Sandilands aquifer system

Aquifer System

Version Metadata
a43992ac-b44a-409c-9205-8aeff2b7e3ea
Project
Sandilands

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Sandilands aquifer system unit description

Update:2014-03-13
Sandy sediments are exposed over most of the study area and form a regional unconfined aquifer. Although glacial till is more prevalent at depth, some till units are discontinuous as a result of erosion which may provide hydraulic connections between surficial and deeper aquifers. Along the western margin of the Sandilands' Bedford Ridge, a channel has eroded into bedrock and provides a hydraulic connection to the underlying basal clastic unit (Winnipeg Formation) bedrock aquifer which subcrops in the area. The Carbonate unit overlies the basal clastic unit to the west of the Sandilands but was not observed within the Sandilands area.
Physiography
Hydrogeological regionWestern Canada Sedimentary Basin
Hydrogeological context
ReliefThe Sandilands forms a regional topographic high with elevations rising to approximately 400 m. The surrounding area is relatively flat and covered by extensive wetlands such that the Sandilands forms a regionally significant upland area with relief up to 65 m. The hydrologic and hydrogeologic divides separating the Red, Brokenhead and Winnipeg River basins occur within the Sandilands.
Area1968.00 km2
Lithology
DescriptionThe Sandilands area include glaciofluvial sand and gravel; glaciolacustrine littoral (sand and gravel) and offshore (silt and clay) deposits; as well as several (mostly silty) glacial tills. Organic deposits are also extensive in the wetlands surrounding the Sandilands. Sandy sediments are exposed over much of the study area and form a regional unconfined aquifer. Thin, discontinuous till overlies a portion of the sandy sediments, particularly within the eastern part of the Sandilands. Silty till and silty stratified units commonly separate deeper sands from the surficial sands. Although the basal clastic unit (Winnipeg Formation) has been encountered beneath the Sandilands study area, it may not be continuously connected with the basal clastic unit to the west because it is very friable and would have been easily eroded where it is not protected by the overlying Carbonate unit west of the Sandilands.
Source
Aquifer
AquifersSandilands regional aquifer system

Unit properties

Surficial aquifer media
Typical value:porous
Description The surficial deposits are predominantly subaqueous outwash sands and gravels, glaciolacustrine littoral (sand and gravel) and offshore (silt and clay) deposits; as well as several (mostly silty) glacial tills.
Source Surficial geology, Sandilands, Manitoba
Methode Surficial mapping and borehole data
Surficial sediment thickness
Description Sediment thickness in the study area varies from values of 70-100 m along the periphery of the Sandilands to 150 meters or more within the central portion.
Source Groundwater Availability Map Series, Winnipeg Area (62-H)
Surficial unit hydraulic conductivity
Range: [1e-08 to 0.0002] m/s
Description From 8E-6 to 2E-4 m/sec for sand units, from 7E-6 to 8E-9 m/s for till units (Cherry, 2000).
Source A multi-tracer estimation of groundwater recharge in a glaciofluvial aquifer in southeastern Manitoba
Regional precipitation
Range: [570 to 654] mm/y
Description Long term average annual precipitation at surrounding EC weather stations range from 570 mm in Beausejour, 581 mm in Zhoda and Steinbach, 606 mm in Piney, 635 mm in Ostenfeld, 638 mm in Sprague, and 654 mm in St. Labre.
Source Canadian Climate Normals - Southeastern Manitoba
Methode Environment Canada climate normals (1981-2010).
Regional evapotranspiration
503 mm/y
Description Estimated actual ET = 503 mm/year, estimated potential ET = 557 mm/year.
Source A multi-tracer estimation of groundwater recharge in a glaciofluvial aquifer in southeastern Manitoba
Methode Thornthwaite method using an annual precipitation of 574 mm/year, the air temperature data from Winnipeg International airport, and a soil water storage capacity of 250 mm.
Regional recharge
Range: [50 to 230] mm/y
Description Long term average recharge rates measured at three sandy sites were 190±60, 230±120, and 230±40 at three sandy sites. At sites with glacial till present, lower recharge rates of 50±3 and 130±10 were measured.
Source Comparison of Groundwater CFC Sampling Methods for Measuring Recharge
Methode Age dating using CFC-11 concentration profiles.
Groundwater Quality
Typical value:fresh
Description Near-surface groundwater in the Sandilands has Ca-Mg-HCO3 type water and dissolved oxygen profiles that decrease rapidly with depth. Regional sampling indicates that groundwater evolves towards a Ca-Mg-Na-HCO3 with reduced conditions, high Fe and low SO42- concentrations.
Source A multi-tracer estimation of groundwater recharge in a glaciofluvial aquifer in southeastern Manitoba
Methode Ion chromatography, ICP-OES, titration, field measurements.