"Trees are stressed": groundwater levels continue to fall

Dryness - "Trees are stressed": groundwater levels continue to fall

Groundwater levels in Bavaria continued to fall in 2023. This trend has been observed for around ten years and has continued this year, Benjamin Kopp, an employee in the Groundwater Protection Department of the Bavarian State Office for the Environment, told dpa on request.

The warming trend is fundamentally negative for the water balance, explained Kopp. The State Office's Low Water Information Service recorded the second hottest summer half-year in almost 150 years in 2023. "When it's warmer, the atmosphere can absorb more water," said Kopp. "This means more water evaporates or runs off the surface as a result of heavy rainfall." This leaves less water that can seep through the soil into the groundwater.

The relatively more extreme weather events in 2023 were particularly noteworthy. A dry start to the year was followed by a very wet spring, a very dry June, an extremely wet August, a dry September and October and an extremely wet November. "It would be better for the water balance if the precipitation were more evenly distributed," says Kopp.

"In many areas, we currently have average conditions in the upper storey," said Kopp. In the lower groundwater level, where the water has to seep through slowly, the Low Water Information Service still recorded dozens of measuring points with very low levels or even new lows in mid-December. The State Office for the Environment measures the levels at more than 1800 measuring points in the state.

According to Kopp, the average level in the upper storey is no surprise, as November was unusually wet after the previous drought. However, the continuing downward trend is a longer-term development due to some winters that were too dry overall and generally very dry years such as 2015, 2018 and 2022.

Such a deficit cannot be compensated for by individual rainy or snowy months. "Groundwater is very sluggish and has a long memory," explained Jörg Drewes, Professor of Urban Water Management at the Technical University of Munich, when asked by dpa. A single rain event, even rain that lasts for several weeks, cannot change the situation. The groundwater situation is too tense due to the dry years. "We are currently in the fifth year of an extreme undersupply." Drewes calls for better monitoring of groundwater extraction.

The first consequences of lower groundwater levels can already be seen, explained Drewes: trees dying in some regions of Franconia, trees losing their leaves as early as August or leaves turning brown before autumn. "The trees are stressed and the water stress will also increase," said Drewes. Springs may also dry up at times.

In higher regions, such as the Bavarian Forest or the Allgäu, where the water supply relies heavily on spring discharges, this could affect the drinking water supply. According to the State Office for the Environment, around 4,500 spring catchments and 4,300 wells are used to obtain drinking water in Bavaria. This covers almost 80 percent of demand.

Although the supply is not at risk - after all, water can be transported from further afield - the local supply, as stipulated by the Bavarian municipal code and which is more sustainable, would no longer be guaranteed.