Morphodynamics of Complex Meander Bends on Large Rivers

本计画将结合联合收割机最新的实地量测技术与河川过程的数学模拟，以探讨大型河川沿着复杂曲流弯道中水流、泥沙运动与河道变迁之间的相互作用。该研究将解决的问题，如何复杂的弯曲形状影响水流和泥沙输运，这些影响如何随不同的流量水平，以及如何这些影响联合收割机，以确定长期变化的形状大曲流弯曲。位于伊利诺斯州和印第安纳州边界的瓦巴什河是美国最后一条几乎不受管制的自由流动的蜿蜒河流之一，它将作为现场。这项研究将利用新的声学技术，测量在不同流量范围内不同形状的曲流弯道内水流、沉积物运输和河床形态变化的三维模式。现场测量将用于开发、校准和测试先进的计算模型，这些模型将允许在比现场可能的更大范围的曲流形状和流量水平上对曲流弯曲动态进行数值模拟。蜿蜒曲折是河流景观中最常见的特征之一，几个世纪以来一直吸引着科学家，艺术家和作家。大型蜿蜒河流的洪泛区也是世界上人口最多的地区之一，在这些地方管理人类基础设施往往至关重要。此外，由蜿蜒河流沉积物形成的岩石可能含有经济上重要的石油，天然气，水和矿物，这些过去环境的重建依赖于现代蜿蜒河流过程的知识。目前，大多数关于曲流河的水流、泥沙运动和河道变化的知识都来自于实验室和野外对小弯道以及形状相对简单的弯道的研究。该项目将改变我们对大型复杂河曲的形式和动力学的理解，并允许测试有关河道几何形状的假设，这些假设长期以来一直被提出用于较小的河曲，但从未在大型河曲中进行过测试。这项研究将量化的三维运动的水，运输的沉积物和演变的河流弯曲的大瓦巴什河（c。250米宽，10米深），并使用这些数据开发和测试曲流弯曲流和侵蚀的数值模型。这种结合场数值方法将直接用于解释复杂的河流弯曲是如何演变的，以及它们在未来可能会如何表现。这将对社会和应用科学的许多领域产生重大影响，这些领域涉及大型蜿蜒河流洪泛区内基础设施和人口的管理，以及未来对河岸侵蚀、河道迁移和蜿蜒废弃的预测。

This project will combine state-of-the-art techniques in field measurement and mathematical modeling of river processes to explore the interactions among flow, sediment movement and channel change in complex meander bends along large rivers. The research will address questions of how the complexity of bend shape affects flow and sediment transport, how these effects vary with different flow levels, and how these effects combine to determine long-term changes in the shapes of large meander bends. The Wabash River on the border of Illinois and Indiana, one of America's last virtually unregulated free-flowing meandering rivers, will serve as the field site. The research will measure, using new acoustic technologies, three-dimensional patterns of water movement, sediment transport and changing riverbed morphology within meander bends of different shape over a range of flow levels. Field measurements will be used to develop, calibrate and test advanced computational models that will allow numerical simulations of meander bend dynamics over a wider range of meander shapes and flow levels than is possible in the field. Meanders are one of the most recognizable and common features of river landscapes, and have fascinated scientists, artists and writers for centuries. The floodplains of large meandering rivers are also among the most populated areas in the world, and management of human infrastructure in these locations is often of critical importance. Additionally, rocks formed from the deposits of meandering rivers may contain economically-important quantities of oil, gas, water and minerals, and reconstruction of these past environments relies on knowledge of processes in modern meandering rivers. At present, most knowledge concerning patterns of flow, sediment movement and channel change in meandering rivers stems from studies of small bends, in the laboratory and field, and bends that have relatively simple shapes. The project will transform our understanding of the form and dynamics of large, complex-shaped, river meanders and allow testing of hypotheses concerning channel geometry that have been long-proposed for smaller river meanders, but never tested in large river bends. The research will quantify the three-dimensional movement of water, transport of sediment and evolution of river bends in the large Wabash River (c. 250m wide, 10m deep), and use this data to develop and test numerical models of meander bend flow and erosion. This combined field-numerical approach will be of direct use in explaining how complex river bends have evolved and how they may behave in the future. This will have significant impact in many realms of social and applied science concerned with the management of infrastructure and populations located within the floodplains of large meandering rivers, and in future predictions of bank erosion, channel migration and meander abandonment.