TEMPORAL AND SPATIAL EVOLUTION OF EXTREME EVENTS

Jacco Groeneweg, Sofia Caires, Kathryn Roscoe

Abstract


In this study two statistical methods for computing time- and space-evolving extreme events are implemented and assessed. The implementation and application of the methods are carried out with a view towards the safety assessment of water defences. With this type of application in mind, the methods are used to produce time- and space-varying extreme wind fields, which are needed to force wave and hydrodynamic models. Furthermore, the results of the two methods are compared and effects of the choice of distribution, threshold and reference location on
the resulting wind fields are assessed. Although the wind fields produced by the methods show more erratic spatial variations, due to the associated uncertainties, than those of the observed wind fields, they seem realistic and can in principle be used to drive wave and hydrodynamic models. However, an assessment of the results of these statistical methods in terms of the underlying physics still needs to be carried out and is part of future work.

Keywords


extreme value analysis; extreme events; wind velocity; non-stationarity; spatial variation

References


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Caires, S., 2009: Extreme wind statistics for the Hydraulic Boundary Conditions for the Dutch primary water defences. SBW-Belastingen: Phase 2 of subproject 'Wind modelling'. Deltares Report 1200264-005.

Caires, S., L. de Haan and R. L. Smith. 2011. On the determination of the temporal and spatial evolution of extreme events. Deltares report 1202120-001-HYE-004 (for Rijkswaterstaat, Centre for Water Management).

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