3.3.18

Flood Defences - Hard Engineering

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Flood Defences - Hard Engineering

Hard engineering strategies aim to reduce the effects of flooding by building man-made constructions that control a river's flow. Examples of hard engineering strategies include:

Illustrative background for Dams and reservoirsIllustrative background for Dams and reservoirs ?? "content

Dams and reservoirs

  • A dam is a large earth, stone or concrete wall built across a river in the upper course. Behind the dam, a reservoir (man-made lake) forms.
    • Reservoirs can reduce flooding risk by filling up with water when there is a lot of rainfall. This water can either be drunk or used to produce energy (hydroelectric power).
    • But, dams are expensive and habitats and towns can be destroyed by the flooding needed to create a reservoir.
  • The soil downstream from a reservoir usually loses some of its fertility because minerals are deposited in the reservoir instead of downstream.
Illustrative background for Channel straighteningIllustrative background for Channel straightening ?? "content

Channel straightening

  • Bends and meanders are removed by constructing man-made, straight channels connecting the meanders.
    • Straight channels reduce flood risk by keeping the water flowing through an area quickly.
    • But, downstream areas are more at risk of flooding and erosion because more water flows there more quickly.
Illustrative background for EmbankmentsIllustrative background for Embankments ?? "content

Embankments

  • Embankments are walls built either side of the river channel to raise the height of the banks.
    • Embankments reduce flooding risk by increasing the capacity of the river.
    • But, embankments are expensive to build and if the banks do burst, then flooding can still happen.
Illustrative background for Flood relief channelsIllustrative background for Flood relief channels ?? "content

Flood relief channels

  • Flood relief channels are secondary channels built alongside rivers that divert water away from particular areas or take it somewhere else if there is too much rainfall.
    • The amount of water flowing through a given point in a river is reduced (river discharge falls).
    • But, the river discharge will increase at the junction between the relief channel and the river it links up with.

Jump to other topics

1The Challenge of Natural Hazards

1.1Natural Hazards

1.2Tectonic Hazards

1.3Weather Hazards

1.4Climate Change

2The Living World

3Physical Landscapes in the UK

3.1The UK Physical Landscape

3.2Coastal Landscapes in the UK

3.3River Landscapes in the UK

3.4Glacial Landscapes in the UK

4Urban Issues & Challenges

5The Changing Economic World

6The Challenge of Resource Management

6.1Resource Management

6.2Food

6.3Water

6.4Energy

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