Flow Structure in Steep Mountain Streams

9313688 Furbish该项目旨在提供可能发生在陡峭的山溪中的复杂流场的一般描述，山溪的形态包括不规则排列的稳定巨石和原木以及小砾石坝。 处理利用线性和非线性制剂，涉及深度集成的动量和质量连续性方程来描述如何流向和横向流速，和水面地形，响应一个不规则的床，其地形是显着更复杂的比冲积自形成的渠道。 这项工作是一个线性模型的扩展，该模型预测新生的弯曲形式的波长可以比占主导地位的弯曲形式的波长长。 理论方面的工作将进行测试，从北博尔德溪，科罗拉多收集的数据。 数据将来自一个长度接近80个河道宽度的单一河段，以及两个选定用于详细测量河床地形和水流的短河段。 结果将提供一个机械基础测试的想法，这些巨石通道可以经历一个自我稳定的时期，涉及到现存的流动条件，可变的河床和河岸材料，局部装甲的床之间的相互作用，和零碎运输的沉积物。

9313688 Furbish This project is aimed at providing a general description of the complex flow fields that can occur in steep mountain streams, whose morphologies consist of irregular arrangements of stable boulders and logs, and small gravel bars. The treatment makes use of both linear and nonlinear formulations involving depth-integrated equations of momentum and mass continuity to describe how streamwise and transverse flow velocities, and water-surface topography, respond to an irregular bed whose topography is significantly more complex than that of alluvial self-formed channels. The work is an extension of a linear model which predicts that the wavelength of nascent bend forms can be longer than that of the dominant bendforms. Theoretical aspects of the work will be tested with data collected rom North Boulder Creek, Colorado. Data will come from a single reach of nearly 80 channel widths in length, and from two short reaches selected for detailed measurements of bed topography and flow. Results will provide a mechanical basis for testing the idea that these bouldery channels can undergo a self-stabilizing period that involves an interaction among extant flow conditions, variable erodibility of bed and bank materials, local armoring of the bed, and piecemeal transport of sediment.