Note on Lag in Bedload Discharge
Publication: Journal of Hydraulic Engineering
Volume 118, Issue 6
Abstract
It is postulated that movable sediment beds comprise of two types of grains, termed undisturbed and disturbed grains. The probability of entrainment by flow of the latter is higher than that of the former. The lag in bedload transport is due to the difference in the entrainment probabilities of the two types of grains. A model is developed to predict lag in bedload transport. The spatial‐ and temporal‐lag coefficients are functions of both the inner and outer variables. The 50% of the equilibrium bedload discharge is attained within about 26% of the total lag distance or lag time. The lag model was verified by conducting laboratory experiments and using experimental data of Bagnold. The proposed model agrees with the experimental data. Both the lag distance and lag time decrease with increasing equilibrium bedload discharge. The findings of the model can be used to improve the Einstein formula for the equilibrium bedload discharge.
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References
1.
Bagnold, A. J. (1936). “The movement of desert sand.” Proc. Royal Soc. London, Royal Society of London, A157, 594–620.
2.
Bell, R. G., and Sutherland, A. J. (1983). “Nonequilibrium bed load transport by steady flow.” J. of Hydr. Engrg., ASCE, 109(3), 351–367.
3.
Brand, L. (1966). Differential and difference equations. John Wiley and Sons, New York, N.Y.
4.
Cantwell, B. J. (1981). “Organized motion in turbulent flow.” Annual Review of Fluid Mech., 13, 457–515.
5.
Daubert, A., and Lebreton, J. C. (1967). “Etude experimentale et sur modele mathematique de quelques aspects des processus d'erosion lits alluvionnaires, en regime permanent et non permanent.” Proc., 12th Congress, International Association for Hydraulic Research, 3 (in French).
6.
Di Silvio, G., and Armanini, A. (1991). “Discussion of Modeling of riverbed evolution for bedload sediment mixtures,” by J. L. Rahuel, F. M. Holly, I. P. Chollet, P. J. Belleudy, and G. Yang. J. Hydr. Engrg., ASCE, 117(7), 949–951.
7.
Einstein, H. A. (1950). “The bed load function for sediment transportation in open channel flow's.” Tech. Bull. 1026, U.S. Dept. of Agric., Soil Conservation Service, Washington, D.C.
8.
Grass, A. J. (1970). “The initial instability of fine sand.” J. Hydr. Div., ASCE, 96(3), 619–632.
9.
Jain, S. C. (1990). “Sediment transport under nonequilibrium conditions.” Movable bed physical models, Kluwer Academic Publishers, Dordrecht, The Netherlands.
10.
Nakagawa, H., and Tsujimoto, T. (1980). “Sand bed instability due to bed load motion.” J. Hydr. Div., ASCE, 106(12), 2029–2051.
11.
Phillips, B. C., and Sutherland, A. J. (1984). “Spatial and temporal lag effects in bedload sediment transport.” Report No. 84‐10, Dept. of Civ. Engrg., Univ. of Cantebury, Christchurch, New Zealand.
12.
Phillips, B. C., and Sutherland, A. J. (1985). “Numerical modeling of spatial and temporal lag effects in bed load sediment transport.” Proc., 21st Congress, International Association for Hydraulic Research, 3, 571–576.
13.
Phillips, B. C., and Sutherland, A. J. (1989). “Spatial lag effects in bed load sediment transport.” J. Hydr. Res., 27(1), 115–133.
14.
Rahuel, J. L., Holly, F. M., Chollet, J. P., Belleudy, P. J., and Yang, G. (1989). “Modeling of riverbed evolution for bedload sediment mixtures.” J. Hydr. Engrg., ASCE, 115(11), 1521–1541.
15.
Shen, H. W., and Lu, J.‐Y. (1983). “Development and prediction of bed armoring.” J. Hydr. Engrg., ASCE, 109(4), 611–629.
16.
Sumer, B. M., and Deigaard, R. (1981). “Particle motion near the bottom in turbulent flow in open channel, part 2.” J. Fluid Mech., 109(Aug.), 311–337.
17.
Sutherland, A. J. (1967). “Proposed mechanism for sediment entrainment by turbulent flows.” J. of Geophysical Res., 72(24), 6183–6194.
18.
Wellington, N. B. (1978). “A sediment‐routing model for alluvial streams.” Master of Engrg. Sci. Dissertation, University of Melbourne, Melbourne, Australia.
19.
Willmarth, W. W., and Lu, S. S. (1972). “Structure of the Reynolds stress near the wall.” J. Fluid Mech., 55(Sept.), 65–69.
20.
Yalin, M. S. (1972). Mechanics of sediment transport. Pergamon Press, Elmsford, N.Y.
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Copyright © 1992 ASCE.
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Published online: Jun 1, 1992
Published in print: Jun 1992
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