CSA W231:25

Preface This is the first edition of CSA W231, Developing and interpreting intensity-duration-frequency (IDF) information under a changing climate. CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support of the Standards Council of Canada. This Standard is considered suitable for use for conformity assessment within the stated scope of the Standard. This Standard was prepared by the Technical Committee on Developing and Interpreting Intensity-Duration-Frequency Information Under a Changing Climate, under the jurisdiction of the Strategic Steering Committee on Natural Resources, and has been formally approved by the Technical Committee. This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group. Scope 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.