4.8 Flood risk and management Flashcards
Why is flood risk increasing?
The frequency of storms in the UK is increasing and this is because of global climate change.
Storms becoming more extreme and more intense rainfall increases the flood impact.
More wet weather means the ground is saturated, meaning flooding is more likely.
There is an increase in impermeable rock due to the UKs population growing and needing more urban areas.
Vegetation is being removed as well as permeable surfaces and this means that water is not stored in the soil or plants and the water now flows downstream.
Development is increasing on the floodplains and this increases the flood risk to developed areas.
How do hard and soft engineering schemes work?
Hard engineering are man-made structures that are made to Control the flow of rivers and stop flooding. Soft engineering though are set up using the knowledge of the river and its processes so it can reduce the effects of flooding from the river.
What are flood walls
This is a wall alongside the river so that the capacity increases to prevent flooding. This is very cheap but can increase flood risk downstream. This is however good for city centres where space is limited.
What are levees?
Levees increase the capacity of the river and are built at a distance from the river. It is however expensive and can increase flood risk downstream. It can also fail with water rising over it. Although, this does allow people to live beside rivers without the fear of flooding.
What is dredging and flood relief?
This increases the channel capacity and speeds up the river flow to get floodwater away quicker. This does need to be done every year as a channel fills with settlement, and it is also expensive to build but cheap to maintain. This does though increase flow risk downstream.
What are floodplain retention?
This is maintaining the rivers flood plain and not building on, it slows down the floodwater and is able to store water in the soil. It is very cheap but restricts development. This cannot be used in urban areas.
What is river channel restoration?
This makes the river more natural so flood plains can flood more naturally. There is less risk of flooding downstream due to discharge being low. River restoration can increase local flood risk if nothing is done to prevent major flooding.
