When do boulders move in steep mountain streams?

该奖项是根据2009年美国复苏和再投资法案（公法11-5）资助的。丘陵和山区景观中的大多数河流都有小而陡峭的河道，通常被很少移动的巨石覆盖。 在这些通道中，巨石减缓了河流的切割速度，使水流变得粗糙，形成了当地的砾石斑块，并为鲑鱼和虹鳟鱼产卵等各种生物提供了重要的栖息地。 粗泥沙也可能被河流洪水夹带，冲下斜坡，造成相当大的破坏性后果。 目前没有理论或经验模型存在，成功地预测阈值的运动巨石或其组织的河流过程。 该研究项目通过理论、实验和实地相结合的方法，解决了基础知识中的这一根本差距。 一个半经验理论的漂砾流动性和步骤池形成将开发和测试使用一个新建成的国家的最先进的实验室水槽在加州理工学院。水槽实验将允许探索在过去的研究中受到严重限制的通道坡度（高达30%）和粒度（高达10厘米）。 实验将被设计成调查的条件下，巨石移动和巨石组织成步骤和池负责的机制。 这些实验的数据将被用来测试和验证预测模型的巨石运输和步骤池的形成。 实验和理论研究结果将进行比较，在巨石运动事件中观察到的流动条件在支流的南福克鳗鱼河在加州大学安杰洛海岸山脉保护区。 其结果将是一个强大的方法来计算巨石运输动力学在陡峭的山溪，与预测景观演变的影响，通过陡峭的渠道，关键的栖息地条件，并有益于利用巨石在恢复项目的沉积物的运动速度。 该研究项目的结果将对基础科学和一些具有社会意义的实际问题产生重大影响。该项目的结果将有助于恢复和减灾工作，其中需要评估巨石的流动性以恢复溪流栖息地（例如，鲑鱼产卵）和功能，以及减轻陡峭城市地区的洪水和泥石流危害。 该研究项目包括指导本科生，博士生和实验，实地和理论科学的博士后研究员。这项研究的研究将被uswd设计一个为期一天的工作坊，为地区高中教师。 目标将是让教师掌握必要的技能，教他们的学生简单的方法来评估洪水和泥石流的危险，可能导致生命和财产损失的洛杉矶地区。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 11-5).Most of the rivers in hilly and mountainous landscapes have small, steep channels, which are typically mantled by boulders that rarely move. In these channels, boulders moderate the rate of river incision, roughen the flow creating local patches of gravel , and provide crucial habitat for a variety of organisms such as salmon and steelhead spawning. Coarse sediment can also become entrained by river floods, which rush down slope with considerable destructive consequences. No current theory or empirical model exists that successfully predicts the threshold of movement of boulders or their organization by river processes. This research project addresses this fundamental gap in basic knowledge through a combined theoretical, experimental and field-based approach. A semi-empirical theory for boulder mobility and step-pool formation will be developed and tested using a newly constructed state-of-the-art laboratory flume at the California Institute of Technology. The flume experiments will allow exploration of channel slopes (up to 30%) and grain sizes (up to 10 cm) that have been severely limited in past studies. Experiments will be designed to investigate the conditions under which boulders move and the mechanisms responsible for boulder organization into steps and pools. Data from these experiments will be used to test and validate predictive models for boulder transport and step-pool formation. The experimental and theoretical findings will be compared to observed flow conditions during boulder movement events in tributaries of the South Fork Eel River in the University of California Angelo Coast Range Reserve. The result will be a robust method for calculating boulder transport dynamics in steep mountain streams, with implications for predicting landscape evolution, the rate of movement of sediment through steep channels, critical habitat conditions, and the beneficial use of boulders in restoration projects. The results from this research project will have significant implications for basic science and a number of practical concerns of societal relevance. Results from this project will aid in restoration and hazard mitigation efforts where assessing boulder mobility is needed for restoring stream habitat (e.g., salmon spawning) and functionality, as well as mitigating flood and debris flow hazards in steep urban areas. This research project includes mentoring undergraduates, a PhD student, and a post-doctoral researcher in experimental, field and theoretical science. Research from this study will be uswd to design a 1-day workshop for area high-school teachers. The goal will be to give teachers the necessary skills to teach their students simple ways to assess flood and debris flow hazards that can result in loss of life and property in the Los Angeles area.