Spatial extreme value analysis of significant wave heights along the French coast

Thomas Bulteau (1) , Sophie Lecacheux (1) , Alexandre Nicolae Lerma (1) , François Paris (1)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)

Extreme value analysis is of paramount importance in coastal engineering, for structure design as well as hazard mapping. The significant wave height (SWH) is the parameter generally used to characterize the intensity of sea states. Extreme value analysis on SWH requires historical buoy records of sufficient length and good quality. However, such observation datasets are often inexistent and numerical hindcasts of waves are used instead. One advantage of using such model outputs is that an extreme value analysis over a large spatial area is possible, enabling one to highlight spatial variations on extremes. In this study, we aim at studying spatial variations of extreme values of SWH along the French coast for current climate. We use wave data from the BoBWA-10kH database (Charles et al, 2012) which is a numerical wave hindcast for the whole West coast, performed with the third generation wave model WWIII (Tolman, 2009) and forced with ERA-40 reanalysis winds. It covers the period 1958-2002 and has a spatial resolution of 10km. Extreme value analysis is performed for about 40 points regularly distributed along the coast. The Peaks-Over-Threshold method is used and a Generalized Pareto Distribution is fitted to the data. Spatial variations along the coast for several return values of SWH (10-year, 50-year, 100-year) are presented and discussed.

Mots clés: probability; extreme wave heights; return period; GPD

Domaines: Applications [stat.AP]; Sciences de la Terre

Thomas Bulteau, Sophie Lecacheux, Alexandre Nicolae Lerma, François Paris. Spatial extreme value analysis of significant wave heights along the French coast. International short conference on advances in extreme value analysis and application to natural hazards : EVAN2013, Sep 2013, Siegen, Germany. ⟨hal-00857627⟩