Doctoral Dissertation Research: Investigation of Interactions Among Near-Bank Turbulence, Flow Structure, and Bank Retreat in a Compound Meander Loop

河道形态、紊流结构和泥沙输运之间的相互作用常常产生复杂的曲流地貌，这些地貌通过横向和下游河道迁移而演变。 随着河曲的迁移，它们往往会增加弯曲度和曲率，通常形成具有多个曲率最大值的细长弯曲，也称为复合环。 流动通过简单的曲折弯曲是高度三维的，但三维流动结构，湍流特性，并在复合环路的平面形状演变之间的关系知之甚少。 特别是，弯曲的河流，这应该是密切相关的侵蚀力作用在银行的外部银行附近的湍流结构的知识是不完整的。 博士论文的研究项目将进行系统的，基于过程的现场调查的近岸湍流，平均流场和银行侵蚀之间的相互作用在伊利诺伊州中部的复合循环。 将在研究现场收集几个流动阶段的河床和河岸形态、时间平均水流结构和近岸瞬时流速的现场数据。 监测渠道形态的变化，包括银行撤退，将再加上重复流量测量，以促进探索和解释的形态，流动结构，湍流的空间结构对复合曲流循环的形态动力学的影响。 将记录河岸位置、河道形态、水流结构和湍流结构的变化，并识别这些过程之间的相互作用。本项目的结果将有助于填补现有的空白，基本了解曲流平面形态、通过弯曲的水流运动和河岸侵蚀之间的相互作用如何与复杂曲流形态的发展和演变相关。 该项目将提供高质量的现场数据，以评估河流科学家用来理解和预测平面形态演变的理论模型。 除了为基础研究人员提供新的信息和见解，曲流地形演变的更多知识将具有实际效用，因为地形变化对人类福利的影响，如位于沿着蜿蜒河流的结构的威胁和潜在的财产损失造成的通道迁移。 人类越来越接近蜿蜒的河流，这就更需要知情的河流管理做法。 通过提高对水流阶段和近岸水流湍流如何影响河岸侵蚀和河道迁移的科学认识，该项目将为管理和政策决策提供信息，包括曲流河系统中或附近的河流和栖息地恢复实践。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

The interaction among channel morphology, turbulent flow structure, and sediment transport often produces complex meander planforms that evolve through lateral and downstream channel migration. As meanders migrate, they tend to increase in sinuosity and curvature, often forming elongate bends with multiple curvature maximums otherwise known as compound loops. Flow moving through simple meander bends is highly three dimensional, but the relationship among 3-D flow structure, turbulence characteristics, and planform evolution in compound loops is poorly understood. In particular, knowledge of the structure of turbulence near the outer bank of meandering rivers, which should be closely related to the erosional forces acting on the bank, is incomplete. The doctoral dissertation research project will conduct a systematic, process-based field investigation of the interactions between near-bank turbulence, the mean flow field, and bank erosion in a compound loop in Central Illinois. Field data on bed and bank morphology, time-averaged flow structure, and near-bank instantaneous flow velocities will be collected at the study site for several flow stages. Monitoring of changes in channel morphology, including bank retreat, will be coupled with repeat flow measurements to facilitate exploration and interpretation of the influence of morphology, flow structure, and the spatial structure of turbulence on the morphodynamics of a compound meander loop. The change in bank position, channel morphology, flow structure, and structure of turbulence will be documented, and the interactions among these processes will be identified.The results of this project will help fill existing gaps in basic understanding regarding how interactions among meander planform, flow movement through a bend, and bank erosion relate to the development and evolution of complex meander forms. The project will provide high-quality field data to evaluate theoretical models river scientists use to understand and predict planform evolution. In addition to providing new information and insights for basic researchers, greater knowledge of meander planform evolution will have practical utility because of the impacts planform change has on human welfare, such as the threat to structures located along meandering rivers and potential property loss caused by channel migration. Increasing human proximity to meandering rivers is creating a greater need for informed river management practices. By improving scientific understanding regarding how flow stage and near-bank flow turbulence influence bank erosion and channel migration, this project will inform management and policy decisions, including river and habitat restoration practices in or near meandering river systems. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.