Influence of fracture anisotropy and lithological heterogeneity on wellfield response in a fluvial sandstone aquifer of the Carboniferous Moncton Subbasin, Canada

Pump tests and geophysical logs acquired in a fluvial sandstone aquifer within the resource-rich Moncton Subbasin of New Brunswick, Canada, have been used to characterize fracture patterns and flow directions for purposes of developing a water-wellfield protection plan. Fracture patterns consist of...

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Bibliographic Details
Published in:Hydrogeology journal 2013-05, Vol.21 (3), p.559-572
Main Authors: DesRoches, Aaron J., Butler, Karl E., Pelkey, Shaun
Format: Article
Language:English
Subjects:
Anisotropy
Aquatic Pollution
Aquifers
Carboniferous
Drawdown
Earth and Environmental Science
Earth Sciences
Fracture mechanics
Fractures
Geological structures
Geology
Geophysics/Geodesy
Groundwater
Groundwater flow
Heterogeneity
Hydrogeology
Hydrology
Hydrology/Water Resources
Lithology
Public concern
Pumps
Resource development
Rocks
Sandstone
Waste Water Technology
Water levels
Water Management
Water Pollution Control
Water Quality/Water Pollution
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Summary:Pump tests and geophysical logs acquired in a fluvial sandstone aquifer within the resource-rich Moncton Subbasin of New Brunswick, Canada, have been used to characterize fracture patterns and flow directions for purposes of developing a water-wellfield protection plan. Fracture patterns consist of three high-angle sets, and a low-angle set parallel to bedding. NW-trending high-angle fractures, predominantly in fluvial sandstone units, appear to be most important in controlling groundwater flow directions. This contrasts with an earlier regional hydrogeological study that attributed most flow to sub-horizontal bedding-plane fractures. Water levels monitored during a 72-h pump test revealed drawdown extension parallel to the NW-trending fracture set. Drawdown curves indicate that the aquifer is laterally constrained—likely reflecting differences in fracturing observed between the channelized sandstone and surrounding shale units. As a result, groundwater flow induced by pumping is influenced by both fracture anisotropy and by the heterogeneity of the fluvial depositional environment. Relationships observed between fracture patterns, regional geological structure and lithology provide a basis for extrapolating the conceptual model to other nearby areas in the region, where potential impacts of geological resource development on groundwater are attracting public concern.
ISSN:1431-2174
1435-0157
DOI:10.1007/s10040-012-0931-6