珊瑚岛礁附近低频长波的产生机理和影响因素研究

With the development of global climate change and subsequent sea level rise, the risk of coastal inundation around low-lying coral reef islands during extreme wave events (e.g., storm surge) is increasing. Low-frequency wave is the dominant component in coastal wave run-up, hence the investigation of low-frequency wave motions around reef islands has important theoretical value and practical significance. Meanwhile, dredging and excavating reef-flat sand is a common practice nowadays and the effect of such projects on coastal inundation under the extreme wave event is still unclear. Therefore, this project is proposed to investigate the low-frequency waves around reef islands experimentally, theoretically and numerically. The laboratory and theoretical work will focus on: (1) The generation of low-frequency wave and its resonance; (2) The response of coastal low-frequency motions to the forcing of incident wave spectrum, tide level, reef-face roughness and surf-zone seabed morphology; (3) Wave transformation over coral reef with excavating activities on the reef flat. Subsequently, a three-dimensional model based on solving Navier-Stokes equations will be improved to simulate the wave interaction with coral reef topography. The research findings will improve our current understanding of wave dynamics over coral reefs, and provide guidance for coastal hazard mitigation as well as excavating activities around those reef islands.

随着全球气候变化导致海平面上升，低海拔珊瑚岛礁沿岸在风暴潮等极端天气引起的波浪作用下面临着严重洪涝灾害风险，低频长波是礁后海岸波浪爬高的主要组成成分，因此研究珊瑚岛礁周围低频长波运动具有重要的理论价值和现实意义。目前在珊瑚礁坪上进行的采砂工程不断增多，极端波浪条件下此类工程给海岸线带来的灾害风险尚不明确。本项目拟通过物理模型实验、理论分析和数值模拟相结合方法对珊瑚岛礁附近的低频长波进行研究。模型实验和理论分析主要研究内容包括：（1）珊瑚礁上低频波及其共振现象的产生机理；（2）海岸低频波对入射波谱、潮位、礁面糙率和破碎带地形变化的响应规律；（3）存在人工采掘工程时珊瑚岛礁周围波浪的传播变形特征。数值模型将通过改进基于Navier-Stokes方程的三维数值模型模拟波浪和珊瑚礁地形的相互作用。本项目的研究成果将丰富和发展珊瑚礁的水动力学理论，并为珊瑚岛礁沿岸的防灾减灾和采掘工程提供理论参考。

随着全球气候变化导致海平面上升，我国南海岛礁工程在风暴潮等极端天气引起的波浪作用下面临着洪涝灾害风险，而低频长波是其中的关键致灾因子。本项目通过物理模型实验、理论分析和数值模拟相结合方法对珊瑚岛礁附近的低频长波进行了系统研究，主要学术贡献有：（1）揭示了水动力因素影响下珊瑚礁海岸低频长波产生机制；（2）揭示了礁形特征因素影响下珊瑚礁海岸低频长波产生机制；（3）阐明了水平二维珊瑚礁-潟湖-裂口系统中低频长波的运动规律；（4）阐明了人工采掘工程影响下珊瑚礁海岸低频长波的运动规律。研究成果为珊瑚岛礁的生态修复和海岸防护工程提供科技支撑，并已在行业内多家单位进行了推广应用，成效显著。依托本项目的资助，项目负责人发表各类期刊论文24篇，其中SCI收录16篇（15篇为第一或通讯作者），获得发明专利授权7项（均排名第1）；获中国航海学会科学技术奖一等奖1项（排名第1）、海洋工程科学技术奖二等奖1项（排名第3）。