Flow Patterns in Compound Channels with Vegetated Floodplains
Publication: Journal of Hydraulic Engineering
Volume 133, Issue 2
Abstract
Understanding the hydraulics of flow in a compound channel with vegetated floodplains is very important for determining the stage-discharge curve and for supporting the management of fluvial processes. In this paper, the flow patterns over different types of vegetation, such as tree, shrub, and grass, are described, based on an experimental study. For vegetation on the floodplain, the authors choose plastic grass, duck feathers, and plastic straws as model grass, shrubs, and trees, respectively. A 3D acoustic Doppler velocimeter was used to measure the local flow velocities for different types of vegetation on the floodplain, and the total discharge and flume slope were measured independently. In the cases of nonvegetated floodplains, all measured streamwise velocity distributions followed the logarithmic distribution, but for vegetated floodplains, they followed an S-shaped profile, exhibiting three zones. For all cases, the fluctuating velocity followed a normal distribution. The influence of different types of vegetation on the distributions of the secondary currents, turbulence intensities, and Reynolds shear stresses were also analyzed.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers gratefully acknowledge the support of the 973 Program of China (No. 2003CB415202) and the National Natural Scientific Foundation of China (No. 50579040). The first author also wishes to acknowledge all the teachers and students in the River Engineering office of SKHL who offered much help during this research. Particular thanks are due to Professor Bing Shi, professor of civil engineering at the Ocean University of China, and his students, Mr. Yong Huang and Mr. Zhiyang Jiao, who participated in the experiments from the beginning to the end.
References
Abril, J. B., and Knight, D. W. (2004). “Stage-discharge prediction for rivers in flood applying a depth-averaged model.” J. Hydraul. Res., 42(6), 616–629.
Ackers, P. (1993). “Flow formulae for straight two-stage channels.” J. Hydraul. Res., 31(4), 509–531.
Darby, S. E., and Thorne, C. R. (1996). “Predicting stage-discharge curves in channels with bank vegetation.” J. Hydraul. Eng., 122(10), 583–586.
Hu, C., and Ji, Z. (1999). “Distribution of boundary shear stress in compound cross section.” J. Sediment Res., 6, 52–55 (in Chinese).
Huang, B., and Cai, J. (1990). “A boundary-layer theory model of jets for interaction between main channel and floodplain in compound channel flow.” J. Chengdu University of Science and Technology, 54(6), 77–84.
Huang, B., Lai, G., Qin, J., and Lin, S. (1999). “Experimental research on influence of vegetated floodplains upon flood carrying capacity of river.” J. Hydrodynamics, Ser. A, 14(4), 468–474 (in Chinese).
Huang, B., Lai, G., Qin, J., and Lin, S. (2002). “Hydraulics of compound channel with vegetated floodplains.” J. Hydrodynamics, Ser. B, 14(1), 23–28.
Ji, Z., and Hu, C. (1998). “Study on flow movement and sediment transport in compound channels.” J. Hydraul. Eng., 9, 1–6 (in Chinese).
Kang, H., and Choi, S. U. (2004). “3D numerical simulation of compound open channel flows with vegetated floodplains by Reynolds stress mode.” 2004 World Water and Environmental Resources Congress, Salt Lake City, 1–10.
Knight, D. W., and Abril, B. (1996). “Refined calibration of a depth-averaged model for turbulent flow in a compound channel.” Proc. Inst. Civ. Eng., Waters. Maritime Energ., London, Vol. 118, Issue 3, Paper No. 11017, 151–159.
Knight, D. W., and Demetriou, J. D. (1983). “Flood plain and main channel flow interaction.” J. Hydraul. Eng., 109(8), 1073–1092.
Knight, D. W., and Hamed, M. E. (1984). “Boundary shear in symmetrical compound channels.” J. Hydraul. Eng., 110(10), 1412–1430.
Knight, D. W., and Sellin, R. H. J. (1987). “The SERC flood channel facility.” J. Inst. Water Environ. Manage., 41(4), 198–204.
