Return period
Culvert, screen and outfall manual, (CIRIA C786) published by CIRIA in 2019, defines return period as: ‘The average length of time between flood events of a similar magnitude, a 100-year flood occurring on average once every 100 years. Annual exceedance probability (EAP) is the preferred term for flood risk management, one percent AEP being equivalent to a 100-year return period.’
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