Density-dependent groundwater movement in sediments overlying salt domes - the Gorleben site example

Abstract

In the multiple-aquifer system in the sediments above the Gorleben salt dome, an upper fresh-water body is underlain by saline water. The salinity of the water generally increases with depth. The salt dome is crossed by a subglacial erosion channel, in which the lowermost aquifer is locally in contact with the caprock or the salt itself. Saturated brines are found in these areas. Information on the flow system can be derived from the observed density distribution. Two-dimensional numerical studies have been conducted to determine the transient density distribution and the associated flow field. They have demonstrated the sensitivity of the system to changes in the hydrogeological structure, initial density distribution, and modeled time period (palaeohydrogeological effects). A few of the calculated present density distributions compare well with measured field data.