decline in Water

Quality

• Water quality in reservoir in 2003 was at levels II and III (drinking water I, II, or III)

• Since 2004 increase in algae blooms

• Caused by collection of fertilizer runoff = hypoxia

• 1,600 factories and abandoned mines will be submerged releasing toxins

• Near by villagers need to find new water sources

• Stagnant water leads to higher spread of diseases

Alagae Blooms

Disadvantages: Impacts on

Sediment • TGD traps 172 million tons annually

• Average trapping efficiency of 75%

• Build up lowers storage capacity

• Less sediment downstream

• Banks more vulnerable to flooding and collapse

Bank collapse in

Yueyang, 2006

Disadvantage: Impacts on

Sediment

•The sediment

flux will decrease

to below 90

million tons in the near future

•18% of the

amount

observed in the

1950s

Disadvantages: Loss of

Biodiversity

• 6000 plant species, 500 terrestrial species, and 160 fish

species in TGD region

• Population migration lead to terrestrial habitat loss and fragmentation

• Water biota habitat negatively effected by TGD

• Fragmented habitats – TGD barrier

• Modified nutrient and sediment flow

• Baiji Dolphin, Finless Porpoise, Chinese Paddlefish

Disadvantages: Population

Displacement

• Major controversy of the TGD

• Reservoir inundates 2 cities, 11 counties, 140

towns, 326 townships and 1351 villages

• About 23,800 hectares

• More than 1.1 people had to be resettled

• 45% of the total cost of TGD

Disadvantages: Cultural Impacts

Major loss of farmland

• Increase crop imports

• Loss of 1300 archeological sites due to

submersion

• Zhangfei Temple

• White Crane Ridge

• Dachang Ancient Town

Works Cited

“Large Rivers” – Avijit Gupta

Chapters 21, 24, 29

“Three Gorges Project: Efforts and challenges for the environment” - Bo-Jie Fu

“50,000 dams later: Erosion of the Yangtze River and its delta” – S.L. Yang

“Three Gorges Dam: The environmental argument surrounding Chinas super dam” – Richard Edmonds