Fluvial Dynamics of Cutoffs and Abandoned Channel Development on Meandering Rivers

该项目将促进对蜿蜒河流断流机制的理解，这是一种普遍存在但知之甚少的河流特征。蜿蜒的河流是地球表面最易识别的地貌之一，其复杂的空间格局长期以来一直引起地理学家和其他地球科学家的兴趣。曲流河的一个典型特征是断流的发展，弯曲的河道彼此迁移得足够近，以便在紧弯曲的内部或颈部形成新的河道。 截流的发展通常会产生牛轭湖，因为在弯曲入口和出口处发生沉积，河流沿着新截流河道的路径流动，通过废弃弯曲的水流停止。 尽管过去有大量关于弯曲河流的研究，但对弯曲截止区形成机制的认识还不完整。因此，准确建模和预测弯曲河流的时空动态的能力是有限的。 为了满足这一研究需要，本项目将解决有关截止河道演变的问题后，他们已经开始，流动结构的模式，以及这些如何影响沉积和侵蚀模式，以及如何在主河道的流动结构以及沉积和侵蚀模式的变化后，截止已经开始。为了解决这些问题，研究人员将使用最先进的现场测量技术，捕捉，在一个高分辨率的三维流动结构和模式的侵蚀和沉积相互作用在一个不断变化的截止瓦巴什河沿着伊利诺伊州-印第安纳州边界上游的汇合处的瓦巴什和俄亥俄州河流。他们还将在一个弯曲截止的物理模型中进行一系列实验室实验，以检查各种截止配置的三维流动结构，床形态和通道变化。 最后，他们将开发数值模型来模拟截止动态，使用现场和实验室数据来调节和验证计算模型。经过验证和充分测试的模型，然后将提供一个先进的理论工具，预测截止动态沿着蜿蜒的河流在扩展范围内的边界条件。 该项目将通过对弯曲截止点发展过程的基本理论理解，以及通过为模拟弯曲河流的动态行为提供改进预测能力的基础，来提高对弯曲河流的认识。该项目还将产生与河流管理有关的实用知识，包括与可能阻碍商业航行的断流有关的沉积问题，断流和牛轭湖所在地河岸生境的保护，以及河流恢复活动，包括保持或建立牛轭湖与主要河道之间的连通性，特别是在河流已经渠化的情况下。 该项目将有助于伊利诺伊大学厄巴纳-香槟分校研究生和本科生的跨学科培训（通过将研究结果纳入课程）。 它还将使高中生，包括来自代表性不足群体的学生，在一年一度的伊利诺伊州科学奥林匹克竞赛和将于2014年由伊利诺伊州主办的国家科学奥林匹克竞赛中接触到前沿科学研究，推动理论发展并为社会服务。

This project will advance the understanding of the mechanics of meandering river cutoffs, a ubiquitous, yet poorly understood feature of rivers. Meandering rivers are among the most recognizable landforms on the earth's surface, and their complex spatial patterns have been of interest to geographers and other earth scientists for a long time. A characteristic feature of meandering rivers is the development of cutoffs, where curved channels migrate close enough to one another for a new channel to developt across the interior portion, or neck, of a tight bend. The development of cutoffs typically produces oxbow lakes as sedimentation occurs at the bend entrance and exit, the river follows the path of the new cutoff channel, and flow through the abandoned bend ceases. Despite an abundance of past work on meandering rivers, knowledge of the mechanisms by which bend cutoffs develop is incomplete. As a consequence, the capacity to accurately model and predict the spatial and temporal dynamics of meandering rivers is limited. In response to this research need, this project will address questions concerning cutoff channel evolution after they have been initiated, the patterns of the flow structures and how these impact sedimentation and erosion patterns, and how flow structures in the main channel as well as sedimentation and erosion patterns change after the cutoff has been initiated. To address these questions, the investigators will use state-of-the-art field measurement techniques to capture, at a high resolution, how three-dimensional flow structure and patterns of erosion and deposition interact at an evolving cutoff of the Wabash River along the Illinois-Indiana border just upstream from the confluence of the Wabash and Ohio rivers. They also will conduct a series of laboratory experiments in a physical model of a bend cutoff to examine three-dimensional flow structure, bed morphology, and channel change for a variety of cutoff configurations. Finally, they will develop numerical models to simulate cutoff dynamics, using field and laboratory data to condition and validate the computational models. The validated and fully tested models will then provide an advanced theoretical tool for predicting cutoff dynamics along meandering rivers over an extended range of boundary conditions. This project will enhance knowledge about meandering rivers by contributing to basic theoretical understanding of the processes involved in the development of bend cutoffs and by providing the basis for improved predictive capabilities for modeling the dynamic behavior of meandering rivers. The project also will yield practical knowledge relevant to river management, including sedimentation problems associated with cutoffs that can impede commercial navigation, the conservation of riparian habitat at the sites of cutoffs and oxbow lakes, and river restoration activities that include maintaining or establishing connectivity between oxbow lakes and the main river channel, especially where rivers have been channelized. The project will contribute to interdisciplinary training for graduate and undergraduate students at the University of Illinois at Urbana-Champaign (by incorporating findings into courses. It will also expose high school students, including students from underrepresented groups, to cutting-edge scientific research that advances theory and serves society at the annual Illinois Science Olympiad and at the National Science Olympiad, which will hosted by the state of Illinois in 2014.