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TitleThree dimensional groundwater flow model of the Nanoose-Deep Bay area, Nanaimo Lowland, British Columbia
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AuthorBenoit, N; Paradis, D
SourceGeological Survey of Canada, Open File 7845, 2015, 33 pages, https://doi.org/10.4095/297046
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediadigital; on-line
File formatreadme
File formatpdf; fem; rtf
ProvinceBritish Columbia
NTS92F/07; 92F/08; 92F/10
AreaNanoose; Deep Bay; Nanaimo Lowlands; Parksville; Qualicum Beach; Bowser; Vancouver Island
Lat/Long WENS-125.0000 -124.2500 49.6167 49.2500
Subjectshydrogeology; surficial geology/geomorphology; aquifers; groundwater regimes; groundwater; groundwater resources; bedrock geology; glacial deposits; hydrostratigraphic units; surface waters; groundwater flow; models; modelling
Illustrationslocation maps; tables; 3-D models; plots
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
Released2015 11 17
AbstractThe Nanaimo Lowland Groundwater Study is a collaboration between the British Columbia (BC) Ministry of Environment (MoE), Ministry of Forests, Lands, and Natural Resource Operations (MFLNRO), the Regional District of Nanaimo (RDN), and the Geological Survey of Canada (GSC). This Open File reports on the three-dimensional (3D) groundwater flow model (3DGFM) for the Nanaimo Lowland aquifer system developed to support improved sustainable groundwater management of the Nanaimo Lowland. The study area represents a coastal strip running from Nanoose to Deep Bay in the eastern part of Vancouver Island and covers approximately 580 km2. The groundwater flow model was based on the 3D hydrostratigraphic model (3DHSM) developed by Benoit et al. (2015). The hydrostratigraphic units were converted into a numerical grid and representative hydraulic properties were assigned based to each unit on statistical analysis of available values. The groundwater resurgences present along the steep slopes of the main riverbanks and at the shoreline were simulated with seepage boundary conditions allowing for a vertical hydraulic link between the main Quadra Sand aquifer and surface water bodies. Hydraulic conductivity and groundwater recharge rate were further calibrated through numerical inversion using static hydraulic heads recorded in existing wells and estimated baseflow values from streamflow records. Simulation results that two distinct groundwater flow systems: (1) the Quadra aquifer system with groundwater divides closely matching watershed boundaries containing relatively fresh water; and (2) the extensive bedrock aquifer system with older water and a flow patterns generally directed toward the sea coast. Simulations also reveal discharge to rivers and streams mainly from the Quadra Sand aquifer and the Capilano sediments, often locally present along the main river channels, with low contribution from the bedrock. Exception is the Englishmen River where the Quadra Sand is inexistent and the river is in direct hydraulic contact with the bedrock aquifer. The Quadra Sand aquifer is naturally protected from sea intrusion due to the higher altitude with respect to sea level, whereas the bedrock aquifer appears vulnerable to encroachment especially under heavy pumping conditions close to the shoreline. This 3DGFM provides then a meaningful framework for the understanding of the regional hydrogeology of Nanoose-Deep Bay aquifer system that would contributes to support sustainable management of groundwater resources.
Summary(Plain Language Summary, not published)
The development of a 3D numerical regional groundwater flow model is described for the Nanaimo Lowlands of eastern Vancouver Island (BC). An earlier developed hydrostratigraphic model was exported to a FeFlow model. This groundwater model is the first regional public domain flow model of the relatively complex aquifer system. The resulting model is suitable to assess the groundwater budget parameters and run different regional groundwater flow scenarios. The groundwater flow model represents a regional framework for understanding groundwater processes, that will be used to support the sustainable management of and planning for groundwater resources in the Nanaimo Lowlands. Annexed electronic files of the groundwater flow model allow its use. The research was carried out by the Geological Survey of Canada (NRCan) under the Groundwater Geoscience Program, in partnership with the BC Ministry of Environment (MoE); Ministry of Forests, Lands, and Natural Resource Operations (MFLNRO); and the Regional District of Nanaimo (RDN).
GEOSCAN ID297046