气候变化和人类活动背景下沙坝-潟湖海岸系统动力地貌演化和生境效应

潟湖海岸是全球自然资源丰富的海岸形式，然而受气候变化和人类活动影响，潟湖生态环境退化。本项目以沙坝-潟湖海岸系统为研究对象，通过水槽动床试验研究典型水生植物作用下潮流垂向结构和波浪变形特征、潮汐能和波浪能空间分布与泥沙输运的定量关系，分析潮流不对称性和波浪非线性对地貌形态演变的作用方式。改进波流耦合作用下多组分地貌演变和水质数学模型，联动现场试验观测和动床试验，甄别有无水生植物作用下不同的风暴侵蚀过程和恢复机制；揭示沙坝-潟湖地貌对不同时间尺度（风暴短周期、潮汐年周期和海平面上升百年周期）气候变化以及人类活动（围垦、筑堤和疏浚）的响应过程和累积效应；厘清高强度人类活动（流域排污、养殖和海岸工程）扰动下，沙坝-潟湖海岸系统中物质输运与要素的时空分布，以及生态环境对外源物质输入的响应机制。预期成果可丰富沙坝-潟湖海岸动力地貌演变理论，为海洋环境保护、潟湖生态修复和生态安全保障提供基础科技支撑。

Coastal lagoon is a typical coastal landform with abundant natural resources around the world. However, the ecological environment of lagoon has been degraded due to climate change and human activities. The barrier-lagoon system is taken as the research object in this study. A series of movable bed flume experiments will be setup to quantify tidal current vertical structure and wave deformation, the relation of tidal energy, wave energy and sediment transport under typical aquatic plant scenarios. Influences of tidal asymmetry and wave nonlinearity on lagoon morphological evolution are analyzed as well. Based on modified multi-sediment fractions morphodynamic and water quality numerical model under wave-current coupling, and combined with field observations and movable bed flume experiments, different erosion processes by a storm surge and restoration mechanisms can be identified with and without aquatic plant scenarios. The response processes and accumulative effects will be revealed, which are influenced by different time scale climate variations (short time scale of storm surge, annual time scale of tide, centurial time scale of sea level rise) and human activities (reclamation, dike construction and dredging) on barrier-lagoon morphology. Under the disturbance of high-intensity human activities (river pollution, aquaculture and coastal engineering), the spatial and temporal distributions of substance transport and elements in the barrier-lagoon coastal system and the response mechanism of ecological environment to the input of exogenous materials can be uncovered. The anticipated achievements will be great theoretical progress in morphodynamic evolution of coastal barrier-lagoon, and also provides the basis technical support for marine environment protection, lagoon ecological restoration and ecological safety guarantee.