Formation and Characteristics of Sandbars at Both Experiment and Prototype Scales
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The large-scale sandbars resulted from the instability of loose sedimentary materials through complex flow phenomena are very common in lowland rivers. These bars, on one hand, make the river highly unstable forming anabranches, influencing bank erosion, etc.; while these are habitats for various species in river ecosystem on the other. Thus the study on their formation processes and their characteristics at natural scale becomes very urgent for better management of river engineering. RIC-Nays, a two-dimensional model for flow and morphology is utilized in this study, where CIP method for convective terms and depth-averaged parabolic eddy viscosity model for turbulence are applied. Formation processes of alternate and multiple bars in experiment scale are examined to verify the simulation results. The results show reasonably good agreement when compared with theoretical and experimental data. It is found that different initial conditions lead to different equilibrium states, and periodic boundary conditions with a small computation domain tend to stabilize multiple bars. The multiple bar patterns as present in the natural rivers are well reproduced in the simulation, where the evolution of bars is apparent with a pool-bar complex with asymmetrical profile in along-stream section and avalanche face on downstream side.
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J.M. Coleman, Brahmaputra River: channel processes and sedimentation. Sedimentary Geology 3, 129–239, 1969.
S. Ikeda, Flow and bed topography in channels with alternate bars. In: River Meandering, Proc. of the Conf. Rivers '83. (ed. by CM. Elliott), ASCE, 733-746, 1984.
Y. Fujita and Y. Muramoto, Studies on the process of development of alternate bars. Bulletin of the disaster prevention research institute 35, Kyoto, pp.55-86, 1985.
Y. Fujita, Bar and channel formation in braided streams, River meandering. Water Resources Monograph 12, pp.417-462, 1989.
E. Hansen, The formation of meanders as a stability problem. Hydraul. Lab., Tech. Univ. Denmark Basic Res. Prog. Rep. 13, 1967.
G. Parker, On the cause and characteristic scales of meandering and braiding in rivers, Journal of Fluid Mechanics, 76(3), pp.457-480, 1975.
S. Fukuoka and M. Yamasaka, Equilibrium height of alternate bars based on non-linear relationships among bed profiles, flow and sediment discharge. Proc. of JSCE, No. 357, pp. 45-54 (in Japanese), 1985.
M. Colombini, G. Seminara, and M. Tubino, Finite amplitude alternate bars. Journal of Fluid Mechanics, 150, pp.213-232, 1987.
A. Pornprommin and N. Izumi, Nonlinear stability analysis of alternate and multiple bars. 2nd Proc. RCEM2001, IAHR, Japan, pp.693-702, 2001.
N. Izumi and A. Pornprommin, Weakly nonlinear analysis of bars with the use of the amplitude expansion method. Proc. of JSCE (in Japanese), 2002.
H. Takebayashi, S. Egashira, and T. Okabe, Stream formation process between confining banks of straight wide channels. 2nd Proc. RCEM2001, IAHR, Japan, pp.575-584, 2001.
H. Kurabayashi and Y. Shimizu, Numerical calculation of bed deformation in braided stream with emerged mid-channel bars. Annual Journal of Hydraulic Eng. 46, JSCE, pp.743-748 (in Japanese), 2002.
T. Yabe, T. Ishikawa, Y. Kadota, and F. Ikeda, A numerical cubic-interpolated pseudoparticle (CIP) method without time splitting technique for hyperbolic equations. J. Phy. Soc., 59(7), 2301-2304, 1990.
A. Teramoto, S. Nakamura and T. Tsujimoto, Bank erosion with bar migration. Int. Sym. Disaster Mitigation & Basinwide Water Management，Niigata, Japan, B06, CD-ROM, 2003．
K. Ashida and M. Michiue, Studies on bed load transportation for nonuniform sediment and river bed variation. Disaster Prevention Research Institute Annuals, Kyoto university, No. 14B, pp. 259-273 (in Japanese), 1972.
K. Hasegawa, Hydraulic research on planimetric forms, bed topographies and flow in alluvial rivers, PhD Dissertation, Hokkaido University (in Japanese), 1983.
F. Engelund, Flow and bed topography in channel bends, Journal of Hydraulic Division, ASCE, Vol. 100, No. 11, pp. 1631-1648, 1974.
Y. Shimizu and T. Itakura, Calculation of flow and bed deformation with a general non-orthogonal coordinate system. Proc. of XXIV IAHR Cong. Madrid, Spain, Vol. C, pp.241-248, 1991.
T. Itakura and T. Kishi, Open channel flow with suspended sediments. Proc. of ASCE, HY8, pp.1325-1343, 1980．
W.W. Rubey, Settling velocities of gravel, sand and silt particles. Am. J. Sci. 225, p. 325, 1933.
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