植被在天然河道、湿地和海洋中的一些区域常以植被群形式存在，水生植物又常以淹没植被群出现。淹没植被群尾端会出现较非淹没植被群更复杂的三维水流结构，影响植被群周围的河床形态。本研究课题以流体力学，泥沙运动力学和河床演变学为基础，研究单一和相邻淹没植被群尾流区的水流结构、动量交换机理、阻力特性、泥沙沉积和输移特性及它们之间的相互影响机制。通过水槽试验和理论分析，确定淹没植被群尾流漩涡尺度与植被群几何形态的定量关系，阐明尾流影响河床演变的关键要素，提出快速测定植被群尾流区长度的方法，揭示相邻淹没植被群间的相互作用关系，提出植被群周围发生泥沙淤积的临界水流条件，实现植被群尾流结构及其对河床演变影响在理论、概念、机理和方法上的完善和创新。课题研究成果将丰富河流动力学的研究内容，为河流生态恢复、河道整治、利用植被群促进污染物沉积等提供理论支持。

Vegetation in natural rivers, wetlands and the ocean often exists in a vegetation patch. Specifically, aquatic vegetation often exists in a submerged vegetation patch. Behind a submerged vegetation patch, three-dimensional flows linked to bed morphology are more complex, compared to the flow patterns behind an emergent patch. Applying the theories of fluid mechanics, mechanics of sediment transport and fluvial processes, the applicants will investigate flow characteristics, momentum exchange, flow resistance, sediment deposition and transport behind a single vegetation patch and two neighboring patches. Also applicants will focus on the interaction of forgoing contents. Through flume experiment and theoretical analysis, the applicants will propose the quantitative relation between the vortex scaling in the wake and the patch geometry, a method capable of estimating the wake length, the critical flow condition for sediment deposition around a patch, and clarify the key factor of wake vortexes relative to bed morphology, the interaction of two submerged vegetation patches. Those breakthroughs will perfect and update the theory, concept and method relative to the wake structure of vegetation patch and its impact on fluvial processes. The research results of this project will enrich the research contents of river dynamics and will provide the theoretical and technical supports for river restoration, river training, and pollutant deposition promoted by vegetation patch, etc.