Geokolloqium, Dr. Zhenyu Wang

- GEOSCIENTIFIC COLLOQUIUM -

Assessing Nationwide Groundwater Drought and Its Impact Using Long-Term Groundwater Level Data in Germany

Lecture by Mr. Dr. Zhenyu Wang
Helmholtz-Zentrum für Umweltforschung (UFZ), Halle/Saale

Climate change and human activities are placing increasing pressure on groundwater resources, even in generally water-rich regions such as Germany, posing risks to social-ecological systems. However, the absence of harmonized and quality-controlled groundwater datasets at a national scale has limited our understanding of groundwater drought and its impacts. We present a large-sample groundwater level dataset for Germany including 37,329 wells with metadata such as geographic location, well depth, and elevation, collated from German state water authorities. The records span 1 to 118 years (median length of 32 years), covering the period from October 1900 to May 2025. We perform comprehensive quality control, including dynamic time warping–based outlier detection, homogeneity assessment through level-shift identification, and linear interpolation for short gaps (i.e. ≤ 1 month). Based on this harmonized dataset, we selected 16,516 wells with at least 30-year groundwater level time series to characterize groundwater drought events in terms of their onset, duration, severity, and spatial extent. We further link these identified drought events to a national drought impact database derived from newspaper reports between 2000 and 2024, allowing us to investigate how groundwater droughts translate into observable societal impacts and public awareness. The dataset and associated analyses are intended to provide new insights into the long-term evolution of groundwater conditions in Germany and help coordinate groundwater resources management and policy development at a national level.