A Study on Sediment Transport and River Bed Variation Based on the Simultaneous Measurements of Flow and Sediment Movement in Various Scales

本研究采用多种新技术，通过对水槽和野外河流等不同尺度的水流和泥沙运动的同步测量，阐明了不同尺度的泥沙运动和河床变化，如涡流悬沙、河床形态、输沙和泥沙分选等。这项工作作为与日本土木工程师学会水力学委员会工作组的联合研究得到了推动。1991年12月，两个小组共同举办了一个名为“水流和泥沙运动的同时测量”的小型研讨会。利用双分量激光测速仪和水位计对沙丘上非恒定流的湍流结构进行了测量，发现洪水上升期的湍流强度和含沙量均高于下行期。Sawai设计了…。此外，还提出了一种利用计算机自动测量任意曲线上的河床形态的新技术，阐明了洪水期间曲流河河床的变化特征，发现河床水位没有明显的变化。池田阐明了大型实验室水槽中的纵向泥沙分选，并讨论了岩石河床在Ooi河中的影响。他还强调了冲刷对河道泥沙粒度变化的作用。Sawada和Ashida通过对金祖河Ashiaraidani流域的长期观测，阐明了山区溪流泥沙径流的特征。研究发现，输沙量的变化与水系的变化高度相关。他们还考虑了在未来的观测中测量什么以及如何准确。长谷川、木下、西田和富米那加通过在石卡里河、什里别特苏河、塔卡斯河和古玛灌溉河道等地的观测，澄清了低地河流的洪水和泥沙输移。Nishida et.Al设计了一种新的技术来支撑探测器，在桥旁边使用一对绳索，并观察了河口附近盐度和速度场的变化。长谷川同时观测了石垣河口附近的水流速度和悬沙，发现剪切速度和含沙量的峰值出现在水位峰值之前。木下试图利用悬停飞行器和流动浮标快速测量床面，发现了一系列波长比约为6。

In this study, the mechanism of sediment transport and river bed variation such as suspension of the sediment by eddies, bed configuration, sediment discharge and sediment sorting with various scales including laboratory flumes and field rivers are clarified through simultaneous measurements of flow and sediment movement with the help of various new techniques. This work had been promoted as the joint research with the Working Group of Hydraulics Committee of Japan Society of Civil Engineers. In December, 1991, a mini-symposium "simultaneous measurements of flow and sediment transport" was co-held by the both groups. The results obtained by each investigator are summarized as follows:Nezu measured the turbulent structure of unsteady flow on dunes in a laboratory flume, using two component laser anemometer and water level gage, and found that the turbulence intensity and suspended sediment concentration are higher in the rising stage than in the descending stage of a flood.Sawai devised … More a new technique to measure a bed form along arbitrary curves automatically using a personal computer and clarified the characteristics of the bed variation in a meandering channel during a flood, in which no remarkable variation of bed level was found.Ikeda clarified the longitudinal sediment sorting in a large scale laboratory flume and discussed about the effect of rocky stream bed in River Ooi. He also emphasizes about the role of abrasion on the sediment size variation along river courses.Sawada and Ashida clarified the characteristics of the sediment runoff in a mountain stream through long term observation in Ashiaraidani basin of Jinzu River. It was found that the variation of sediment discharge is highly correlated with stream variation. They also considered about what and how accurate to measure in future observation.Hasegawa, Kinoshita, Nishida and Tominaga clarified the flood flow and sediment transport in low land rivers through observation in River Ishikari, River Shiribetsu, River Takase and Gumma Irrigation Channel etc. Through Tominaga's work, the similarity of flow structure between laboratory flumes and field rivers was ascertained. Nishida et. al devised a new technique to support the probes using a pair of ropes beside a bridge and observed the variation of salinity and velocity field near a river mouth. Hasegawa observed the flow velocity and suspended sediment simultaneously near the mouth of River Ishikari and found that the peak of shear velocity and sediment concentration appears before that of the water level. Kinoshita tried to utilize a hover craft and a flowing buoy to measure bed profile quickly and found out a series of bed forms with the wave length ratio about 6. Less