Developing Mechanistic Models for Bedrock Erosion at Waterfalls.

瀑布的上游运动控制了许多景观的形状，并决定了景观对气候和构造变化的反应速度。然而，我们目前缺乏瀑布侵蚀的机制模型，这抑制了我们预测景观对环境扰动的反应的能力。这个项目的目标是通过室内瀑布实验室的实验和自然界中瀑布过程的监测来填补这一知识空白。瀑布实验将在加州理工学院最新的最先进的水力和沉积物水槽中完成。这一工作将为瀑布式跳水池的输沙能力和侵蚀提供数学理论依据。从水槽实验中开发的模型将根据我们将在加利福尼亚州圣盖博山脉的一个活动瀑布收集的沉积物运输数据进行测试，并在更长的时间尺度上根据以前的研究编制的瀑布退缩率的新数据库进行测试。除了推导和测试瀑布退却的模型外，我们的工作将有助于了解山涧中的沉积物路径和储存，因为瀑布跳水池是天然的临时沉积物汇，对于减轻河流洪水危害和了解夏季依赖于水池的水生生物的栖息地具有重要意义。该提案的一个重点是综合研究和教育计划。瀑布是自然景观中无处不在、令人敬畏的地貌；它们提供了一个很好的媒介，让学生和公众对侵蚀、沉积以及景观演变等问题产生兴趣。拟议的教育计划包括指导将直接参与研究的夏季本科生研究员和博士生。通过加州理工学院暑期本科生研究奖学金计划，本科生将定义和开发一个项目，撰写研究提案，开展实验室和实地工作的子集，提交一篇技术论文，并在模仿专业技术会议的研讨会上进行口头报告。外展活动将集中在帕萨迪纳联合学区（p.u.s.d）的学生和教师的参观、课堂参观和实地考察，该学区的大多数学生来自地球科学领域代表性不足的群体。

The upstream movement of waterfalls controls the shape of many landscapes and sets the rate by which landscapes respond to changes in climate and tectonics. However, we currently lack mechanistic models for waterfall erosion which inhibits our ability to predict landscape response to environmental perturbations. The goal of this project is to fill this knowledge gap through a combination of experiments in an indoor waterfall laboratory and monitoring waterfall processes in nature. The waterfall experiments will be completed in a new state-of-the-art hydraulic and sediment flume at the California Institute of Technology. This work will lead to mathematical theories for the sediment transport capacity and erosion of waterfall plunge pools. The models developed from flume experiments will be tested against sediment transport data that we will collect at an active waterfall in the San Gabriel Mountains, CA, and over longer timescales against a new database of waterfall retreat rates compiled from previous studies. In addition to deriving and testing models for waterfall retreat, our work will aid understanding sediment routing and storage in mountain streams because waterfall plunge pools are natural temporary sediment sinks, with importance for mitigating river flood hazards and understanding habitats of aquatic organisms that depend on pools in summer months. A focus of this proposal is an integrated research and education program. Waterfalls are ubiquitous and awe-inspiring landforms in the natural landscape; they provide a great medium through which to interest students and the public in issues of erosion and sedimentation, as well as landscape evolution. The proposed educational program includes mentoring summer undergraduate research fellows and PhD students who will be directly involved with the research. Through the Caltech Summer Undergraduate Research Fellowship program, undergraduate students will define and develop a project, write research proposals, carry out subsets of the laboratory and field work, submit a technical paper, and give an oral presentation at a symposium modeled on a professional technical meeting. Outreach events will be focused on tours, classroom visits, and field excursions for students and teachers in the Pasadena Unified School District (P.U.S.D.), a district where the majority of students are from groups under-represented in geosciences.