Unstability of meandering streams and river bed erosion by meandering streams

曲流的不稳定及曲流对河床的侵蚀

基本信息

批准号：
07650602
负责人：
FUJITA Masaharu
金额：
$ 1.28万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650602/
关键词：
meandering stream meander river bed erosion 2-dimensional bed variation river morphology numerical simulation 水みち侵食シミュレーション

项目摘要

An formation process of meandering streams on river beds with non-uniform sediment was investigated experimentally and a simulation method for this process was developed using a 2-dimensional bed variation model. The results of this research are mainly as follows :(1) A formation process of meandering streamsAt the sirst step of the formation process observed in an experiment, the largest gravel stops at the crest of the untidunes. The gravel makes it easy for the transported sediment to be deposited just upstream of the gravel. A sand bar is formed through such a process and consequently a meandering stream is formed. The longitudinal and lateral sorting of bed material makes the stream more stable, but it turn unstable if the fine sediment flows out of the bar.(2) Development of simulation modelA method for simulating the formation process is developed using a 2-dimensional bed variation model. The comparison between the experimental and calculated results on the bed variation have shown the validity of the method.(3) ApplicationThe simulation model was applied to the formation process of the meandering streams observed in an experiment. The number and wave length of meandering streams are simulated by this method, but not the changeability of meandering streams. The simulated stream was fixed because the flow structure and sediment transport mechanism near the side walls are not precisely introduced in the model.

对沉积不均匀的河床上蜿蜒溪流的形成过程进行了实验研究，并利用二维河床变化模型建立了该过程的模拟方法。本研究的主要成果如下： (1)曲流溪流的形成过程在实验中观察到的曲流溪流形成过程的第一步，最大的砾石停在了曲流的顶部。砾石使得输送的沉积物很容易沉积在砾石的上游。经过这样的过程，就形成了沙坝，从而形成了蜿蜒的溪流。床质的纵向和横向排序使河流更加稳定，但如果细泥沙流出坝体，河流就会变得不稳定。（2）模拟模型的开发开发了一种利用二维床层变化模拟形成过程的方法。模型。床层变化的实验结果与计算结果的比较表明了该方法的有效性。(3)应用将模拟模型应用于实验观测到的曲流流的形成过程。该方法模拟了曲流的数量和波长，但没有模拟曲流的变化性。由于模型中没有精确引入侧壁附近的流动结构和泥沙输送机制，因此模拟的河流是固定的。