Hard Engineering: River management

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  • Hard Engineering Strategies
    • Diversion Spillways
      • Converts water away from built up areas. During periods of high flow, sluice gates are opened to allow water to flow into the new channel.
      • The flow needs to permanently monitored and controlled to stop the river abandoning a channel.
      • In some places, the channel is a permanently flowing part of the river.
      • Jubilee River channel off the Thames in Maidenhead. 11km long, cost £80 million. Created new wetlands and popular for recreation.
    • Straightening
      • Removes meanders which creates a higher river velocity reducing the flooding risk as water moves away faster.
      • Advantages: Cheap and reduces risk of flooding in populated areas.
      • Increases flooding risk downstream as water arrives quicker. Ruins natural habitats at the meander and downstream and looks unnatural.
      • Eg. Damascus, Syria.
    • Dams
      • Disadvantages: very expensive and often flood huge areas of land behind the dam, meaning arable land, habitats and settlements are destroyed. They are unsightly, and if they break, flooding effects would be devastating.
      • Advantages: Effective at regulation of river flow and reducing flooding. They are multi-purpose and can be used for water supply, recreation, HEP and irrigation. Can be used anywhere in the world.
      • Eg. 3 Gorges Dam, China. 660km reservoir, provides 14% of China's electricity. £2.5 billion and forced 1.2 million people to relocate.
    • Levees and Embankments
      • Raises the height of the banks to increase river channel capacity. Dredgers scoop sediment from the bed to make it deeper and dump it on the banks to make it higher.
      • Advantages:  Sustainable and is easy and cheap to carry out. Alternatives include using concrete walls as levees which are used to protect towns and are very effective.
      • Disadvantages: (for natural levees) destroys habitats on the river bed. (for concrete walls): expensive and intrusive on the natural environment.
      • Eg. River Rhone, France- suffered serious flooding from ice melt in Alps.

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