Hard vs Soft Engineering - Rivers

  • Created by: mbull
  • Created on: 14-01-18 20:22
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  • Hard vs Soft Engineering - Protecting against flooding
    • Hard Engineering
      • Man-made structures built to control the flow of rivers and reduce flooding.
      • Dams and Reservoirs
        • Dams (huge walls) are built across the rivers, usually in the upper course.
          • A reservoir (artificial lake is formed behind the dam.
        • Reservoirs store water, especially during periods of prolonged/   heavy rain.
          • Reducing the risk of flooding.
        • The water in the reservoir can be used as drinking water and to generate hydroelectric power.
      • Channel straightening
        • The river's course is strengthened - meanders are cut out by building artificial straight channels.
        • Water moves out of the area more quickly because it does not travel as far.
        • Flooding may happen downstream as water is carried there faster.
        • More erosion downstream.
      • Embankment
        • Raised walls are built along the river banks.
        • River can hold more water.
          • It will flood less frequently, protecting buildings on the floodplain
        • Expensive
          • Risk of severe flooding if water rises above level of embankments
      • Flood relief channels
        • Channels are built to divert the water.
        • Flooding prevented because river discharge is reduced
          • Gates on flood relief channels mean release of water can be controlled
          • If levels get too high for the relief channels they could also flood.
    • Soft Engineering
      • Schemes set up by using knowledge of a river and its processes to reduce the effects of flooding.
      • Flood warnings
        • The Environment Agency warns people about possible flooding through TV, radio, newspapers and the internet.
        • Impact of flooding is reduced, gives people time to move possessions.
        • Warnings do not stop a flood from happening,
          • People may not hear or have access to warnings.
      • Preparation
        • Buildings are modified to reduce amount of damage a flood could cause.
        • Impact of flooding is reduced.
        • Preparation don't guarantee safety.
          • Expensive.
      • Flood plain zoning
        • Restrictions prevent building on parts of a flood plain.
        • Risk of flooding reduced
        • Expansion of an urban area is limited if there aren't any other suitable building sites.
          • No help in areas that have already been built on.
      • Planting trees
        • Increases interception of rainwater and also increases the lag time.
        • Discharge and flood risk are reduced
        • Less land is available for farming.
      • River Restoration
        • Involves making river more natural so flood plain can flood naturally.
        • Less risk of flooding downstream because discharge is reduced.
        • Local flood can increase





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