Agriculture

What are the three major drainage basins in Western Canada?

which of the basins is the biggest?
which are likely to suffer from:
a)urban sources
b)agriculture sources
c)industrial sources

1. Arctic Drainage
This basin of 3.58 million km2 receives streamflow from the northern two-thirds of Alberta, northern BC, northern Saskatchewan, the YT, the NWT and Nunavut, including the arctic islands. The estimated average annual discharge rate is 15 500 m3/s. The largest river of the region is the MACKENZIE. Its watershed, 1.787 million km2, comprises about 50% of the arctic drainage area, about 20% of Canada’s area and 60% of the drainage water of the arctic region. The most important tributaries, the PEACE, ATHABASCA and LIARD rivers, all rise on the eastern slopes of the Rocky Mountains.
The Mackenzie River valley has been the subject of intensive technical, social and cultural studies during the 1970s because of concern over the potential impact of proposed petroleum PIPELINES. The delicate ecological balance existing between native people and their natural environment has given rise to many questions about the effects of TRANSPORTATION corridors in the valley.

2. Pacific Drainage
The 1.08 million km2 Cordilleran region, west of the Continen tal Divide and extending from the international border at the boundary of Alberta and BC into the YT near the Mackenzie Delta, sheds water into the Pacific Ocean at an average rate of 21 200 m3/s. The 1368 km FRASER RIVER flows through spectacular canyons and rich agricultural land to provide drainage to more than 230 000 km2 of interior BC. The COLUMBIA RIVER system in southeastern BC has an average flow at the international boundary of 2800 m3/s. The Okanagan River, which flows to join the Columbia south of the international boundary, is of great benefit to fruit growers in the semiarid valleys. The other large rivers, the SKEENA, NASS and STIKINE, discharge a combined average of 3800 m3/s into the Pacific. The Yukon, with a drainage area of 800 000 km2, has an average discharge of 2300 m3/s where it crosses into Alaska. In addition to the benefits to fisheries and agriculture and for HYDROELECTRICITY, the waters of the Pacific drainage provide a valuable resource to the LUMBER, PULP AND PAPER and mineral processing industries and to municipalities. In terms of your query- (c) -industrial sources.

3. Western Hudson Bay and Mississippi Drainage
This region of 2.64 million km2 includes all of Manitoba, most of Saskatchewan, the southern third of Alberta, most of the District of Keewatin, a part of Ontario west of Lake Superior and about 150 000 km2 immediately south of the international boundary. A 27 500 km2 zone of southern Saskatchewan and southeastern Alberta drains into the Mississippi Basin and thence to the Gulf of Mexico. The major rivers discharging into western HUDSON BAY are the HAYES, NELSON, CHURCHILL, KAZAN, and THELON.
The North and South Saskatchewan river system is important to agriculture since it flows through a region of fertile soils limited in their productivity by uncertain rainfall. The water supply from the Bow, Oldman, North and South Saskatchewan rivers and their tributaries is vital to cities, towns and industries of Alberta and Saskatchewan. The high variability of local tributary flow has necessitated construction of many dams to provide carry-over storage from years of abundant flow to years of low discharge. (a) urban sources and (b) industrial sources.

Crop Conditions In Western Canada, Challenges in Agriculture.