ABSTRACT: Karstic interpretation of the Winnipeg acquifer

CGRG Bibliography of Canadian Geomorphology
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Abstract

At Winnipeg, the Upper Carbonate Aquifer lies 10 to 15 m below an erosion surface that bevels dolomites, limestones, and minor shales. The aquifer extends over more than 3400 sq km and is confined by overlying glacial tills and lake clays. This preglacial limestone pavement karst was preserved intact because glacial ice was frozen at the base and could neither scour nor infill it. Karst aquifer capability was greatly enhanced by glacial action. The Upper Carbonate Aquifer displays high storage and transmissibilty: transmissibility ranges from 25 to 2500 cu m/day. Two hundred commercial and industrial wells and thousands of commercial wells have been drilled in this aquifer over a period of at least 130 years. Overlying lake clays function as an aquiclude, shielding the aquifer from pollution by surficial sources. A 20 to 22 m thick Lower Carbonate Aquifer is confined to basal dolomitic limestones: transmissibility nowhere exceeds 60 cu m per day. Two underlying sandstone aquifers are confined by shales at the base of the sedimentary rock section: they contain highly saline water (TDS = 30,000 to 80,000 mg/l). The Upper Carbonate aquifier is probably not being expanded by further solution. High dissolved solids recorded in the aquifer are attributed to contamination from wells drilled into the sandstone aquifers

Bibliography of Canadian Geomorphology