St. Narcisse Moraine

Hydrogeological Context




St. Narcisse Moraine unit description

The territory sections, where St. Narcisse moraine is present count three aquifers: Precambrian bedrock aquifer, sedimentary formations aquifer and St. Narcisse moraine aquifer. The Precambrian bedrock is massive and little fractured, showing an unproductive aquifer. Sedimentary formations are highly fractured and shales are very brittle, demonstrating good potential aquifer. These units are covered by till layer. The till is overlain by St. Narcisse morainic deposit and sand and gravel. The sand and gravel are just found on the flanks of the moraine. It is formed of a mixture of blocks of sand and gravel contained in a silty sandy matrix. Although the aquifer potential of Moraine has not yet been demonstrated, the presence of sand and gravel suggests that the aquifer has a good potential. Since the summit of the moraine is not covered by sand and gravel, the water table is unconfined allowing surface water to percolate. The aquifer is vulnerable to surface contamination. The water type is sodium bicarbonate.
Hydrogeological regionSt. Lawrence Platform
Hydrogeological context
ReliefThe Saint-Narcisse moraine is oriented parallel to the St. Lawrence River. To the south, the moraine is found at low altitudes, while it has medium altitudes in the north. Aside from this slight increase in altitude from south to north, the terrain is relatively flat.
Area71.00 km2
DescriptionTwo rock formations are associated with the hydrogeological unit of Saint-Narcisse moraine: Precambrian bedrock and sedimentary formations. Sections of the Precambrian bedrock considered are located in the center and north of the sector. It is mainly composed of orthogneiss and granodiorite gneiss. Sedimentary formations, located south include the Trenton Group limestones. A till unit followed by morainic deposits and sands and gravels cover the rock formations. The sands and gravels are only found on the moraine flanks.
AquifersList of aquifer surficial St.Narcisse moraine aquifer

Unit properties

Surficial aquifer media
Typical value:porous
Description The moraine is composed of a mixture of boulders, gravel and sand contained in a silty sand matrix.
Bedrock aquifer media
Typical value:fractured
Description The igneous metamorphic rocks and the sedimentary rocks are the hydrogeological units underlying morainic deposit. The Precambrian rocks don't represent productive aquifer.
Typical value:unconfined
Description The top part of the moraine outcrops, however the flanks are covered with sand and gravel.
Well depth
23.15 m Range: [0 to 120.4] m
Groundwater depth
0.73 m Range: [0 to 3.14] m
Surficial unit hydraulic conductivity
0.0000079 m/s
Description The morainic deposits hydraulic conductivity is 7.9E-6 m/s
Methode Hazen formula, based on 5 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 Although the regional aquifer potential of Moraine has not yet been demonstrated, the presence of sand and gravel areas suggests that the potential of this aquifer is good.
Aquifer vulnerability
4 Range: [0 to 6]
Groundwater Quality
Description Water type is sodium bicarbonate