How does the development of particle scale structure control river scale morphology?

颗粒尺度结构的发育如何控制河流尺度形态？

• 批准号: NE/K013386/1
• 负责人: Julian Leyland
• 金额: $ 34.43万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FK013386%2F1
• 关键词: How; does; development; particle; scale

The transport of sediments is a key process in the global geological cycle, a cornerstone of aquatic ecosystems and has a multi-billion pound impact on agricultural, industrial and urban, flood- and erosion-risk hazards. Understanding and being able to predict the stability of gravel river beds is important for multiple reasons: changes in river bed shape will change the channel capacity and thus affect flood risk; the bed stability affects the amount of sediment that can be moved by the flow, which will have impacts on the downstream channel morphology and dynamics; the river bed is a habitat for many species, and thus changes in the river bed will have implications for the river ecosystem; and in order to manage and restore rivers effectively, channels need to be designed with a known level of stability.However, current ability to predict sediment entrainment and thus river bed stability is limited by our understanding of the factors that affect sediment movement. Grain size is typically accounted for, but other factors such as sediment structure (the way in which individual sediment grains are packed together in 3D) and the role of fine sediments in cementing grains together are not. Furthermore, these factors vary spatially across the bed of a river, producing a spatial pattern of areas that are more or less easily entrained, i.e. a template of erodibility. We hypothesis that this spatial pattern of erodibility plays an important role in controlling both the shape of the river bed, and how this shape changes under different flow conditions. We will test this hypothesis by quantifying, for the first time, the development of 3D sediment structure in both a field and a laboratory environment using high energy CT-scanning. These data will allow us to identify causal relationships between the different controls and sediment structure. The application of this technique to large numbers of samples from both field and laboratory settings will provide a significant and unique dataset for understanding the structure and production of 3D bed sediments.Using an existing theoretical framework, we will use the data from both the flume and field data to produce relationships that can be used to predict sediment structure, and consequently the erodibility of the bed, from the controlling factors of sediment input and flow. This relationship will be implemented within a numerical modelling framework in which we will upscale from the field and flume to represent additional range of channel and flow conditions. We will work with end-users to ensure that the new knowledge is transferred effectively into guidance for policy and operational activity within the river management community.

沉积物的运输是全球地质周期中的关键过程，这是水生生态系统的基石，对农业，工业和城市，洪水和侵蚀风险危害的危害具有数十亿英镑的影响。理解并能够预测砾石河床的稳定性非常重要，这是由于多种原因：河床形状的变化将改变通道容量，从而影响洪水风险；床稳定性会影响流动可以移动的沉积物量，这将影响下游通道的形态和动态。河床是许多物种的栖息地，因此河床的变化将对河流生态系统产生影响。为了有效地管理和恢复河流，需要以已知的稳定水平设计渠道。但是，当前预测沉积物夹带的能力，因此河床稳定性受到我们对影响沉积物运动因素的理解的限制。通常会考虑晶粒尺寸，但是其他因素，例如沉积物结构（单个沉积物晶粒在3D中堆积在一起的方式），而细沉积物在将晶粒结合在一起中的作用却没有。此外，这些因素在河床的床上有空间变化，从而产生或多或少容易夹带的区域的空间模式，即可侵蚀性的模板。我们假设这种可侵蚀性的空间模式在控制河床的形状以及这种形状如何在不同的流动条件下变化起着重要作用。我们将首次使用高能量CT扫描的田间和实验室环境中的3D沉积物结构来量化3D沉积物结构，以检验这一假设。这些数据将使我们能够确定不同控制和沉积物结构之间的因果关系。该技术在现场和实验室环境中的大量样品中的应用将提供一个重要而独特的数据集，以了解3D床沉积物的结构和生产。使用现有的理论框架，我们将使用Flume和Field数据中的数据来产生可用于预测泥沙结构的关系，从而预测床的结构，从而从床位的床位上的繁殖因子的可靠性和控制因素的可靠性和流量。这种关系将在数值建模框架内实现，在该框架中，我们将在该框架中从现场上升并进行水槽，以代表渠道和流程条件的其他范围。我们将与最终用户合作，以​​确保将新知识有效地转移到河流管理社区内的政策和运营活动指导中。

项目成果

X-ray computed tomography reveals that grain protrusion controls critical shear stress for entrainment of fluvial gravels

• DOI: 10.1130/g46883.1
• 发表时间: 2019-11
• 期刊: Geology
• 影响因子: 5.8
• 作者: R. Hodge;H. Voepel;J. Leyland;D. Sear;Sharif Ahmed

Development of a vector-based 3D grain entrainment model with application to X-ray computed tomography scanned riverbed sediment

开发基于矢量的 3D 颗粒夹带模型，并将其应用于 X 射线计算机断层扫描河床沉积物

• DOI: 10.1002/esp.4608
• 发表时间: 2019
• 期刊: Earth Surface Processes and Landforms
• 影响因子: 3.3
• 作者: Voepel H