Map 2.2
Water yield variability index, selected drainage region, 1971 to 2013

Map 2.2 Water yield variability index, selected drainage region, 1971 to 2013

Description for Map 2.2

The title of this map is "Water yield variability index, selected drainage regions, 1971 to 2013." On this map, the darker colours represent a higher the variability index. Category 1 (red) is 1.45 to 2.49, Category 2 (dark orange) is 0.93 to less than 1.45, Category 3 (burnt orange) is 0.63 to less than 0.93, Category 4 (cream) is 0.50 to less than 0.63 while Category 5 (white) represent regions where data are not available.

The Assiniboine–Red has the highest coefficient of variation for monthly flows, meaning the volume of water supplied in each month can vary widely from year to year. This was followed by the Missouri, Okanagan–Similkameen and the South Saskatchewan drainage regions. The Pacific Coastal drainage region had the lowest variability index indicating monthly water yield varies less from year to year.

Each drainage region boundary is outlined in black and labeled with a number to identify the area. A table is included which provides the full name of each drainage region, grouped by ocean drainage areas. The locations and names of some major cities in each province and territory are included on the map. Land areas outside of Canada are coloured light grey. Water is pale blue and major bodies, like oceans and bays, are named.

Notes: Variability is measured by using a coefficient of variation (CV) that allows the comparison of all months in all years of the 42-year time period. The CV of the water yield data is a measure of the dispersion or variation in the monthly yield values over the period 1971 to 2013 (and 1971 to 2012 for drainage region 1). It is defined as the ratio of the standard deviation of the monthly values to the mean. A higher CV indicates that the monthly data are more variable from year to year. The monthly variability was not calculated for drainage regions 5, 7, 8, 16, 17, 18, or the Labrador portion of 25.

Sources: Statistics Canada, Environment, Energy and Transportation Statistics Division, 2017, based on data from Environment and Climate Change Canada, 2015, Water Survey of Canada, Archived Hydrometric Data (HYDAT), (accessed December 3, 2015).

Data table for Map 2.2 Legend
Water yield variability index, 1971 to 2013, classification showing category colour
Table summary
This table displays the results of Water yield variability index. The information is grouped by Category (ap pearing as row headers), Variability index and Colour (appearing as column headers).
Category Variability index Colour
1 1.45 to 2.49 Red
2 0.93 to < 1.45 Dark orange
3 0.63 to < 0.93 Burnt orange
4 0.50 to < 0.63 Cream
5 Data not available White
Data table for Map 2.2 Data
Water yield variability index, selected drainage regions, 1971 to 2013
Table summary
This table displays the results of Water yield variability index. The information is grouped by Ocean drainage areas and drainage regions (appearing as row headers), Code and Water yield variability index, 1971 to 2013, calculated using number and monthly CV units of measure (appearing as column headers).
Ocean drainage areas and drainage regions Code Water yield variability index, 1971 to 2013Map 2.2 Note 1
number monthly CV
Pacific Ocean    
Pacific Coastal 1 0.50
Fraser–Lower Mainland 2 0.83
Okanagan–Similkameen 3 1.44
Columbia 4 1.04
Yukon 5 Note ..: not available for a specific reference period
Arctic Ocean    
Peace–Athabasca 6 1.01
Lower Mackenzie 7 Note ..: not available for a specific reference period
Arctic Coast–Islands 8 Note ..: not available for a specific reference period
Gulf of Mexico    
Missouri 9 2.14
Hudson Bay    
North Saskatchewan 10 1.04
South Saskatchewan 11 1.10
Assiniboine–Red 12 2.49
Winnipeg 13 0.87
Lower Saskatchewan–Nelson 14 0.92
Churchill 15 0.75
Keewatin–Southern Baffin Island 16 Note ..: not available for a specific reference period
Northern Ontario 17 Note ..: not available for a specific reference period
Northern Quebec 18 Note ..: not available for a specific reference period
Atlantic Ocean    
Great Lakes 19 0.72
Ottawa 20 0.80
St. Lawrence 21 0.76
North Shore–Gaspé 22 0.91
Saint John–St. Croix 23 0.89
Maritime Coastal 24 1.03
Newfoundland–Labrador 25 Note ..: not available for a specific reference period
Newfoundland (Island)Note 2 This cell is empty  0.62
Date modified: