Groundwater recharge in Brandenburg is
declining – but why?

Description

Brandenburg is one of the driest federal states in Germany and has low groundwater recharge in many regions. However, this is crucial for the water supply and the preservation of natural ecosystems. Measurements show that groundwater recharge has been steadily decreasing since 1980. Rivers are carrying less water and groundwater levels are falling in the long term. In this study, five largely unaffected river catchment areas were investigated to determine the causes of this decline.

Results

The analysis shows that rising temperatures, increasing solar radiation and denser vegetation have reduced groundwater recharge since 1980. Depending on the region, the water loss is between 4 and 21 mm per decade. The increase in the leaf area of plants (LAI) in particular contributes to this, as more water evaporates before it reaches the ground.
Although precipitation varies in the regions studied, long-term rainfall trends are not clear. Nevertheless, in four out of five regions there is a clear contradiction between the model calculations and the actual measured water levels. This indicates that other factors such as land use changes, irrigation or other influences not previously taken into account play a role.
For water management in Brandenburg, this means that a further decline in groundwater recharge is possible. As future precipitation is uncertain, we should not assume that increasing winter precipitation will solve the problem.

Background

The 2024 project was partially funded by the Ministry of Agriculture, Environment and Climate Protection of the State of Brandenburg (MLUK) and was associated with the Climate Change Center Berlin Brandenburg (CCC).

Read the paper