ASSESSMENT OF COASTAL EROSION USING RELIABILITY DESIGN METHOD

The purpose of this study is to assess beach erosion for long-term numerical simulation considering erosion and accretion using Xbeach model. Stationary mode and surfbeat mode were used to simulate beach erosion and accretion, respectively. The stationary mode does not consider the influence of infra-gravity waves and is used in calm wave conditions. The surfbeat mode is used in storm wave conditions considering the influence of infra-gravity waves. The parameters of the Xbeach model were obtained with a reasonable standard of Brier Skill Score (BSS) > 0.3. In order to assess the long-term beach erosion, we adopt reliability design method which was typically used for hard structures in coastal region such as breakwaters. In this study, we considered the beach system as a soft structure and applied the reliability design method for assessment of beach erosion. Monte-Carlo Simulation (MCS) was used to simulate wave height and period variability. Also, random storm conditions were generated with monthly storm occurrence probability. After a long-term numerical simulation, the beach erosion probability were calculated and compared with the monitored field data in Munam Beach, Korea. The probability of failure (beach erosion) is 75% and the probability of recovery is 25%. This result are expected to be useful for future coastal maintenance projects.