Observational evidence of an intensifying hydrological cycle in northern Canada

Abstract

Trends and variability in the 1964-2007 annual streamflow for 45 rivers spanning 5.2 × 106 km2 of northern Canada are investigated. Discharge averages 1153 km3 yr-1 with a standard deviation of 71.4 km3 yr-1 and coefficient of variation (CVQ) of 6.2% over the 44-year period. A trend analysis reveals a recent (1989-2007) 15.5% increase in the annual flows owing to much-above average values recorded over the past decade. Trends in CVQ computed from 11-year moving windows of annual streamflows exhibit spatially coherent signals with increasing variability across most of northern Canada, excluding some rivers with outlets to the Labrador Sea and eastern James Bay. For the period of interest, 46% and 30% of the available gauged area and river discharge, respectively, experienced detectable increases in variability. This provides observational evidence of an intensifying hydrological cycle in northern Canada, consistent with other regions of the pan-Arctic domain. Copyright 2009 by the American Geophysical Union.