Bedrock Groundwater Could Improve Mikkeli’s Water Supply in the Future
The Geological Survey of Finland GTK has started groundwater surveys in the Mikkeli area. The surveys are carried out to investigate if the city’s water supply could be supported by exploiting lesser-known bedrock groundwater. The aim is to secure future water supply and improve water security.
In Finland, water supply in urban areas is mainly provided from groundwater in soil formations. This is also the case in Mikkeli where the city centre is partly located on top of an esker formation. Less attention has been paid to bedrock groundwater, which is often better protected from various groundwater threatening activities and the risks of changing climate.
GTK has started the MIKAPO project, which is looking at alternative water supply options, particularly for the Mikkeli city centre area.
“We are investigating the presence of bedrock aquifers in the area and looking at options for the city’s water supply. We are also developing survey methods that can be used more generally in bedrock groundwater surveys,” says Jari Hyvärinen, Project Manager from GTK. ″Even if not all sites meet the desired quality and quantity criteria for groundwater, the results will provide valuable information for water supply planning.″
Surveys proceed in stages
Groundwater is formed in fairly common fracture and weakness zones in the bedrock. The fracture zones can be up to tens of kilometres long, but to locate them more precisely requires geological, hydrogeological, and geophysical surveys. It is mandatory to situate a borehole in a fracture zone to an accuracy of just a few metres.
Surveys in the Mikkeli area started in late summer on a preliminary basis, including bedrock fracture interpretation. Geophysical field surveys will be carried out and informed locally before the work begins in the spring of 2026. Test drillings of boreholes are carried out in the summer based on the results of the geophysical surveys. The project will run until the end of October 2026.
The results will benefit not only the water supply of the city of Mikkeli but also its surrounding areas and the results will deepen the understanding of the occurrence and conditions of bedrock groundwater in Eastern Finland. The survey methods developed may also help other cities and municipalities to plan their water supply alternatives and improve their security of supply.
The MIKAPO project has received funding from the South Savo ELY Centre with support from the European Union. GTK, Mikkeli Waterworks and the City of Mikkeli are also contributing to the project.
Further information
Jari Hyvärinen, Project Manager
Geological Survey of Finland GTK
jari.hyvarinen@gtk.fi
tel. +358 29 50 33406
Project introduction on GTK`s website:
MIKAPO – Developing Water Supply Security in a Changing Climate, Mikkeli’s Bedrock Groundwater Potential
