Sediment routing in gravel-bed rivers following dam removal

该奖项是根据2009年《美国恢复和再投资法案》(公法111-5)资助的。了解河流如何应对泥沙供应变化的基础知识，对于管理与拆除大型大坝相关的问题至关重要。大坝拆除也为了解对大型泥沙脉冲的响应创造了机会，这对规划和溪流恢复至关重要。该项目将研究2008年拆除密苏里州克拉克福克河上的米尔敦大坝，以开发对沉积和地貌过程的新见解，包括沉积物脉冲在河流中移动的速度、沉积位置、渗透到砾石河床的程度、传播距离以及如何影响河道形态。这将通过测量推移质输运；对床料取样以评估质地变化、入渗动力学和污染物输送；以及重复调查河床、沙洲和滩涂地形，以确定泥沙沉积和侵蚀的空间和时间模式，实现这一目标。与现场工作相辅相成的是对沉积物地球化学的实验室分析、对细微沉积物进行指纹分析、调查含金属水库沉积物的运移、以及水流和泥沙运移过程的模拟。这项研究通过开发一个关于大型大坝拆除的地貌响应的综合数据集，并将这些结果推广到研究区域之外，将有助于发展更具预测性的科学，为大坝拆除和河流恢复提供信息。这项研究还将对砾石河床河流中泥沙脉冲的运动和命运进行现场实验，用于评估来自水槽和较小河流的理论和数据如何应用于更大的河流。鉴于可能用于下游运输的水库沉积物的数量(约300万立方米)和质量(不同程度的采矿产生的污染)，这里调查的大坝拆除尤其重要。这个项目将建立在美国国家科学基金会探索性研究小额拨款项下，在米尔敦大坝拆除之前和之后立即收集的数据基础上。外展工作将包括为蒙大拿州部落学院的学生和参加大天空科学伙伴关系的K-8教师举办关于河流过程和大坝拆除的讲习班。教育和外展还将通过蒙大拿大学S中心的河流科学和河流复原化会议以及对研究生和本科生的支持来实现。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Fundamental knowledge of how rivers respond to changes in sediment supply is essential to the management of issues associated with the removal of large dams. Dam removal also creates an opportunity for learning about the response to large sediment pulses, which is critical for planning and stream restoration. This project will examine the 2008 removal of Milltown Dam on the Clark Fork River, MT, to develop new insights into sedimentary and geomorphic processes, including how quickly sediment pulses move through rivers, where they deposit, the extent to which they infiltrate into gravel river beds, how far they propagate, and how they affect channel morphology. This will be achieved through measurements of bedload transport; sampling of bed material to assess textural changes, infiltration dynamics, and contaminant transport; and repeat surveys of river bed, bar and floodplain topography to identify spatial and temporal patterns of sediment deposition and erosion. Field efforts will be complemented by laboratory analysis of sediment geochemistry, to fingerprint fine sediment and investigate transport of metal-laden reservoir sediments, and modeling of flow and sediment transport processes.This research, by developing a comprehensive dataset on geomorphic response to a large dam removal and generalizing those results beyond the study area, will contribute to emerging efforts to develop more predictive science for informing dam removals and river restoration. This research will also represent a field-scale experiment into the movement and fate of sediment pulses in gravel-bed rivers that will be used to evaluate how theory and data from flumes and smaller streams can be applied to larger rivers. The dam removal investigated here is especially significant in light of the quantity (approximately 3 million cubic meters) and quality (varying degrees of mining-derived contamination) of reservoir sediments potentially available for downstream transport. This project will build on data collected immediately before and after the Milltown dam removal under a NSF Small Grant for Exploratory Research. Outreach efforts will include workshops about river processes and dam removal for students from Montana Tribal Colleges and for K-8 teachers participating in the Big Sky Science Partnership. Education and outreach will also be achieved through the University of Montana?s Center for Riverine Science and Stream Renaturalization conferences and support for graduate and undergraduate students.