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Hazard information for extreme flood events on the rivers Aare and Rhine (EXAR)


The main goal of the EXAR project is to create a consistent data set in order to assess the hazard for riparian infrastructure caused by extreme flood events on the rivers Aare and Rhine. In several pre-studies, relevant information and data has been collected, and a methodology approach has been suggested.


Goals of the main study

  • Hazard assessment of extreme flood events (frequencies ranging from 10-3 up to 10-7) on the river Aare by using consistent hazard scenarios.
  • The common data set will contain information on water levels, flow velocities, morphological changes of the riverbed, and event probabilities.
  • The assessment will also involve hazard processes connected to flood events to evaluate interactions. The phenomena considered will be i.e. erosion, fluvial bedload transport, channel migration, landslides, blockages by large wood, and failure of dams.

Project organisation

The individual tasks of the project are attributed to four work packages (WP) in total, which are executed by different institutions and project partners:

  • WP1 Synthesis: WSL, PSI
  • WP2 Precipitation/discharge scenarios: University of Zurich, University of Berne, ETH Zurich, EPFL, Grenoble Institute of Technology
  • WP3 Hydraulics & morphology, WP4 Hydraulic infrastructure: ARGE GEOTEST-HZP-IUB with VAW-ETH and IM Maggia Engineering AG

Role of WSL

In collaboration with Paul Scherrer Institute PSI (Dr. Vinh Dang), WSL is responsible for AP1 „Coordination / Synthesis“ and will take charge of the following tasks:

  • Coordination of the work packages and work flows (interfaces)
  • Event tree analysis of the total system and of individual assessment sites
  • Formulation of scenarios of extreme flood events (workshops with expert group)
  • Handling of uncertainties and their propagation
  • Documentation / synthesis of results (reports)


  • Start of main study: January 2016
  • Phase A: Pre-analysis (January 2016 - March 2017)
  • Phase B: Analysis and synthesis (April 2017 - December 2018)