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Groundwater level situation 13.9.2023
Groundwater levels are above average in many places
The water levels of small groundwater deposits have already started rising in many places as usual in the autumn. In larger groundwater bodies, the decline in water levels is slowing down and they are gradually starting to rise. Small groundwater deposits react faster and more strongly to changes in weather conditions than larger groundwater bodies.
In the southern and central parts of the country, the water levels of small groundwater deposits are mainly close to the averages for the period or 10–60 cm above them. In the north, the levels of small deposits are mostly close to the average or 10–70 cm higher. In some places, water levels are still slightly lower than average.
In the southern part of the country, the water levels of large and medium-sized groundwater bodies are mainly normal for the time period. In the central part of the country, the water levels are in many places close to average or 10–55 cm higher. However, the regions with the highest levels of precipitation in the West have significantly higher water levels in places. In the northern part of the country, the water levels of large and medium bodies are mostly close to or 10–25 cm above the average.
In the autumn, the decline in groundwater levels will slow down as the amount of evaporation decreases due to cooler weather and the end of the growing season. Water levels usually start rising in September and October. In winter, the rise will turn into a decline again as frozen soil and precipitation in the form of snow slow down the absorption of water into soil and the formation of groundwater.
The groundwater situation provides an overview of groundwater levels
The groundwater situation is based on groundwater level measurements carried out at monitoring stations in different parts of Finland. The stations are established in areas that are as natural as possible. They represent different climatic and soil conditions. The monitoring network is sparse, and it is therefore important to note that the situation may vary greatly depending on local conditions. The best local groundwater information can be obtained from water utilities, water co-operatives and well users. The observations may also differ from the values calculated by the hydrological model shown on the map.
Local observers perform groundwater level measurements with observation tubes installed vertically in the ground twice a month. At several groundwater stations, the water level is also measured with automatic equipment. The measurement results are presented as water levels above sea level in the N2000 system and recorded in the groundwater register (POVET) maintained by the Finnish Environment Institute and regional Centres for Economic Development, Transport and the Environment.
Groundwater data in open environmental information systems (Hertta service, available in Finnish)
Why is groundwater important?
After glaciers, groundwaters make up the second largest fresh water reserve on the Earth. Compared to our population, we have plenty of high-quality and accessible groundwater in Finland, and around 65% of domestic water supplied by water utilities in this country is groundwater.
What is actually groundwater?
Groundwater refers to all water under the ground surface that fills open spaces in the soil and bedrock fractures. Groundwater is formed when rainwater, water from snowmelt or surface water infiltrates into soil layers or flows into cracks in the bedrock. Impurities are removed from groundwater as it is filtered through soil layers, making it ideal as a source of drinking water. Some of our tap water comes from artificially recharged groundwater deposits, where surface water has been infiltrated into the soil. While the groundwater reserves in Finland recharge rapidly, there are great variations in the recharge rate globally.
Where can groundwater be found?
Groundwater occurs everywhere but particularly large volumes are formed in areas with sand and gravel deposits ideal for the infiltration of water. Areas with a rich supply of groundwater are called groundwater areas. Groundwater levels are affected by geographical location, soil types, seasons, weather conditions and human actions. The groundwater surface is usually found at a depth of two to five metres below the ground level, and considerably deeper at the centre of sand and gravel deposits. If you have a well, you can see the groundwater level by looking into it. A spring is an outlet where groundwater bubbles out of the ground.
Groundwater and the seasons
Groundwater levels fluctuate naturally as seasons come and go. As the lengths of the seasons vary in different parts of the country, so do fluctuations in groundwater levels. The volume of groundwater decreases in winter because precipitation mainly comes as snow and soil frost prevents the infiltration of water into the soil. Groundwaters are typically at their lowest level in late summer as plants use up water and it evaporates in large quantities throughout the summer, and there may also be long periods of drought. The largest quantities of new groundwater are formed during spring snowmelt and autumn rains.
Fun facts about groundwater
Plenty of groundwater
Groundwater areas are delineated based on the quality of the water and factors affecting its recharging. In Finland, there are around 3,900 groundwater areas suitable for water abstraction with the largest number in Lapland and the smallest in Åland and Savo. Groundwater is recharged at a rate of approx. 5.4 million cubic metres a day, whereas its consumption amounts to around 0.7 million cubic metres a day. Groundwater resources may be reduced by drought, large-scale abstraction and land drainage.
In Finland, groundwater is usually good in quality, and water utilities prefer to use it as raw water. Groundwater resources with the best quality and yield are found in sand and gravel deposits. The quality of groundwater may be affected by soil and bedrock type, the seasons, weather conditions and human actions. Threats to groundwater quality include chemicals and other hazardous substances from industry, consumption and agriculture, as well as excavation, sand and gravel extraction, mining and peatland drainage.
Groundwater resources are utilized increasingly, and we are also better informed about risks affecting groundwater. Consequently, the need to protect groundwaters and groundwater areas has increased, and many legislative and other measures have already been taken to this end. The aim is to ensure the good quality and quantity of groundwater, to reduce its contamination, and to promote the sustainable use of water resources. If groundwater becomes contaminated, it will be extremely difficult, expensive and time consuming to clean it.
Groundwater and climate change
Climate change is bringing us extreme weather events more frequently. Drier and hotter summers will reduce groundwater resources, while earlier springs and snowmelts mean that the water table will start to decrease earlier in the summer. Increased evaporation and a longer growing season will additionally reduce groundwater levels. On the other hand, groundwater resources will be replenished by longer autumns with higher precipitation and mild winters that bring rain instead of snow. Rainstorms and floods may carry impurities into groundwaters.