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 waterfall is a step in the long profile of the valley. It is where water falls down the vertical drop in the channel usually from a considerable height.

Find out more about the landforms of erosion in the upper course of a river.

Soft engineering involves working with nature and adapting to a river and learning to live with it.

Find out more about soft engineering.

It becomes more rounded and smaller.

Find out more about river erosion.

Deposition can occur:

• where a river enters a shallow area (this could be when it floods and comes into contact with the flood plain)
• at the base of a waterfall
• on the inside bend of a meander
• towards its mouth where it meets another body of water.

Find out more about river deposition.