Annual Exceedance Probability … the probability a certain `annual-type’ event, e.g. annual river high flow/flood), etc., will occur (or be exceeded) in any particular year. See more … here.
So, what is the probability that we will experience a 100-year flood next year? … in the `next 100 years’? Glad you asked. Next year? … 1/100 or 1% chance. Next 100 years? … see … here