Advanced · 3 min
From rainfall to flood risk
Paving can reduce infiltration and send rainfall into drains and streams more quickly. Flood risk depends on the hazard as well as the people and assets exposed and their vulnerability. Increasing runoff does not guarantee a flood, but can increase pressure on drainage systems.
Visual explanation
How paving can change runoff
- More impermeable surface
- Less water enters the ground
- More rapid surface runoff reaches drains and rivers
This pathway can increase flood pressure. Rainfall, storage, drainage capacity, and exposure still determine the outcome.
Simplified diagram. Read the explanation for the conditions and limits.