Flood Management on the Yangtze River in China

Hard Engineering is used to control flooding. The Yangtze River flows through China, it is 6380 km long making it third largest river in world. During China’s rainy season ( June to August) during rainy season discharge increases rapidly. Flooding causes problems with the farmland that surrounds much of the river and also floods cities such as Nanjing. Most recent flood was in 1998. The 1998 flood caused 3000 deaths and 14 million made homeless.

Hard Engineering Techniques:

  • Levees embankment built up to prevent flooding of the river eg 3600 km along middle and lower parts of river
  • Dams such as the Three Gorges Dam:
  • 100m high and work began in 1994.
  • 3 miles wide
  • The Three Gorges Dam has a reservoir behind it with a capacity of 22 km3.
  • 26 hydroelectric turbines – largest hydroelectric power station in world.
  • Locks allow ships to pass

Positive and Negative effects of Hard Engineering:

Positive:

  • Major flooding reduced from once every 10 year to every 100 years estimate benefiting 15 million people.
  • Turbines supply 3% of China’s energy need
  • Safer to navigate Yangtze river – bigger and more ships

Negative:

  • 13 cities, 1352 villages and between 1.3 million and 2 million people have to relocate.
  • Cost of $22.5bn
  • 1998 and 2004 the amount of sediment transported by the river fell by 50% meaning more erosion downstream.
  • Sediment carried down river is stopped in the future this could lead to failure of dam and severe flooding.
  • Could destroy habitats and kill endangered animals eg Siberian Crane. 100 remaining Baiji dolphins may have food supply restricted.
  • Increases flooding on some tributaries such as Daning River

Levees:

  • Many levees broke in 1998 floods contributing to the severe flooding
  • However in 2002 they were reinforced meaning they were effective at reducing the flooding affect then.