In the present work, a methodological framework, based on nonstationary extreme value analysis of nearshore sea-state parameters, is proposed for the identification of climate change impacts on coastal zone and port defense structures. The applications refer to the estimation of coastal hazards on characteristic Mediterranean microtidal littoral zones and the calculation of failure probabilities of typical rubble mound breakwaters in Greek ports. The proposed methodology hinges on the extraction of extreme wave characteristics and sea levels due to storm events affecting the coast, a nonstationary extreme value analysis of sea-state parameters and coastal responses using moving time windows, a fitting of parametric trends to nonstationary parameter estimates of the extreme value models, and an assessment of nonstationary failure probabilities on engineered port protection. The analysis includes estimation of extreme total water level (TWL) on several Greek coasts to approximate the projected coastal flooding hazard under climate change conditions in the 21st century. The TWL calculation considers the wave characteristics, sea level height due to storm surges, mean sea level (MSL) rise, and astronomical tidal ranges of the study areas. Moreover, the failure probabilities of a typical coastal defense structure are assessed for several failure mechanisms, considering variations in MSL, extreme wave climates, and storm surges in the vicinity of ports, within the framework of reliability analysis based on the nonstationary generalized extreme value (GEV) distribution. The methodology supports the investigation of future safety levels and possible periods of increased vulnerability of the studied structure to different ultimate limit states under extreme marine weather conditions associated with climate change, aiming at the development of appropriate upgrading solutions. The analysis suggests that the assumption of stationarity might underestimate the total failure probability of coastal structures under future extreme marine conditions.

中文翻译：

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气候变化影响下近岸海况参数的非平稳极值分析：在希腊海岸带和港口结构中的应用

在目前的工作中，提出了一种基于近岸海况参数的非平稳极值分析的方法论框架，用于识别气候变化对沿海地区和港口防御结构的影响。应用涉及对典型的地中海微潮沿岸带的海岸危害的估计和希腊港口典型碎石堤防波堤的失效概率计算。所提出的方法取决于对影响海岸的风暴事件引起的极端波浪特征和海平面的提取，使用移动时间窗口对海况参数和海岸响应进行非平稳极值分析，将参数趋势拟合到非平稳参数估计极值模型，以及对工程端口保护的非平稳故障概率的评估。分析包括估计极端总水位（TWL ) 在几个希腊海岸上近似估计 21 世纪气候变化条件下预计的沿海洪水灾害。该TWL计算考虑了波浪特征、风暴潮引起的海平面高度、平均海平面 (MSL) 上升和研究区域的天文潮差。此外，在基于非平稳广义极值的可靠性分析框架内，考虑到 MSL 的变化、极端波浪气候和港口附近的风暴潮，针对几种失效机制评估了典型海防结构的失效概率。 GEV) 分布。该方法支持调查未来安全水平和研究结构在与气候变化相关的极端海洋天气条件下对不同极限状态的脆弱性增加的可能时期，旨在开发适当的升级解决方案。