COLLABORATIVE RESEARCH: Experimental Study of the Effect ofSediment Sorting on Bed Forms, Bed-Surface Texture and Fractional Transport Rates in Coarse, Mixed-Size Sediments

当一股单向水流流过粗砂层时 混合大小的沉积物，各种床的形式产生， 在装载物、床层、和床层之间存在颗粒尺寸的分离 表面层和基底。 有一种强烈而复杂的 河床形态、输移泥沙 和衬底。 许多研究在良好分选的砂，无论是在 在实验室和现场，已经导致了相当好的 了解熟悉的沙丘床形态的行为， 河床形态和运输之间的相互作用。 最近， 各种各样的特征被描述为推移质层，砾石波， 据报道，碎屑堵塞的情况发生在分选不良的河流上， 砂砾混合物 这些看起来 不同的床层特征，以及它们对 床，不清楚。 这是一项关于河床特征性质的实验研究 在单向流动中，作为流动强度的函数， 沉积物分选涉及几种沉积物混合物， 平均尺寸相同，约为4 mm，但分选差异很大， 以几个平均流速在每个 沉积物混合物 目标是统一描述 基本特点和相互关系的各种 在这些流动中产生的各种床特征。 这项工作将与Hiroshi教授合作完成 池田教授、高山茂美教授和 筑波大学环境研究中心。 这 建议书包括PI和毕业生的工资和差旅费 研究助理两年。 一项配套提案， Peter R.教授提交了相同的科学文本。 约翰霍普金斯大学。 这家日本集团 已经有了建造实验装置的资金， 进行实验。

When a unidirectional current passes over a bed of coarse mixed-size sediment, a variety of bed forms are generated, and there is segregation of particle sizes among the load, the bed surface layer, and the substrate. There is a strong and complex interdependence between the bed forms, the transported sediment, and the substrate. Many studies in well sorted sands, both in the laboratory and in the field, have led to fairly good understanding of the behavior of the familiar dune bed forms and the interaction between bed forms and transport. More recently, features variously described as bed-load sheets, gravel waves, and clast jams have been reported in flows over poorly sorted sand-gravel mixtures. The relationships among these seemingly diverse bed features, and their dependence on size segregation in the bed, is unclear. This is an experimental study of the nature of bed features in unidirectional flows as a function of flow strength and sediment sorting involving several sediment mixtures with the same mean size of about 4 mm but with widely varying sorting and making series of runs at several mean flow velocities over each sediment mixture. The objective is a unified picture of the fundamental characteristics and interrelationships of the various kinds of bed features produced in these flows. The work will be done in cooperation with Prof. Hiroshi Ikeda, Prof. Shigemi Takayama and Dr. Fujiko Iseya of the Environmental Research center at the University of Tsukuba. This proposal covers salary and travel for the PI and a Graduate Research Assistant for two years. A companion proposal with identical scientific text is being submitted by Prof. Peter R. Wilcock (The Johns Hopkins University). The Japanese group already has funds for building the experimental apparatus and conducting the experiments.