Igneous/metamorphic rocks overlain by a continuous till cover

Hydrogeological Context

Version	Metadata
	0ea68738-1bd5-4755-9ed6-ce341fd5f47c

Project
Portneuf

Update:2014-01-30

Physiography
The crystalline bedrock is mainly composed of gneisses, granites and migmatites with the presence of gabbro and crystalline limestones. These rock formations are massive, slightly fractured and have a terrain of locally rugged hills. A continuous till unit overlies these rock formations. Depending on the extent and thickness of till that overcomes the aquifer, the water table conditions are highly variable. It is the same for the vulnerability of the aquifer, which is also function of the till deposits characteristics. The aquifer potential is weak and the water of calcic bicarbonate type show low mineralization.
Hydrogeological region	Canadian Shield
Hydrogeological context
Relief	The igneous/metamorphic rocks covered by a continuous till unit have little scope in the area. They are mainly found in the north-east. The ground elevation varies according to their location. The altitudes are higher to the north, where the terrain is locally rugged. They gradually decrease towards the south.
Area	130.00 km2
Lithology
Description	The crystalline bedrock of the geological Grenville Province dated Precambrian. The rocks are mainly gneisses, granites and migmatites with the presence of gabbro and crystalline limestones. These rock formations are massive, slightly fractured and have a terrain of locally rugged hills. A continuous till unit overlies these rock formations.
Source
Aquifer
Aquifers	Igneous rock aquifer

Bedrock aquifer media


Typical value:	fractured
Description	The crystalline bedrock is massive and slightly fractured.

Confinement

Typical value:	semi confined - unconfined
Description	Conditions of water table in these aquifers can be highly variable, depending on the extent and thickness till deposits which surmount.

Surficial sediment thickness

Description	In the Laurentides sector, the sediment coverage thickness is often less than 5 m.

Well depth
38.1 m Range: [0.5 to 144.2] m

Groundwater depth
1 m Range: [0 to 1.61] m

Surficial unit hydraulic conductivity
9E-7 m/s
Description	The till unit has a mean hydraulic conductivity of 9,0E-7 m/s.
Methode	Hazen formula, based on 10 samples

Regional precipitation
1121.5 mm/y Range: [1063.1 to 1168.2] mm/y
Methode	Precipitation data are from Environment Canada. The value represents the average of the climate normals (1981-2010) measured on the stations distributed in or near the hydrogeological unit. The stations were selected so the average precipitation is as representative as possible of the whole hydrogeological unit.

Hydrogeological unit potential

Description	This hydrogeological unit shows a weak aquifer potential.

Aquifer vulnerability
4 Range: [0 to 6]

Groundwater Quality

Description	The water type is calcic bicarbonate and groundwater shows low mineralization.