Kurikka Aquifer Project 5, 6

Introduction

KURIKKA AQUIFER PROJECT

The Geological Survey of Finland continues its groundwater research in the Kurikka region in cooperation with Vaasan Vesi, Kurikan Vesihuolto Oy and the Southern Ostrobothnia ELY Centre. The ambitious aim of the research is to find enough groundwater in the Kurikka region to meet the demands of 150,000 people and the large food industries in the Vaasa and Kurikka regions.

Groundwater surveys (for GTK’s part) started some ten years ago, when hydrogeological geological structural surveys were carried out in the groundwater area of Aronlähde and Kuusistonloukko. At that time, very thick sand and gravel inter till layers located in a bedrock depression were found by deep drilling. This brought up the possibilities for larger scale water abstraction in the Kurikka region, and thus the City of Vaasa also became interested in Kurikka’s potential for deep groundwater.

The sediment cover in Kurikka is exceptionally thick and complex in structure, and the fragmented bedrock surface of the area contributes to the significance of the groundwater body. Groundwater is recharged in wide highland areas to flow aquifers that are located at lower elevations and the quality of (deep) groundwater has also proven to be good. In addition, the groundwater in the area is well protected under thick clay deposits.

After finding the Kurikka buried valley aquifer, a Kurikka’s deep groundwater system have been surveyed in several separate projects since 2014. Therefore the groundwater surveys will continue for several more years and many more steps are required to find out the hydrology and hydrogeology of deep groundwater in the Kurikka region with the precision required for water supply planning.

The aim of the project phases 5 and 6 is to expand the existing Kurikka research area into the surrounding area in order to secure the water supply of the cities of Vaasa and Kurikka for years to come. Work is conducted on a broad front to increase understanding of the surficial geology by various methods. Analysing the rock surface and the sediments above it by drilling and with gravity measurements is the backbone of the entire deep groundwater project’s hydrogeology and the results are primarily used as a basis for the 3D sediment model. Further information on the rock surface details can be obtained with more detailed seismic surveys, which can also be used to find the fracture systems located in the bedrock. The geophysical measurements of the boreholes support the drilling results and contribute to the improvement of the 3D sediment model. The second main task of the project phases is to find new suitable locations for production wells, to build the wells and to carry out three months of monitored test pumping. The monitoring reports are used to assess and describe the sustainable use of groundwater. Subsequently, the pumping stations will be used to extract water for public supply.

The project is financed by Vaasan Vesi, Kurikan Vesihuolto Oy, South Ostrobothnia ELY Centre and GTK.

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