Due to the extreme sensitivity of the superconductive gravimeter GWR T020, based at Metsähovi Research Center in Kirkkonummi, Southern Finland, various local meteorological and hydrological changes influence or disturb its measurements. This study is part of a large research project which aims to identify the contribution of the local hydrology at Metsähovi to these gravimeter measurements.
For this purpose a study is made to investigate the geological structure of the subsurface and the hydrological properties of the stratigraphic layers. In order to perform numerical calculations a digital model is made using digital modeling software. A field investigation is performed consisting of:
• A literature study on hydro-geological setting in Southern Finland.
• An extensive fieldwork consisting of bore holes, field observations and various field measurements (among others GPS, GPR, slug tests and monitoring of soil moisture with soil sensors).
• Laboratory work to obtain necessary soil properties. Main property which was found is the grain size distribution.
A large amount of data is gathered and processed in order to integrate the data into a structural model. A method is found to integrate a maximum amount of information into a model and by optimally using the understanding and knowledge of the geological setting.
A model is constructed with several layers. The area can be characterized in two hydrogeological domains. One is the higher area where overburden is thin and only till covers the bedrock, the other is a lower area dominated by a low permeable silt and clay layer. The till is low permeable but is still found to infiltrate water considerably.
The hydrological setting of Metsähovi is analyzed and theories of the hydrogeological processes which govern moisture changes in the area are investigated. Main focus is how these processes can be modeled with their governing laws and parameters. It is recommended to initially make a 1 dimensional model with software such as CoupManual.