UK River Defences (Edexcel GCSE Geography A)
Revision Note
Written by: Bridgette Barrett
Reviewed by: Jenna Quinn
Rivers - Hard Engineering
The key cause of flooding is the amount and duration of precipitation; this cannot be altered
There are a number of methods of managing floods and reducing their severity and/or impact
The two main categories of flood management are hard and soft engineering:
Hard engineering involves building structures or changing the river channel
Soft engineering works with natural processes of the river and surrounding environment
Advantages and Disadvantages of Hard Engineering
Method | Advantages | Disadvantages |
|---|---|---|
Dams and reservoirs | Enables the amount of discharge downstream to be controlled Stores water Can also be used for Hydro-electric power (HEP) | Expensive to build Can affect habitats downstream |
Embankments and levees | Increase the capacity of the river Use natural materials which blend with the environment | May fail due to erosion or water overtopping Can be expensive Increase flood risk downstream |
Channelisation | Water is able to move downstream more quickly | May increase flood risk downstream Visually unattractive |
Flood relief channels | Allow some water to flow out of the main channel, reducing the discharge and protecting areas in the immediate area | This can lead to flooding elsewhere |
Impacts on the landscape
Dams and reservoirs lead to the flooding of the river valley
Sediment may be prevented from moving downstream, which affects the formation of deposition landforms
Hard engineering is often visually unattractive, affecting the look of the landscape
In channelisation meanders are replaced by artificially straight channels
Rivers - Soft Engineering
Advantages and Disadvantages of Soft Engineering
Method | Advantages | Disadvantages |
|---|---|---|
Washlands | Areas are left undeveloped so that floodwaters can flow into them. This reduces discharge within the river channel downstream When not flooded it provides a space for leisure/recreation | Reduces the land available for development and agriculture Significant cost for creation and maintenance Only protects against floods of a certain size |
Floodplain zoning | This means that only certain land uses are allowed on the floodplain, reducing flood risk Provides areas for leisure and recreation | Reduces the land for development and agriculture |
Afforestation | Reduces discharge by increasing infiltration and interception | Not possible in all areas |
Impacts on the landscape
Soft engineering methods have less impact on the landscape around the river
The methods preserve the natural landscapes
Examiner Tips and Tricks
You should ensure that you are confident in your knowledge of the advantages and disadvantages of flood defences. This has come up as an 8 mark question in a past paper which means you need to identify key facts about the flood defences and issues surrounding them.
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