潮流脊影响下开敞型潮滩的地貌动力过程及演化模式

以南黄海江苏近岸海域潮滩-潮流脊复合系统中的开敞型潮滩为研究对象，应用现代化仪器MIDAS400、ADV、OBS、GPS-TRK等沿典型断面进行水动力和地形地貌的现场观测，获取高时空分辨率的沉积物输运及潮滩演化信息；采取沉积动力学与数学模型相结合的方法，重点分析两种类型潮滩（复合型及离岸型）体系中沉积物输运趋势、地貌-动力反馈机制，辨析潮滩演化对人类活动的响应。结合理论分析，估算潮滩的生长空间和沉积物可获得率，分析极浅水非线性余流的形成机理及其输沙效应，进而探讨物源供应和水动力条件对潮滩演化时间尺度的影响机制，验证两种新的潮滩演化模式的工作假说：潮流脊横向迁移、并陆形成复合型潮滩，及岸外潮流脊垂向淤长至大潮低潮位之上形成沙脊型潮滩；其滩顶高程和滩面展布受相应理论生长极限控制。该项研究成果将为构建新的潮滩演化模式理论奠定基础，并为海岸带资源开发、环境保护和海洋防灾减灾提供科学依据。

The high spatial and temporal resolution of suspended sediment concentration and seabed elevation changes will be measured to estimate the sediment transport and tidal flat profile evolution by using the advanced instruments (e.g. MIDAS400, ADV, OBS and GPS-RTK) along the cross-sections in the tidal flat-sand ridge system in the southern Yellow Sea. On the basis of the sediment dynamics and numerical model, the sediment transport rate and net transport pathways can be determined in quantity. Then the feedback between the tidal flat geomorphology and associated hydrodynamics can be investigated, in terms of their response to the human activities. In addition, the parameters, including the tidal flat accommodation, sediment availability (or capacity), are calculated by detailed theoretical analysis for the tidal flat-sand ridge system of the study area. Further, the nonlinear residual currents in the extreme shallow water associated with sediment transport can be set forth. The sediment source and hydrodynamic controlls on the tidal flat evolution scales (in spatial and temporal) will then be evaluated. Finally, a scientific hypothesis could be tested: the sand ridge moves landward and form a "recombination tidal flat" with multimodal profile in terms of elevation along the onshore-offshore cross-sections; the offshore sand ridge could grow upward and form another type of tidal flat named "sand-ridge tidal flat". However, the highest elevation and extending of such tidal flats are limited by the accommodation space. This study could put forward a novel theory of tidal flat evolution and make contributions on the coastal exploitation, environment protection, oceanic disaster forecasting and alarm.