Prince Edward Island regional bedrock aquifer

Aquifer System

Version Metadata
64a7aa50-4652-4d50-ad00-38948203313f
Project
Prince Edward Island

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Prince Edward Island regional bedrock aquifer unit description

Update:2014-03-20
Prince Edward Island is a crescent-shaped cuesta of continental red beds. This sequence is composed of fractured sandstone with minor siltstone red beds. These units show rapid lateral and vertical facies changes and strong cross-bedding features. An unconsolidated sandy till unit overlies almost entirely the bedrock sequence. The till thickness varies from few centimeters to several meters. Commonly, the surficial deposits are not significant aquifers. However, the uppermost portion of the sandstone formation forms a fractured-porous aquifer. This latter is characterized by significant fracture permeability dominated by horizontal bedding plane fractures, in addition to intergranular porosity. The sandstones aquifer is unconfined, except in local areas where less permeable mudstone beds alternate with sandstone to generate semi-confined conditions. The aquifer is vulnerable to surface contamination. It is recharged by precipitation percolating through the till or outcropping bedrock. Water flows in the uppermost part of the aquifer, which is strongly fractured and constitutes a fast path layer for groundwater flow. Groundwater flow follows surface topography and decreases with depth due to lower fracturing causing lower hydraulic conductivity. The aquifer discharges in rivers and seepage at the coastline. It represents one of the few sources of drinkable water. Groundwater is extracted for domestic, industrial/commercial and agricultural uses. Groundwater quality is good, however the nitrate concentration is high due to agricultural activities. This economic sector constitutes a threat to water quality due to its nitrate inputs.
Physiography
Hydrogeological regionMaritime Bassin
Hydrogeological context
ReliefPrince Edward Island terrain is relatively flat. Commonly, the elevations vary from 0 to 100 m. There are only three sectors of higher elevations; Glen Valley (142 m), eastern Belfast sector (125 m) and New London sector.
Area5731.00 km2
Lithology
DescriptionPrince Edward Island forms a crescent-shaped cuesta of continental red beds. This sequence is composed of fractured sandstone with minor siltstone red beds. These units show rapid lateral and vertical facies changes and strong cross-bedding features. The continuity of these units is unknown. An unconsolidated sandy till unit overlies almost entirely the bedrock sequence. The till thickness varies from few centimeters to several meters.
Source
Aquifer
AquifersList of aquifer Prince Edward Island regional bedrock aquifer

Unit properties

Bedrock aquifer media
Typical value:porous - fractured
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Confinement
Typical value:unconfined
Description The aquifer is unconfined, except in small zones where less permeable mudstone beds alternate with sandstone to form semi-confined conditions.
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Surficial sediment thickness
Description Till thickness varies from few centimeters to several meters.
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Bedrock hydraulic conductivity
Range: [9e-07 to 0.0004] m/s
Description Hydraulic conductivity generally decreases with depth, a result of decreasing fracture aperture and frequency with depth as seen during our multi-level testing.
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Methode Hydraulic conductivities were determinated from multi-level slug tests.
Regional precipitation
1134 mm/y
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Regional evapotranspiration
567 mm/y
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Regional runoff
11 mm/y
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Regional recharge
363 mm/y
Description The recharge values can vary from 0 mm/yr in the wetland area to 704 mm/yr in areas with coarse sandy sediments. The aquifer is recharged through the tills or outcropping red beds.
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Regional discharge
Description The aquifer discharges as a combination of base flow, pumping withdrawals and seepage at the coastline.
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Groundwater usage
Typical value:agricultural - domestic - industrial
Description Residential : 11 875 000 m3/yr Industrial/commercial : 8 665 100 m3/yr Agricultural : 3 922 442 m3/yr Total : 24 462 542 m3/yr
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island
Aquifer vulnerability
Typical value:high regional
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Threats
Typical value:agriculture
Description Nitrate concentration due to intense agricultural activities
Source Impact of agricultural activities on nitrates in ground and surface water in the Wilmot watershed, PEI, Canada
Groundwater Quality
Typical value:fresh
Description In many areas, nitrate in GW is significantly exceeding the natural background. Moreover, there is evidence to suggest that nitrate levels are continuing to rise.
Source Consequences of climatic changes on contamination of drinking water by nitrate on Prince Edward Island