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Doctoral Dissertation Research: The Impact of Lateral Channel Confinement on River Morphology

博士论文研究：侧向河道限制对河流形态的影响

基本信息

批准号：
1734840
负责人：
Mark Fonstad
金额：
$ 1.59万
依托单位：
University of Oregon Eugene
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2020-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1734840&HistoricalAwards=false
关键词：
Doctoral Dissertation Research Impact Lateral

项目摘要

This doctoral dissertation project will address the complex ways in which the lateral, or riverbank, boundaries of a river impact the river's form. This includes how tributaries and hillslope erosion processes contribute sediment, and how laterally confining features such as roads, railroads, and bridge abutments alter both sediment contributions and channel morphology by modifying the flow regime of the river, thus altering the effectiveness of the river to erode or deposit material. This project will also provide new insights into how river shape and form is organized in terms of the distribution of sediment type, as well as channel width and depth in the downstream direction. The student will focus on investigating the role of tributaries and hillslope erosion processes as sources of additional sediment, and riverbank constrictions as locations where human activity has altered the natural river flow, often degrading habitat for culturally and environmentally important aquatic and riparian species. The findings of this project will contribute to the understanding of how rivers respond to changing lateral conditions. This information can be used in river restoration projects to enhance the health of river ecosystems. Additionally, the information gained from the research has the potential to inform future construction along rivers by providing a more thorough understanding of the importance of the link between a river and its floodplain. The methodologic approach to this project is designed to be low-cost and widely accessible, with the objective of showing the wide applicability of this approach to river conservation and restoration efforts across the country. As a Doctoral Dissertation Improvement award, this project will also provide support to enable a promising young scholar to establish a research career.This project focuses on deepening the "sediment links" concept. This theoretical approach frames river tributaries as sediment links, creating a series of distinct river sections, defined by local changes in channel slope and gravel size. The student proposes that lateral channel constrictions can be thought of as "sediment breaks" within this context, as places where the increase in shear stress at the channel bottom, due to a lack of floodplain access during high-flow events, will result in a similar morphologic change as sediment links, but due to an increase in erosion, rather than a surplus of supply. The methods used in this project research include the use of a small unmanned aerial system as well as underwater photography to generate primary data which will be used to quantify particle size distributions, channel depth, and channel width. Existing aerial imagery and LiDAR data will be used to classify channel constriction severity using accepted definitions. The data sources will be used to address several research questions relating the severity of channel constriction to the magnitude of departure in channel morphology variables from a natural control reach. The research questions will also further analyze the relationship between tributaries and local changes in channel morphology and patterns of water surface roughness and velocity vectors. This research will be conducted along the Rogue River in Southern Oregon, USA but its findings will be broadly applicable in other river systems.

这个博士论文项目将解决复杂的方式，其中的横向，或河岸，河流的边界影响河流的形式。这包括支流和山坡侵蚀过程如何贡献沉积物，以及道路、铁路和桥台等横向限制特征如何通过改变河流的流态来改变沉积物贡献和河道形态，从而改变河流侵蚀或存款物质的有效性。该项目还将提供新的见解，了解河流的形状和形式是如何组织在沉积物类型的分布方面，以及下游方向的河道宽度和深度。学生将专注于调查支流和山坡侵蚀过程作为额外沉积物来源的作用，以及人类活动改变自然河流流量的河岸收缩，通常会降低文化和环境重要水生和河岸物种的栖息地。该项目的研究结果将有助于了解河流如何应对不断变化的横向条件。这些信息可用于河流恢复项目，以增强河流生态系统的健康。此外，从研究中获得的信息有可能通过更深入地了解河流与其洪泛区之间联系的重要性，为未来沿着建设提供信息。该项目的方法论方法设计成本低，可广泛使用，目的是显示这种方法对全国河流保护和恢复工作的广泛适用性。作为博士论文改进奖，该项目还将提供支持，使有前途的年轻学者能够建立研究事业。该项目侧重于深化“沉积物联系”概念。这种理论方法将河流支流视为沉积物连接，创建了一系列不同的河流断面，由河道坡度和砾石尺寸的局部变化定义。该学生提出，在这种情况下，横向河道收缩可以被认为是“沉积物断裂”，因为在高流量事件期间，由于缺乏洪泛区通道，河道底部的剪切应力增加，将导致与沉积物连接类似的形态变化，但这是由于侵蚀增加，而不是供应过剩。本项目研究中使用的方法包括使用小型无人驾驶航空系统以及水下摄影来生成原始数据，这些数据将用于量化粒度分布，通道深度和通道宽度。现有的航空影像和激光雷达数据将被用于使用公认的定义来分类通道收缩的严重程度。数据源将被用来解决几个研究问题的严重程度有关的渠道收缩的通道形态变量从一个自然控制达到的偏离幅度。研究问题还将进一步分析支流与当地河道形态变化以及水面粗糙度和流速矢量模式之间的关系。这项研究将沿着美国俄勒冈州南部的罗格河进行，但其研究结果将广泛适用于其他河流系统。