Developing and Interpreting Intensity-Duration-Frequency (IDF) Information Under a Changing Climate
Scope:
Note: The scope for this NOI (originally published on May 2, 2023) was updated by the responsible SDO on November 19, 2024.
1.1 Inclusions
This Standard applies to methods to formulate and interpret IDF curves in a climate change context. It includes consideration of methods for establishing historical IDF rainfall estimates, and approaches and methods for incorporating climate change into IDF information.
1.2 Users and applicability
This Standard is intended for engineers involved in the mapping of floodplains and the design and build of stormwater infrastructure, as well as water resource managers involved in the operation and maintenance of such infrastructure.
Other potential users include those involved in the collection and provision of climate and weather-related information and data, as well as urban planners and policy-makers. An example of a use by the latter would be using IDF curves to inform emergency preparedness policies and practices as it relates to flooding.
1.3 Terminology
In this Standard, “shall” is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the Standard; “should” is used to express a recommendation or that which is advised but not required; and “may” is used to express an option or that which is permissible within the limits of the Standard.
Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material.
Notes to tables and figures are considered part of the table or figure and may be written as requirements.
Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.
Project need:
Intensity-Duration-Frequency (IDF) curves are graphical tools used to describe the likelihood of extreme rainfall events using liquid precipitation (rain) data and statistical methods. The curves demonstrate the average precipitation intensity of a precipitation event expected for a particular duration and frequency. They are used in planning, designing, and decision-making in a variety of contexts and applications to manage the risks associated with extreme rainfall. The latter, for example, can result in flooding, which can lead to landslides and severe damage to infrastructure such as buildings and bridges. IDF curves are used by engineers, urban planners, and water resource managers, among others. With climate change being an ever-present concern, historical data is no longer an accurate predictor of future precipitation levels. Consequently, this presents a challenge in calculating IDF curves, which have traditionally been based on historical information alone.
Note: The information provided above was obtained by the Standards Council of Canada (SCC) and is provided as part of a centralized, transparent notification system for new standards development. The system allows SCC-accredited Standards Development Organizations (SDOs), and members of the public, to be informed of new work in Canadian standards development, and allows SCC-accredited SDOs to identify and resolve potential duplication of standards and effort.
Individual SDOs are responsible for the content and accuracy of the information presented here. The text is presented in the language in which it was provided to SCC.