The sewage farm districts in the map are based on maps (scale: 1 : 10,000 or 1 : 25,000) produced in the 1960’s commissioned by the Berlin Water Supply and Waste Water Treatment (WAB). The boundaries presented in these were checked against older maps from the archives of the WAB Berlin, the Berlin State Library and the Berlin Waterworks (BWB). Sewage farms discontinued before 1960 could thus be defined.
Further information on operation periods, type and intensity of use, and special-use areas was obtained from written information or information provided by employees of WAB Berlin, the Berlin Waterworks (BWB), WAB Potsdam and Königs-Wusterhausen and the Brandenburg State Office for the Environment (LfU).
The following data was used to digitise the geographical boundaries of the sewage farms:
- Geoportal Berlin / ATKIS® DTM – 2021 Digital Terrain Model with 1 m grid size (DTM1),
- Digital terrain model with a ground resolution of 1 m, Brandenburg and Berlin © GeoBasis-DE/LGB 2021,
- Geoportal Berlin / aerial photographs 1928, scale 1 : 4,000,
- Geoportal Berlin / aerial photographs 1953, scale 1 : 22,000,
- Geoportal Berlin / digital colour orthophotos from 2021 (DOP20RGBI) with a ground resolution of 0.2 m, and
- Georeferenced sewage farm district maps of the WAB from the 1960s.