潮滩极浅水边界层水沙过程及其地貌效应

The very shallow water Bottom Boundary Layer (BBL) of tidal flats means a sheet flow occurring during initial flood and post ebb stages, when the surge of velocity and suspended sediment concentration occurs and ripples develop fast. It indicates that the very shallow water BBL is vital for morphological evolution of tidal flats. Field observational techniques of near bed velocity profile with high accuracy, micro-topography and sediment characteristics will be comprehensively employed in this study, as well as morphodynamic numerical modeling of the very shallow water BBL on tidal flats. The characteristics and the spatial variations of hydrodynamic and sediment transport in the very shallow water BBL of tidal flats in the central Jiangsu coast are to be explored, and the characteristic parameters are to be quantified. An instrument will be developed for field measurements of sediment features. The contributions of sediment re-suspension and bed load transport in BBL on morphological evolution of tidal flats are to be calculated. A morphodynamic numerical model suitable for the very shallow water BBL of tidal flats will be built. The morphological effects of hydrodynamic and sediment transport processes in the very shallow water BBL are to be explored. Overall, this research aims to deepen our insights on morphodynamic processes of tidal flats, and enrich the knowledge of coastal processes and sediment dynamics.

潮滩极浅水边界层指潮滩涨潮初期和落潮末期出现的水深远小于正常潮流边界层厚度的水层，在此阶段出现流速含沙量突增现象，沙纹演化迅速，对潮滩地貌演变至关重要。申请人拟综合运用近底高分辨率流速剖面观测技术、微地貌观测技术、潮滩泥沙特性原位观测技术，以及潮滩极浅水边界层动力地貌数值模拟手段，探究江苏中部沿海典型潮滩的极浅水边界层水沙动力特性，阐明其沿潮滩横剖面的空间变化规律，定量描述边界层特征参数；研发潮滩泥沙特性原位观测装置，量化极浅水期间泥沙再悬浮、推移质输运在地貌变化中的贡献；建立潮滩极浅水边界层水-沙-地貌数学模型，探明极浅水边界层内水沙输运过程及其地貌效应。本研究对于加深潮滩地貌动力过程的认识，丰富海岸动力学和泥沙运动力学的内涵，具有重要的理论价值和学科意义。

潮滩极浅水边界层指潮滩涨潮初期和落潮末期出现的水深远小于正常潮流边界层厚度的水层，在此阶段出现流速含沙量突增现象，沙纹演化迅速，对潮滩地貌演变至关重要。本研究综合运用近底高分辨率流速剖面观测技术、微地貌观测技术、潮滩泥沙特性原位观测技术，以及潮滩极浅水边界层动力地貌数值模拟手段，阐明了极浅水时段流速和含沙量突增现象的空间变化规律，证实了水位变化率是影响流速突增量值的重要因素；基于溃坝波水槽试验模拟生成阶段恒定的极浅水水流，研究涨潮前锋边界层结构和底部切应力，提出了涨潮前锋边界层底部切应力计算公式；基于无网格粒子法，构建了涨潮阶段极浅水过程的水动力数学模型，为极浅水边界层水-沙-地貌过程机理研究提供了模拟工具；基于冬夏两季水沙实测资料时空变化特性分析，阐明了南黄海西洋水道悬沙输运机制的季节性差异；基于潮滩现场观测资料和水沙数值模拟，探究了江苏中部沿海潮滩对风暴潮的响应过程，从动力学角度解释了潮滩间不同区域演变特征差异的原因；设计和研制了一种潮间带泥沙起动切应力现场测量系统，可以准确获得现场泥沙起动参数，减小对原状土的扰动；发明了一种适用于潮间带潮滩极浅水时段的局部微地貌观测装置，可以更准确地获取极浅水时段水面变化、床面变形等数据。本研究对于加深潮滩地貌动力过程的认识，丰富海岸动力学和泥沙运动力学的内涵，具有重要的理论价值和学科意义。