植被海岸消浪和平衡剖面形成机制研究

The dynamic processes, including hydrodynamics and morphodynamics of vegetation coasts recently attract broad attention in the scope of eco-hydraulics. By present, most studies focus on wave-vegetation interaction and few of them aim at the beach response. This proposal plans to conduct a laboratory experiment in the wave flume to study the interaction among the wave, vegetation and beach profile, measuring the cross-shore wave dissipation and beach profile at the equilibrium state. A comparison analysis of different initial wave conditions, different vegetation configurations, different water levels, different beach slopes, and different sediment grain sizes will be done to study the wave damping and the formation of beach profile. Further, based on experimental data and the conservation law of wave energy flux, a wave damping model on the inclining vegetated beach will be established in order to solve the drag coefficient. Moreover, we intend to explore the formation mechanism of equilibrium beach profile at vegetation coasts, which is fundamental research for future works. The innovation of this proposal is to extend the study of wave-vegetation interaction to the interaction of wave-vegetation-beach profile , and it has a great significance for the development, planning and protection of coastal zone.

植被海岸的动力过程作为生态相关的海岸动力学问题受到广泛关注，现有的研究主要针对波浪-植被的相互作用，对于植被海岸剖面的响应和反馈机制尚未明确。物理模型实验是机理研究的常用方法，因而本项目拟在波浪水槽中构建人工沙质植被海岸，通过调控水位（低、中、高水位的转换）来模拟涨落潮过程，对比分析波浪要素、植被密度、初始地形坡度以及泥沙级配对沿程波高衰减和海岸剖面形态的影响，阐明植被带对波浪的衰减作用及其与海岸剖面平衡态形成的关系。进而基于实验数据和波能流理论，1）建立斜坡海岸的植被消浪模型，研究并优化植被拖曳力系数的参数化方案；2）探讨植被海岸平衡剖面的形成机制，从而建立考虑植被因子影响的平衡剖面模型。本项目的创新之处在于将波浪-植被之间的相互作用延伸为对波浪-植被-海岸剖面三者之间动力学问题的讨论，对植被海岸的发展、规划和保护有着重要的意义。

海岸是陆海相互作用的重要地带，由于波浪等水动力作用，对海岸有一定的侵蚀作用。而海岸植被带的存在（如红树林），通过对水动力条件的衰减，对海岸起到了很好的保护作用。本课题采用物理模型实验的研究方法，模拟了植被海岸剖面受波浪冲击的演变和准静态平衡下的剖面形态。基于物理模型实验数据，探讨了植被-波浪-岸滩剖面三者之间的动态响应和反馈机制。在机理研究的基础上，提出了评估海岸岸滩剖面对波浪动力、地形特征和植被参数变化的响应程度的几何参数模型。此外，基于人工神经网络方法，选取了表征岸滩剖面的侵蚀冲刷情况的五个参数（损坏参数、冲淤平衡点水平位置、侵蚀长度、侵蚀最大深度、以及侵蚀冲刷槽的面积）建立了机器学习的预测模型，发现其优于经验几何模型。