481 / 2024-04-23 00:24:26

A Copula-joined wind-surge risk analysis: a case study of Quinhon coast, Vietnam

joint probability distribution,,Copula theory,Quinhon coast,storm wind,storm surge,wind-surge risk

Subtheme 8: Estuarine and Coastal Engineering > Topic 1: Estuarine Coastal Evolution and Dynamic Mechanisms

Coastal areas are vulnerable to extreme weather events such as storms, storm induced elements (e.g. storm wind and storm surge) are interdependent. Neglecting the correlation of the key elements could cause a relative difference in structure design and coastal risk management. Considering the mutual dependency between these variables, establishing a joint probability distributions model for storm risk analysis is an urgent and challenging task.

 The Copula theory has found more and more applications in coastal engineering in recent years, which provides increased flexibility in modelling the joint probabilities of ocean hydrodynamic factors. This study employs a two-dimensional copula function which is sensitive to correlated extreme effects between storm wind and storm surge, to investigate storm risk along Quinhon coast, Vietnam. Firstly, the best track typhoon data from the meteorological administration is used to extract the storm wind, and to simulate storm surge. Then, the marginal distribution is defined to measure how well the model explains the data. Finally, four Archimedean families of copulas (T, Clayton, Frank and Gumbel) are applied in this study to describe the relationship between storm surge and storm wind variables.

Results show that the Frank-copula model with log-normal distribution marginal is the optimistic model for predicting the joint effect of storm wind and storm surge. Quinhon city may expect possible extreme storms with intensity of 160km/h and surge height of 2.87m, in 50- year return period. Study also provides reliable and realistic design guidelines for coastal engineering activities.