Provenance of buried esker groundwater: the case of Vars-Winchester esker aquifer, Eastern Ontario, Canada | Provenance des eaux souterraines au sein des eskers: le cas de l’aquifère de l’esker de Vars-Winchester, dans l’Est de l’Ontario, Canada Procedencia del agua subterránea en un esker enterrado: el caso del acuífero del esker de Vars-Winchester, Ontario del este, Canadá 埋藏蛇形丘地下水的起源:加拿大安大略省东部Vars-Winchester蛇形丘含水层案例 Proveniência da água subterrânea num esker soterrado: o caso do aquífero do esker Vars-Winchester, Ontário Oriental, Canadá
2016
Sauriol, Jacques
An innovative mode of groundwater recharge to a buried esker aquifer is considered. The current conceptual model affords a natural safeguard to underlying aquifers from the overlying muds. A hypothesis of groundwater recharge to a buried esker aquifer via preferential pathways across its overlying muds is tested here by heuristic numerical one-dimensional and two-dimensional modeling simulations. The hypothesis has been tested against two other conventionally accepted scenarios involving: (1) distal esker outcrop areas and (2) remote shallow-bedrock recharge areas. The main evidence comes from documented recharge pressure pulses in the overlying mud aquitard and in the underlying esker hydraulic-head time series for the Vars-Winchester esker aquifer in Eastern Ontario, Canada. These perturbations to the potentiometric surface are believed to be the aquifer response to recharge events. The migration rate of these pressure pulses is directly related to the hydraulic diffusivity of the formation. The measured response time and response amplitude between singular radar precipitation events and well hydrographs constituted the heuristic model calibration targets. The main evidence also includes mud-layering deformation (water escape features) which was observed in seismic surveys of the over-esker muds. These disturbed stratigraphic elements provide a realistic mechanism for migrating water to transit through the muds. The effective hydraulic conductivities of these preferential pathways in the muds were estimated to be between 2 × 10⁻⁶ and 7 × 10⁻⁶ m/s. The implications of these findings relate to the alleged natural safeguard of these overlying muds.
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