DK 3: Development and testing of high-resolution near-surface methods for improved groundwater vulnerability assessment
Responsible beneficiary: GEUS
The goal in the Varde Pilotarea is to develop a new high-resolution mapping method and new interpretation and modelling procedures aimed at areas with complex geology.
A large part of the Danish subsurface is strongly disturbed by glacial deformation formed by thrusting and folding. This has produced a high geological heterogeneity which to a large extent affects the vulnerability of the aquifers. Glacial deformation is generally widespread in the formerly glaciated areas of Northern Europe including the North Sea region. The existing methods used for the groundwater mapping has a limited resolution capability and the resulting models do not describe the subsurface in scales less than bout 50-100 m. Since glacially deformed areas are often composed of structures smaller than this scale, the existing methods and routines used in the groundwater mapping are not sufficient for detailed vulnerability assessments and action planning in such areas.
The town of Varde is located in the southwestern part of Jutland. The area suffers from lack of clean ground water. Very often nitrate and pesticides pollute the known aquifers and it has for many years been difficult to find new clean aquifers. Recent investigations show that the area is heavily deformed with thrusting and folding of the subsurface. This means that gateways for pollution along these structures to the aquifers frequently exist in the area. Due to the presence of the complex geology a new high-resolution mapping method is needed. New ways of data interpretation and modelling of such dense data also has to be developed.
The objectives are:
•Stakeholder consultation and compilation of existing data.
•Development of a new electromagnetic geophysical sensor system covering mapping of the depth interval from 0 – 30 m which is not covered by any other rapidly deployed groundbased system. The system will partly be based on hardware developed for the SkyTEM system, and will be capable of being towed by an ATV.
•An efficient procedure for constructing high-resolution 3D geological models and groundwater models will be developed. These will include semi-automatic cognitive geological modelling and combined with stochastic training image methods.
•Development and demonstration of new management/regulation systems based on the new technological possibilities.
Stakeholders are DIN Forsyning (the local water supply), farmers and farming organisations, Varde Municipality, Region Syddanmark, The Nature agency.