COLLABORATIVE RESEARCH: Clarifying the ingredients and significance of nonlocal versus local sediment transport on steepland hillslopes

合作研究：阐明陡峭山坡上非局部与局部沉积物迁移的成分和意义

• 批准号: 1420898
• 负责人: Joshua Roering
• 金额: $ 13.45万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1420898&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Clarifying; ingredients; significance

Hillslopes of varying steepness cover much of Earth's terrestrial surface, and may be entirely mantled with regolith or consist of bare bedrock surfaces, or involve mixtures of these conditions. Because of the central role of hillslope behavior in landscape dynamics, and because of the importance of soils and soil transport in critical zone processes that sustain much of life on Earth, the topic of sediment transport on hillslopes has a particularly rich legacy. Viewed at a human timescale, this topic is central to studies of erosion and erosion control in the agricultural and environmental sciences. Further, this topic is central in geomorphic studies focused on descriptions of transport that can be used in models of hillslope and landscape evolution. This project is aimed at clarifying the factors that contribute to "local" transport, where downslope sediment movement involves small particle motions controlled by local soil and land-surface conditions, versus "nonlocal" transport associated with soil slips, biotic disturbances (e.g., tree-throw), particle ravel following fire, etc., which can involve relatively rapid, long-distance sediment motions. The research will combine theoretical, experimental, and field-based work in the Oregon Coast Range and the Sierra Nevada Mountains to clarify rates of sediment transport and the effects of transport on changing steepland topography. The work is a collaborative research and education effort involving students and faculty from Vanderbilt University and the University of Oregon. It will provide teaching tools deriving from visualizations of experiments and numerical simulations, and it will provide data sets to the science community.Recent work on hillslope sediment transport suggests the need to clarify the ingredients and implications of "nonlocal" versus "local" transport processes and associated formulations of the sediment flux, as expected hillslope behavior under these two conditions is quite different. However, the supporting theory has outpaced experimental and field-based observations needed to inform this theory. This project is aimed at closing that gap, as implications for understanding hillslope evolution are far-reaching. The project will: (1) combine experiments with scaling analyses to clarify ingredients of rarefied particle-surface interactions during their downslope motions, as these influence key processes of sediment disentrainment; (2) explore theoretical formulations of nonlocal transport for two-dimensional topography that is convergent-divergent in planform; (3) combine field observations with modeling work centered on hillslopes in the Oregon Coast Range and moraines in the Sierra Nevada Mountains that were selected to reveal ingredients of nonlocal transport behavior; and (4) formulate descriptions of nonlocal transport with appropriate space-time averaging to take into account the discontinuous (patchy, intermittent) nature of sediment motions on steepland hillslopes, as is necessary for treating the sediment flux as a time differentiable quantity.

各种陡峭的山坡覆盖着地球的大部分地面，并且可能完全用雷果地覆盖或由裸露的基岩表面组成，或者涉及这些条件的混合物。 由于山坡行为在景观动态中的核心作用，并且由于土壤和土壤运输在关键区域过程中的重要性，在地球上维持生命的大部分时间，因此在山坡上的沉积物传输的话题具有特别丰富的遗产。 在人类的时间范围内，该主题是农业和环境科学中侵蚀和侵蚀控制的研究至关重要的。 此外，该主题在地貌研究中是核心，该研究的重点是用于传输的描述，可用于山坡和景观演化模型。 该项目的目的是阐明有助于“本地”运输的因素，在该因素下，下坡沉积物运动涉及由当地土壤和土地表面条件控制的小粒子运动，而与土壤滑移相关的“非局部性”运输，生物干扰（例如，脱落树），粒子ravel ravel the the the the Firfect offect offect offects offectance sef。 这项研究将在俄勒冈州海岸范围内和内华达山脉山脉中结合理论，实验和现场工作，以阐明沉积物运输速度以及运输对变化陡峭地形的影响。 这项工作是一项合作研究和教育工作，涉及范德比尔特大学和俄勒冈大学的学生和教职员工。 它将提供源自实验和数值模拟的可视化的教学工具，并将为科学界提供数据集。在Hillslope Sediment Transport上进行的工作表明，需要澄清“非局部”与“本地”运输过程的成分和含义，如预期的山坡浮雕的两种条件，这是完全不同的。 但是，支持理论已经超过了为这一理论提供信息所需的实验和基于现场的观察。 该项目旨在缩小这一差距，因为了解山坡进化的意义是深远的。 该项目将：（1）将实验与缩放分析相结合，以阐明稀有粒子表面相互作用在下坡运动过程中的成分，因为这些会影响沉积物隔离的关键过程； （2）探索非局部转运的理论公式，以示为二维地形，在平面形成中发散； （3）将现场观测与以俄勒冈海岸山脉的山坡为中心的建模作品和内华达山脉中的莫莱纳人相结合，这些山区被选为揭示非本地运输行为的成分； （4）用适当的时空平均进行非局部运输的描述，以考虑到陡峭的山坡上沉积物运动的不连续（斑块，间歇性）性质，这对于将沉积物通量作为时间微小的数量进行处理是必要的。