钱塘江涌潮、泥沙和河床相互作用研究

The sediment movement is very complicated in Qiantang Estuary due to the presence of tidal bore. The velocity of flow is great when the tidal bore arrives, so riverbed is eroded violently and sediment concentration increases dramatically, resulting in a profound effect on sediment transport and riverbed evolution. At the same time, sediment transport and riverbed evolution has a larger reaction on the tidal bore. Based on the deepening cognition of the hydraulic structure and propagation of the tidal bore, a riverbed resistance formula in the estuary is derived through unsteady fluid flow equations. A mechanical mechanism of smaller riverbed resistance is drawn out combined with other research techniques. Full coupling sediment mathematical models with high resolution are set up, which can simulate strong discontinuity, multi scale tidal bore, sediment transport, and riverbed deformation. Combined with field observation, data analysis, flume experiment and theoretical analysis, the dynamic response characteristics of sediment transport and riverbed deposition process under tidal bore are analyzed. It also studies the reaction of the concentration gradient before and after tidal bore and river morphology on the height, shape and propagation of the tidal bore. And it reveals the differences of the height and propagating law of the tidal bore under fixed bed and movable bed conditions. The research findings would have an important significance to the protection and disaster prevention of the tidal bore, estuarine regulation and the construction of wading engineering, and also facilitate the cross development among hydrodynamics, estuary geography and other subjects.

钱塘江河口因存在涌潮，泥沙运动非常复杂。涌潮到达时，因流速大，河床受到剧烈冲刷，水体含沙量剧增，对泥沙输移和河床演变产生深刻影响。同时，涌潮引起的泥沙输移和河床冲淤对涌潮也有较大的反作用。本项目在深化认知涌潮水力学结构和传播规律的基础上，计划从流体非恒定流基本方程出发，推导河口河床阻力公式，结合其它研究手段，揭示钱塘江河口河床阻力大大偏小的力学机理；构建能模拟强间断、多尺度的涌潮、泥沙输移及河床变形全耦合的高分辨率动床数学模型，结合现场观测、资料分析、水槽试验、理论分析等研究手段，分析泥沙输移与河床冲淤过程对涌潮水流的动力响应特性，以及涌潮前后含沙量梯度、河床形态等对涌潮大小、形态和传播的反作用，揭示定床和动床条件下涌潮大小和传播规律的差异。研究成果对涌潮保护和防灾、河口治理以及涉水工程建设均具有重要意义，并且对水动力学、河口学等学科和其他学科的交叉发展亦有一定促进作用。

钱塘江河口因存在涌潮，泥沙运动非常复杂。涌潮到达时，因流速大，河床受到剧烈冲刷，水体含沙量剧增，对泥沙输移和河床演变产生深刻影响。同时，涌潮引起的泥沙输移和河床冲淤对涌潮也有较大的反作用。本项目在深化认知涌潮水力学结构和传播规律的基础上，结合二、三维考虑泥沙斜压作用的全耦合动床数学模型，初步研究了钱塘江河口河床阻力大大偏小的机理；构建了能模拟强间断、多尺度的涌潮、泥沙输移及河床变形全耦合的高分辨率动床数学模型，结合现场观测、资料分析、水槽试验、理论分析等研究手段，分析泥沙输移与河床冲淤过程对涌潮水流的动力响应特性，以及涌潮前后含沙量梯度、河床形态等对涌潮大小、形态和传播的反作用，分析了定床和动床条件下涌潮大小和传播规律的差异；揭示了涌潮对钱塘江盐水入侵的影响规律。研究成果对涌潮保护和防灾、河口治理以及涉水工程建设均具有重要意义，并且对水动力学、河口学等学科和其他学科的交叉发展亦有一定促进作用。