Recent Variations in Climate and Hydrology in Canada

Abstract

Climatic and hydrologic variations between the decades 1976–1985 and 1986–95 are examined at 210 climate stations for temperature, 271 climate stations for precipitation, and 642 hydrology stations from across Canada. The variations in climate are distributed across a broad spatial area. Temperatures were generally warmer in the more recent decade, with many stations showing significant increases during spring and fall. Significant decreases in temperature were found during winter in eastern Canada. Significant increases in temperature were more frequent in western Canada than in the east. Significant decreases in precipitation were also more prevalent in the north, as were increases in the south, except for Ontario and Quebec where little or no change has taken place. The hydrologic responses to these variations in climate are classified into four hydrograph types and six patterns of shifts in streamfiow between the two decades. The 642 hydrologic stations fall into 16 of the potential 24 groups. These 16 classes demonstrate a strong correspondence to the distribution of ecozones in Canada. In addition, these recent variations illustrate the leverage effect of small variations in climate, particularly temperature, on different hydrologic systems. © 2000 Taylor & Francis Group, LLC.