New Groundwater Formation 2017

Map Description

In the areas with unconfined aquifers, new groundwater formation rates correspond to the percolation rates shown in Map 02.13.2. The new groundwater formation rates shown in the map are lower than the percolation water rates in the areas with confined aquifers, depending on the conditions and the reduction factors determined. In the areas with confined aquifers, a reduction of at least 18 % (Wuhle) and at most 76 % (Tegel Stream) compared with the percolation water rates occurs; in most areas with confined aquifers, the new groundwater formation rate is approx. 40 % – 50 % lower than the percolation water rate.

The percentage areas of the different percolation water rates according to Map 02.13.2 and the derived new groundwater formation rates (Map 02.17) are shown in Figure 2. The category with >150-200 mm/a predominates. A shift from higher to lower values occurs in the new groundwater formation values compared with the percolation water rate (due to the reduction in confined areas), which is mainly reflected in the mean values. Thus, the percentage areas of category >50-100 mm account for 10.5 % of the percolation water rate, but for only 23.4 % the new groundwater formation rate. On the other hand, the percentage areas for the percolation water rates of the categories above 150 mm are all larger than for new groundwater formation rates.

Fig. 2: Percentage areas of percolation and water new groundwater formation rates (without bodies of water) (as of 2017)

Taking into account the area sizes, total figures can be derived for the area the State of Berlin from the new groundwater formation rates. In Tab. 2, these values are compared with the corresponding values calculated from the total runoff formation and the percolation water:

Tab. 2: Water balance and new groundwater formation in Berlin, as of 2017

Remarks:
All values not including bodies of water. The shares of bank filtrate (which e.g. are pumped into the Berlin waterworks from the Havel and Spree Rivers) are not taken into account in the percolation water or new groundwater formation.

It must be noted that the calculations for percolation water rates were carried out taking into consideration impervious soil coverage. This means that the values given for new groundwater formation represent a mean value across the hard surfaced (impervious) and unsurfaced (pervious) areas of a block segment shown, including the road space surrounding them. Since the impervious surface cover and the different degrees of sewer availability affect the water balance considerably, the values given are not transferable to the pervious parts of the respective areas.