Brine or saline groundwater aquifer

Hydrogeological Context

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Version Metadata
63619729-b0c7-476d-a993-0df9451f975f
Project
Basal Clastic Unit (Winnipeg)

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Brine or saline groundwater aquifer unit description

Update:2014-02-25
The Winnipeg Formation is a continuous, extensive geological unit that is composed of shales and sandstones. On the area, the upper and lower sections consist of a northern sandstone facies, a central transitional facies of interbedded sandstone and shale and a southern shale facies. The Winnipeg Formation overlies the Precambrian bedrock and is located below the Carbonate Aquifer which is covered by Quaternary sediments: a till unit followed by a clay layer which is overlain by glaciofluvial sediments. Saline and brackish groundwaters extend into the western Interlake region and as far east as the outcrop area south of Lake Winnipeg. The Winnipeg Formation aquifer consists largely of brackish groundwater as the formation dips towards the center of the province. Point-water heads of the Winnipeg Formation indicate the presence of an updip flow out of the Williston Basin from southwest to northeast in western Manitoba and the Interlake area. The Winnipeg Lake is an important discharge area. Saline waters and brines in south-central Manitoba have Cl-Br ratios, which are much higher than the average value of sea water. However, these ratios are also considerably lower than the Cl-Br ratios found in minerals of the Williston Basin suggesting mixing of these two types of water. The interface between saline and freshwater in the unit is complex, and is marked by an increase in Sodium and Chloride levels. Hydraulic head distribution indicates that saline formation waters from the Williston Basin are moving eastward and resalinizing portions of the aquifer currently occupied by freshwater.
Physiography
Hydrogeological regionWestern Canada Sedimentary Basin
Hydrogeological context
ReliefThe Manitoba Lowland is an area of gentle relief lying to the east of the Manitoba Escarpment. Surface elevation generally does not exceed 350 m above sea level with relief seldom exceeding 30 m.
Area121802.00 km2
Lithology
DescriptionThe Winnipeg Formation is a continuous, extensive geological unit that is composed of shales and sandstones. Sandstones of the Winnipeg Formation predominantly consist of well-rounded, frosted and pitted quartz grains. Sandstones are generally poorly cemented. Shales vary from massive pure shales to arenaceous shales. On the area, the upper and lower sections consist of a northern sandstone facies, a central to southwestern transitional facies of interbedded sandstone and shale and a southern shale facies. The Winnipeg Formation overlies the Precambrian rocks and is located below the Carbonate Aquifer which is covered by Quaternary sediments: a till unit followed by a clay layer which is overlain by glaciofluvial sediments.
Source
Aquifer
AquifersList of aquifer Winnipeg formation aquifer - saline, brackish and mixed waters

Unit properties

Bedrock aquifer media
Typical value:porous
Description The Winnipeg Formation is composed of two units consisting of sandstone and shale.
Source Hydrogeology of the Winnipeg Formation in Manitoba, Canada
Confinement
Typical value:confined
Description Winnipeg Formation is covered by carbonate rock formations, a till unit and a clay layer. Moreover, the Winnipeg Formation is protected from overlying units by a thin, but highly effective shale aquitard
Source Hydrogeology of the Winnipeg Formation in Manitoba, Canada
Groundwater storage
Description The storage coefficient for the Winnipeg formation is: for sandstone aquifer: 5E-6 for shale: 1E-6
Source Sustainability of the Bedrock Aquifer Systems in South-Central Manitoba: Implications for Large-Scale Modelling
Hydrogeological unit thickness
Range: [5 to 60] m
Description The thickness ranges between 30 to 60 m in the south to about 5 m in the north.
Source Sustainability of the Bedrock Aquifer Systems in South-Central Manitoba: Implications for Large-Scale Modelling
Well depth
19.81 m Range: [0 to 574.55] m
Groundwater depth
4.88 m Range: [0 to 684] m
Bedrock hydraulic conductivity
Range: [1e-06 to 0.0001] m/s
Source Hydrogeology of the Winnipeg Formation in Manitoba, Canada
Regional precipitation
486 mm/y Range: [449.9 to 521.1] mm/y
Methode Precipitation data are from Environment Canada. The value represents the average of the climate normals (1981-2010) measured on the stations distributed in or near the hydrogeological unit. The stations were selected so the average precipitation is as representative as possible of the whole hydrogeological unit.
Regional evapotranspiration
23.1 mm/y
Methode Evapotranspiration data is from normal climates (1981-2010) of Environment Canada.
Regional discharge
Description Winnipeg Lake is a regional discharge.
Source Groundwater Resources in the Red River Basin Area of Manitoba
Hydrogeological unit yield
Description Reported yields from wells completed into the Winnipeg Formation aquifer range from 0.2 l/s to 10 l/s.
Source Groundwater in Manitoba: Hydrogeology, quality concerns, management
Groundwater Quality
Typical value:saline - brackish - mixed
Description Saline waters and brines have Cl-Br ratios, which are much higher than the average value of sea water. The interface between saline and freshwater is marked by an increase in Sodium and Chloride levels.
Source On elevated fluoride and boron concentrations in groundwaters associated with the Lake Saint-Martin impact structure, Manitoba