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TitreGeostatistical mapping of leakance in a regional aquitard, Oak Ridges Moraine area, Ontario, Canada
AuteurDesbarats, A J; Hinton, M J; Logan, C E; Sharpe, D R
SourceHydrogeology Journal vol. 9, no. 1, 2001 p. 79-96,
LiensOak Ridges Moraine web site
LiensMoraine d'Oak Ridges, site web
Séries alt.Commission géologique du Canada, Contributions aux publications extérieures 2000183
ÉditeurSpringer Nature
Documentpublication en série
Mediapapier; en ligne; numérique
Référence reliéeCette publication est reliée Desbarats, A J; Hinton, M J; Logan, C E; Sharpe, D R; (2000). Geostatistical mapping of leakance in a regional aquitard, Oak Ridges Moraine area, Ontario
SNRC30M/13; 30M/14; 30M/15; 30M/16NE; 30M/16NW; 31C/04SW; 31C/04NW; 31D/01; 31D/02; 31D/03; 31D/04
Lat/Long OENS -80.0000 -77.7500 44.2500 43.7500
Sujetsgéostatistiques; analyse statistique; méthodes statistiques; statistiques; analyses hydrauliques; écoulement de la nappe d'eau souterraine; aquifères; dépôts glaciaires; tills; établissement de modèles; Moraine d'Oak Ridges ; Till de Newmarket ; géomathématique; hydrogéologie; Cénozoïque; Quaternaire
Illustrationssketch maps; graphs; plots; histograms; block diagrams
ProgrammeProjet de la Moraine d'Oak Ridges du CARTNAT
Résumé(disponible en anglais seulement)
The Newmarket Till forms a regionally extensive aquitard separating two major aquifer systems in the Greater Toronto area, Canada. The till is incised, and sometimes eroded entirely, by a network of sand- and gravel-filled channels forming productive aquifers and, locally, high-conductivity windows between aquifer systems. Leakage through the till may also be substantial in places. This study investigates the spatial variability of aquitard leakance in order to assess the relative importance of recharge processes to the lower aquifers. With a large database derived from water-well records and containing both hard and soft information, the Sequential Indicator Simulation method is used to generate maps of aquitard thickness and window probability. These can be used for targeting channel aquifers and for identifying potential areas of recharge to the lower aquifers. Conductivities are modeled from sparse data assuming that their correlation range is much smaller than the grid spacing. Block-scale leakances are obtained by upscaling nodal values based on simulated conductivity and thickness fields. Under the "aquifer-flow'' assumption, upscaling is performed by arithmetic spatial averaging. Histograms and maps of upscaled leakances show that heterogeneities associated with aquitard windows have the largest effect on regional groundwater flow patterns.