Innovative analysis of half-century (1973–2022) spatial-temporal variability and trends in climate indices across the Czech Republic

Understanding variability and trends in river-basin climate is critical for water-resources management, food security, and ecosystem resilience in the era of climate change. This study assesses the spatio-temporal variability and trends of climate conditions across the Czech Republic using observations from nine stations over half a century (1973–2022). We apply two aridity metrics, the UNEP and De Martonne indices, computed from precipitation and potential evapotranspiration (UNEP) and from precipitation and temperature (De Martonne). Climate variability is evaluated with the Innovative Trend Analysis (ITA) together with tests from the Mann–Kendall family. Results show values concentrated in the 40th–60th percentiles for both indices, indicating predominantly moderate aridity, especially in the central region extending toward the southwest (Upper and Lower Vltava, Berounka, Dyje, and Upper and Middle Elbe basins). During spring, the UNEP and De Martonne indices indicate semi-arid (0.2–0.5) and Mediterranean (20–24) conditions, respectively, in the Dyje and Lower Vltava basins. By contrast, the eastern sector such as Upper Oder and parts of the Morava and Váh tributaries shows a transition to wetter conditions, with UNEP values of 1.61–3.61 and De Martonne values of 94.94–238.21, indicating flood-prone areas. We also find a consistent increase in dryness in the typically wet Upper Oder basin, except in summer, whereas a dry-climate area in Lower Vltava exhibits significant decreasing aridity across all four seasons and annually. Abrupt shifts in aridity are detected for the De Martonne index in winter 2012 at Přibyslav and in summer 1989 at Praha Ruzyně. Overall, the study provides critical insights into the variability and trends of climate conditions across the Czech Republic's nine major river basins, supporting adaptive water-resources planning, food security, and efforts to mitigate cascading impacts of global change and the biodiversity crisis.