Regional Frequency Analysis Of Significant Wave Heights Based On L-moments

The determination of the significant wave heights should be considered while the engineers deal with some coastal engineering problems such as erosion control, scour protection, foundation, environmental and marine structures. The extreme wave heights play an important role in the design of the marine structures in both safety and economics. The uncertainty analysis is conducted in the process of designing the extreme wave height by different stochastic analysis model and parameter estimation method. An regional frequency analysis based on L-moments is introduced to estimate the extreme wave height.L-moments are linear combinations of order statistics, which are robust to outliers and virtually unbiased for small samples, making them suitable for frequency analysis, including identification of distribution and parameter estimation. It is introduced to the coastal engineering field. A Monte-Carlo simulation is conducted to analyze and compare the parameter estimation performance of four estimation methods. L–moments is unbiased and has the smallest variations in small sample among the four methods.The theoretical background and scope of various common stochastic models are discussed in the second chapter. L-moments is applied to estimate the extreme wave heights using the data of California coastline from NDBC and historical field measure data from Qinghuangdao port. The difference between two models (Peak over threshold and Annual Maximum) are discussed.Enough historical information is of vital importance to the accuracy of the extreme wave height design. However, in practice, the record length is not long enough to give assuring estimation. Regional frequency is a way using the nearby information to add the record length of the interest site. Significant wave height data of 7 California coastline stations are used to perform the regional frequency analysis, including discordancy measure, heterogeneity measure, goodness-of-fit measure and regional quantile estimation. The study shows regional frequency can be used to give reliable quantile estimation using available scrutinized neighborhood historical data...