近海岸冲流带在垂直海岸方向较窄、但水动力特性复杂、泥沙含量高，是海岸环境重要的水沙运动区域。然而，以往理论与数值研究不同程度上忽略了水、沙和滩面之间的相互作用（如忽略滩面变形对冲流的反作用、假定推移质向饱和状态的瞬间调整、仅考虑均匀泥沙输移等）。这严重制约着对冲流带水沙运动特性和规律的认识，影响工程效应。本项目基于流体力学水沙两相基本的质量和动量守恒律、应用高性能激波捕捉数值格式，建立冲流带深度积分水沙耦合数值模式和多重时间尺度理论，揭示冲流带冲流、非均匀泥沙运动和海岸滩面变形之间的相互作用机制，阐明冲流带推移质水流挟沙力概念适应性、滩面变形对波浪水流反作用机制、以及滩面地形对均匀与非均匀泥沙输移的响应规律，界定现有冲流带数值模型的适应性及适应条件；为海岸防护、海岸线整治规划和合理开发提供理论基础和科学预测。

The narrow swash zone is characterized by complex hydrodynamics and active sediment transport, and thus strong interactions among the swash, sediment transport and beach deformation. However, previous theoretical and numerical investigations on the swash zone ignore these interactions to different extents (e.g., ignorance of the feedback impacts of beach deformation, assume instant adaptation of bed load to transport capacity, uniform sediment transport etc), which greatly confines our understanding to swash hydro-morphodynamics, and thus contributes to uncertainty for engineering application. In this project, a depth-averaged fully coupled modelling framework, which is based on the basic laws of fluid mechanics and a high-resolution numerical scheme, will be established for swash zone. Classical swash events will be numerically reproduced, so that the interactions among the swash, sediment transport and beach deformation can be systematically investigated. Specifically, the adaptation features of sediment, the applicability of the concept of sediment transport capacity, the feedback impacts of beach morphological change, and the beach evolution in response to uniform or nonuniform sediment transport will be clarified. Finally, the derived understanding on these aspects will help us to delimit the validity of existing numerical modelling techniques of the swash zone.