Hydrogeological map of Lower Saxony 1: 50000 – Mean annual groundwater regeneration of the hydrological winter half-year for the 30-year period 1961-1990 (WMS Service)

The map shows the average annual groundwater regeneration of the hydrological summer half-year for the 30-year period 1991-2020. Groundwater is a raw material that can regenerate and renew itself.
The main supplier of groundwater supplies is rainwater leaking in Lower Saxony. It ensures that the groundwater deposits of the storage rocks are replenished in the underground. The new groundwater formation is particularly high in winter, as at this time a large part of the rainfall is leaking in the soil. In the warmer seasons, however, a large part of the precipitation evaporates on the surface or is absorbed by plants. The formation of groundwater is widely distributed in different areas.
It depends on the distribution of precipitation and evaporation, the characteristics of the soil, the land use (growth, degree of sealing), the relief of the land surface, the artificial drainage by drainage, the groundwater level and the properties of the near-surface rocks. Since these parameters differ significantly in Lower Saxony, in some cases in the smallest space, the formation of groundwater is also subject to large lateral fluctuations. In order to determine the new formation of groundwater, there are various methods.The present maps show the area-differentiated designation of the mean groundwater formation, which was calculated using the mGROWA method (short for “monthly large-scale water balance”).
The model mGROWA was developed for the large-scale simulation of the water balance at Forschungszentrum Jülich in cooperation with the LBEG (HERRMANN et al. 2013) and since 2016 for Lower Saxony updated methodologically. In addition, a number of new input data was used to provide an up-to-date data base for water management planning work and water licensing procedures.

Daily and monthly measured and then spatially interpolated climate observation data from the German Weather Service were used as climatic input data. These are the potential evaporation calculated on the basis of the FAO grass reference evaporation (DWD, unpublished) and the precipitation based on the REGNIE product (Rauthe et al, 2013) corrected by judge (Judges, 1995). For better regionalisation, the climatic input parameters of precipitation and potential evaporation with bilinear interpolation were scaled down to a 100 x 100 m grid for mGROWA22.