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

本研究利用各种新技术，通过对水流和泥沙运动的同步测量，阐明了包括实验室水槽和野外河流在内的各种尺度的泥沙输移和河床变化的机理，如漩涡对泥沙的悬浮、河床形态、输沙量和泥沙分选等。这项工作已作为与日本土木工程师协会水力学委员会工作组的联合研究得到推广。1991年12月，两个研究组共同举办了一次小型的“水流泥沙同步测量”研讨会。研究结果如下：根津在实验室水槽中，用双分量激光风速计和水位计测量了沙丘上非恒定流的湍流结构，发现在洪水上升阶段湍流强度和悬沙浓度高于下降阶段。 ...更多信息 本文介绍了一种利用微机自动测量沿着任意曲线的河床形态的新技术，阐明了在洪水期间没有发现明显的床面变化的弯曲河道中的河床变化特征。池田阐明了在大型实验室水槽中的纵向泥沙分选，并讨论了大井河中岩石河床的影响。Sawada和Ashida通过对Jinzu河Ashiaraidani流域的长期观测，阐明了山区河流泥沙径流的特征。结果表明，输沙量的变化与河流的变化密切相关。长谷川、木下、西田、富永等人通过对石狩川、白别川、高濑川、群马灌溉渠等的观测，明确了低地河流的洪水和泥沙输移。富永等人通过实验室水槽和野外河流的水流结构的相似性，明确了水流结构的相似性。西田等al设计了一种新技术，在桥边用一对绳子支撑探针，并观察了河口附近盐度和流速场的变化。长谷川在石狩川河口附近同时观测了流速和悬沙，发现剪切流速和含沙量的峰值出现在水位峰值之前。木下曾尝试利用气垫船和流动浮标快速测量床面剖面，发现了一系列波长比约为6的床面形态。少

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