Increasing volatility of reconstructed Morava River warm-season flow, Czech Republic

• Published in: Journal of hydrology. Regional studies 2023-12, Vol.50, p.101534, Article 101534
• Main Authors: Torbenson, Max C.A., Brázdil, Rudolf, Stagge, James H., Esper, Jan, Büntgen, Ulf, Vizina, Adam, Hanel, Martin, Rakovec, Oldrich, Fischer, Milan, Urban, Otmar, Treml, Václav, Reinig, Frederick, Martinez del Castillo, Edurne, Rybníček, Michal, Kolář, Tomáš, Trnka, Miroslav
• Format: Article
• Language: English
• Subjects: Baseflow; Extremes; Morava; Reconstruction; Tree rings
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2023.101534

The Morava River basin, Czech Republic, Danube Basin, Central Europe. Hydrological summer extremes represent a prominent natural hazard in Central Europe. River low flows constrain transport and water supply for agriculture, industry and society, and flood events are known to cause material damage and human loss. However, understanding changes in the frequency and magnitude of hydrological extremes is associated with great uncertainty due to the limited number of gauge observations. Here, we compile a tree-ring network to reconstruct the July–September baseflow variability of the Morava River from 1745 to 2018 CE. An ensemble of reconstructions was produced to assess the impact of calibration period length and trend on the long-term mean of reconstruction estimates. The final estimates represent the first baseflow reconstruction based on tree rings from the European continent. Simulated flows and historical documentation provide quantitative and qualitative validation of estimates prior to the 20th century. The reconstructions indicate an increased variability of warm-season flow during the past 100 years, with the most extreme high and low flows occurring after the start of instrumental observations. When analyzing the entire reconstruction, the negative trend in baseflow displayed by gauges across the basin after 1960 is not unprecedented. We conjecture that even lower flows could likely occur in the future considering that pre-instrumental trends were not primarily driven by rising temperature (and the evaporative demand) in contrast to the recent trends. •Tree rings are used to reconstruct Morava River baseflow since 1745 CE.•Hydrological model output help validate pre-calibration estimates.•Negative trends in baseflow have reoccurred during the past 250 years.•Climate change may amplify extreme low flows beyond the natural variability.