The term new groundwater formation (groundwater recharge) as used here refers to the process by which groundwater is formed from the percolation of precipitation. The amount of new groundwater formation differs from the amount of percolation water. Compared with the percolation water rate, it is reduced by the proportion of interflow, i.e., the portion of the runoff that flows into the receiving waters from the near-surface layers of soil. For these reasons, a New Groundwater Formation map (Map 02.17, Edition 2019), has been drafted in addition to the Percolation (Map 02.13.2, Edition 2019) and the Total Runoff (Map 02.13.3, Edition 2019) maps.
Given the expected change in water balance due to climate change, knowledge of the level of new groundwater formation is particularly important. Not only for long-term and sustainable use of groundwater resources, but also for estimating the potential risk of the transport of pollutants from the unsaturated zone into the groundwater (Verleger und Limberg 2013, Löschner 2008). The amount of new groundwater formation shown in Map 02.17 as the new groundwater formation rates (mm/year) differentiated by area, is an important initial parameter for deriving the dwell time of the percolation water in the groundwater overburden (Map 02.16, Edition 2004).