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.