River Bed Variation Research Articles

Exclusion of Deposited Sediments in Reservoir by the Water Level Drop at the Downstream End

The method of excluding the deposited sediment by dropping water level and increasing the tractive force in dam-reservoir was discussed. But, when this method is applying into the diffusive theory of river-bed variation, it is not clear that which boundary condition must be used for different width of excluding gate and river. This study is concentrated on finding such a suitable boundary condition. experimently and theoreticaly. The comparison between the theoretical curve and the experimental data shows fairly good agreement.

Characteristics of Bed Variation at River Contraction during Flood

The characteristics of river bed variation at the contraction during the flood are investigated exprimentally. Moreover its characteristics for natural river which have several types of contraction are investigated by the numerical simulation on the basis of one dimensional bed variation method. From the experimental results, it is found the tendency that the bed level approaches to the bed level on equilibrium condition of sediment discharge for flood discharge. As the results, the bed level lowers during rising stage and then phenomenon of bed aggradation during the falling stage occurs at the up-stream end of the contraction. It is found from the numerical simulations that the bed variation of the contraction is influenced by the approach length, length of contraction and duration of the flood.

River bed Variation in Hinuma River by 8610 Flood

River bed Variation in Hinuma River by 8610 Flood

RIVER BED VARIATION DUE TO A FLOOD RUNOFF IN KAMANASHI RIVER (FUJI RIVER)

It has been pointed out that clarification of the river bed variation characteristics is an important problem in river engineering.In this paper, results of the research on the actual conditions of the bed variation based on detailed field survey in Kamanashi river are presented. The field survey is conducted for getting data of the bed form at two stages, just before and after a flood runoff, in the river.Putting emphasis of consideration on the bars in the river bed, changes of bar geometry during the flood runoff are discussed. On the basis of existing theoretical and experimental study, migration distance and velocity of the bars during the runoff are tried to estimated. For quantitative evaluation of the bed variation characteristics, some effective methods to analyze various field data are also presented.

Use of Airphotographs in Survey of River-bed Variation

Quantitative and morphologic variation of river-bed deposits are surveyed by comparison of airphotographs taken in different stages in order to check the annual variation and the influence of disaster of Typhoon No. 26, 1966.Many profiles along each same cross line settled on the airphotographs taken in 1957 and 1966 are drafted by stereoplanigraph C-8 and the areal variation of each profiles are summarized in connection with the river length between each cross line. In this surveyed area, river bed deposits are increased 2, 740, 000m3in volume for 9 years, and about 370, 000m3are derived by Typhoon No. 26.The greater part of increased deposits are derived from ready-transported river-bed deposits, terrace deposits and talus deposits along river side, and volume from mountain land slides are not so much.