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TitleHydrogeology and hydrogeochemistry of the Chaudière River aquifers, Québec, Canada
AuthorBenoit, N; Nastev, M; Blanchette, D; Molson, J
SourceCanadian Water Resources Journal vol. 39, no. 1, 2014 p. 32-48, https://doi.org/10.1080/07011784.2014.881589
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20130101
PublisherTaylor & Francis
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf
ProvinceQuebec
NTS21L/11
AreaChaudière River
Lat/Long WENS-71.5000 -71.0000 46.7500 46.5000
Subjectshydrogeology; watersheds; hydrogeochemistry; hydraulics; hydraulic analyses; groundwater resources; Chaudiere River watershed
ProgramAquifer Assessment & support to mapping, Groundwater Geoscience
AbstractA comprehensive hydrogeological study has been conducted in the Chaudière River watershed (6695 km2) located south of the St. Lawrence River, near Québec City. Updated maps of simplified bedrock geology and surficial sediments are presented together with the newly generated maps of the regional potentiometric surface, spatial distribution of the annual infiltration rate and spatial distribution of encountered groundwater types. Detailed analyses of the hydraulic conductivity, groundwater use, salinity sources and isotopic signatures are conducted. At the end, a conceptual model describing the hydrogeological setting is proposed for the regional groundwater flow system. In the watershed, about 150,000 inhabitants or roughly 80% of the total population depend almost entirely on groundwater as a source of potable water. Fine-grained sedimentary rocks of the Appalachian geological province form the major regional aquifer unit. The aquifer is generally unconfined to semi-confined in the Appalachian Uplands, and semi-confined to confined in the Appalachian Piedmont. Local granular aquifers are composed of coarse river valley sediments, but their extent and thickness vary throughout the watershed. The hydraulic connection between the granular units and bedrock is strongly influenced by the nature of the ubiquitous glacial sediments. The overall recharge rate to the bedrock aquifers is estimated at about 27 mm/y, or roughly 180 Mm3/y, compared to the average groundwater use of 17.4 Mm3/y. The low hydraulic conductivity, K~8×10?7 m/s, constrains groundwater flow to the top portion of the fractured strata. Groundwater flow in the Appalachian Uplands occurs at local scale and is dominated by recent recharge. Further along the flowpath in the Appalachian Piedmont, the concentrations of the major chemical constituents gradually increase along with the radiocarbon age of groundwater. Still, independent of their location along the flowpath, groundwater samples always contain a fraction of relatively young water (< 50 years).
Summary(Plain Language Summary, not published)
In the scope of the Geological Survey of Canada's Groundwater Mapping Program, a comprehensive hydrogeological study has been conducted in the Chaudière River watershed. The objective of the study was to summarize the current knowledge on the geology, hydrogeology and hydrogeochemistry and to propose a conceptual model for the regional groundwater flow and typical hydrogeological settings. Sedimentary rocks of the Appalachian geological province represent major regional aquifer unit of relatively low hydraulic conductivity. It is generally unconfined to semi-confined in the Appalachian Uplands, and semi-confined to confined in the Appalachian Piedmont. The calibrated recharge rate is estimated at ~27 mm. The groundwater use represents about 9.7% of the annual recharge. There is overwhelming evidence of fresh recharge water throughout the watershed, still occasional mixing with deeper saline is possible.
GEOSCAN ID292722