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Run-off process of suspended sediment in mountain rivers

山区河流悬浮泥沙径流过程

基本信息

批准号：
09460069
负责人：
FUJITA Masaharu
金额：
$ 2.88万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09460069/
关键词：
Suspended load Mountain river Runoff process Diffusion theory Diffusion equation Source term Field observation Flood 土砂流出流砂濃度分布乱流

项目摘要

1. Stream flows and runoff process of suspended sedimentWe observed suspended sediment concentration, flow discharge and rainfall intensity simultaneously in the Takahara river basin and discussed their relationship. As a result, the following matters were found out. Suspended load concentration is strongly dependent on rainfall intensity, but the relation between them is not unique because the soil on slopes is quickly washed out. The relation between flow discharge and suspended load concentration is not also unique because of the same reason. This change in the situation of source areas should be studied in future.2. Diffusion theory of suspended sedimentAccording to previous study, the diffusion equation of suspended sediment which is generally used cannot explain a suspended sediment concentration in a steep channel with a large roughness without the much larger diffusion coefficient In this paper, we have presented a diffusion equation with a source term and shown the concentration in the above-mentioned channel can be expressed by means of the equation with the ordinary diffusion coefficient.3. Modeling of runoff process of suspended sedimentIf the boundary condition of suspended load concentration is given, the runoff process of suspended sediment in river systems can be analyzed by means of the presented diffusion theory. However, the boundary condition can not be easily evaluated because the sediment production process is too complex. We will study more about this point.

1. 在高原河流域同时观测了悬沙浓度、流量和降雨强度，并讨论了三者之间的关系。结果，发现了以下事项。悬载集中与降雨强度密切相关，但两者之间的关系并非唯一，因为斜坡上的土壤很快被冲刷掉。由于同样的原因，流量与悬载浓度之间的关系也不是唯一的。这种源区情况的变化应在今后进行研究。2 .悬沙扩散理论根据以往的研究，如果没有更大的扩散系数，一般使用的悬沙扩散方程就不能解释大粗糙度陡峭河道内的悬沙浓度。本文提出了一个带源项的扩散方程，并表明可以用普通扩散系数的方程来表示上述河道内的悬沙浓度。悬沙径流过程的建模如果给出了悬沙浓度的边界条件，就可以利用所提出的扩散理论对水系悬沙径流过程进行分析。但是，由于产沙过程过于复杂，边界条件难以确定。我们将进一步研究这一点。