Water use and availability ratio
The water use to availability ratio map identifies what proportion of renewable fresh water is used by Canadians within each of Canada's major drainage basins.
A stressed watershed is defined by the Organisation for Economic Co-operation and Development (OECD) as a watershed in which greater than 40% of the available renewable water within the watershed is used by humanity for industrial, agricultural, or personal uses. According to the OECD, at least 60% of renewable flows are required to maintain a healthy, functioning ecosystem. However, ecosystem water requirements are poorly understood and vary depending on the ecosystem.
While Canada appears to have lots of fresh water (7% of the world's renewable freshwater, 25% of its global wetlands), this water is not always available where needed. With 85% of the population living along the southern border with the United States (most of the country's fresh water drains to the north) and Canada being the second highest per capita water user in the OECD, it is not surprising that those drainage basins with higher freshwater use to availability ratios are also located in southern Canada.
The drainage area of greatest concern (exceeding the OECD's 40% threshold) is the South Saskatchewan, Missouri and Assiniboine-Red area. This area is of particular concern, as flows in the South Saskatchewan are already fully allocated and predictions of glacial retreat and reduced winter snow coverage due to global warming may significantly impact a river system that relies on glacial and snow melt for most of its summer flows.
Data on streamflow and surface freshwater intake (by drainage area), is also available for download. | Excel |
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