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Water Resources (A Canadian Perspective)

    WATER RESOURCES


       (A Canadian Perspective)
 
 
 
Understanding the vulnerability of Canada’s water resources to climate change is vitally important.  Water is one of Canada’s greatest resources.  We depend on the availability of a clean, abundant water supply for domestic use; food, energy and industrial production; transportation and recreation; and the maintenance of natural ecosystems.  It is estimated that water’s measurable contribution to the Canadian economy reaches $7.5 to 23 million per year.    
 
 
 
 
Canada has a relative abundance of water, possessing 9% of the world’s renewable freshwater, yet only 0.5%of the global population. However, the water is not evenly distributed across the country, and water availability varies both between years and with the changing seasons.  As a result, most regions of the country have experienced water-related problems, such as shortages (droughts), excesses (floods) and associated water quality issues.  For example, the drought of 2001 affected Canada from coast to coast (Table 1), with significant economic and social impacts.  In the 1990s, severe flooding in the Saguenay region of Quebec (1996) and Manitoba’s Red River valley (1997) were two of the costliest natural disasters in Canadian history. 
 
In its Third Assessment Report, the Intergovernmental Panel on Climate Change projects an increase in globally averaged surface air temperatures of 1.4 - 5.8ºC by 2100.  Changes of this magnitude would significantly impact water resources in Canada.  Climatic variables, such as temperature and precipitation, greatly influence the hydrological cycle, and changes in these variables will affect runoff and evaporation patterns, as well as the amount of water stored in glaciers, snowpacks, lakes, wetlands, soil moisture and groundwater.  However, there remains uncertainty as to the magnitude and, in some cases, the direction of these changes. This is related to the difficulty that climate models have in projecting future changes in regional precipitation patterns and extreme events, and to our incomplete understanding of hydroclimatic processes  
 
 
                                  TABLE 1: The 2001 drought across Canada
 

          Region

       Conditions in 2001

  
British Columbia
 
Driest winter on record, with precipitation half of historic average across coast and southern interior
 
 
Snowpacks in southern regions were at or below historic low

            
Prairies
 
Saskatoon was 30% drier than 110-year record
 
Many areas experienced lowest precipitation in historic record
 
Parts of the Palliser Triangle experienced second or third consecutive drought
 
 
Great Lakes
        St. Lawrence basin
 
Driest summer in 54 years
 
Southern Ontario (Windsor-Kitchener) experienced the driest 8 weeks on record
 
Montréal experienced driest April on record and set summer record with 35 consecutive days without measurable precipitation
 
                
Atlantic
 
Third driest summer on record
 
Large regions experienced only 25% of normal rainfall in July, and August was the driest on record
 
July, with 5mm of rain, was the driest month ever recorded in Charlottetown
 
                     
 
In addition to the expected shifts in hydrological parameters, potential changes in the economic, demographic and environmental factors that influence water resources must also be considered.  The response of water users, as well as water management mechanisms, to climate change will greatly influence the vulnerability of water resources.  Both the ability and the willingness of society to undertake appropriate adaptive measures are critically important. 
 
The impacts of climate change on water resources will vary across the country, due to regional differences in climate changes, hydrological characteristics, the major potential impacts are listed in Table 2.
 
From this table, it is evident that the potential impacts of extreme events, seasonal shifts in flow issues for several regions of Canada.
 
 
 
                 TABLE 2:  Potential impacts of climate change on water resources     

    

       Regions                            Potential changes                     Associated concerns

 

Yukon and coastal British Columbia

 

Increased spring flood risks (BC), impacts on river flows caused by glacier retreat and disappearance

 

Reduced hydroelectric potential, ecological impacts (including fisheries), damage to infrastructure, water apportionment

 

 

Rocky Mountains

 

Rise in winter snowline in winter-spring, possible increase in snowfall, more frequent rain-on-snow events

 

Decrease in summer streamflow and other changes in seasonal streamflow

 

 

Increased risk of flooding and avalanches

 

 

 

Ecological impacts, impacts on tourism and recreation

 

Prairies

 

Changes in annual streamflow, possible large declines in summer streamflow

 

Increased likelihood of severe drought, increasing aridity in semiarid zones

 

Increases or decreases in irrigation demand and water availability

 

 

Implications for agriculture, hydroelectric generation, ecosystems and water apportionment

 

Losses in agricultural production, changes in land use

 

 

Uncertain impacts on farm sector incomes, groundwater, streamflow and water quality

 

Great Lakes basin

 

Possible precipitation increase, coupled with increased evaporation leading to reduced runoff and declines in lake levels

 

Decreased lake-ice extent, including some years without ice cover

 

 

Impacts on hydroelectric generation, shoreline infrastructure, shipping and recreation

 

 

Ecological impacts, increased water loss through evaporation and impacts on navigation

 

 

Atlantic

 

 

Decreased amount and duration of snow cover

 

Changes in the magnitude and timing of ice freeze-up and break-up

 

Possible large reductions in streamflow

 

 

Saline intrusion into coastal aquifers

 

Smaller spring floods, lower summer flows

 

Implications for spring flooding and coastal erosion

 

 

Ecological impacts, water apportionment issues, hydroelectric potential

 

Loss of potable water and increased water conflicts

 

 

Arctic and Subarctic

 

Thinner ice cover, 1- to 3-month increase in ice-free season, increased extent of open water

 

 

Increased variability in lake levels, complete drying of some delta lakes

 

 

Ecological impacts, impacts on traditional ways of life, improved navigation, changes in viable road networks

 

Impacts of ecosystems and communities

 

 

 

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