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

第一部分波浪支持重力流（WSGC）对陆架细颗粒泥沙的近海输移是泥沙从源到汇输移的重要组成部分，但人们对它的认识还很不够。目前，这一过程的模型集中在悬浮和运输的淤泥和粘土大小的颗粒。然而，最近的实验室实验表明，即使是沉积层中的少量沙子也可能对输送层的动态产生主导控制。本研究将探讨沙粒率对WSGC中泥沙输移的影响，特别是输移模式之间的转换、下坡输移和沉积特征。这些目标将通过一系列全面的实验室实验、三维分辨率数值模拟以及对WSGC关于活动大陆边的现有实地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地球化学循环的研究。外联活动包括向K-12学生介绍沉积过程的相关性，并在大学实验室进行动手实验，并邀请当地学校进行演讲。 本科生和研究生将参与其中。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模拟系统（CSDMS）框架进行传播。第二部分波浪支持重力流（WSGC）对大陆架细颗粒沉积物的近海输送是沉积物源汇的一个关键组成部分，但人们对它的认识还很有限。目前，这一过程的模型集中在悬浮和运输的淤泥和粘土大小的颗粒。然而，最近的实验室实验表明，即使是沉积层中的少量沙子也可能对输送层的动态产生主导控制。本文主要研究了砂粒率对WSGC中泥沙输移的影响，特别是输移模式之间的转换、下坡输移和沉积特征。该项目围绕两个主要目标形成：1）确定砂部分在控制WSGC内的动力学和运输以及与其相关的床沉积物中的作用。2)评估事件演变（风暴的涌动和减弱）对重力流内的沉积物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全面的实验室实验、三维分辨率数值模拟以及对WSGC活动大陆边缘现有现场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地球化学循环的研究。外联活动包括向K-12学生介绍沉积过程的相关性，并在大学实验室进行动手实验，并邀请当地学校进行演讲。 本科生和研究生将参与其中。除了期刊论文和会议报告，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.