In view of assessing the importance of diffuse and spot material inputs into Berlin’s groundwater, the current condition of all groundwater bodies was characterized on the basis of existing hydrochemical data provided by the regional groundwater-condition measuring network. Existing data and findings of drilling programmes, which were carried out from the 1970s to 1990s, were included. Furthermore, the database was completed with data from the catchment areas of waterworks, which were provided by Berliner Wasserbetriebe (BWB), data from special investigations of areas containing hazardous waste and from the surrounding area of Brandenburg. A total of 1,364 measuring sites were assessed. Other hydrogeological and hydrodynamic aspects were also involved. Major point sources were separately analysed and an assessment was made as to whether they result in a significant pollution of the groundwater bodies (Hydor 2003).
Selected measuring sites
For regionalisation purposes it is important to define a reference horizon for the calculations. Only measuring sites whose sets of filters – and thus the place of sampling – are situated in this groundwater horizon are included in the database. Because of the vertically and hydrogeologically oriented reduction in the number of measuring sites, only those measuring sites with a depth of less than 50 metres below the ground remain in the database. The overwhelming majority of the above mentioned 1,364 measuring sites are installed at a depth of less than 25 metres (= 60 %).