Flooding and flood management - OCRFlood management strategies
Hard engineering management involves using artificial structures, such as dams and embankments. Soft engineering management is a more natural approach to manage flooding, such as flood plain zoning.
Flooding can cause damage to homes, businesses, infrastructure and communications. The impact of flooding can be reduced in a variety of ways.
Hard engineering
hard engineeringThe use of man-made structures to control the coast. involves building artificial structures which try to control rivers. They tend to be more expensive, and have a significant impact on the natural environment. Each hard engineering strategy has its advantages and disadvantages.
Dams and reservoirs
A dam traps water, which builds up behind it, forming a reservoir. Water can be released in a controlled way.
Advantages
Can be used to produce electricity by passing the water through a turbine within the dam.
Reservoirs provide a water supply for nearby towns and cities.
Reservoirs can attract tourists.
Disadvantages
Very expensive.
Spoil the look of the natural environment.
Dams trap sediment which means the reservoir can hold less water.
Habitats are flooded often leading to rotting vegetation. This releases methane which is a greenhouse gasThe gases responsible for global warming - carbon dioxide, methane, nitrous oxide and CFCs (chlorofluorocarbons)..
Settlements are lost leading to the displacement of people. In developing countries locals are not always consulted and can have little say in where they are relocated.
River straightening and dredging
Straightening the river speeds up the water so high volumes can pass through an area quickly. Dredging makes the river deeper so it can hold more water.
Advantages
More water can be held in the channel.
It can be used to reduce flood risk in built-up areas.
Disadvantages
Dredging needs to be done frequently.
Speeding up the river increases flood risk downstream.
Embankments
Raising the banks of a river so that it can hold more water.
Advantages
Cheap with a one-off cost.
Allow for flood water to be contained within the river.
Disadvantages
Look unnatural.
Water speeds up and can increase flood risk downstream.
Flood relief channels
The floodwater flows into the relief channel and is taken either to an area where it can be absorbed, or re-enters the river further down its course.
Advantages
Remove excess water from the river channel to reduce flooding.
Disadvantages
Expensive to build.
If water levels continue to rise, the relief channel may also flood.
