Author(s): Emiel Moerman; Reimer De Graaff; Joao De Lima Rego; Deepak Vatvani
Keywords: Extreme value analysis; Typhoon; Modeling; Delft3D; Pearl River
Abstract: Extreme events such as tropical storms and typhoons are often the determining factor for the extreme values of wind, wave and water level conditions. The stochastic behavior of typhoons and tropical storms, however, lead to uncertainty in the standard extreme value analysis of these parameters, because a slight variation of the typhoon track, propagation speed or wind speed intensity can have a significant impact on the local extreme hydrodynamic conditions. To determine the significance of the stochastic behavior of typhoons a numerical model assessment (Delft3D) has been performed comparing standard extreme value analysis values of measured water levels (e. g. values of 1/10, 1/50, and 1/100 year return periods) against model results of both historic and artificial typhoons. By quantifying the potential impact of artificial typhoons the uncertainties in the extreme water level values in typhoon prone areas are better assessed. From the assessment it shows that the total water level can be 10%higher for the modeled artificial typhoon and can exceed the once per 100 year extreme total water level estimates. They are however generally within the 95%confidence interval of the estimate. Although the results are within the confidence intervals of the extreme value analysis it is concluded that the modeling of artificial typhoons could be a valuable addition to the standard extreme value analyses and scenario based modeling commonly performed.