TOWARDS QUANTIFYING GROUNDWATER RESOURCES OF THE PALOLUOMA VALLEY IN WEST-CENTRAL FINLAND

The Paloluoma buried bedrock valley located near Kurikka, Finland, has attracted great interest from its larger neighbouring city, Vaasa, owing to the nature of its highly productive groundwater system. The possible increase in groundwater exploitation of the Paloluoma valley raises concerns of aquifer integrity and groundwater sustainability. The sustainable management of this groundwater resource requires an improved quantitative understanding. The valley of interest is comprised of glaciofluvial aquifers confined underneath thick glaciomarine aquitards interbedded with poorly-sorted glacial sediment (till), which also form aquitard layers. The goal of this study is to form an initial quantitative understanding of the Paloluoma groundwater system through the development of a groundwater flow model based on a sound conceptual model.

The Paloluoma valley and its recharge area (approx. 30 km² watershed) can be conceptualized through the analysis of the system’s recharge mechanisms and hydraulic connectivity. Recharge has been estimated to be approximately 100 mm/a. Pumping tests have revealed the presence of a positive boundary limit due to a delayed release in water. Early modeling using the finite element method in FEFLOW indicate flow pathways with high connectivity along the length of the valley. These results suggest greater permeability/fractures within the bedrock as well as potentially higher vertical connectivity between aquifer units than previously understood. This information has been important to advance the understanding of the Paloluoma groundwater system. The simulation of groundwater residence time using the method developed by Goode (1996) is also intended. The model will also be run under pumping conditions to explore varying exploitation scenarios.