Question Constellation Sign up for free AQA · GCSE · Geography · Higher
Physical controls on flood risk
Explain how physical factors can affect flood risk.
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Marking points
- 1 Explains at least one physical factor affecting flood risk.
- 2 Links the factor to runoff, lag time, discharge or likelihood of flooding.
- 3 Covers more than one relevant factor for full marks.
Full-mark answer
Heavy rainfall can saturate the soil, so infiltration is reduced and more water flows over the surface into the river. This shortens lag time, increases discharge and raises flood risk. Steep slopes also increase flood risk because water runs quickly downhill into the channel. In contrast, more vegetation can reduce flood risk by intercepting rainfall and storing water before it reaches the river.
Why this answer loses marks
Flood defences reduce flooding.
Human management is not credited because the question asks for physical factors affecting flood risk.