SPATIAL ASSESSMENT OF EXTREME SIGNIFICANT WAVES HEIGHTS IN THE GULF OF LIONS

Romain Chailan,Anne Laurent,Gwladys Toulemonde,Florence Sevault,Heloïse Michaud,Frederic Bouchette

doi:10.9753/icce.v34.management.17

Abstract

In the analysis of coastal hazards, the features of extreme waves are determining information to question the impact of storms to the coast. The spatial behaviour of extreme waves is even more valuable especially since it is sparsely provided. Regarding recent applications in other contexts, a kind of statistical models called max-stable processes is relevant for modelling spatial extreme events. Max-stable processes are extensions of the well-known Generalised Extreme Value (GEV) distribution. Unlike univariate approaches, max-stable processes consider spatial dependence of a phenomenon. Such a modelling also overtakes a standard multivariate approach by providing information continuously over the area studied, even where no observation is available. Relying on such a stochastic modelling, the aim of this study is to discuss the extreme waves hazards in the Gulf of Lions, focusing on their spatial behaviour.

Highlights

Coastal hazards are physical phenomena of many concerns
We focus our study on the extreme waves in the Gulf of Lions by stochastically modelling the extreme significant wave heights (Hs)
From the best fitted model we can seamlessly produce stochastic simulations of monthly maxima processes. These processes implicitly take into account the modelled dependence structure and the spatial Generalised Extreme Value (GEV) parameters via a back-transformation to original scale

Summary

Introduction

Coastal hazards are physical phenomena of many concerns. Infrastructures, environment, activities, population. Max-stable processes overtake them by bringing information continuously over the area studied, even where no observation is available The performance of such modelling has been shown in applications in other environmental contexts, like for instance the study of heavy snow events in Blanchet and Davison (2011) or heatwaves in Davison and Gholamrezaee (2011). The aim of this study is not to debate the use of other extreme value analyses but rather bring to the front the benefit of considering the dependence structure of extreme In this sense we present the use of max-stable models to 1) map extreme return levels of wave features and 2) provide accurate joint probabilities.

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Results

Conclusion