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.