高浊度河口近底高浓度泥沙形成机制与数值模拟研究

本研究拟聚焦于高浊度河口特别最大浑浊带区域的近底高浓度泥沙过程，研究其形成过程中的水动力、上层低浓度悬沙、近底高浓度泥沙、沉积物之间相互作用的物理机制，从而确定近底高浓度泥沙的形成机制，并对其物理过程进行合理的参数化表达，在此基础上建立多种物理过程耦合并能够合理考虑近底高浓度泥沙的产生、输运，以及其与上层低浓度悬沙层和河口底床相互作用的动力学数值模型，并选择具有代表性的长江河口，采用近底观测系统对河口最大浑浊带区域的近底高浓度泥沙过程进行高分辨率观测，在分析其泥沙动力学机制的同时率定验证参数化方案和数值模型系统，模拟研究长江口最大浑浊带区域近底高浓度泥沙形成过程，以及其空间分布及在不同动力条件下的变化特征和输运机制。

This study is aimed to reveal the physical mechanisms of dynamic formation of near-bed high-concentrated mud suspension (HCMS) in the high-turbidity estuaries, with the focus on the physical interactions among hydrodynamics, low-concentrated sediment suspension in the upper water column, high-concentrated sediment suspension within the near-bed column, and deposited sediment at the seabed. The parameterizations of these physical processes of the formation, propagation, resuspension, consolidation and breakdown of HCMS are then re-visited and summarized based on previous studies and field observation. An integrated cohesive sediment modeling system is then developed to simulate the formation, transport and transformation of HCMS, which includes multiple physical interactions of hydrodynamics, low- and high-concentrated suspension, and seabed. A state-of-art tripod system is deployed in the high-turbidity Changjiang Estuary to investigate the near-bed high-concentrated sediment dynamics. With the survey data, the modeling system is then validated to make reasonable simulation of formation of the near-bed HCMS around the turbidity maximum zone of the Changjiang Estuary. The spatial and temporal variations of HCMS under different dynamic conditions, such as riverine source, tide, wave and atmospheric forcing will be simulated and studied to reveal the mechanism of the HCMS transport.