Sensitivity of River Regions to Climate Change

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Abstract

The most sensitive river regions include the Atlantic coast, the Great Lakes-St. Lawrence Valley regions, the Rocky Mountains and the Prairies. The sensitivity projection for Canada's river regions in response to climate warming was derived based on an examination of the effects of projected precipitation changes on landscapes. Climate warming has the potential to cause substantial changes to flow in rivers. The most direct effects of projected climate change would be an increase in floods and river erosion.

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The Theme

On average, a warmer Earth will be a wetter Earth, although many land areas may actually become drier. Furthermore, summer precipitation over land is likely to become more intense when the warming occurs. This has the potential to cause substantial changes to flow in Canada's rivers. Some rivers will experience more frequent extreme low flows, and all rivers could see an increase in the frequency and magnitude of floods, thus increasing the risk to humans, buildings and other structures. Conversely, the impacts caused by human activity on rivers, such as dams and irrigation systems, may become amplified with the projected warming. This map summarizes the regional sensitivity of rivers to projected climate change in Canada.

Sensitivity Projection

The sensitivity projection for Canada's river regions in response to climate warming was derived based on an examination of the effects of projected precipitation changes on landscapes.

As shown in this map, the most sensitive regions include the Atlantic coast and the Great Lakes-St. Lawrence Valley regions. The main flood generator due to climate change is likely to be more intense rainstorms (rather than any increases in snowmelt). Small streams in urban areas may be particularly problematic. Flows are also likely to increase in the southern Cordillera and in the eastern slopes of the Rocky Mountains. This will affect large Prairie streams while smaller Prairie-fed streams risk flooding from increases in thunderstorm activity. In the Northern Shield area, permafrost is at risk of being reduced. This will likely alter the seasonality of runoff and affect soil instability, which will have implications for the landscape, ecosystems and infrastructure. The direct impact of climate change on permafrost is currently still under study.

While the most direct effect of projected climate change will be an increase in flood and river erosion, these impacts will extend to the use and value of rivers for recreation, habitat, fisheries, water supply, and transportation.

Data Source

P. Ashmore and M. Church. 2000. The Impact of Climate Change on Rivers and River Processes in Canada. Geological Survey of Canada Bulletin 555. Ottawa: Natural Resources Canada.