Contents - Winter 2008
Vol. 1 No. 1
What’s Happening with our Water and Weather? Managing Climate Change and Water Resources
By Mari-Louise Rowley
John Pomeroy. Photo courtesy Kasdorf Photographics.
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.
John Pomeroy and technician Jackie Randell measure
snow depth and density the traditional way. Photo courtesy Jaime Hood.
“What we want to do is incorporate the useful information from these models with better statistics on the frequency of extreme weather and water conditions at scales that are of interest to people—generally, the size of a farmer’s field or a city neighbourhood,” says Pomeroy.
One climate change paradox Pomeroy has discovered is that as winters become warmer, the Prairies can become wetter. This is not necessarily because there is more snowfall and rainfall (which are also predicted), but because more snow stays on the ground as snowpack. Blowing snowstorms are suppressed in warmer winters, and the heavier, wetter snow is not readily blown from fields and evaporated by cold and wind.
In addition, after a warm winter, ice layers in the snow and soil induce meltwater to run off into streams and sloughs, which can result in high water levels right through the summer.
Pomeroy and colleagues have been working to incorporate the effects of increased rainfall and snowfall, snowpack, permafrost and glacial melt on climate and water supply computer models. In the process, they’ve developed some unique tools, such as a snow sonar device.
“This doesn’t mean an end to drought as our climate changes,” Pomeroy cautions. “There will always be droughts, and they could be more extreme. However, in between droughts, there will also be very wet periods.”
The last drought in Canada lasted from 1999 to 2003. That drought was particularly severe, because it occurred on the Prairies and in the mountains at the same time.
“Our cities, industries and farms rely on the Saskatchewan River system for their water supply. The problem occurs when you have a high demand for water, for both cities and irrigation, when the river flow is lowest,” explains Pomeroy.
He notes that industries such as ethanol production and tar sands extraction require enormous amounts of water. For example, up to 10 litres water is required to produce one litre of ethanol.
The goal of the Centre for Hydrology’s drought research initiative is to improve drought prediction in Canada so that government and industry can better manage water resources. Droughts can be meteorological (lack of rain), agricultural (lack of soil moisture) and hydrological (lack of surface or groundwater). The centre is focusing on hydrological drought.
Fortunately for Saskatchewan, the Gardiner Dam holds back the spring snowmelt water to maintain summer flows in the South Saskatchewan River. By creating Lake Diefenbaker, it provides a reliable source of water for irrigation and of pipeline water supplies to communities and industry.
“The summer of 2007 was the first time Saskatchewan has had to deal with both flooding in the northeast and drought in the southwest. With our research, we hope to be able to help people and governments plan for and manage this extreme hydrology.”
– John Pomeroy, Canada Research Chair in Water Resources and Climate Change
Pomeroy notes Saskatchewan still has plenty of water in its rivers—in the short term at least. Alberta, on the other hand, has reached the limit of what it can supply for irrigation and industry. And this could have consequences for Saskatchewan, which relies on Alberta to honour an interprovincial agreement to pass on 50 per cent of the natural flows arising in the Saskatchewan River system.
Centre for Hydrology researchers are involved in several projects at the national and international level and provide advice to governments on climate change issues. In addition to major funding from the Canadian Foundation for Climate and Atmospheric Sciences, partners include Environment Canada, many Canadian universities, NATO, the U.K. Natural Environment Research Council, the University of Wales, the Russian Academy of Sciences, the USDA Agricultural Research Service, the University of Idaho, and the U.S. National Oceanic and Atmospheric Administration.
“As long as we consider and preserve water as an essential part of the ecosystem, we will be okay,” Pomeroy states. “When it becomes a commodity to be bought and sold, then it becomes problematic. Water is not a luxury item. It is essential for life.”
Snow Sonar Device Attracts NASA
Snowpack measurement with U of S acoustic sounder. Photo courtesy John Pomeroy.
Until recently, methods for measuring snow on the ground have been pretty primitive—dig a pit manually and sample snow density at various layers.
U of S student Nicholas Kinar has devised an ingenious solution—snow sonar.
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.”
Impact of Human Intervention on South Saskatchewan River Flows
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.
