Information about the different methods
Afforestation £
This involves planting trees on either side of the river. It would need a very
large area of land to plant the trees. It would take a long time for the trees to
grow. Afforestation reduces the amount of water getting into the river, as the
trees intercept water by their leaves or soak it up in their roots. This is a very
cheap scheme but would take 10 years before the trees were fully grown.
Dam £££
A large concrete barrier which is constructed across a river. A reservoir
normally forms behind it. If they are built across rivers they can control the
water flow and stop flooding very quickly. However, large areas are flooded
behind the dam which could affect farmland and housing. This scheme is
extremely expensive.
Letting Rivers Flood £
An area of land either side of the river that is left undeveloped (e.g. farmland)
and when the river floods this area will be covered by water. When a river is in
flood it will drop sediment making the land very good for farming. A natural
method of flood prevention, it allows the river to flood onto land which will then
soak it up. This is a very cheap method.
Embankments ££
Banks usually made of earth are built along the sides of the river to stop the
water from overflowing. This greatly reduces the chance of flooding. Normally
built from natural materials so there is no damage to the environment. Needs to
be constantly repaired as the banks can get eroded in a flood (especially if they
are made from earth.)
River Straightening £££
A new channel is made for the river taking out the meanders (bends) so that the
flow of the river is faster. This speeds up the flow of the water going from the
source to mouth, therefore keeping water levels down. This needs to be
constantly checked, as the river naturally wants to meander. This is a very
expensive method and can look quite unnatural.
Evacuation Scheme ££
With reliable weather forecasts, flooding can be predicted and people will be
able to leave their homes before it happens. This gives people plenty of warning
to leave the danger areas. It also gives people time to prepare and reduce
damage to their property. However, this does not stop the flood from happening
and so the damage is still done and has to be cleared up afterwards.