A Review of Applied Methods in Europe for Flood Frequency Analysis in a Changing Environment H. Madsen, D. Lawrence, M. Lang, M. Martinkova, T.R Kjeldsen To cite this version: H. Madsen, D. Lawrence, M. Lang, M. Martinkova, T.R Kjeldsen. A Review of Applied Methods in Europe for Flood Frequency Analysis in a Changing Environment. [Research Report] irstea. 2012, pp.189. hal-02597863 HAL Id: hal-02597863 https://hal.inrae.fr/hal-02597863 Submitted on 15 May 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. European Cooperation in Science and Technology www.cost.eu COST ACTION ES0901: European procedures for flood frequency estimation (FloodFreq) Working Group 4: Flood frequency estimation methods and environmental change A REVIEW OF APPLIED METHODS IN EUROPE FOR FLOOD-FREQUENCY ANALYSIS IN A CHANGING ENVIRONMENT Published by the Centre for Ecology & Hydrology on behalf of COST. ISBN: 978-1-906698-36-2 Year of publication 2012 Preface This report has been prepared as part of the COST Action ES0901 “European procedures for flood frequency estimation (FloodFreq)”. The main objective of the FloodFreq COST Action is to undertake a Pan-European comparison and evaluation of methods for flood frequency estimation under the various climatologic and geographic conditions found in Europe, and different levels of data availability. The report has been prepared by Working Group 4 “Flood frequency estimation methods and environmental change”. It provides a review of methods used and results of detection of trends in observations and climate projections of extreme precipitation and flood frequency in Europe. More information about the COST Action ES0901 can be found at the FloodFreq website http://www.cost-floodfreq.eu Review of Applied European Flood Frequency Analysis Methods iii Summary The report presents a review of methods used in Europe for trend analysis, climate change projections and non-stationary analysis of extreme precipitation and flood frequency. In addition, main findings of the analyses are presented, including a comparison of trend analysis results and climate change projections. Existing guidelines in Europe on design flood and design rainfall estimation that incorporate climate change are reviewed. The report concludes with a discussion of research needs on non-stationary frequency analysis for considering the effects of climate change and inclusion in design guidelines. Trend analyses are reported for 21 countries in Europe with results for extreme precipitation, extreme streamflow or both. A large number of national and regional trend studies have been carried out. Most studies are based on statistical methods applied to individual time series of extreme precipitation or extreme streamflow using the non-parametric Mann-Kendall trend test or regression analysis. Some studies have been reported that use field significance or regional consistency tests to analyse trends over larger areas. Some of the studies also include analysis of trend attribution. The studies reviewed indicate that there is some evidence of a general increase in extreme precipitation, whereas there are no clear indications of significant increasing trends at regional or national level of extreme streamflow. For some smaller regions increases in extreme streamflow are reported. Several studies from regions dominated by snowmelt- induced peak flows report decreases in extreme streamflow and earlier spring snowmelt peak flows. Climate change projections have been reported for 14 countries in Europe with results for extreme precipitation, extreme streamflow or both. The review shows various approaches for producing climate projections of extreme precipitation and flood frequency based on alternative climate forcing scenarios, climate projections from available global and regional climate models, methods for statistical downscaling and bias correction, and alternative hydrological models. A large number of the reported studies are based on an ensemble modelling approach that use several climate forcing scenarios and climate model projections in order to address the uncertainty on the projections of extreme precipitation and flood frequency. Some studies also include alternative statistical downscaling and bias correction methods and hydrological modelling approaches. Most studies reviewed indicate an increase in extreme precipitation under a future climate, which is consistent