Standard Drainage Area Classification (SDAC) 2003

• Introduction
• Description of major drainage areas
• Conformity to relevant nationally recognized standards

Introduction

The Standard Drainage Area Classification (SDAC) 2003 was developed to enable the production of integrated statistics by hydrographic areas. It provides a range of geographical units that are convenient for data collection and compilation, and useful for spatial analysis of environmental, economic and social statistics. A drainage area is composed of a drainage basin as well as adjacent areas, such as coasts and islands that may not drain into the outlet^{Footnote 1}. A drainage basin is an area in which all contributing surface waters share the same drainage outlet. This classification covers drainage areas and therefore applies to all of Canada including coasts and islands that may not drain into an outlet.

The Standard Drainage Area Classification (SDAC) 2003 covers all the land and interior freshwater lakes of the country. Some drainage areas straddle the Canada-United States border. This classification includes only the parts within Canada since it is used for reporting Canadian data.

There are three levels in the 2003 version of the classification - 11 major drainage areas, 164 sub-drainage areas and 974 sub-sub-drainage areas. All drainage areas, sub-drainage areas and sub-sub-drainage areas are named and have an identifying unique code. The code used is a four-character alphanumeric code. Two leading numeric digits represent the major drainage areas, the third alphabetic character represents the sub-drainage areas and a fourth alphabetic character represents the sub-sub-drainage areas.

Structure of the Standard Drainage Area Classification (SDAC) 2003

Level	Characters in Code (cumulative)
major drainage area	2
sub-drainage area	3
sub-sub-drainage area	4

Among the levels in this classification, the detailed sub-drainage area level is generally used for disseminating statistics.

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Description of major drainage areas

Canada is divided into eleven major drainage areas:

The table displays the name (first column) and are information (second (square kilometres) and third (%) columns).

Major drainage areas

Major drainage area name	Area
	square kilometres	%
Maritime Provinces	163,990	1.6
St. Lawrence	1,067,879	10.7
Northern Quebec and Labrador	1,158,292	11.6
Southwestern Hudson Bay	735,320	7.4
Nelson River	987,015	9.9
Western and Northern Hudson Bay	1,253,213	12.6
Great Slave Lake	974,853	9.8
Pacific	666,349	6.7
Yukon River	337,036	3.4
Arctic	2,605,138	26.1
Mississippi River	27,097	0.3
Canada	9,976,182	100.0
Note: The classification covers all of Canada including islands and freshwater lakes; however, the classification does not cover marine water. The numbers in the table show the area covered in the classification.

The Maritime Provinces drainage area covers New Brunswick, Prince Edward Island, Nova Scotia and part of the Gaspé Peninsula in eastern Quebec. This area drains into the Gulf of St. Lawrence and the Atlantic Ocean. Halifax, Fredericton and Charlottetown are located in this drainage area.

The St. Lawrence drainage area includes all of southern Quebec, southern Ontario and Newfoundland. Cities in this drainage area include Montréal, Toronto, Ottawa, Thunder Bay, St. John's and Corner Brook.

The Northern Quebec and Labrador drainage area covers all the area just north of the St. Lawrence drainage area. Most of the water in this drainage area drains into Hudson, James and Ungava bays. The Labrador portion of the drainage area drains directly into the Atlantic Ocean. Communities in this drainage area include Chibougamau and Kuujjuaq in Quebec and Happy Valley-Goose Bay in Labrador.

The Southwestern Hudson Bay drainage area covers a large portion of northern Ontario, a small part of western Quebec and northeastern Manitoba. Communities in this drainage area include Val-d'Or in Quebec and Kapuskasing and Timmins in Ontario.

The Nelson River drainage area covers most of the southern Prairie provinces, from the Rockies to northwestern Ontario. Major cities within this drainage area are Winnipeg, Regina, Saskatoon, Calgary and Edmonton. Water from the Nelson River drainage area ultimately drains into Hudson Bay.

The Western and Northern Hudson Bay drainage area includes parts of eastern Alberta, all of the middle portions of Saskatchewan, northwestern Manitoba, the northeastern portion of the Northwest Territories, southeastern Nunavut, the Hudson Bay islands and part of Baffin Island. The following communities are found in this drainage area: Bonnyville, Alberta; La Ronge, Saskatchewan; and Rankin Inlet, Nunavut.

The Great Slave Lake drainage area is composed of northern Alberta, northern Saskatchewan, southern Northwest Territories and a small portion of British Columbia. Cities within this drainage area include Grande Prairie and High Level in Alberta, Yellowknife and Hay River in the Northwest Territories, and Fort St. John in British Columbia.

The Pacific drainage area includes all the area that is west of the continental divide, representing about 70% of the province of British Columbia. The southwestern part of the Yukon is also part of this drainage area. Some of the communities in the eastern portion of the drainage area are Kimberley, Golden and Invermere, all in British Columbia. Cities in the western portion include Vancouver, Victoria, Abbotsford and Whistler. Terrace and Prince Rupert in British Columbia are among the northern communities in this drainage area.

The Yukon River drainage area contains most of the western portion of the Yukon territory. The most southerly portion of this drainage area is in British Columbia. Communities and cities in this drainage area are Whitehorse, Dawson and Old Crow in the Yukon. The Yukon River flows through central Alaska, and ultimately into the Bering Sea.

The Arctic drainage area covers most of the arctic islands and large portions of the Northwest Territories, Nunavut, Yukon and, to a lesser extent, British Columbia and Alberta. Communities within this drainage area include Inuvik in the Northwest Territories, Fort Nelson in British Columbia, and Pangnirtung, Iqaluit and Resolute in Nunavut.

Finally, the Mississippi River drainage area covers a small area in the southernmost parts of Alberta and Saskatchewan.

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Conformity to relevant nationally recognized standards

In 2000, Natural Resources Canada, Environment Canada and Statistics Canada formed a partnership to produce a single national drainage area dataset at a scale of 1:1,000,000. As a result of the partnership The National Scale Frameworks Hydrology - Drainage Areas, Canada, Version 5 was completed in 2003. In the drainage area classification of this Frameworks dataset, Canada has eleven major drainage areas which are divided into 164 sub-drainage areas; the 164 sub-drainage areas are then further divided into 978 sub-sub-drainage areas. All drainage areas, sub-drainage areas and sub-sub-drainage areas are named and have an identifying code. This classification is used by Statistics Canada as the basis for the Standard Drainage Area Classification (SDAC) 2003. The Standard Drainage Area Classification (SDAC) 2003 also contains the major drainage areas, sub-drainage areas and sub-sub-drainage areas but with the following modifications:

• Some drainage areas in the Frameworks dataset straddle the Canada-United States border; the Standard Drainage Area Classification (SDAC) 2003 includes only the parts within Canada since this is used for reporting Canadian data. The SDAC 2003 excludes 4 of the sub-sub-drainage areas that are entirely outside the boundary of Canada. Therefore, the Standard Drainage Area Classification (SDAC) 2003 contains only the 974 sub-sub-drainage areas that are within Canada.
• The Great Lakes were not assigned a drainage area in the Frameworks dataset; Canadian islands in the Great Lakes are assigned a drainage area in the Standard Drainage Area Classification (SDAC) 2003 for the purposes of data reporting.

The Frameworks dataset as well as the SDAC classification cover all of Canada including islands and freshwater lakes; however, the classification does not cover marine water. Further information on the development of drainage areas is presented in the Additional information on SDAC.

A digital representation of the national scale frameworks hydrology - drainage areas is available for free on Natural Resources Canada's Geogratis website.