Author(s): Hiroshi Miwa; Atsuyuki Daido; Jun Yokogawa
Linked Author(s): Hiroshi Miwa
Keywords: Lternate bars; Meandering streambed; Sediment supply; Emerged bar; Non-uniform sediment
Abstract: Effects of sediment supply on the formation of meandering stream bed in a straight channel with alternate bars are investigated through flume tests using the uniform and the non-uniform sediment. Results are summarized as follows: (1) Meandering streams develop in consequence of the emerged bar formation due to the concentration of the flow to the pools of alternate bars. The meandering streams are shallow and fluctuate actively because the emerged bars repeat appearance and disappearance when the bed level does not vary. However, the deep and stable meandering streams are formed because the emerged bars are stable when the bed degradation progresses. (2) An individual emerged bar in the non-uniform sediment bed is formed with grain sorting, and its upper and lower part mainly consists of coarse grains and fine grains, respectively. Even if the emerged bars repeat appearance and disappearance, its period is longer than the uniform sediment bed and the emerged bars are relatively stable. (3) An individual pool migrates to downstream when the riverbed level does not vary, whereas it stops when the meandering stream becomes stable. (4) The wavelength of the meandering stream considerably increases with progression of the bed degradation, and the wavelength in the non-uniform sediment bed is longer than that in the uniform one.
Year: 2004