| Overlying on till covering the bedrock, the esker is composed of glaciofluvial sediments, including sands, gravels, pebbles and a greater or lesser amount of blocks and some fine sediment such as silts and clays. The confined aquifer designates the esker part that is located below 344 m and is overlaid by clay unit. Littoral deposits followed by organic deposits overlie that clay unit. The sediments overlying the esker provide good protection against surface contamination and thus limit the aquifer vulnerability. The esker is recharged with precipitation percolating in the upper part of the esker. Once in the system, water flows from the esker center to its borders, forming a transverse component of the flow. When the water level is equal or higher than the esker/clay limit, groundwater exits the aquifer system in the form of diffuse or punctual discharges. There are two main sources; Crepeault and St. Mathieu. In some places, the appearance of peatland along the esker is associated with diffuse discharges of the confined aquifer of the esker. The groundwater of the confined aquifer is modern to intermediate (50 to 6000 yr BP). It is characterized by great quality. |
| Overlying on till covering the bedrock, the esker is composed of glaciofluvial sediments, including sands, gravels, pebbles and a greater or lesser amount of blocks and some fine sediment such as silts and clays. The unconfined aquifer designates the top part of the esker, which is located above 344 m whereas no deposit covers the esker; the unconfined aquifer is vulnerable to contamination from the surface. The esker is recharged with precipitation percolating in the upper part of the esker. Once in the system, water flow includes two components; longitudinal and transversal. The latter is associated with the confined aquifer. The longitudinal component is the one that seems to mostly control groundwater flow and designates groundwater flow in the unconfined aquifer. Water flows south from the rocky topographic high to north at least up to Eska. Further north between Amos and Eska pumping, it is difficult to determine flow directions as the piezometric surface is relatively flat. In the northern part of the esker, water flows southward towards Amos catchment area. It is also possible to identify three water divide lines, one of which corresponds to the point rise in the bedrock. This boundary, located between Amos and Eska pumping is mobile. Its locations is influenced by the pumping and isn't waterproof. There are two sub-basins; Eska and Amos which are interconnected. The other two water divide lines are located in the southern extension of the esker and the northern part of the esker. The north line also seems to be mobile and can move in function of the pumping rate of Amos. Groundwater is exploited for municipal purposes by the city of Amos and for bottling by Eska. It is characterized by an impressive quality. In the center of the esker, the water is modern (younger than 1950), while it is considered fossils (more than 6000 years BP) at the base of the esker. |
Groundwater Information Network