Find out more about meanders and oxbow lakes.

Geology can increase the risk of flooding when:

• The upland bedrock is impermeable, such as slate, which means there is more surface run-off
• Soil in low lying areas is made up of clay. Because it is so compact it is difficult for infiltration to occur.
• Areas of permeable rock, such as limestone, become inundated with water leading to increased surface run-off

Find out more about human and physical causes of flooding.

A steep, V-shaped cross-profile is typical in the upper course. This is because of vertical erosion by the river combined with weathering and mass movement of the valley slopes.

In the middle course, the river is flowing through lower-lying land. The gradient is gentler, so the river begins to meander (bend). As it does this the dominant type of erosion becomes lateral, eroding the valley sides. The makes the valley broader. Also, the rate of weathering increases on the softer rocks of the valley sides.

In the lower course, the river is passing through the low-lying country. Flooding results in deposition building up the flood plain and this, along with migrating meanders builds up and widens the valley further.

Find out more about the cross profile of a river.

Social:

• Safer from flooding due to the increased carrying capacity of the river so the risk of flooding to nearby settlements is reduced.
• Embankments are often used for walking routes which makes the embankment a more attractive walkway for local people.

Economic:

• Cheap compared to other methods of hard engineering

Environmental:

• Habitats are provided for riverbank animals such as otters, voles and kingfishers

Find out more about hard engineering.

Hard engineering involves the use of heavy machinery to build artificial structures which work against nature to reduce flood risk.

Find out more about hard engineering.