URI: http://environment.data.gov.au/def/ba/glossary/returnperiod
βββAn event has a return period (or recurrence interval) of T years if its magnitude is equalled or exceeded once on average every T years. The reciprocal of the return period is the exceedance probability of the event, that is, the probability that the event is equalled or exceeded in any one year. For example, a flood with a return period of 10 years has a 0.1 or 10% chance of being exceeded in any one year and a flood with a return period of 50 years has a 0.02 or 2% chance of being exceeded in any one year. The actual number of years between floods of any given size varies a lot because of climatic variability.
description 
An event has a return period (or recurrence interval) of T years if its magnitude is equalled or exceeded once on average every T years. The reciprocal of the return period is the exceedance probability of the event, that is, the probability that the event is equalled or exceeded in any one year. For example, a flood with a return period of 10 years has a 0.1 or 10% chance of being exceeded in any one year and a flood with a return period of 50 years has a 0.02 or 2% chance of being exceeded in any one year. The actual number of years between floods of any given size varies a lot because of climatic variability.

editorial note 
Approved June 2017

label 
return period

license 
au

note 
This term and definition is used in technical products in the Bioregional Assessment Programme, a collaboration between the Australian Government Department of the Environment and Energy, the Bureau of Meteorology, CSIRO and Geoscience Australia. For more information see http://www.bioregionalassessments.gov.au.

pref label 
return period

rights 
The definition for this term is modified from Wikipedia and is licensed under the Creative Commons AttributionShareAlike License.

source 
return period
 http://streamflow.engr.oregonstate.edu/terminology/

type 
Concept

.. none found