Researchers Study Effects Of Global Warming, Human Activity And Drought On Western Canadian Water Supply

The Canadian prairies are facing an unprecedented water crisis due to a combination of climate warming, increase in human activity and historic drought, according to new research by the University of Alberta's Dr. David Schindler.

"The western prairies are worse than other areas of Canada," Schindler said. "One of the referees on this paper said, 'wow, this is like looking out the window of a locomotive 10 seconds before the train crashes.' It is a very dire situation."

Although most global studies rank Canada among the top five countries in terms of per-capita water supply, those rankings can be deceptive, argue Schindler and Dr. Bill Donahue, co-researcher.

In their research on the cumulative effects of climate warming, drought and human activity on water shortages, Schindler and Donahue found that the biggest threat was a combined one, made up of several ingredients. First, there is now considerable evidence that the 20th century, when settlers arrived, was the wettest century for at least a couple of millenia. What we think of as normal was not normal in the long-term, the researchers said. "Most earlier centuries had one or more prolonged droughts, some of 10 years to 40 years," said Schindler. "So we should probably not expect a second wet century in a row."

Climate warming is a second factor that will exacerbate any droughts. This new research shows that there is already a decline in glaciers that supply water to our rivers, snowpacks are dwindling and there is higher precipitation evaporation. The western prairies have already warmed by two to four degrees and this is expected to double by mid-century, the researchers argue in the paper.

Canada's rapidly growing population also means the increased use of water for industry and agriculture, both of which are increasing as well, the researchers said. Some rivers -- the Bow and Oldman in southern Alberta -- already are oversubscribed, Schindler said.

Making it worse, the features of the watersheds that protect these rivers are being destroyed, Schindler said. "We drain or fill wetlands and destroy our riparian forests -- all of the features that could help our landscape to retain the water it does get."

One reason this dismal situation has been underestimated is that previous analyses have considered total annual flow, which has declined only slightly for most rivers, according to the researchers. Schindler and Donahue looked at summer -- May to August -- flows. This is the period when human demand is at the highest for irrigation, agriculture and municipalities and when coldwater fisheries are vulnerable to high temperature and low oxygen.

Although reducing greenhouse emissions would have the greatest effects several decades from now, it would have little short-term impact, Schindler said. "We cannot replace the glaciers so our only alternative is to get very serious about water conservation and protection of the watersheds that supply our water," he said. For example, it is imperative to use less water for agriculture through drought resistant crops or incentives for water conservation and to consider reusing water and low-flow devices as ways to conserve the supply.

"As we show, the less water available to dilute pollutants, the more water quality problems we will see," Schindler said.

David Schindler: http://www.biology.ualberta.ca/faculty/david_schindler/index.php

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