GEOSCAN, résultats de la recherche

Menu GEOSCAN


TitreThree dimensional hydrostratigraphic model of the Nanoose - Deep Bay area, Nanaimo Lowland, British Columbia
TéléchargerTéléchargements
AuteurBenoit, N; Paradis, D; Bednarski, J M; Hamblin, T; Russell, H A J
SourceCommission géologique du Canada, Dossier public 7796, 2015, 30 pages, https://doi.org/10.4095/296302
LiensErratum
Année2015
ÉditeurRessources naturelles Canada
Documentdossier public
Lang.anglais
DOIhttps://doi.org/10.4095/296302
Medianumérique; en ligne
Liensreadme
Formatspdf; adf; xml; ovr
ProvinceColombie-Britannique
SNRC92F/07; 92F/08; 92F/10
Lat/Long OENS-125.0000 -124.2500 49.6167 49.2500
Sujetsaquifères; régimes des eaux souterraines; eau souterraine; ressources en eau souterraine; géologie du substratum rocheux; dépôts glaciaires; unités hydrostratigraphiques; eaux de surface; hydrogéologie; géologie des dépôts meubles/géomorphologie
Illustrationslocation maps; cross-sections; stratigraphic columns
ProgrammeAquifer Assessment & support to mapping, Géoscience des eaux souterraines
Diffusé2015 04 22; 2016 10 25
Résumé(disponible en anglais seulement)
To support improved sustainable groundwater management of the Nanaimo Lowland, British Columbia (BC), a three-dimensional (3D) hydrostratigraphic model was developed for the Nanaimo Lowland aquifer system. The study area is a coastal strip running from Nanoose to Deep Bay on eastern Vancouver Island (~580 km2). The 3D model was developed using existing driller's logs, published cross-sections and new data which include rotosonic coring, borehole geophysics logs, seismic reflection profiles and surficial geology mapping. The detailed surficial geology consists of 31 different units which, for modelling, are grouped into 9 major hydrostratigraphic units (from youngest to oldest): Capilano-Salish (sand aquifer), Capilano glaciomarine (silty clay aquitard), Vashon-Capilano (coarse sand and gravel aquifer), Vashon (till aquitard), Quadra (sand aquifer), Cowichan-Dashwood (compact silt aquitard), Dashwood-Mapleguard (sand aquifer), sedimentary bedrock and metamorphic bedrock (aquifer near surface with potential decreasing with depth). This succession of Late Pleistocene to Holocene sediments is up to 140 m thick and is present over most of the study area, thinning to the southwest with rising topography and bedrock outcrops. Capilano-Salish and Vashon-Capilano deposits are shallow and contain unconfined aquifers with relatively high vulnerability to surface contamination and low groundwater resource potential due to their limited thicknesses. Quadra Sand is the most exploited aquifer unit. It underlies the ubiquitous and low permeability Vashon till and it overlies Cowichan-Dashwood aquitard or bedrock. Quadra sediment has an average thickness of 19 m and it is generally above sea and river levels. This would minimize the potential of seawater intrusion and direct surface water extraction, respectively, in the event of intensive groundwater extraction in Quadra unit. The Quadra is an important aquifer, however only about one-third of its thickness is saturated likely due to the overlying Vashon till aquitard that limits groundwater replenishment. Dashwood-Mapleguard sand is a lower confined aquifer unit that extends below sea level. It may have hydrogeological properties and resource potential similar to the Quadra sand, but it is present only in areas where the bedrock elevation is low, generally closer to the coastline. It may be more vulnerable to sea water intrusion, and remains poorly understood. The relatively low permeability regional bedrock aquifers of the Nanaimo Group are generally exploited only where the Quadra aquifer is not present. Their hydrogeological potential is poorly understood due to lack of subsurface data. This hydrostratigraphic model will be used to support groundwater flow modelling.
Résumé(Résumé en langage clair et simple, non publié)
Ce dossier public décrit le développement d'un modèle numérique hydrostratigraphique régional en trois dimensions (3D) des basses terres de Nanaimo en Colombie-Britannique. Ce modèle permet une meilleure compréhension du système aquifère, relativement complexe, de cette région. Il a été utilisé pour construire un modèle d'écoulement des eaux souterraines, évaluer les paramètres de bilan hydrogéologique et exécuter différents scénarios d'utilisation des eaux souterraines. En tant que tel, le modèle hydrostratigraphique représente un outil de soutien à l¿amélioration de la gestion durable des eaux souterraines des basses terres de Nanaimo en Colombie-Britannique. Les fichiers électroniques annexés permettent l'utilisation du modèle pour le développement de stratégies de gestion régionales. La recherche a été réalisée par la Commission géologique du Canada (CGC) dans le cadre du Programme géoscientifique des eaux souterraines, en collaboration avec le ministère de la de l'Environnement de la Colombie-Britannique (MoE); le Ministère des Forêts, des Terres et des Ressources naturelles (MFLNRO) et le district régional de Nanaimo (DRN).
GEOSCAN ID296302