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

博士论文研究：复合曲流环路中近岸湍流、流动结构和岸后退之间相互作用的研究

• 批准号: 1003622
• 负责人: Bruce Rhoads
• 金额: $ 1.17万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-15 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1003622&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Investigation; Interactions

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.

河道形态、湍流结构和沉积物输送之间的相互作用常常产生复杂的曲流平面形态，这些平面形态通过横向和下游的河道迁移而演变。 当曲流迁移时，它们的蜿蜒度和曲率往往会增加，通常形成具有多个曲率最大值的细长弯曲，也称为复合环。 通过简单曲折弯道的流动具有高度三维性，但复合环路中的 3D 流动结构、湍流特征和平面演化之间的关系却知之甚少。 特别是，对曲流河流外岸附近湍流结构的认识并不完整，这些湍流结构应该与作用在河岸上的侵蚀力密切相关。 该博士论文研究项目将对伊利诺伊州中部复合环路中近岸湍流、平均流场和河岸侵蚀之间的相互作用进行系统的、基于过程的现场调查。 将在研究地点收集多个流动阶段的有关河床和河岸形态、时间平均流动结构和近岸瞬时流速的现场数据。 对河道形态变化（包括河岸退缩）的监测将与重复流量测量相结合，以促进探索和解释形态、流动结构和湍流空间结构对复合曲流环路形态动力学的影响。 将记录河岸位置、河道形态、流动结构和湍流结构的变化，并确定这些过程之间的相互作用。该项目的结果将有助于填补关于曲流平面、通过弯道的水流运动和河岸侵蚀与复杂曲流形式的发展和演变有关。 该项目将提供高质量的现场数据来评估河流科学家用来理解和预测平面演变的理论模型。 除了为基础研究人员提供新的信息和见解外，对蜿蜒平面演变的更多了解也将具有实际用途，因为平面变化对人类福祉产生影响，例如对蜿蜒河流沿岸建筑物的威胁以及河道造成的潜在财产损失迁移。 人类越来越接近蜿蜒的河流，因此更加需要明智的河流管理实践。 通过提高对水流阶段和近岸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，包括蜿蜒河流系统内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，该奖项还将为有前途的学生建立强大的独立研究生涯提供支持。