https://doi.org/10.5194/hess-2019-312 Preprint. Discussion started: 9 July 2019 c Author(s) 2019. CC BY 4.0 License. The role of flood wave superposition for the severity of large floods Björn Guse1, Bruno Merz1,2, Luzie Wietzke1, Sophie Ullrich1, Alberto Viglione3,4, and Sergiy Vorogushyn1 1GFZ German Research Centre for Geosciences, Hydrology Section, Potsdam, Germany 2University of Potsdam, Institute for Environmental Sciences and Geography, Potsdam, Germany 3Vienna University of Technology, Institute of Hydraulic Engineering and Water Resources Management, Vienna, Austria 4Politecnico di Torino, Department of Environment, Land and Infrastructure Engineering (DIATI), Torino, Italy Correspondence: Björn Guse (
[email protected]) Abstract. The severity of floods is shaped not only by event and catchment specific characteristics but also depends on river network configuration. At the confluence of relevant tributaries to the main river, flood event characteristics may change de- pending on magnitude and temporal matching of flood waves. This superposition of flood waves may potentially increase flood severity. However, this aspect is up to now not analysed for a large data set. 5 To fill this gap, the role of flood wave superposition in determining flood severity is investigated. A novel methodological approach to analyse flood wave superposition is presented and applied to mean daily discharge data of 37 triple points from the four large river basins in Germany and Austria (Elbe, Danube, Rhine and Weser). A triple point consists of the three gauges at the tributary as well as upstream and downstream of the confluence to the main river. At the triple points, differences and similarities in flood characteristics are jointly analysed in terms of temporal matching and magnitudes of flood peaks.