植物对弯曲复式河道泥沙输移及河床演化影响的机理研究

Currently compound channel flow is a critical topic, owing to the importance of the flow interaction between a main channel and its adjacent floodplain. Due to the influences of vegetation and the shape of the channel, the interaction between the vegetated floodplains and an alluvial meandering river channel is considerably more complex than that for a rigid or straight compound channel or meandering compound channel without vegetation, hence leading to the corresponding complex behaviors of sediment transport and channel changes. Applying the related theories of fluid mechanics, mechanics of sediment transport and fluvial processes, the applicants will investigate turbulent flow structure, momentum transfer, flow resistance, energy loss mechanism, incipient motion condition and transport of sediment, channel stability in meandering compound channels with vegetated floodplains. Besides the foregoing contents, the applicants will further investigate the inner relations along them. Through flume experiment and theoretical analysis, on the basis of the understanding of the flow structure and sediment transport mechanism, the applicant will propose the physical picture of flow movement and sediment transport, develop the computational methods of summation and division of flow resistance, the computational methods of conveyance capacity, sediment transport and fluvial processes in meandering compound channels with vegetation, which will perfect and update the theory, concept and method related to the sediment transport and fluvial process in meandering compound channels with vegetated floodplains. The research results of the project will be enrich the research contents of river dynamics and will provide the theoretical and technical supports for river restoration, flood control and disaster reduction, design and training of stable channels, channel training, integrated utilization of floodplains etc.

由于水流在主槽与相邻滩地之间相互作用的重要性，漫滩水流研究是一个紧要的课题；而植物条件下的弯曲复式河道由于河道形态及植物的影响，其漫滩水流结构、泥沙输移及河床演化规律更为复杂。本申请课题将以流体力学、泥沙运动力学、河床演变学理论为基础，研究植物条件下的弯曲复式河道漫滩水流结构、动量交换机理、阻力特性、能量损失机理、泥沙起动及输移规律、河道稳定特性以及它们之间的内在联系。通过水槽试验与理论分析，在探明植物条件下动床弯曲复式河道水流结构及泥沙输移规律的基础上，建立该类河道水沙运动的物理图形，提出水流阻力分解和合成的计算方法，提出该类河道过流能力、泥沙输移和河床演化的计算方法，实现植物条件下的弯曲复式河道泥沙输移及河床演化研究在理论、概念与方法上的完善和更新。项目研究成果将丰富河流动力学的研究内容，将为河流生态修复、防洪减灾、稳定河道设计、河道整治、河滩地综合利用等提供理论和科技支撑。

由于水流在主槽与相邻滩地之间相互作用的重要性，漫滩水流研究是一个紧要的课题；而植物条件下的弯曲复式河道由于河道形态及植物的影响，其漫滩水流结构、泥沙输移及河床演化规律更为复杂。本申请课题以流体力学、泥沙运动力学、河床演变学理论为基础，研究植物条件下的弯曲复式河道漫滩水流结构、动量交换机理、阻力特性、能量损失机理、泥沙起动及输移规律、河道稳定特性以及它们之间的内在联系。通过水槽试验与理论分析，建立了植物条件下弯曲复式河道水位流量关系，探明了该类河道流速分布、二次滚运动机理、紊动强度变化特性、雷诺应力空间布特性等，揭示了该类河道推移质输移规律以及河床演变特性，建立了该类河道水流运动的物理图形，提出了滩地有非淹没或淹没植被的流速及床面切应力横向分布、弯曲复式河槽沿程流速分布等一整套水流运动的计算方法，提出了植被河道的推移质输沙率公式及河相关系，提出该类河道过流能力计算方法，实现了植物条件下的弯曲复式河道泥沙输移及河床演化研究在理论、概念与方法上的完善和更新。本项目研究成果可丰富河流动力学的研究内容，可为河流生态修复、防洪减灾、稳定河道设计、河道整治、河滩地综合利用等提供理论和科技支撑。