Collaborative Research: Role of lithologic variability in controlling downstream channel response to sediment pulses

合作研究：岩性变异在控制下游河道对沉积物脉冲响应中的作用

• 批准号: 2138505
• 负责人: Jonathan Czuba
• 金额: $ 16.09万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2138505&HistoricalAwards=false
• 关键词: Collaborative; Research; Role; lithologic; variability

Landslides in mountainous regions produce large volumes of debris that are eroded by rivers and travel downstream to populated lowland areas. The gravel-size components of these landslides can accumulate on the streambed and increase the frequency of flooding in downstream communities. The resultant changes in the rock sizes in the riverbed can alter habitat for fish and insects that live there. Alternatively, if the sediment in the landslide is smaller than sand, it can result in cloudier water that requires costly filtration for drinking water or irrigation and is often harmful to the fish, insects, and other animals living in the river. The downstream effects of different river and landslide sediment characteristics are important as climate change threatens to increase landslides and the amount of sediment moving within affected rivers. This project will determine the degree to which the rock type (density and durability) of the sediment controls the timing and magnitude of sediment accumulation and size composition on the riverbed, with specific attention to those rivers in the volcanic terrain of the Pacific Northwest. The project will introduce new students to the Earth Sciences through short overnight field excursions to participate in the research and share results with regional flood managers.In the Pacific Northwest, a disproportionate number of major mass-wasting events occur in volcanic terrain, producing sediment pulses of variable density and abrasion rate. This project will use field observations and modeling to characterize river channel sensitivity to these large sediment pulses. The research focuses on how the lithologic characteristics of sediment pulses control the timing and magnitude of downstream channel response. This question will be addressed by: quantifying the variability in the sedimentary characteristics of mass-wasting deposits in several basins; modeling the downstream fate of a specific mass-wasting event in a river for which there are good field constraints on downstream abrasion and channel response; and determining the sensitivity of the river system to observed ranges of sediment pulse and channel characteristics using the model, which is based on Lagrangian tracking of individual sediment “parcels” that have unique characteristics such as abrasion rate and density.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.

山区的滑坡产生了大量碎屑，这些碎屑由河流发出，并下游到人口稠密的低地地区。这些滑坡的重力大小的组成部分可以在流中积聚，并增加下游社区的洪水频率。河床中岩石尺寸的最终变化可以改变居住在那里的鱼类和昆虫的栖息地。另外，如果滑坡的沉积物比沙子小，则可能导致更云层的水，需要饮用水或灌溉的昂贵过滤，并且通常对河里的鱼类，昆虫和其他动物有害。不同河流和滑坡沉积物特征的下游影响很重要，因为气候变化威胁会增加山体滑坡以及在受影响河流中移动的沉积物量。该项目将确定沉积物的岩石类型（密度和耐用性）控制河床上沉积物积累的时机和大小，并特别注意西北太平洋火山地形的那些河流。该项目将通过短暂的隔夜野外游览将新学生介绍给地球科学，以参与研究并与区域洪水管理者共享结果。在太平洋西北地区，在火山地形中发生了数量不成比例的重大大规模浪费事件，产生了可变密度和磨损率的沉积物。该项目将使用现场观测和建模来表征对这些大型沉积物脉冲的敏感性。该研究的重点是沉积物脉冲的岩性特征如何控制下游通道响应的时间和幅度。这个问题将通过：量化几种低音中浪费沉积物的沉积特征的变异性；建模在河流中特定的浪费事件的下游命运，在下游磨损和渠道反应上有良好的田间限制；并确定使用该模型观察沉积物脉冲和渠道特征范围的敏感性，该模型基于对单个沉积物“包裹”的拉格朗日跟踪，它们具有独特的特征，例如磨损率和密度，例如NSF的宣传奖，反映了NSF的立法任务，并通过评估通过基金会的知识效果和广泛的评估来评估，并被视为珍贵。