A mechanistic and predictive understanding of temporal variations in the onset of sediment motion

对沉积物运动开始时间变化的机械和预测理解

• 批准号: 1921790
• 负责人: Elowyn Yager
• 金额: $ 34.9万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921790&HistoricalAwards=false
• 关键词: mechanistic; predictive; understanding; temporal; variations

The movement of rocks along river beds, called sediment transport, is essential for estimating river channel stability and therefore risks to infrastructure and human lives during floods. Sediment transport predictions are also used to help restore rivers for numerous aquatic species. Despite its importance, sediment transport is notoriously difficult to predict, and this project will investigate how changes in river bed structure (e.g. rock arrangement) influences sediment transport. Such information will then be used to improve sediment transport predictions. Through a collaboration with artists, sculptures will be temporarily placed in rivers to serve as 1) flow obstructions (e.g. boulders and wood) that provide habitat for a range of fish species, and 2) public outreach installations through signs posted near the sculptures with links to websites containing information and videos about the science of this project. Errors in sediment transport predictions can be partly explained by the common assumption that the onset of sediment motion always occurs at the same flow magnitude in a given river. Large temporal changes in the onset of sediment motion can occur because of variations in the channel bed structure. The goals of this proposal are to better understand these temporal changes in bed structure and to use this understanding to accurately predict the onset of sediment motion. Laboratory experiments and a mechanistic theory are used to identify and quantify the channel bed parameters that control variations in the onset of sediment motion. This theory will be tested using field measurements in a well instrumented channel and could replace the often arbitrary choice of a single flow magnitude that causes the start of sediment movement.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.

岩石沿着河床的移动，也就是沉积物的移动，对于估计河道的稳定性以及洪水期间对基础设施和人类生命的威胁至关重要。泥沙运移预测也被用来帮助恢复河流中许多水生物种的生存。尽管它很重要，但沉积物的运输是出了名的难以预测，该项目将研究河床结构（如岩石排列）的变化如何影响沉积物的运输。然后，这些信息将用于改进沉积物运输预测。通过与艺术家的合作，雕塑将被暂时放置在河流中，作为1)水流障碍物（如巨石和木头），为一系列鱼类提供栖息地；2)通过在雕塑附近张贴链接到包含该项目科学信息和视频的网站的公众宣传装置。泥沙运动的开始总是发生在某条河流中相同的流量大小这一普遍假设，可以部分地解释泥沙运动预测中的错误。由于河床结构的变化，泥沙运动开始的时间会发生很大的变化。这项建议的目标是更好地理解这些床结构的时间变化，并利用这种理解来准确预测沉积物运动的开始。实验室实验和机械理论被用来确定和量化控制泥沙运动开始变化的河床参数。这一理论将在仪器完备的河道中进行实地测量，并可以取代通常任意选择导致泥沙开始移动的单一流量大小。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。