Knight, D. W., and Shiono, K. (1990). “Turbulence measurements in a shear layer region of a compound channel.” J. Hydraul. Res., 28(2), 175–214.
Knight, D. W., and Shiono, K. (1996). “River channel and floodplain hydraulics.” Floodplain processes, Anderson, Walling, and Bates, eds., Wiley, New York, 139–181.
Knight, D. W., Yuen, K. W. H., and Alhamid, A. A. I. (1994). “Boundary shear stress distributions in open channel flow.” Physical mechanisms of mixing and transport in the environment, K. Beven, P. Chatwin, and J. Millbank, eds., Wiley, New York, 51–87.
Lai, C. J., and Knight, D. W. (1988). “Distributions of streamwise velocity and boundary shear stress in compound ducts.” Proc. 3rd Int. Symp. on Refined Flow Modelling and Turbulence Measurements, Tokyo, Japan, 527–536.
Liu, P., and Dong, J. (1995). “Hydraulic computation of steady-uniform flows in open channels with compound cross section.” J. Yangtze River Scientific Research Institute, 12(3), 61–66 (in Chinese).
Myers, W. R. C., and Elsawy, E. M. (1975). “Boundary shear in channel with floodplain.” J. Hydr. Div., 101(7), 933–946.
Naot, D., Nezu, I., and Nakagawa, H. (1996a). “Hydrodynamic behavior of partly vegetated open channels.” J. Hydraul. Eng., 122(11), 625–633.
Naot, D., Nezu, I., and Nakagawa, H. (1996b). “Unstable patterns in partly vegetated channels.” J. Hydraul. Eng., 122(11), 671–673.
Posey, C. J. (1967). “Computation of discharge including over-bank flow.” Civ. Eng. (N.Y.), 37(4), 62–63.
Rajaratnam, N., and Ahmadi, R. M. (1979). “Interaction between main channel and floodplain flows.” J. Hydr. Div., 105(5), 573–588.
Sellin, R. H. J. (1964). “A laboratory investigation into the interaction between the flow in the channel of a river and that is over its floodplain.” Houille Blanche, 7, 793–802.
Shi, Y. (2002). “Hydrodynamic behavior of compound channel with vegetated floodplains.” MS thesis, Xinjiang Agricultural Univ., China.
Shiono, K., and Knight, D. W. (1991). “Turbulent open-channel flows with variable depth across the channel.” J. Fluid Mech., 222, 617–646.
Thornton, C. I., Abt, S. R., Morris, C. E., and Fischenich, J. C. (2000). “Calculating shear stress at channel-overbank interfaces in straight channels with vegetated floodplains.” J. Hydraul. Eng., 126(12), 929–936.
Tong, H., Huai, W., and Zhang, L. (2003). “Velocity ratios and discharge ratios in compound channel.” Engineering J. Wuhan Univ., 36(5), 9–15 (in Chinese).
Wang, S. (1986). “2-D velocity distribution of overbank flow and hydraulic computation.” J. Hydraul. Eng., 11, 51–59 (in Chinese).
Wang, W. (1989). “Law of flow and sediment movement in curved channels and discharge distribution in straight channels.” Ph.D. thesis, Chengdu Univ. of Science and Technology (in Chinese).
Xie, H. (1982). “Simplifying computation of overbank flow.” J. Nanjing Hydraulic Research Institute, 2, 84–92 (in Chinese).
Zheleznyakov, G. V. (1971). “Interaction of channel and floodplain streams.” Proc., Int. Association for Hydraulic Research Congress, Paris, Vol. 5, 144–148.
Zhou, Y. (1994). “A study on transverse distribution of overbank flow.” J. Wuhan University of Hydraulic and Electric Engineering, 27(6), 678–684 (in Chinese).
Information & Authors
Information
Published In
Copyright
© 2007 ASCE.
History
Received: May 23, 2005
Accepted: Dec 16, 2005
Published online: Feb 1, 2007
Published in print: Feb 2007
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.