ORIGINAL ARTICLE
Satellite-based Determination and Analysis of Groundwater Drought Index Time Series in Europe
1
Department of Geoinformation and Cartography, University of Warmia and Mazury in Olsztyn, Poland
Submission date: 2025-07-09
Final revision date: 2025-10-17
Acceptance date: 2026-04-08
Online publication date: 2026-04-15
Publication date: 2026-04-15
Corresponding author
Monika Biryło
Department og Geoinformation and Cartography, University of Warmia and Mazury in Olsztyn, Poland
Department og Geoinformation and Cartography, University of Warmia and Mazury in Olsztyn, Poland
Civil and Environmental Engineering Reports 2026;36(1):159-178
KEYWORDS
TOPICS
ABSTRACT
According to the European Drought Observatory, more than 30% of Europe has been under drought warning conditions since 2018. This situation is primarily attributed to a persistent decline in groundwater resources. Satellite observations confirm that groundwater levels have not been recovering; in some regions, they continue to decrease. Data from the Global Gravity-based Groundwater Product (G3P) project, which employs satellite gravimetric measurements, enable continuous monitoring of groundwater variations and provide a globally consistent map of gravity field changes, directly converted into terrestrial water storage variations, of which groundwater is a key component.
This study aims to estimate groundwater storage using models from the Global Gravity-based Groundwater Product derived from the Gravity Recovery and Climate Experiment (GRACE) mission. Based on the estimated groundwater storage, the Groundwater Drought Index (GDI) was calculated for climatically homogeneous regions in Europe, as defined by the Köppen–Geiger climate classification. To enhance the analysis of temporal GDI variations, the index time series was decomposed using the Fourier transform, allowing for the identification of dominant periodic components and long-term trends.
Time series decomposition revealed a strong seasonal dependence of groundwater. The highest levels are observed in spring and the lowest in autumn. A positive trend of groundwater resources was found for Scandinavia region (0.0006 cm). In other areas, a decline in groundwater resources is noticeable since 2016, with the biggest decline in areas of Central and Eastern Europe (-0.0011 cm) and Balkan Peninsula (0.0006 cm).
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| eISSN: | 2450-8594 |
| ISSN: | 2080-5187 |
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