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

山区的滑坡产生大量的瓦砾，这些瓦砾被河流侵蚀并向下游移动到人口稠密的低地地区。这些滑坡的砾石成分会堆积在河床上，增加下游社区发生洪水的频率。河床中岩石大小的变化可能会改变生活在那里的鱼类和昆虫的栖息地。或者，如果滑坡中的沉积物比沙子小，它可能导致浑浊的水，需要昂贵的过滤饮用水或灌溉，往往是有害的鱼类，昆虫和其他动物生活在河里。 不同河流和滑坡沉积物特性的下游影响很重要，因为气候变化可能会增加滑坡和受影响河流内的沉积物移动量。该项目将确定沉积物的岩石类型（密度和耐久性）在多大程度上控制河床上沉积物积聚的时间和规模以及粒度组成，特别注意太平洋西北部火山地形中的河流。该项目将通过短暂的过夜实地考察向新生介绍地球科学，让他们参与研究并与区域洪水管理人员分享成果。在太平洋西北部，大量重大的质量浪费事件发生在火山地带，产生不同密度和磨损率的沉积物脉冲。该项目将使用现场观测和建模来描述河道对这些大的沉积物脉冲的敏感性。研究的重点是沉积物脉冲的岩性特征如何控制下游河道响应的时间和幅度。这一问题将通过以下方式解决：量化几个盆地中质量浪费沉积物沉积特征的变化;模拟河流中特定质量浪费事件的下游命运，其中下游磨蚀和通道响应具有良好的现场约束;以及使用该模型确定河流系统对沉积物脉冲和河道特征的观测范围的敏感性，该奖项反映了NSF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。

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.