How can you manage floods?

There is no perfect way to protect floods. The traditional choices

are….• To build flood defences

• To straighten and deepen the river and cut off meanders

• To make storage areas for extra water

These are all called hard management.

The types of hard management are……

Dams

• These trap and store water, and let it out in a controlled way.

• They can generate electricity.

• Upstream of the dam the land floods to make a reservoir.

• They are expensive but very effective

• Makes a massive change to the ecosystem

Embankments

• These are raised banks along the river.

• They effectively make the river deeper so it can hold more water before it floods.

• They are expensive and don’t look natural.

• They do protect the land around them.

Flood walls

• These are built around settlements and important factories or roads.

• They are quite expensive and don’t look very natural.

• They are pretty effective.

Straightening and deepening the river

• This is called channelising the river.

• It makes the water move through the river faster.

• So it doesn’t build up and is less likely to flood.

• Changes the ecosystem in the river and spoils the natural look.

• Further downstream, where the river is not channelised the water builds up and floods.

Storage areas

• The water can be pumped out of the river and stored in temporary lakes.

• Then it is pumped back in after the water in the river has gone down a bit.

• Effective, but you need to have a large bit of spare land that isn’t used, so that you can flood it!

Area of land

Soft Management

Washlands

• These are parts of the floodplain that are allowed to flood.

• They can’t be built on.• They are usually used

for sports pitches or nature reserves.

Area of land at Swanage set aside to flood if needed.

Land-use zoning

• This is where land has different building controls depending on how far away from the river it is.

• Land next to the river isn’t allowed to be used for building, the next land can be but only for low-risk housing.

• The last zone is for high-risk buildings like hospitals, old peoples homes and dangerous factories

Afforestation

• This is re-planting trees in the catchment

Warning Systems

• Warnings are issued by the Environmental Agency (in the UK) so that local people can put sandbags by their homes, take furniture upstairs or evacuate the area.