Collaborative Research: The effect of sand fraction and event evolution on fine-sediment transport and the depositional record in wave-supported mud flows

通过波浪支撑重力流（WSGC）向大陆架输送细粒沉积物是沉积物从源到汇的关键组成部分，但对其了解甚少。目前这一过程的模型集中在泥沙和粘土颗粒的悬浮和运输上。然而，最近的实验室实验表明，即使沉积层中少量的沙子也可能对输运层的动力学起主导作用。在此基础上，研究了砂粒率对WSGC沉积物输运的影响，特别是输运模式之间的转换、下坡输运和沉积特征。这些目标将通过一系列全面的实验室实验、三维湍流解析数值模拟以及对活动大陆边缘WSGC现有野外数据的重新分析来实现。这项工作涉及广泛的领域，从流体力学和水资源工程到生物地球化学循环的研究。外展活动包括在大学实验室通过动手实验向K-12学生介绍沉积过程的相关性，并邀请学生到当地学校进行演讲。本科生和研究生都将参与其中。除了期刊论文和会议报告外，开源代码将通过社区表面动力学建模系统（CSDMS）框架传播。通过波浪支撑重力流（WSGC）向大陆架近海输送细粒沉积物是沉积物源沉降的关键组成部分，但对其了解甚少。目前这一过程的模型集中在泥沙和粘土颗粒的悬浮和运输上。然而，最近的实验室实验表明，即使沉积层中少量的沙子也可能对输运层的动力学起主导作用。本文主要研究了砂粒率对WSGC沉积物输运的影响，特别是输运模式的转换、下坡输运和沉积特征。该项目围绕两个主要目标形成：1)确定砂粒在控制WSGC内部动力学和输运以及与之相关的床层沉积中的作用。2)评估事件演化（风暴的涌动和减弱）对重力流中沉积和流动动力学的影响，以及由此产生的沉积特征。这些将通过一系列综合的实验室实验、三维湍流解析数值模拟和对WSGC在活动大陆边缘的现有野外数据的重新分析来解决。这项工作涉及广泛的领域，从流体力学和水资源工程到生物地球化学循环的研究。外展活动包括在大学实验室通过动手实验向K-12学生介绍沉积过程的相关性，并邀请学生到当地学校进行演讲。本科生和研究生都将参与其中。除了期刊论文和会议报告外，开源代码将通过社区表面动力学建模系统（CSDMS）框架传播。

Part 1Offshore delivery of fine sediment on the continental shelf via wave supported gravity currents (WSGC) is a key component of sediment transport fromsource to sink, yet it remains poorly understood. Current models of this process focus on suspension and transport of silt and clay sized particles. However, recent laboratory experiments show that even a small amount of sand in the sediment layer may exert a dominant control on the dynamics of the transport layer. The proposed effort will investigate the effect of sand fraction on sediment transport in WSGC, particularly, the transition between transport modes, the downslope transport and the depositional signatures. The objectives will be addressed using a comprehensive series of laboratory experiments, 3D turbulence-resolving numerical simulations, and re-analysis of existing field data from WSGC on active continental margins. The work is relevant to a broad range of fields, from fluid mechanics and water resource engineering, to studies of biogeochemical cycles. Outreach include introduction of the relevance of sedimentary processes to K-12 students with hand-on experiments in the university labs, and invited presentations to local schools. Undergraduate and graduate students will be involved. In addition to journal papers and conference presentations, open-source codes will be disseminated through Community Surface Dynamics Modeling System (CSDMS) framework.Part 2Offshore delivery of fine sediment on the continental shelf via wave supported gravity currents (WSGC) is a key component of sediment source to sink, yet it remains poorly understood. Current models of this process focus on suspension and transport of silt and clay sized particles. However, recent laboratory experiments show that even a small amount of sand in the sediment layer may exert a dominant control on the dynamics of the transport layer. The proposed effort investigates the effect of sand fraction on sediment transport in WSGC, particularly, the transition between transport modes, the downslope transport and the depositional signatures. The project is formed around two main objectives: 1) Determine the role of the sand fraction in controlling dynamics and transport within WSGC and the bed deposits associated with them. 2) Evaluate impacts of event evolution (surging and waning of a storm) on the sediment and flow dynamics within a gravity flow and the resulting depositional signatures These will be addressed using a comprehensive series of laboratory experiments, 3D turbulence-resolving numerical simulations, and re-analysis of existing field data from WSGC on active continental margins. The work is relevant to a broad range of fields, from fluid mechanics and water resource engineering, to studies of biogeochemical cycles. Outreach include introduction of the relevance of sedimentary processes to K-12 students with hand-on experiments in the university labs, and invited presentations to local schools. Undergraduate and graduate students will be involved. In addition to journal papers and conference presentations, open-source codes will be disseminated through Community Surface Dynamics Modeling System (CSDMS) framework.