The Influence of the Pacific Decadal Oscillation on Annual Floods in the Rivers of Western Canada1. (22nd July 2016)

• Record Type: Journal Article
• Authors: Gurrapu, Sunil; St‐Jacques, Jeannine‐Marie; Sauchyn, David J.; Hodder, Kyle R.
• Is Part Of: Journal of the American Water Resources Association. Volume 52:Number 5(2016:Oct.)
• Page Start: 1031
• Page End: 1045
• Publication Date: 2016-07-22
• Subjects: Western Canada -- floods -- independently and identically distributed assumption (i.i.d.) of flood frequency analysis -- multi‐decadal variability -- Pacific Decadal Oscillation -- Fraser River Basin -- Columbia River Basin -- North Saskatchewan River Basin -- permutation test for quantile‐quantile plots; Water-supply -- Periodicals; Hydrology -- Periodicals; Water resources development -- Periodicals; Water resources development -- Environmental aspects -- Periodicals; 333.9100973
• DOI: 10.1111/1752-1688.12433
• Languages: English
• ISSNs: 1093-474X

Abstract

Abstract: We analyzed annual peak flow series from 127 naturally flowing or naturalized streamflow gauges across western Canada to examine the impact of the Pacific Decadal Oscillation (PDO) on annual flood risk, which has been previously unexamined in detail. Using Spearman's rank correlation ρ and permutation tests on quantile‐quantile plots, we show that higher magnitude floods are more likely during the negative phase of the PDO than during the positive phase (shown at 38% of the stations by Spearman's rank correlations and at 51% of the stations according to the permutation tests). Flood frequency analysis (FFA) stratified according to PDO phase suggests that higher magnitude floods may also occur more frequently during the negative PDO phase than during the positive phase. Our results hold throughout much of this region, with the upper Fraser River Basin, the Columbia River Basin, and the North Saskatchewan River Basin particularly subject to this effect. Our results add to other researchers' work questioning the wholesale validity of the key assumption in FFA that the annual peak flow series at a site is independently and identically distributed. Hence, knowledge of large‐scale climate state should be considered prior to the design and construction of infrastructure.