Blöschl et al. (2020) Current European flood-rich period exceptional compared with past 500 years

Identification

• Journal: Nature
• Year: 2020
• Date: 2020-07-22
• Authors: Günter Blöschl, Andrea Kiss, Alberto Viglione, Mariano Barriendos i Vallvé, O. Böhm, Rudolf Brázdil, Denis Cœur, Gaston R. Demarée, María Carmen Llasat, Neil Macdonald, Dag Retsö, Lars A. Roald, Petra Schmocker-Fackel, Inés Amorim, Monika Bělínová, Gerardo Benito, Chiara Bertolin, Dario Camuffo, Daniel Cornel, Radosław Doktor, Líbor Elleder, Silvia Enzi, Joao Carlos García, Rüdiger Glaser, Julia Hall, Klaus Haslinger, Michael Hofstätter, Jürgen Komma, Danuta Limanówka, David Lun, А. В. Панин, Juraj Párajka, Hrvoje Petrić, F. S. Rodrigo, Christian Röhr, Johannes Schönbein, Lothar Schulte, Luís Pedro Silva, W.H.J. Toonen, Peter Valent, Jürgen Waser, Oliver Wetter
• DOI: 10.1038/s41586-020-2478-3

Research Groups

• Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology, Vienna, Austria
• Department of Environment, Land and Infrastructure Engineering (DIATI), Politecnico di Torino, Turin, Italy
• Department of History and Archaeology, University of Barcelona, Barcelona, Spain
• Institute of Geography, University of Augsburg, Augsburg, Germany
• Institute of Geography, Masaryk University, Brno, Czech Republic
• Global Change Research Institute, Czech Academy of Sciences, Brno, Czech Republic
• Royal Meteorological Institute of Belgium, Brussels, Belgium
• Department of Applied Physics, University of Barcelona, Barcelona, Spain
• Department of Geography and Planning, School of Environmental Sciences, University of Liverpool, Liverpool, UK
• Department of Economic History and International Relations, Stockholm University, Stockholm, Sweden
• Norwegian Water Resources and Energy Directorate, Oslo, Norway
• Hydrology Division, Federal Office for the Environment (FOEN), Bern, Switzerland
• Department of History, Political and International Studies, University of Porto, Porto, Portugal
• Department of Geology, National Museum of Natural Sciences, CSIC, Madrid, Spain
• Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, Trondheim, Norway
• National Research Council, Institute of Atmospheric Sciences and Climate, Padua, Italy
• VRVis Research Center for Virtual Reality and Visualization, Vienna, Austria
• Centre for Flood and Drought Modelling, Institute of Meteorology and Water Management, National Research Institute, Warsaw, Poland
• Czech Hydrometeorological Institute, Prague, Czech Republic
• Kleio Studio Associate Research Company, Padua, Italy
• Faculty of Arts, University of Porto, Porto, Portugal
• Department of Physical Geography, University of Freiburg, Freiburg, Germany
• Climate Research Department, Central Institute of Meteorology and Geodynamics (ZAMG), Vienna, Austria
• Centre for Poland’s Climate Monitoring, Institute of Meteorology and Water Management, National Research Institute, Cracow, Poland
• Institute of Geography, Russian Academy of Sciences, Moscow, Russia
• Lomonosov Moscow State University, Moscow, Russia
• Department of History, Faculty of Humanities and Social Sciences, University of Zagreb, Zagreb, Croatia
• Department of Chemistry and Physics, University of Almería, Almería, Spain
• Department of Economic, Social and Environmental History, Institute of History, University of Bern, Bern, Switzerland
• Department of Geography, University of Barcelona, Barcelona, Spain
• Transdisciplinary Research Centre Culture, Space and Memory, University of Porto, Porto, Portugal
• Department of Physical Geography, Utrecht University, Utrecht, The Netherlands
• Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Bratislava, Slovakia
• ACTHYS-Diffusion, Grenoble, France

Short Summary

This study analyzes over 100 high-resolution historical flood series across Europe to compare recent flood activity with the past 500 years, revealing that the period 1990-2016 was an exceptionally flood-rich period, distinct from previous ones due to its spatial extent, warmer temperatures, and altered flood seasonality.

Objective

• To determine if recent decades constitute an exceptional flood-rich period in Europe compared to the past 500 years, by identifying and characterizing historical flood-rich periods and comparing their extent, associated air temperatures, and flood seasonality.

Study Configuration

• Spatial Scale: Europe, covering 103 river reaches across all major regions, with an interpolated voxel size of 41 km × 48 km. The total land area examined was 3.9 × 10^6 km^2.
• Temporal Scale: 500 years (1500–2016), with sub-annual resolution for flood series and an interpolated temporal voxel size of 4 years.

