ASPO, SE SWEDEN - A NATURAL GROUNDWATER-FLOW MODEL DERIVED FROM HYDROGEOCHEMICAL OBSERVATIONS

Hydrogeochemical studies form an essential part of current geoscientif ic investigations carried out in conjunction with excavations of an un derground experimental facility as part of the Swedish programme to di spose of high-level spent nuclear fuel in crystalline bedrock. A large part of the hydrogeochemistry has been devoted to the detailed invest igation of each individual zone hydraulically selected, tested and sam pled for hydrogeochemical characterisation. The data have been used to describe the chemistry and origin of the Aspo groundwaters; models ha ve been developed to illustrate groundwater mixing, and equilibrium mo delling approaches have been employed to understand water-rock interac tion processes. Hydrogeochemical observations have been integrated wit h known geological and hydrogeological parameters to construct a groun dwater flow model for the island.