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TitleRegional groundwater flow in inter-till and buried-valley aquifers, southwestern Manitoba
AuthorHinton, M J; Logan, C E; Oldenborger, G A; Pugin, A J M
SourceIAH-CNC 2015 Waterloo Conference, abstracts; 2015, 1 pages
Year2015
Alt SeriesEarth Sciences Sector, Contribution Series 20140493
PublisherInternational Association of Hydrogeologists - Canadian National Chapter
MeetingIAH-CNC 2015 Waterloo Conference; Waterloo; CA; October 27-30, 2015
Documentbook
Lang.English
Mediapaper
File formatpdf
ProvinceManitoba
NTS62F; 62G; 62J; 62K; 62N; 62O
AreaSW
Lat/Long WENS-102.0000 -98.0000 52.0000 49.0000
Subjectshydrogeology; bedrock aquifers; aquifers; groundwater; electromagnetic mapping; computer mapping; seismic reflection surveys; digital terrain modelling; fractures
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
AbstractInter-till and buried-valley aquifers are among the main sources of groundwater in the Prairies. The Spiritwood buriedvalley
aquifer system extends from Manitoba and across North Dakota where it has been a significant source for
groundwater supply for decades yet its resource potential in Manitoba has not been evaluated. The Geological Survey of
Canada (GSC) has been studying the regional geology and hydrogeology of the Spiritwood buried-valley aquifer in
southwestern Manitoba. Helicopter time domain electromagnetic (HTEM) and high resolution seismic reflection (HRSR)
surveys permitted detailed mapping of inter-till and buried-valley aquifers within the study area. The main buried valley is
a broad 10-15 km wide and 60-70 m deep valley cut into Cretaceous Pierre shale. A series of nested channels of
different age, origin, dimensions and orientations are cut into bedrock and within the sand/silt till. Where these channels
are filled with coarse sediment, they form aquifers: deep buried-valley aquifers (60-100 mbgs) incised into shale below
the base of the broad buried valley, and inter-till aquifers within the till. A 3D numerical geological model of the regional
bedrock surface and sediments was developed, using Leapfrog Hydro™ geological modelling software. A significant
feature of the geological model is that the nested channels and fans that form inter-till aquifers together with the fractured
bedrock surface may provide more permeable pathways to deep buried-valley aquifers. Another significant finding is the
discovery that the buried-valley aquifer outcrops in incised surface valleys where sustained baseflow was measured
during a period of extended drought.
Regional groundwater flow generally follows topography but is perpendicular to the orientation of the main buried valley.
However, flow also occurs along the deep buried valley which acts as a regional drain towards the incised surface
valleys. Both hydraulic and HTEM results suggest that there are no transverse hydraulic boundaries within the deep
buried-valley aquifer. A steady state finite element numerical groundwater model has been developed from the
geological model to: i) assess the different flow pathways within the inter-till and deep buried-valley aquifers, and ii)
constrain the estimates of groundwater flow. The numerical flow model replicates the regional flow patterns, discharge
zones and the groundwater divide in the deep buried-valley aquifer. Results to date suggest that, despite the presence of
preferred hydraulic pathways, natural replenishment of the deep buried-valley aquifer is small. © Her Majesty the Queen
in right of Canada 2015.
Summary(Plain Language Summary, not published)
The Geological Survey of Canada (GSC) has been studying the regional geology and hydrogeology of the Spiritwood buried-valley aquifer in southwestern Manitoba. Geophysical surveys permitted detailed mapping of aquifers within the study area. A 3D geological model of the regional bedrock surface and sediments was developed using geological modelling software. A significant feature of the geological model is the presence of several nested channels that form aquifers within the till and together with the fractured bedrock surface may provide more permeable pathways to deep buried-valley aquifers. Regional groundwater flow generally follows topography but is perpendicular to the orientation of the main buried valley. However, flow also occurs along the deep buried valley which acts as a regional drain towards the incised surface valleys. A computerized groundwater model has been developed from the geological model. Results to date suggest that, despite the presence of preferred hydraulic pathways, natural groundwater flow to the deep buried-valley aquifer is small.
GEOSCAN ID296066