Analysis of wave height return period based on joint probability analysis of different typhoon disaster factors

In the past, the application of composite extreme value distribution to calculate wave height design value only focused on typhoon frequency, ignoring the influence of other disaster causing factors. Additionally, in the process of calculating the return period, existing multivariate return period calculation methods commonly led to overestimation or underestimation of marine engineering design standards. In order to comprehensively reflect the influence of different typhoon disaster factors on the wave height design value of the multi-year return period, this study has constructed three types of multidimensional composite extreme value distribution models. The first and second models consider the effect of typhoon frequency and typhoon intensity separately, although the third model considers both parameters. The present investigation further proposes the calculation formula for the return period applicable to different sampling methods, using the hazard probability in the design life of marine engineering as the control condition. Because there exists the significant impact of sample selection on the estimation of the return period for wave height design value. Finally, Kendall return period is introduced to make up for the shortcomings of joint return period and co-occurrence return period in overestimating or underestimating dangerous areas. The case analysis of the South China Sea demonstrates that the return period should be converted when calculating the wave height design value. The first model of composite distribution results in the maximum wave height design value, the second one leads to the minimum design value, and the third one are located between the aforementioned two models. Meanwhile, the design value of Kendall's return period falls between the joint return period and the co-occurrence return period, which causes a more reasonable wave height design value.