100-year event
A 100-year event (or 100-year return period event) is an event that occurs (or is exceeded) on average once in every one hundred years (such as a storm, flood or rainfall event). This can also be expressed as 1 in 100 or 1:100.
For example, a 100-year storm is a storm that is likely to occur once every hundred years.
A ‘return period’ is an estimate of the likelihood of a particular event occurring. The return period of a rainfall event is the average time between events of at least a given magnitude.
Events can also be described by their ‘probability of occurrence’ (or frequency of occurrence) which is expressed as a percentage, or as 1 divided by the return period. The probability of occurrence of a 100-year event is 1%.
The ‘critical duration’ is the duration of the event for a specified return period event.
Ref CIRIA. 2015. C753. The SuDS Manual.
[edit] Related articles on Designing Buildings Wiki
Featured articles
Check out some of the best features and news from Designing Buildings as well as key stories from around the web.
Construction Management, 8 July
NEETs crisis drives interest in trades, but apprenticeships barriers remain.
Passive fire protection webinar
MEP services penetration seals.
Where its at podcast (and video) - The role of the Architectural Technologist as an Expert Witness.
More than 200 remarkable buildings added to SAVE’s Buildings at Risk register.
Government scraps pre-application consultation for Nationally Significant Infrastructure Projects.
Historic England and infrastructure
New projects offer opportunities for the historic environment and local communities.
Construction Management, 2 July
Construction deaths halve in two years.
Green Book changes to drive investment in all parts of UK.
Minimum energy efficiency standards (MEES)
CIAT briefing on response to consultations for privately rented non-domestic properties.
Connect, collaborate, shape the future
Registration now live for UK Construction Week Birmingham.
CIOB announces Saul Humphrey FCIOB as new President for 26/27 term.
A quick, simple, and zero-bills solution to prevent overheating.