Expected Mean Highest Groundwater Level (EMHGL) 2016

Map Description

The EMHGL map for the Berlin glacial valley and the Panke valley (2015) covers slightly more than half of the area of the State of Berlin. The expected mean highest groundwater level is represented by lines of equal height in metres above sea level. The difference in height between groundwater isolines is 0.1 m. Thus the map shows the groundwater surface for the EMHGL of the main aquifer, which is predominantly unconfined in this area, and its piezometric surface where it is confined. In the glacial valley, this is GWL (Grundwasserleiter, aquifer) 1.3 and GWL 2, in the Panke valley it is GWL 1.2 according to the aquifer nomenclature following Limberg & Thierbach (2002).

It is evident from the course of the contour lines that the Spree and the Havel and their tributaries form the receiving waters for the groundwater close to the surface. The groundwater flow direction lies perpendicular to the contour lines from the higher to the lower level. The EMHGL varies between about 58.0 m above sea level in the northern Panke valley on the state border and 30.5 m above sea level near the canalised Lower Havel in Spandau. The closer clustering of the contour lines in the Panke valley shows that the height gradient of the groundwater is larger here than in the glacial valley, as expected. Thus the course of the EMHGL isolines shows a plausible picture for the case that neither groundwater extractions nor artificial groundwater replenishments occur.

On the digital map, the EMHGL value for a certain location can be displayed on screen by a mouse click.

Thus the user receives an EMHGL value for his question in a simple manner.

The following should be noted:

The map value applies to the groundwater level of the uppermost aquifer. In the represented area of the glacial and Panke valley, the groundwater in the uppermost aquifer is predominantly unconfined. Thus, as a rule the map value indicates the height of the groundwater surface. However, in some places overlying layers with low water conductivity, such as boulder clay and boulder marl, clay, silt and organic soils, cause the groundwater to be confined (e.g. in the area of a boulder marl “island” in Charlottenburg designated on the map). In these cases, the map does not specify the height of the groundwater surface, but rather that of the piezometric surface of the confined groundwater.

Due to the scale and the rather heterogeneous individual sedimentation conditions, the two possible deviations from the usual hydrogeological configuration that were mentioned are not, or not completely, representable in the Geological Outline provided. However, they can be recognised in the framework of a subsoil expertise, which is principally required for construction activity. In addition, in concrete cases advice may be sought from the State Geological Service regarding the geological substructure of the subsoil, and the strata-log sheets from the digital drilling map can be consulted online.

It should also be noted that the EMHGL may lie above ground level. In this case, the formation of groundwater ponds cannot be excluded.

Near surface waters, in addition to high groundwater levels, short-term local flooding may occur, which cannot be inferred from the map of the expected mean highest groundwater level. Information on this is available at www.berlin.de/sen/uvk/umwelt/wasser-und-geologie/hochwasser/ [in German].

In the Panke valley, in particular in its northern part, the groundwater measuring points are sometimes relatively far apart in view of the heterogeneity of the aquifer and the mostly large natural groundwater gradient. As a result, the EMHGL map is more fraught with uncertainty here than in the area of the glacial valley. This also applies to areas in the immediate vicinity of surface waters (the Panke and its small tributaries). If new investigations (drillings, groundwater level measurements) yield results in such areas that clearly contradict the EMHGL value of the map (e.g. current groundwater level within metres above the map value), the EMHGL should be locally modified by an expert. In such cases, the Berlin Groundwater Service (Landesgrundwasserdienst) kindly requests to be notified.

Regulation for planning percolation facilities in the water conservation areas

When planning percolation facilities for precipitation water outside of the water conservation areas, the EMGHL is to be taken as the design groundwater level in large parts of Berlin. Within the individual conservation zones of a water conservation area, however, the following provisions apply:

  • outer conservation zone III B
    In order to guarantee a higher protection of the groundwater within the outer conservation zone III B, the harmless percolation of runoff or collected precipitation water is possible here without permission under the conditions of the precipitation water exemption ordinance (Niederschlagswasserfreistellungsverordnung). However, instead of the EMHGL, the EHGL, which is usually a few decimetres higher, has to be taken as the basis.
  • outer conservation zone III A
    Percolating precipitation water without permission is not possible here. A permission under water law must be obtained from the water authority.
  • outer conservation zone III
    Percolating precipitation water without permission is not possible here. A permission under water law must be obtained from the water authority.
  • inner conservation zone II
    Construction is generally prohibited here, which also applies to percolation facilities for precipitation water.