Mapping Extreme Rainfall Statistics for Canada under Climate Change Using Updated Intensity-Duration-Frequency Curves.

Climate change is expected to alter the frequency and intensity of extreme rainfall events, affecting the rainfall intensity-durationfrequency (IDF) curve information used in the design, maintenance, and operation of water infrastructure in Canada. Presented in this study are analyses of precipitation data from 567 Environment Canada hydro-meteorological stations using the web-based IDF_CC tool, which applies a novel equidistance quantile-matching downscaling method to generate future IDF curve information. Results for the year 2100 based on The Second Generation Canadian Earth System Model (CanESM2) and a multimodel ensemble median of 24 global climate models (GCMs) were generated. A natural neighbor spatial interpolation method was used to generate results for ungauged locations. One in 5-year, 2-h and one in 100-year, 24-h precipitation events were explored. Results based on CanESM2 indicated a reduction in extreme precipitation in central regions of Canada under specific analyses and increases in other regions. Relative to the multimodel ensemble median approach, the CanESM2 results suggested more spatial variability in change of IDFs, and the ensemble median generated generally lower values than CanESM2. By using the median value that lowers the importance of extreme outputs, the ensemble median approach obscured uncertainty associated with GCM outputs. While the IDF_CC tool helps fill an important gap related to accessing local climate change information, it is important to consider uncertainty in GCM outputs when making climate change adaptation decisions. [ABSTRACT FROM AUTHOR]