广西沿岸人工海滩养护效应及动力地貌变化机制

It is one of important countermeasures for beach nourishment to coastal protection and shoreline restoration of the world, which is of great significance to safety of coastal engineering. Here, the macro-tidal region located at Guangxi Province with artificial beaches being carried out is considered as a typical research area in this study. Based on continually two years observations including beach topography, hydrology and suspended sediment, and deposition samples collection, as well as deposition cores and multi-temporal remote images, beach deposition and processes were analyzed by statistical techniques, analytic and mathematical model with reciprocal validations. The results can indicate characteristics of the nearshore hydro-dynamic actions, sediment movement patterns, and changed principle of shoreline and beach profile. The beach morphodynamic states and shifted mechanism can be clarified. Moreover, the changed models of shoreline and beach profile impacted by beach nourishment will be finally provided. This conclusions of this project should be available and vital to assessment of beach nourishment effects along regional macro-tidal coastal environment, which also brought out theoretical and technical supports for application and extension for beach nourishment engineering to other similar region in the world.

海滩养护是目前国内外海岸防护和岸线恢复的重要举措，对港工建筑的安全具有重要意义。以正在实施人工海滩措施的广西强潮沙质海岸为研究区，通过连续2年的海滩地形、水文和沉积物观测和分析，同时结合沉积钻孔以及多时相遥感影像采集，基于统计、解析和数值模型的研究和相互验证，分析海滩养护后的近岸动力作用特征、沉积物迁移方式以及岸线与剖面变化规律，弄清海滩养护后动力地貌的变化状态与转换机制，提出海滩养护工程影响的岸线与剖面变化模式，为评估区域强潮环境海滩养护效应及工程的应用与推广提供理论基础和技术支撑。

海滩养护是目前国内外海岸防护和岸线恢复的重要举措，对港工建筑的安全和滨海旅游的健康可持续发展具有重要意义。本项目以正在实施人工海滩措施的广西强潮沙质海岸为研究区，基于历史水、沙及地貌资料和原型观测数据，将统计技术和数值模拟结合，研究控制人工海滩岸线变化的动力因素，探讨海滩沉积物变化特征及其迁移方式，揭示人工海滩的动力地貌变化机制，探究了海滩周边河流水沙及其河口沉积地貌，主要成果包括：1）不同波能环境下三个海滩地貌高程变化出现不同的频率分布特征，其中在台风高能环境下，海滩地貌高程变化构成的频率分布遵循高斯分布特征；2）造成区域较大增水的台风可大幅度提高各级别波浪扰动范围，对银滩整体剖面造成侵蚀；3）相比浅水区，破波带内波浪破碎和辐射应力产生强烈的底部逆流，这导致破波带内存在更大的瞬时和潮周期净横向悬沙通量；4）通过退养（塘）还滩、促淤保滩、人工补沙和完善冲淤监测体系等方式可提升广西海滩养护修复功能。研究成果丰富了海滩养护理论体系，为评估区域中-强潮环境海滩养护效应及工程的应用与推广提供理论基础和技术支撑。