Doctoral Dissertation Research: Influence of Riparian Vegetation on Near-Bank Flow Structure and Erosion Rates on a Large Alluvial River

博士论文研究：河岸植被对大型冲积河流近岸水流结构和侵蚀率的影响

• 批准号: 1129889
• 负责人: Bruce Rhoads
• 金额: $ 1.16万
• 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: 2011
• 资助国家: 美国
• 起止时间: 2011-07-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1129889&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Influence; Riparian

The process of bank erosion in meandering alluvial rivers occurs through the dynamic interactions between channel contours, the three dimensional structure of water flow, sediment transport, and the geotechnical characteristics of the channel banks and floodplains. Rates of bank erosion are also influenced by the type of vegetation growing on the banks - a factor that is still poorly understood and therefore commonly neglected in models of river shape evolution. The goal of this doctoral dissertation research project is to examine the influence of bank vegetation on the migration of meanders in large alluvial rivers by characterizing the geotechnical properties of channel banks as well as the near-bank water flow structure for forested and non-forested bends. Channel banks and floodplains will be characterized by obtaining data on the bulk grain size distribution, cohesion, root-tensile strength, and hydraulic conductivity for forested and non-forested river bends. Time-averaged and instantaneous velocity measurements will be taken at various water flow stages in forested and non-forested meander bends to characterize the water flow structure near the river bends and how this interacts with the channel banks under differing conditions. In addition, repeat detailed bathymetric and morphologic surveys of the channel bed and banks will be obtained using state-of-the-art technologies. Analysis will focus on interactions among flow structure, vegetation, and the geotechnical properties of floodplain sediments to evaluate differences in bank erosion in forested and non-forested bends. The results of this research will provide basic insight into the dynamics of how the shapes of channels in large meandering rivers evolve and the influence of vegetation in this process. The research will produce data that can be used to calibrate, test, and evaluate numerical models of river shape dynamics, allowing for more accurate simulations of channel change in meandering rivers. Prediction of channel change is important because meandering rivers often form political boundaries between states and countries, are used as traffic ways for goods, and provide a vast range of habitats for aquatic organisms. As a meandering river migrates across its floodplain, it can result in loss of land, damage to human infrastructure, and introduction of large amounts of sediment into the river system. Thus, an improved understanding of bank-erosion processes in meandering rivers is not only important scientifically, but has important implications for environmental and societal concerns.

弯曲冲积河流的河岸侵蚀过程是通过河道轮廓、水流三维结构、泥沙输移以及河道河岸和漫滩的岩土特性之间的动态相互作用而发生的。 河岸侵蚀速率还受到河岸上植被类型的影响--这一因素至今仍知之甚少，因此在河流形态演变模型中常常被忽视。这个博士论文研究项目的目标是研究银行植被对迁移的河曲在大型冲积河流的岩土工程特性的通道银行以及近银行水流结构的森林和非森林弯曲的影响。将通过获得关于森林和非森林河流弯道的散装粒度分布、内聚力、根抗拉强度和水力传导率的数据来表征河道河岸和漫滩。将在森林和非森林曲流弯道的不同水流阶段进行时间平均和瞬时流速测量，以表征河流弯道附近的水流结构以及在不同条件下如何与河道河岸相互作用。此外，还将利用最新技术对河床和河岸进行详细的水深测量和地貌测量。分析将集中在流动结构，植被和河漫滩沉积物的岩土工程性质之间的相互作用，以评估在森林和非森林弯曲的银行侵蚀的差异。这项研究的结果将提供基本的洞察如何在大型蜿蜒河流的渠道形状演变的动力学和植被在这个过程中的影响。该研究将产生可用于校准，测试和评估河流形状动态数值模型的数据，从而更准确地模拟蜿蜒河流的河道变化。河道变化的预测是很重要的，因为蜿蜒的河流往往形成国家和国家之间的政治边界，被用作货物的运输方式，并为水生生物提供了广泛的栖息地。当一条蜿蜒的河流穿过其洪泛区时，它会导致土地的丧失，人类基础设施的破坏，以及大量沉积物进入河流系统。因此，提高对弯曲河流河岸侵蚀过程的认识不仅在科学上很重要，而且对环境和社会问题具有重要意义。