The statistical base for West Berlin was given by the Map of Groundwater Vulnerability to Pollution (scale 1:50,000) in the first edition of the Environmental Atlas (SenStadtUm 1985) and the Map of Depth to Groundwater (from the surface) in West Berlin (scale 1:50,000) of the present edition of the Environmental Atlas (SenStadtUm 1992). Both maps are based on data from 1983. Data for groundwater depths from the surface in the Spandau forest were gathered in 1987.
The statistical base for East Berlin included the Map of Threats to Groundwater from the Hydrogeologic Cartography of the GDR (scale 1:50,000) (ZGI 1984). Data from the 60’s and 70’s were used in this map.
Areas previously used by the GDR as border security strips around West Berlin appear in white on the maps. Data for these border security strips were bore samples from the Archiv des Landesamtes für Geowissenschaften und Rohstoffe Brandenburg (Archives of the Brandenburg State Office for Geo-Sciences and Raw Materials), and from the Archive der Senatsverwaltung für Stadtentwicklung und Umweltschutz Berlin (Berlin Department of Urban Development and Environmental Protection), as well as hydrogeological reports from the Archiv der Bundesanstalt für Geowissenschaften und Rohstoffe, Aussenstelle Berlin (Archives of the Federal Office for Geo-Sciences and Raw Materials, Berlin Office).