By Mari-Louise Rowley
Saskatchewan has always been known for its extreme weather and highly variable water supplies. Lately, however, the extremes have become more severe and less predictable.
In 2007, the spring snow melt set records in east central Saskatchewan, while a drought developed in the southwest. August was one of the coldest and wettest on record in parts of the province. Flooding destroyed homes and communities and ruined crops—if the intense heat in July hadn’t already burnt them.
University of Saskatchewan hydrologist John Pomeroy is trying to decipher why this is happening and how we can best cope with the effect of climate change on water resources.
“Saskatchewan agriculture is set up for extremes already, as every farmer has had to deal with drought or floods at various times,” says Pomeroy. “Our interest in climate change is in understanding how it causes these extreme variations in water supply and weather.”
The Canada Research Chair in Water Resources and Climate Change and director of the U of S Centre for Hydrology says his team’s work will help cities, farmers and industry plan and prepare for the effect of extreme weather on water resources.
Rain calculations, for example, would be used by urban engineers for designing adequate drainage systems and by highway engineers in deciding the size of culverts.
Current global climate models are not directly useful to predicting extreme rainfall and flooding. They make predictions over very large areas—much of southern Saskatchewan, for example. Such a model would show only moderate rainfall averaged out over the large area and would not indicate that it had rained intensely over a given small area.
The handheld device, developed and fabricated at U of S as part of Kinar’s master’s degree research, uses sound waves to measure the depth and density of snow.
“NASA is interested in this device for use in confirming their satellite measurements,” says Pomeroy. “Weather services and provincial water departments can also use it to survey snow in spring and better assess flood potential. We think it may help predict avalanches as well.”
This graph shows that river withdrawals for irrigation and municipal water use in Alberta have resulted in significantly reduced annual water flows into Saskatchewan during the period 1970-2002 compared with annual flows that would have occurred without human intervention in the river system in Alberta.
Natural flows (blue column) are compared with recorded flows (green column) measured by the Water Survey of Canada. Water consumption has been growing steadily since 1970. In drought years (1988, 2001) water consumption was 42 per cent of the natural flow.