Hydraulic Jump Mechanics and Channel Interactions in Mountain Rivers

0207713 pasternackmountain河流中的水力跳跃是空气和水的湍流混合物，产生显著的动能耗散、空气娱乐、表面波和喷雾。尽管它们普遍存在，但天然水力跳跃在河流流动力学、泥沙运输、河道变化和盆地演化中的作用尚不清楚，主要是因为不利的场地条件限制了以前的现场数据收集。该项目的总体目标是克服过去在自然环境中研究水力跳跃流体力学及其与河流地貌的相关性方面的限制，借助新技术，首次实现精确的原位测量。加州大学戴维斯分校开发和测试的新技术包括河流桁架、空气含量传感器和大规模粒子图像测速仪。新技术将用于解决三个假设，预测渠道几何形状和流量外部控制的系统变化如何直接影响水面地形、速度、压力、空气含量、空气娱乐和能量耗散的响应变量。响应变量在泥沙运移、河道变化和盆地演化中的作用将遵循对响应变量本身的彻底调查，特别是在处理河床附近的条件时。在3年的时间里观察美国河流域的13个天然水力跳跃将检验假设。结果将在跳跃之间进行比较，并与使用理论和经验方程的基于工程水槽的研究结果进行比较。更好地理解自然跳跃在河道变化中的作用对科学具有重要意义，因为它将改进景观演化模型的物理学，为河流恢复和修复中纳入河内特征提供必要的指导，并对生态学和水生地球化学做出跨学科贡献。在未来的研究中，其他科学家将能够应用新验证的现场技术和由此产生的模型来更好地理解山区河流中复杂的流动力学和渠道相互作用。

0207713PasternackHydraulic jumps in mountain rivers are turbulent mixtures of air and water that produce significant kinetic energy dissipation, air entertainment, surface waves, and spray. Despite their prevalence, the role of natural hydraulic jumps on river flow mechanics, sediment transport, channel change, and basin evolution is unknown primarily because of adverse site conditions that previously limited field data collection. The overall goal of this project is to overcome past constraints on investigating hydraulic jump fluid mechanics in the natural setting and its relevance to fluvial geomorphology with the aid of new technologies that enable precise in situ measurement for the first time. New technologies developed and tested at UC Davis include a River Truss, an air content sensor, and large-scale particle image velocimetry. The new technologies will be used to address three hypotheses that predict how systematic changes in the external controls of channel geometry and discharge directly affect the response variables of water surface topography, velocity, pressure, air content, air entertainment, and energy dissipation. The role of response variables in sediment transport, channel change, and basin evolution will follow from a thorough investigation of the response variables themselves, especially when addressing conditions near the bed. Observing 13 natural hydraulic jumps in the American River basin over a 3-year period will test hypotheses. Results will be compared between jumps and against results from engineering flume-based studies using theoretical and empirical equations. A better understanding of the role of natural jumps in channel change is very important to science because it would improve the physics of landscape evolution models,provide needed guidance for including in-stream features in river restoration and rehabilitation, and make interdisciplinary contributions to ecology and aquatic geochemistry. In future research, other scientists will be able to apply the newly proven field technologies and resulting models to better understand the complex flow mechanics and channels interactions occurring in mountain rivers.