How is water storage changing in Germany?

A summer time series from 2002 to 2026 

Since 2002, the GRACE satellites have been monitoring terrestrial water storage worldwide, including in Germany. The maps of Germany shown here illustrate not only year-on-year variations, but also a clear negative trend towards a water deficit in both the temporal and spatial pattern.

Colour coding and meaning
The colour scale, ranging from red through white to blue, shows a decrease or increase in terrestrial water storage in June compared with the reference period (2002–2020), measured in millimetres. The darker the red, the greater the decrease in stored water. Blue areas, by contrast, indicate a water surplus. Whitish areas roughly correspond to conditions during the reference period.

In the early years of the time series, positive anomalies in water storage (shown in blue) indicate high water availability.

This is particularly evident in 2002, as shown by the large area of blue. The months of June in 2010 and 2013 also stand out due to increased water storage, partly due to exceptional rainfall during these periods.

From around 2015 onwards, the situation began to change significantly. The maps show a decline in terrestrial water storage. This trend became particularly noticeable from 2018 onwards, with Germany predominantly coloured orange to dark red for several consecutive years. This illustrates the pronounced period of drought and associated water shortage. According to data from the GRACE satellite missions, the long-term trend of water shortage had already become apparent by 2015. June 2023 was the driest June on record to date. 2024 represents a slight interruption to this drought trend. Although higher rainfall alleviated the drought to some extent, it did not lead to a permanent return to the high water storage levels of previous years.

Geographical distribution
In addition to the temporal trend, spatial variations are also evident within Germany. The changes are not equally pronounced everywhere. In some years, certain regions appear more intensely blue or red than others. This demonstrates that terrestrial water storage is influenced by both general precipitation trends and regional hydrological conditions.

Conclusion

Overall, the series of maps shows a clear shift from a water surplus to a persistent water deficit. Although some years with high precipitation, such as 2002, 2010, 2013 and 2024, show signs of recovery and a slight positive trend, negative deviations have become increasingly prevalent since around 2015. A pronounced water deficit has been evident since 2018. Thus, the series of maps illustrates that Germany’s terrestrial water storage has decreased significantly over a prolonged period. However, it also demonstrates that years with high precipitation can result in short-term recovery.

Text and maps: Eva Boergens, GFZ