【摘要】 潮滩围垦对海岸带洪涝灾害风险增加影响显著，尤其在未来海平面上升和风暴潮加剧背景下，对新围低地越浪评估具有重要意义。本文以上海杭州湾北岸为例，通过建立近岸波浪传播-水动力耦合的数值模型，利用实测海堤高度、遥感解译的潮滩面积和植被变化及未来预测的海平面上升和堤坝沉降，设置多重现期情景，评估现在及未来杭州湾北岸发生越浪的范围和强度变化。结果表明：潮间带及上覆盐沼作为重要的风浪缓冲带，对降低越浪具有积极作用；近35年来杭州湾北岸潮滩围垦增加了目前及未来发生越浪的范围，例如在200年重现期风暴潮影响下，2020年几乎不发生大规模越浪灾害，但到2050年上海金山滨海公园岸段越浪高度可达0.12 m，到2100年接近30%的岸段存在严重越浪灾害，其中金山滨海公园和奉贤岸段最大越浪高度接近1 m。基于近岸波浪高度小于本地堤顶高度的原则，采用潮滩修复和种植盐沼植被的软措施提高设防能力。结果表明到2050年需重点修复金山滨海公园附近约13.5 km长岸线，平均拓宽（抬升）潮滩约0.7 km(1.3 m)；到2100年需整体修复杭州湾岸线，修复长度约100 km，平均拓宽0.5～1 km，抬升潮滩1.3 m，且需在重点越浪区种植海三棱藨草增加底摩擦阻力，但在金山滨海公园和奉贤岸段总水位仍十分接近堤顶高度，需同时加高、加固本地硬质海堤，构建潮滩-植被-海堤一体化复合型防洪综合体降低本地洪涝灾害。更多还原

【Abstract】 Tidal flat reclamations significantly increased the coastal flooding disasters during the past half-century, especially in the newly reclaimed low-lying area and under future sea level rise and storm surge intensifying conditions. Taking the North Hangzhou Bay in Shanghai as an example, we developed a coupled coastal hydrodynamics and wave propagation numerical modelling system to assess the current and future coastal wave overtopping change under multi-recurrence scenarios based on the data such as tidal flat elevation and vegetation distribution change interpreted from remote sensing, measured seawall height, and predicted sea level rise and seawall subsidence information. The results show that coastal wetlands and saltmarshes play an essential role in nearshore wave mitigation; reclamation of tidal flat over the past 35 years significantly increased the current and future wave overtopping risks along North Hangzhou Bay. For example, wave overtopping under impacts of a 200-year return period storm surge was not evident in 2020. However, the wave overtopping height will reach0.12 m by 2050 at Shanghai Jinshan Coastal Park and further expand to 30% of the Shanghai coastline by 2100, when the maximum wave overtopping height will reach 1 m at Jinshan Coastal Park and Fengxian coastline. To improve the coastal resilience, tidal flat recovery and saltmarsh restoration measures were tested in the numerical model according to the principle of nearshore wave run-ups lower than the local seawall height. The results show that the 13.5-km long coastline near Jinshan Coastal Park should be restored by widening and raising the tidal flat of 0.7 km and 1.3 m by 2050, respectively. Notably, nearly the entire North Hangzhou Bay needs to be restored by the widening of 0.5-1 km and the raising of 1.3 m by 2100. In addition,salt marshes such as Scirpus marigueter needs to be planted in the heavily overtopped area,where the wave height is still very close to the top of the seawall at Jinshan Coastal Park and the Fengxian coastal area. Hence, to reduce the extreme coastal flood risks, an integrated mudflat-vegetation-seawall flood defense complex should be constructed by combining tidal flat restorations with conventional embankment rise and strengthening measures.更多还原