Originally published as: Merz, B., Nguyen, D., Apel, H., Gerlitz, L., Schröter, K., Steirou, E.-S., Vorogushyn, S. (2018): Spatial coherence of flood-rich and flood-poor periods across Germany. - Journal of Hydrology, 559, pp. 813—826. DOI: http://doi.org/10.1016/j.jhydrol.2018.02.082 Manuscript 26043, Journal of Hydrology Spatial coherence of flood-rich and flood-poor periods across Germany 1 2 Authors: 3 Bruno Merz1,2, Nguyen Viet Dung1, Heiko Apel1, Lars Gerlitz1, Kai Schröter1, Eva 4 Steirou1, Sergiy Vorogushyn1 5 6 1Section Hydrology, GFZ German Research Center for Geosciences, 14473 Potsdam, 7 Germany 8 2Institute of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, 9 Germany 10 11 Corresponding author: Bruno Merz,
[email protected] 12 13 Keywords: flood timing, spatial coherence, flood regimes, climate variability, catchment 14 wetness 15 Abstract 16 Despite its societal relevance, the question whether fluctuations in flood occurrence or 17 magnitude are coherent in space has hardly been addressed in quantitative terms. We 18 investigate this question for Germany by analysing fluctuations in annual maximum series 19 (AMS) values at 68 discharge gauges for the common time period 1932-2005. We find 20 remarkable spatial coherence across Germany given its different flood regimes. For 21 example, there is a tendency that flood-rich/-poor years in sub-catchments of the Rhine 22 basin, which are dominated by winter floods, coincide with flood-rich/-poor years in the 23 southern sub-catchments of the Danube basin, which have their dominant flood season in 24 summer. Our findings indicate that coherence is caused rather by persistence in catchment 25 wetness than by persistent periods of higher/lower event precipitation.