In the Berlin-Brandenburg region, the salinisation of groundwater, due to the rise of deep saline waters, is a widespread problem. Around 29% of the area is already affected by such geogenic groundwater salinisation. The GeoSalz project is investigating the influence of this on drinking water supplies and possible countermeasures.

Depending on the location, up to 3 aquifer complexes are present in the Berlin area, whose available water, in addition to bank filtration and groundwater recharge, secures the drinking water supply of the city of Berlin. These so-called freshwater aquifers are largely hydraulically isolated from the underlying saltwater aquifer by an 80 to 100 meter thick geological unit called the Rupelton. However, at defects in the Rupelton, e.g. at glacial erosion gullies, highly mineralized saltwater may rise, which in many cases irreversibly contaminates the freshwater reservoirs. This may be a natural process, but it can be exacerbated if groundwater pumping causes local hydraulic discharge and contributes to the mobilisation of deep saline groundwaters.

For sustainable resource management, it is necessary to identify such salinity upwelling sites and to better understand the temporal and spatial dynamics of salinisation in the subsurface. The proposed approach includes the combination of investigations of groundwater properties with geophysical measurements and evaluation of hydrochemistry and isotope measurements. In parallel, a hydro-geological structural model and other various models will be developed. The aim of the project is to develop new concepts for well construction and operation, particularly at affected well fields, for sustainable well operation.

Photos by Iryna Dazhura for KWB