How floods vary in severity?
The flood volume (the total amount of water in the flood): this contributes to both the level and duration of flooding. Dams and detention basins are less effective at flood mitigation during large volume floods. • The rate of rise (how fast the flood rises): a flood that rises quickly provides less time for warning and evacuation. • The flow velocity (how fast the water is flowing): faster flow causes a higher risk to human life, a higher risk of erosion, and more damage to infrastructure. • The flood duration: a flood that lasts for a longer time can have a greater impact due to the increased duration of the disruption to transport, business and personal networks. • The areal extent of flooding: flooding that affects a larger area often has a greater impact.
