Short Biography:

- Born in April 1952

- Civil engineer of Ecole polytechnique fédérale de Lausanne, Switzerland (1976)

- MS in Hydrology & Water resources, Colorado State University, USA (1982)

- PhD in Hydrology & Water resources, Princeton University, USA (1986)

-           1986-2002: Swiss federal railways, Division Energy

  In charge of dam safety, hydrology, hydrometry, water resources and related issues, energy planning, water right concessions

- 2002 Stucky Ltd

  Project manager, expert (hydrology, dam safety, energy planning, water resources, flood evaluation, due diligences)

- since June 2009, ICOLD, Technical Committee on Dams and Floods

Abstract:

The design of a flood evacuation system of a dam usually relies on two criteria:

- the dam must master a flood of a given return period (design flood) without damages

- it must also resist an extreme flood (check flood, usually a PMF), with at most limited damages.

The classical approach for determining the magnitude of a flood concentrates on purely hydrological considerations. Flood frequency analysis (for the design flood) and deterministic analysis (for the PMF) are the most common applied methods.

The most widely applied criteria for selecting adequate flood return periods in more than thirty countries around the world will be presented. These criteria are in general based on either one of two lines:

- the risks linked to a failure of the structures (dam height, reservoir volume, etc.)

- or the potential damages downstream of the reservoir in case of a serious dam problem.

A new trend in flood hydrology will also be sketched, consisting in integrating reservoir operation and hydrology in the reflections aimed at determining the "right" magnitude of the extreme event. Unlike the classical methods addressing only the hydrological process per se, this new approach sets on a stochastic generation encompassing the causes and the effects of the flood. The result of the analysis is not an inflow hydrograph as usual, but the probability distribution function of a key design constraint (maximum water level, maximum released outflow, rapidity of the outflow variation, etc.).

Paper