with the observed trend of extreme precipitation. Hydrological projections of peak flows and flood frequency show both positive and negative changes. Large increases in peak flows are reported for some catchments with rainfall- dominated peak flows, whereas a general decrease in flood magnitude and earlier spring floods are reported for catchments with snowmelt-dominated peak flows. The latter is consistent with the observed trends. The review of existing guidelines in Europe on design floods and design rainfalls shows that only few countries explicitly address climate change. These design guidelines are based on climate change adjustment factors to be applied to current design estimates and may depend on design return period and projection horizon. The review indicates a gap between the need for considering climate change impacts in design and actual published guidelines that incorporate climate change in extreme precipitation and flood frequency. Most of the studies reported are based on frequency analysis assuming stationary conditions in a certain time window (typically 30 years) representing current and future climate. There is a need for developing more consistent non-stationary frequency analysis methods that can account for the transient nature of a changing climate Review of Applied European Flood Frequency Analysis Methods v Editors Madsen, H. 1* , Lawrence, D. 2, Lang, M. 3, Martinkova, M. 4, Kjeldsen, T.R. 5 *Corresponding author ([email protected]) 1 DHI, Hørsholm, Denmark 2 Norwegian Water Resources and Energy Directorate, Oslo, Norway 3 Irstea, UR HHLY, Lyon, France 4 T. G. Masaryk Water Research Institute, Prague, Czech Republic 5 Centre for Ecology & Hydrology, Wallingford, UK Contributors Willems, P., KU Leuven, Hydraulics Division, Leuven, Belgium Neykov, N., National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Sofia, Bulgaria Balabanova, S., National Institute of Meteorology and Hydrology, Bulgarian Academy of Sciences, Sofia, Bulgaria Toumazis, A., Dion Toumazis & Associates, Nicosia, Cyprus David, V., Faculty of Civil Engineering, Czech Technical University, Prague, Czech Republic Karsten Arnbjerg-Nielsen, DTU Environment, Technical University of Denmark, Denmark Veijalainen, N., Finnish Environment Institute, Freshwater Centre, Helsinki, Finland Renard, B., Irstea, UR HHLY, Lyon, France Vidal, J.P., Irstea, UR HHLY, Lyon, France Merz, B., Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences, Section Hydrology, Potsdam, Germany Loukas, A., Department of Civil Engineering, University of Thessaly, Pedion Areos, Volos, Greece Vasiliades, L., Department of Civil Engineering, University of Thessaly, Pedion Areos, Volos, Greece Pistocchi, A., GECOsistema srl – Cesena, Italy and Regione Emilia Romagna – Autorità dei Bacini Regionali Romagnoli, Forlì, Italy Kriau čiūnien ė, J., Lithuanian Energy Institute, Lithuania Sarauskiene, D., Lithuanian Energy Institute, Lithuania Wilson, D., Norwegian Water Resources and Energy Directorate, Oslo, Norway Strupczewski, W., Department of Hydrology and Hydrodynamics, Institute of Geophysics, Polish Academy of Sciences, Poland Romanowicz, R., Department of Hydrology and Hydrodynamics, Institute of Geophysics, Polish Academy of Sciences, Poland Review of Applied European Flood Frequency Analysis Methods vii Osuch, M., Department of Hydrology and Hydrodynamics, Institute of Geophysics, Polish Academy of Sciences, Poland Hlav čová, K., Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovakia Szolgay, J., Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovakia Kohnová, S., Department of Land and Water Resources Management, Faculty of Civil Engineering, Slovak University of Technology, Bratislava, Slovakia Kobold, M., Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia Šraj, M., Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia Brilly, M., Faculty of Civil and Geodetic Engineering, University of Ljubljana, Ljubljana, Slovenia Mediero, L., Department of Civil Engineering, Hydraulic and Energy Engineering, Technical University of Madrid, Madrid, Spain Garrote, L., Department of Civil Engineering, Hydraulic and Energy Engineering, Technical University of Madrid, Madrid, Spain Hernebring, C., DHI, Göteborg, Sweden Olsson, J., Swedish Meteorological and Hydrological Institute, Norrköping, Sweden Yücel, I., Middle East Technical University, Civil Engineering Department, Ankara,