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Joint Probability Analysis of Extreme Waves and Water Levels at a Typhoon Invaded Coastal Region

Author(s): C. W. Li; Y. Song

Linked Author(s): Chi Wai Li, Yuntian Song

Keywords: Waves; Surges; Typhoons; Joint probability

Abstract: The coastal areas of Hong Kong are always subjected to the invasion of typhoons in summer. The typhoon-generated waves and surges are the extreme events that should be considered in setting the design criteria of coastal structures. As there is usually a time lag between the occurrence of the maximum waves and the occurrence of maximum water level (mainly due to surges), joint probability analysis of the joint events of wind waves and water levels is important. This work reports the joint probability analysis of wind waves and surges in the coastal waters of Hong Kong. Criteria of selection of extreme joint events are first obtained by the analysis of available field data. Fifty years of synthetic data of annual extreme wind waves and surges are then generated by means of a 3rd generation wind wave model and a flow model, with the tide level data produced by harmonic analysis. The bivariate logistic model is used in the joint probability analysis. To demonstrate the application of the results to coastal engineering design, various environmental loading functions due to waves and water level are selected. And the failure probabilities are calculated directly using the joint density function of waves and water level. The results show that the failure probabilities are not sensitive to the common design functions for coastal and offshore structures, and the simplest case of failure probability for total water level can be used as a close approximation.


Year: 2005

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