Photo: Mirjam Orvomaa
Groundwater is found everywhere – however in Finland groundwater formations are mainly situated in eskers, moraine formations and end moraine formations. The aquifer thickness is generally around 10 meters and the formations are scattered and small in worldwide comparison. The groundwater table is commonly 3-5 meters below the surface and in eskers up to 50 meters. The aquifers in Finland’s glacial deposits rank in intrinsic quality among the best reserves of groundwater in the world (excluding areas with quality weakening geological characteristics). As protective layers are thin, the quality is sensitive to contamination and climate change impacts.
The main purpose of mapping and classifying groundwater areas has been water supply management. The information can also be used to support land use planning and groundwater protection. The main aquifers were mapped and classified in the 1990’s into so called groundwater areas according to the needs of water supply management and protection requirements ( previous classes I- III). The average groundwater area size 1-2 km2.
The legislation on protecting groundwater was updated in February 2015 and groundwater dependant ecosystems (both terrestrial and surface water) were acknowledged. According to the prior classification there are over 6000 classified groundwater areas of which:
- over 2,000 are important for water supply (class-1)
- 1,600 are suitable for water supply (class-2)