Development of a hydrogeological model description of intrusive rock at different investigation scales: an example from south-eastern Sweden

Site investigations at Oskarshamn, south-eastern Sweden, to determine a suitable repository for spent nuclear fuel, are dependent on hydrogeological modelling, and one part of the modelling rests upon a deformation zone model. One main objective of the investigations, to locate and characterize major and minor deformation zones in the Simpevarp and Laxemar areas, has been largely met with the use of remote sensing and ground geophysics data. Most major deformation zones in the bedrock were initially identified as lineaments using digital elevation models and helicopter-borne geophysics data. Supplementary information was received from a light detection and ranging (LIDAR) survey and dense ground geophysics surveys, providing data also for minor deformation zones. However, surface investigations are needed to explore and confirm the geological and hydrogeological character of the lineaments identified by remote sensing to indicate that a lineament probably represents a deformation zone. The approach, involving two- and three-dimensional planar models to create a site descriptive model of geology and hydrogeology, may be suitable for other parts of the world with a similar geological environment of crystalline bedrock.