The Hydrologic Balance from a Large Prairie Drainage Basin in Central Alberta, Canada

This study area includes representative basins IWB-RB-5-6-7, which are drained by the Kneehills, Threehills, Ghostpine, and Lonepine Creeks. The area is generally bounded by longitude lines 113^o 00' and 114^o 00' and by latitudes 51^o 21' and 52^o 10' and covers an area of approximately 4,569 km², or 1,767 square miles. The elevation ranges from 2,500 to 3,300 feet (4,500-5,940) meters above MSL. The area is dominantly prairie parkland, grain is the main farm product. The mean annual amount of precipitation varies from 17 inches over the northern part of the area to 14 inches over the southern part; more than 1/3 of the precipitation occurs in June and July. Annual runoff approximates 1/2 inch over the area.

The surficial material consists of a veneer of till, outwash, and/or lake deposits of Pleistocene to post-Pleistocene age, overlying Paskapoo Sandstone of Tertiary age. At the confluence of the basins the main creeks cut through the Paskapoo Formation into the sandstones and shales of the underlying Edmonton Formation (Upper Cretaceous age). Generally the tills and lake deposits have low permeability values, while the permeability values of the Paskapoo Sandstone and outwash deposits are fair to good.

This study is being conducted by D.R. Stevenson for the Groundwater Division, Research Council of Alberta.

Co-operating agencies are the Meteorological Branch, Canada Department of Transport, who supplied and installed the weather instruments at the meteorological sites, two of which have been incorporated into the 'National Climate' network, and the Water Survey of Canada, Inland Waters Branch Department of Energy, Mines and Resources, who are installing the steam-discharge stations.

The objectives of this study are the following:

1.To establish the hydrologic budget of a prairie watershed under cultivation where natural soil moisture and drainage conditions exist;

2.To establish relationships among land-use, precipitation, runoff, soil moisture, and water-table fluctuation; and

3.To establish a relationship between the hydrologic cycle and the physiographic characteristics of the watershed.

The attached maps show the existing meteorological instrumentation, stream-discharge stations, and groundwater instrumentation. The regional groundwater observation well network was initiated in 1962 by Dr. Toth as part of a separate study. Monthly measurements of water-table fluctuation in 34 of these wells are being recorded. Continuous measurements are being recorded in a seven well cross section across the upper part of Threehills basin. The presence of existing instrumentation and its central location favored the Threehills basin being selected as the natural model for a water budget study. The hydrologic model derived from the Threehills study will be applied to the Ghostpine and Kneehills basin. In 1966 two small sub-basins drained by tributaries of Threehills Creek were selected for more detailed instrumentation. The Innisfail sub-basin covers 17.6 square miles (45.4 sq. km.) and is characteristic of the rolling, more densely wooded northern part of the area; the Threehills sub-basin covers 21.3 square miles (55.0 sq. km.) and is characteristic of the less hilly, more widely cultivated, arid southern part of the area.