The Berlin groundwater measurement network grew rapidly: By 1937, there were already more than 2000 measurement points. At present, following an optimization of the measurement network in the city, the State Groundwater Service operates approx. 1000 measurement points which are installed into the five different aquifers. The measurement points are equipped with automatic data loggers, and provide daily measurements. Meantime the data base contains more than six million measured values.
In addition, the Berlin Water Utility and the Brandenburg state Environmental Agency as well as other waterworks operators in Brandenburg provide groundwater level measurement data for the Berlin area and the surrounding areas, for the most part monthly. If the groundwater has a direct connection to surface water (effluent situation, Fig. 4a), additional level data from surface-water measurement points are used.
The present map incorporates measurements from 1771 groundwater measurement points and 33 surface-water measurement points for the main aquifer (Aquifer 2), and from 42 groundwater measurement points and seven surface-water measurement points for the Panke Valley groundwater aquifer (Aquifer 1) on the Barnim plateau. At the measurement points which are measured daily, the value of May 15, 2009 was used; for the others, the value taken during the month of May which was closest to this date.
The distribution of the measurement points is irregular: The measurement network is densest in the city center and in the immediate intake areas of the waterworks, and less dense at the outskirts of the city, especially in the surrounding areas in Brandenburg.