Methodology and Data

• Models used:
  • Thin plate spline regression algorithm (fastTps function in R package fields) for spatial and temporal interpolation of flood intensities.
  • An algorithm to connect neighboring voxels exceeding an intensity threshold to identify contiguous flood-rich periods.
• Data sources:
  • A new database of 103 high-resolution (sub-annual) historical flood series for Europe (1500–2016), compiled from documentary evidence (chronicles, annals, administrative/legal records, newspapers, private/official correspondence). Flood events were classified into a three-scaled intensity index (notable, great, extraordinary).
  • A 500-year central European air temperature reconstruction (Dobrovolný et al., 2010), derived from documentary evidence and instrumental records, used to assess temperature anomalies.

Main Results

• The period 1990–2016 was identified as one of the most flood-rich periods in Europe over the past 500 years.
• This recent flood-rich period (Period IX) is exceptional compared to previous periods in terms of its spatial extent, associated air temperatures, and flood seasonality.
• Nine flood-rich periods were identified, with the most significant being 1560–1580, 1760–1800, 1840–1870, and 1990–2016.
• The recent flood-rich period (1990–2016) was the second largest in spatial extent (1.77 × 10^6 km^2) and the third largest in spatio-temporal extent (18.7 × 10^6 km^2 yr).
• Most previous flood-rich periods occurred during cooler-than-usual phases, with average central European temperatures approximately 0.3 °C lower than interflood periods.
• In contrast, the current flood-rich period (1990–2016) was significantly warmer, averaging about 1.4 °C higher than the preceding interflood period across all regions.
• Flood seasonality has become more pronounced in the recent period:
  • In central Europe, summer floods increased from 41–42% in previous periods to 55% in 1990–2016.
  • In southern Europe, autumn floods increased from 41–43% to 54% in 1990–2016.
  • In western Europe, winter floods increased from 46–49% to 55% in 1990–2016.
• The recent flood-rich period was preceded by a 90-year "disaster gap" with fewer floods in most of Europe.

Contributions

• Developed the most comprehensive and high-resolution dataset of historical flood series for Europe spanning 500 years, enabling unprecedented large-scale analysis of flood-rich periods.
• Provided clear, continent-wide evidence of a relationship between flood-rich periods and air temperatures, a finding previously unclear at the European scale.
• Identified the exceptional nature of the current flood-rich period (1990–2016) in terms of its spatial extent, warmer temperatures, and altered seasonality, highlighting the need for updated flood-risk assessment and management strategies.
• Demonstrated the significant potential of documentary evidence to extend the temporal window for flood-risk analysis, offering a more complete guide to future flood changes.
• Explained the potential reason for public and flood manager surprise regarding recent flood severity, attributing it to a preceding 90-year "disaster gap."

Funding

• ERC Advanced Grant ‘FloodChange’ project (no. 291152)
• Horizon 2020 ETN ‘System Risk’ project (no. 676027)
• DFG project FOR 2416
• FWF projects I 3174 and W1219-N22
• Spanish Agency of Science and FEDER/UE projects CGL2016-75475/R, CGL2017-86839-C3-1-R, CGL2016-75996-R and CTM2017-83655-C2-2-R
• ICREA Academia programme
• Project CZ.02.1.01/0.0/0.0/16_019/0000797, Ministry of Education, Youth and Sports of the Czech Republic

Citation

@article{Blöschl2020Current,
  author = {Blöschl, Günter and Kiss, Andrea and Viglione, Alberto and Vallvé, Mariano Barriendos i and Böhm, O. and Brázdil, Rudolf and Cœur, Denis and Demarée, Gaston R. and Llasat, María Carmen and Macdonald, Neil and Retsö, Dag and Roald, Lars A. and Schmocker-Fackel, Petra and Amorim, Inés and Bělínová, Monika and Benito, Gerardo and Bertolin, Chiara and Camuffo, Dario and Cornel, Daniel and Doktor, Radosław and Elleder, Líbor and Enzi, Silvia and García, Joao Carlos and Glaser, Rüdiger and Hall, Julia and Haslinger, Klaus and Hofstätter, Michael and Komma, Jürgen and Limanówka, Danuta and Lun, David and Панин, А. В. and Párajka, Juraj and Petrić, Hrvoje and Rodrigo, F. S. and Röhr, Christian and Schönbein, Johannes and Schulte, Lothar and Silva, Luís Pedro and Toonen, W.H.J. and Valent, Peter and Waser, Jürgen and Wetter, Oliver},
  title = {Current European flood-rich period exceptional compared with past 500 years},
  journal = {Nature},
  year = {2020},
  doi = {10.1038/s41586-020-2478-3},
  url = {https://doi.org/10.1038/s41586-020-2478-3}
}