ABSTRACT

Intensity–duration–frequency (IDF) curves need to be reliable to serve as a relevant tool in preventing or reducing potential damage to society. This often requires accounting for the effect of climate change due to evidence of its effect on extreme precipitation. There is a large number of approaches for IDF curve estimation under climate change in the literature; however, a general framework with practical guidelines for facilitating their application by practitioners is not readily available. The aim of the present study is to provide practical guidelines and recommendations for helping federal and provincial agencies, as well as others who might produce practice guidelines, to develop standardized procedures for the estimation of future IDF curves in Canada that can then be used by practitioners in infrastructure design, management and risk assessment. This is done by gathering and summarizing findings in rainfall frequency analysis from the Canadian FloodNet Research Group, under a practically oriented perspective. Technical recommendations are presented within a methodological framework to facilitate understanding; decision-making procedure-specific flowcharts are provided to facilitate their application. The proposed methodological framework is based on the use of pooled frequency analysis for reasonable estimation of extreme rainfall intensities, and on the estimation of gridded relative changes for IDF updates under climate change following different approaches depending on rain gauge network density. In particular, three methods that do not compete against each other but rather are different methodologies to be applied depending on the case study are proposed: pooled estimation of extreme rainfall in Canada (Method I), gridded relative changes in 24-h extreme rainfall intensities in Canada (Method II) and gridded relative changes in 24-h and sub-daily extreme rainfall intensities in regions of Canada with a relatively high station density (Method III).

摘要

强度-持续时间-频率 (IDF) 曲线需要可靠，以作为预防或减少对社会的潜在损害的相关工具。由于有证据表明气候变化对极端降水的影响，这通常需要考虑气候变化的影响。文献中有大量关于气候变化下 IDF 曲线估计的方法；然而，目前还没有现成的通用框架和实用指导方针，以方便从业者应用这些指导方针。本研究的目的是提供实用的指导方针和建议，以帮助联邦和省级机构以及其他可能制定实践指导方针的机构制定标准化程序来估计加拿大未来的 IDF 曲线，然后可供从业者使用在基础设施设计中，管理和风险评估。这是通过在面向实际的角度收集和总结加拿大 FloodNet 研究小组的降雨频率分析结果来完成的。在方法框架内提出技术建议以促进理解；提供了特定于决策程序的流程图以方便其应用。所提出的方法框架基于使用合并频率分析来合理估计极端降雨强度，并基于根据雨量计网络密度采用不同方法估计气候变化下 IDF 更新的网格相对变化。特别是，