Effect of Floodplain Obstructions on the Discharge Conveyance Capacity of Compound Channels
Publication: Journal of Irrigation and Drainage Engineering
Volume 143, Issue 11
Abstract
Results of an experimental study into steady uniform flows in compound open channels with cylindrical obstructions designed to mimic emergent vegetation is presented. Two configurations—fully covered floodplain and one-line obstructions—are considered, and the hydraulic properties are compared to those of a smooth, unobstructed compound channel. Particular attention is given to the effect of obstruction (i.e., vegetation) density on the rating curve, drag coefficients, and spanwise profiles of streamwise velocity. Flow resistance is estimated using an established approach, and the results are in agreement with other experimental studies. It was shown that the obstruction configuration significantly influences the flow velocity in the main channel, and in the case of one-line obstructions the floodplain velocity is higher than for an unobstructed channel for a given flow rate. Spanwise velocity profiles exhibit markedly different characters in the one-line and fully covered configurations.
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Acknowledgments
This work was supported by the Iraqi government and the U.K. Engineering and Physical Sciences Research Council (EPSRC; Grant No. EP/k041088/1).
References
Azevedo, R., Leal, J. B., and Rojas-Solórzano, L. (2012). “Influence of vegetation on compound-channel turbulent field.” River flow 2012—Proc., Int. Conf. on Fluvial Hydraulics, CRC Press, Boca Raton, FL, 209–216.
Ben-sheng, H., Guan-wen, L., Jing, Q., and Shu-zhong, L. (2002). “Hydraulics of compound channel with vegetated floodplain.” J. Hydrodyn. Ser. B, 14(1), 23–28.
Chen, G., Huai, W., Han, J., and Zhao, M. (2010). “Flow structure in partially vegetated rectangular channels.” J. Hydrodyn. Ser. B, 22(4), 590–597.
Cheng, N., and Nguyen, H. (2011). “Hydraulic radius for evaluating resistance induced by simulated emergent vegetation in open-channel flows.” J. Hydraul. Eng., 995–1004.
Hamidifar, H., and Omid, M. (2013). “Floodplain vegetation contribution to velocity distribution in compound channels.” J. Civil Eng. Urbanism, 3(6), 357–361.
Hamimed, A., Nehal, L., Benslemani, M., and Khalid, A. (2013). “Contribution to the study of the flow resistance in a flume with artificial emergent vegetation.” Layhyss J., 15, 55–63.
Hin, L. S., Bessaih, N., Ling, L. P., Ghani, A. A., Zakaria, N. A., and Seng, M. (2008). “A study of hydraulic characteristics for flow in equatorial rivers.” Int. J. River Basin Manage., 6(3), 213–223.
Hirschowitz, P. M., and James, C. S. (2009). “Conveyance estimation in channels with emergent bank vegetation.” Water SA, 35(5), 8.
Huthoff, F. (2007). “Modeling hydraulic resistance of floodplain vegetation.” Ph.D. thesis, Univ. of Twente, Enschede, Netherlands.
Ismail, Z., and Shiono, K. (2006). “The effect of vegetation along cross-over floodplain edges on stage discharge and sediment transport rates in compound meandering channels.” Proc., 5th WSEAS Int. Conf. on Environment Ecosystems and Development, WSEAS Press, Stevens Point, WI.
Järvelä, J. (2002). “Determination of flow resistance of vegetated channel banks and floodplains.” River Flow 2002, Int. Conf. on Fluvial Hydraulics, Louvain-la-Neuve, D. Bousmar and Y. Zech, eds., Swets and Zeilinger, Lisse, Netherlands, 311–318.
Kothyari, U. C., Hayashi, K., and Hashimoto, H. (2009). “Drag coefficient of unsubmerged rigid vegetation stems in open channel flows.” J. Hydraul. Res., 47(6), 691–699.
Li, Y., et al. (2014). “An open-channel flume study of flow characteristics through a combined layer of submerged and emerged flexible vegetation.” Ecohydrology, 7(2), 633–647.
Liu, C., and Shen, Y. (2008). “Flow structure and sediment transport with impacts of aquatic vegetation.” J. Hydrodyn. Ser. B, 20(4), 461–468.
Masterman, R., and Thorne, C. (1992). “Predicting influence of bank vegetation on channel capacity.” J. Hydraul. Eng., 1052–1058.
Mulahasan, S., Stoesser, T., and Alvarez, F. (2015). “Visualization of shear layers in compound channel flows.” 10th Pacific Symp. on Flow Visualization and Image Processing, