Causes of Flooding

Question 1

How does flooding occur?

Answer 1

Flooding occurs when water reaches the river too quickly or there is too much precipitation. This can also be for human and physical causes.

Question 2

Physical causes of flooding? eg…

Answer 2

• Too much surface run-off - Too much of this will cause discharge in the channel to increase and if the channel can’t cope it will flood.
• If there’s a series of heavy rainfall or it has been raining for a long time, the soil will become saturated as its water table will be full and this leads to more surface run-off…
• Impermeable rock leads to high surface run-off and steep land leads to rapid surface run-off
• If there is a rapid snowmelt it can increase surface run-off
• If there is lack of vegetation there is no interception so more surface run-off

Question 3

Human causes of flooding? eg…

URBAN LAND USE

Answer 3

• Population increase and urbanisation leads to more houses and roads being built, more buildings and concrete or tarmac roads means more impermeable surfaces so more surface run-off
• People pace their back gardens or have concrete front yards to accommodate their cars so more impermeable surfaces…

Question 4

Human causes of flooding? eg…

RURAL LAND USE

Answer 4

Arable farming: Plants, greenhouses etc.

• Loss of hedgerows due to farming and felling (chopping) trees means less interception and more surface run-off
• Furrows are ploughed in farming which go up and down hills so water can easily run down hill.