Critical duration event
The SuDS Manual published by CIRIA in 2015 defines a critical duration event as:
‘The duration of rainfall event likely to cause the highest peak flows or levels at a particular location, for a specified return period event.’
Where a rainfall event is: ‘A single occurrence of rainfall before and after which there is a dry period that is sufficient to allow its effect on the drainage system to be defined.’
And a return period is: ‘An estimate of the likelihood of a particular event occurring. A 100-year storm refers to the storm that occurs on average once every hundred years. In other words, its annual probability of exceedance is 1% (1:100).’
A design event is: 'A synthetic rainfall event of a given duration and return period that has been derived by statistical analysis.'
Rainfall intensity is the: ‘amount of rainfall occurring in a unit of time, expressed in mm/hr.’
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
Pressure increases on councils and communities to deliver common-sense housing
As government follows up with mandatory housing targets.
CIOB photographic competition final images revealed
Art of Building produces stunning images for another year.
HSE prosecutes company for putting workers at risk
Roofing company fined and its director sentenced.
Strategic restructure to transform industry competence
EBSSA becomes part of a new industry competence structure.
Major overhaul of planning committees proposed by government
Planning decisions set to be fast-tracked to tackle the housing crisis.
Industry Competence Steering Group restructure
ICSG transitions to the Industry Competence Committee (ICC) under the Building Safety Regulator (BSR).
Principal Contractor Competency Certification Scheme
CIOB PCCCS competence framework for Principal Contractors.
The CIAT Principal Designer register
Issues explained via a series of FAQs.
Conservation in the age of the fourth (digital) industrial revolution.
Shaping the future of heritage
Embracing the evolution of economic thinking.
Ministers to unleash biggest building boom in half a century
50 major infrastructure projects, 5 billion for housing and 1.5 million homes.
RIBA Principal Designer Practice Note published
With key descriptions, best practice examples and FAQs, with supporting template resources.
Electrical businesses brace for project delays in 2025
BEB survey reveals over half worried about impact of delays.
Accelerating the remediation of buildings with unsafe cladding in England
The government publishes its Remediation Acceleration Plan.
Airtightness in raised access plenum floors
New testing guidance from BSRIA out now.
Picking up the hard hat on site or not
Common factors preventing workers using head protection and how to solve them.