Richibucto, Balfron, Pictou, Cumberland Formations fractured bedrock aquifer

Hydrogeological Context

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f64ad8c6-548f-4f2a-927d-a28f36a47c67
Project
Carboniferous Basin

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Richibucto, Balfron, Pictou, Cumberland Formations fractured bedrock aquifer unit description

Update:2014-02-03
In ascending order, the geological groups are: basement complex and Horton, Windsor, Riversdale-Mabou, Cumberland, and Pictou Groups (Richibucto, Balfron, and Pictou und). The internal stratigraphy of these units is complex and often laterally discontinuous, as a result of different sedimentation rates, synsedimentary faulting, and reworking. Horton, Windsor and Mabou groups form a hydrogeological unit characterized by a poor aquifer potential. The undivided Cumberland and Pictou (sandstone, mudstone and siltstone), Richibucto (sandstone), and Balfron (sandstone and mudstone) formations form a hydrogeological unit that assembles the main aquifer units of the area. Cumberland formation is separated of the others by low permeability Salisbury formation. The hydrogeological unit has moderate hydraulic conductivity values suggesting a significant presence of fractures. Groundwater flows in the rock through fractures and interconnected pores between grains. Since the fractures have a much higher permeability than the surrounding matrix, the water flows essentially in the fractures. The hydrogeological unit is covered with a till layer, extending throughout the area. Some alluvial deposits and rock outcrops can be observed. Marine deposits are found along the Northumberland Strait. Considering the general characteristics of the till, the hydrogeological unit underlying is under semi- confined conditions. It therefore presents a moderate vulnerability to contamination. It is the third most important recharge area of the region. Confined and unconfined conditions can also be present locally depending on the composition and thickness of the till. The water is of good quality, but there are some issues as chlorine, iron, fluoride, manganese, sodium, barium, and alkaline ph.
Physiography
Hydrogeological regionMaritime Bassin
Hydrogeological context
ReliefGenerally, the hydrogeological unit has altitudes of 0-50 and 50-100 m. The lowest elevations (0-50 m) are located along Nortumberland Strait. The altitude increases from the strait to inland (50-100 m). Altitude increases west of Canaan, where the hill reaches 200-250 m. The terrain is commonly flat, with some slope of 2-5%. Some more pronounced slopes (10-15%) are observed along streams.
Area6078.00 km2
Lithology
DescriptionIn ascending order, the geological groups are: bedrock complex and Horton, Windsor, Mabou, Cumberland and Pictou Groups. The internal stratigraphy of these units is complex and often laterally discontinuous. The Horton Group consists of a sequence of sedimentary and volcanic rocks that is overlain by the marine limestone and evaporates strata of the Windsor Group. The marine beds are overlain by thick assemblages of continental origin, which correspond to the Riversdale-Mabou, Cumberland and Pictou groups. In this case, only the Cumberland undivided formation is present for the Cumberland group. It is composed of variable lithological rock sequences. For the Pictou group, the Richibucto (sandstone), Balfron (sandstone and mudstone) and Pictou undivided (sandstone, mudstone and siltstone) are present. These rock groups are covered by a till unit which extends over the entire area. Marine deposits are located along Northumberland Strait.
Source
Aquifer
AquifersList of the aquifers Richibucto-Balfron-Pictou rock aquifer Salisbury rock aquifer Cumberland undivided rock aquifer

Unit properties

Bedrock aquifer media
Typical value:porous - fractured
Description roundwater circulates within the rock through fractures and interconnected pore spaces between the individual grains. Since fractures have a much higher permeability than the matrix around them, groundwater flows predominantly through fractures. This unit is divided in 2 rock aquifers: Cumberland undivided and Richibucto-Balfron-Pictou. These are separated by low permeability Salisbury formation.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Confinement
Typical value:semi confined
Description The system can be considered semi-confined, but confined and unconfined conditions can be found, mainly depending on the till layer composition.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Surficial sediment thickness
Description In New Brunswick, the till thickness varies between 0-20 m. The average thickness is 8 m for New Brunswick and Nova Scotia.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Well depth
32 m Range: [0 to 212] m
Groundwater depth
4.8 m Range: [0 to 46.8] m
Surficial unit hydraulic conductivity
1E-8 m/s
Description Hydraulic conductivity of the matrix of all rock formations, except Cumberland one, for the first 40 cm: K=1,4E-6 m/s Hydraulic conductivity of the matrix of all rock formations, except Cumberland one for depth exceeding 40 cm: K=6,5E-9 m/s.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Bedrock hydraulic conductivity
Range: [1e-06 to ] m/s
Description Generally, hydraulic conductivity is above 1E-6 and below 5E-5 m/s, along Northumberland Strait, the hydraulic conductivity is above 5E-5 m/s.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Regional precipitation
1093 mm/y Range: [928 to 1120] mm/y
Regional evapotranspiration
Range: [345 to 440] mm/y
Regional recharge
192 mm/y
Description 3rd largest recharge area of the region
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Regional discharge
Description Northumberland Strait is an important discharge of this hygeological unit.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Hydrogeological unit potential
Typical value:high - high regional - high local
Description Aquifer potential Undivided Cumberland Group: variable Balfron Formation: variable Richibucto Formation: generally good Undivided Pictou Group: generally good tills: poor Richibucto and Balfron formations and undivided Pictou group form the main aquifer units of the area.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin
Aquifer vulnerability
Typical value:Moderate
Groundwater Quality
Typical value:fresh
Description Groundwater shows some problematics of chlore, iron, fluoride, manganese, sodium, barium and alkaline pH.
Source Hydrogeological Atlas of South-Central Area of the Maritimes Carboniferous Basin