River management

3.6.2 MEDC - Central Europe floods, 2013

3.8 Water transfer - Case study: China south-north water transfer project

River management

  1. Hard engineering

    1. Hard engineering strategies involve the use of technology in order to control rivers
    2. A dam is a barrier across the river that prevents the flow of the river, causing water to fill the area behind it and create a reservoir, which can be released or held depending on circumstances such as current and expected rainfall
    3. Straightening meanders involve making the river follow a shorter and straighter route, causing it to flow faster so there is less change of it flooding
    4. Embankments are raised banks along a river, effectively making them deeper so they can hold more water before flooding
    5. Flood walls are build around settlements and important areas that stop the movement of water
    6. Storage areas are areas of land where water is pumped from the river to make a temporary lake before being pumped back in after river levels fall
  2. Soft engineering

    1. Soft engineering strategies seek to work with the natural river processes to reduce the effects of flooding
    2. Flood warnings and preparation involves identifying places at risk and issues warnings, giving people time to prepare by moving possessions upstairs; turning off gas, water and electricity; gathering important papers and taking basic precautions against flooding, or even evacuating
    3. Floodplain zoning involves assessing the flood risk across the floodplain and determining land use accordingly, so as the risk falls, the quality & value of the land rises, in the following order: pastures for grazing, playing fields, roads and car parks, industry and housing
    4. Washlands involves allowing part of the floodplain to be flooded, and are normally reserved for sports pitches
    5. Afforestation involves planting trees to increase interception and delay flooding
  3. Monitoring

    1. Doing nothing allows natural events to happen, even if this involves the risk of flooding and is a necessary approach in some poorer areas of the world
  4. Cost-benefit analysis

    Strategy Advantages Disadvantages
    Dams Highly effective Expensive
    Not natural-looking
    Load & waste can build up in the reservoir
    People may need to move to accommodate it
    Straightening the river Highly effective Expensive
    Not natural-looking
    Embankments Highly effective Expensive
    Unsustainable
    Storage areas Highly effective Needs a large area of unused land
    Warning systems Cheap People do not always receive or heed warnings
    Land-use zoning Important land less likely to be flooded Large areas of land are unutilised
    Afforestation Natural-looking Takes up a lot of land
    Cannot prevent serious flooding