RII Track-4: Improving Understanding of River Flood Dynamics by Relating Flow and Sediment Movement to Shapes of River Dunes in three dimensions

RII Track-4：通过将流量和泥沙运动与三个维度的河流沙丘形状联系起来，增进对河流洪水动力学的理解

• 批准号: 2032910
• 负责人: Robert Mahon
• 金额: $ 22.41万
• 依托单位: University of New Orleans
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2032910&HistoricalAwards=false
• 关键词: RII; Track; Improving; Understanding; River; RII; Track; Improving; Understanding; River

Much of the world’s population and commerce exist along river corridors. The sustainability of human settlements and the impacts they have on their environments are inextricably tied to river flood and sediment dynamics. Bedforms, migrating mounds of sand such as ripples and dunes, are a primary feature observed on the bottom of dynamic river systems. Their geometries and motions are closely tied to river flow and sediment transport and each one influences the other in complex feedback loops. Direct measurement of all components of these coupled feedbacks is challenging in modern rivers and difficult to interpret in their ancient sedimentary deposits, hindering complete, understanding over long timescales. Over a century of study has attempted to relate bedform shapes, motions, and ancient deposits to the flow and sediment transport conditions that form them. Much of this effort has focused on two-dimensional frameworks. This project establishes a new set of experimental and field techniques in a collaborative setting for collecting coupled measurements of flow, sediment transport, and bedform evolution in three dimensions. In so doing, this work will expand the physical and intellectual capacity of the University of New Orleans to address problems in sediment transport research that extend beyond the scope of this project. This expanded capacity will broaden participation and serve the diverse university community as well as the southeastern region by establishing a highly capable sediment transport facility with state-of-the-art methods at a highly diverse public university in New Orleans. Bedforms are a primary observable feature of sediment transport systems. Their geometries and kinematics (motions) are closely coupled to the dynamics (forces) of flow and sediment transport. As such, bedforms and their stratal elements are key to understanding river conditions, past and present. Flow and sediment transport conditions in sand-bed alluvial systems are tightly coupled to the kinematics of bedforms. Bedforms serve to transport bed material sediment, and their forms extract momentum from the flow in alluvial river systems. Understanding their geometry and behavior can inform models that evaluate bed material flux and shear stress partitioning in modern river systems, as well as enhance interpretation of ancient fluvial strata. This project seeks to build capacity, establish lab protocols, and collect data to address three independent hypotheses: First, that cross-stream, relative to downstream, bedload particle excursion length and velocity increase with increasing turbulent energetics of the flow; second, that increasing probabilities of cross-stream particle collisions enable the establishment of three-dimensionality of bedform topography; and third, that turbulent characteristics of flow, namely shear velocity, can be inverted from three-dimensionality of bedforms and the curvature of cross set bounding surfaces in stratigraphy. A complete assessment of these hypotheses will enhance the ability to forward model bedform geometries and kinematics based on flow and sediment transport conditions. This will bolster inverse models used to quantitatively interpret past sediment transport and flow conditions based on observations of stratigraphy. In collaboration with researchers at the University of California, Santa Barbara, this fellowship will address both regionally and nationally relevant problems of river flood dynamics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

世界上大部分人口和商业都存在于河流走廊上。人类设置的可持续性及其对环境的影响与河流洪水和沉积物动态密不可分。床形，迁移的沙子（如波纹和沙丘）是动态河流系统底部观察到的主要特征。它们的几何形状和动作与河流和沉积物的运输密切相关，每个都会在复杂的反馈回路中影响彼此。在现代河流中挑战了这些耦合反馈的所有组成部分的直接测量，并且在其古老的沉积沉积物中难以解释，从而阻碍了对长时间尺度的理解。一个多世纪的研究试图将床形状，动作和古老的沉积物与形成它们的流量和沉积物的运输条件联系起来。这项工作的大部分都集中在二维框架上。该项目在协作环境中建立了一套新的实验和现场技术，用于在三个维度上收集流量，沉积物传输和床形演化的耦合测量。这样一来，这项工作将扩大新奥尔良大学的身体和智力能力，以解决超出该项目范围的沉积物运输研究中的问题。这种扩展的能力将扩大参与，并通过在新奥尔良一所高度多样化的公立大学建立一种强大的沉积物运输设施来为潜水员大学社区以及东南地区提供服务。床形是沉积物传输系统的主要可观察特征。它们的几何形状和运动学（运动）与流动和沉积物传输的动力学（力）紧密耦合。因此，床形及其地层元素是了解过去和现在的河流状况的关键。砂床冲积系统中的流量和沉积物传输条件与床形的运动学紧密耦合。床形可用于运输床材料沉积物，其形式从冲积河系统中的流动中提取动量。了解它们的几何形状和行为可以为您评估现代河流系统中评估床材料通量和剪切应力分配的模型，并增强对古代河流地层的解释。该项目旨在建立能力，建立实验室协议并收集数据以解决三个独立的假设：首先，相对于下游，床载粒子偏移长度和速度随着流量的增加而增加；其次，越来越多的跨流粒子碰撞的可能性使得能够建立床形地形的三维。第三，流动的湍流特征，即剪切速度，可以从床形的三维性和层学中交叉设置边界表面的曲率倒置。对这些假设的完整评估将增强基于流量和沉积物传输条件的床形几何形状和运动学模型的能力。这将基于层学观察结果定量解释过去的沉积物传输和流动条件的逆向模型。与加利福尼亚大学圣塔芭芭拉分校的研究人员合作，该奖学金将解决河流洪水动态的区域和国家相关问题。该奖项反映了NSF的法定使命，并通过使用基金会的知识分子优点和更广泛的影响评估标准来评估我们被认为是诚实的支持。