Regional frequency analysis of autumnal floods in the province of Quebec, Canada

A large number of models have been proposed over the last years for regional flood frequency analysis in northern regions. However, these models dealt generally with snowmelt-caused spring floods. This paper deals with the adaptation, application, and comparison of two regional frequency analysis methods, canonical correlation analysis (CCA) and universal canonical kriging (UCK), on autumnal floods of 29 stations from the Cte-Nord region (QC, Canada). Three possible periods during which autumnal floods can take place are tested. The absolute and specific flood peak and volume quantiles are also studied. A jack-knife resampling procedure is applied to compare the performance of each model according to the selected period and the type of quantile. The period of September 1st to December 15th is found to be optimal to represent autumnal floods and specific quantiles were shown to lead to better results than absolute quantiles. Variables that explain best the autumnal floods are the basin area, the fraction of the area covered with lakes, and the average of mean July, August, and September maximal temperatures. The CCA model performs slightly better than UCK.