Expected Mean Highest Groundwater Level (EMHGL)
The rises and falls of the groundwater; on the one hand, they are based on the seasonal weather changes throughout the year. On the other hand, humans have been influencing the groundwater level for many decades by digging canals and tunnels and extracting water for drinking and industrial purposes.
A prediction of the expected mean highest groundwater level (EMHGL) is essential for the percolation of precipitation on plots of land. The EMHGL indicates what is assumed to be the average of the maximum levels for the year. It is calculated based on the heights which groundwater has risen to in the past and the path it takes underground. It does not take into account new, long-term human interventions, such as an underground railway construction project or the extraction of groundwater by the waterworks as part of the drinking water production process.
So far, EMHGLs have been defined for the Berlin glacial valley and the Panke valley. This covers almost 50 percent of the area of Berlin. Both areas display relatively high groundwater levels compared with the rest of Berlin. Some of the predicted numbers may therefore lie above ground, meaning that small groundwater lakes may form. Additionally, short-term flooding may occur along surface waters.
Dive into this next page to discover the EMHGLs predicted for the Berlin glacial valley and the Panke valley. In the field of water conservation areas, you can learn about existing regulations for the planning of percolation facilities. Click here to access the EHGL you would need to plan the construction of a basement, for example.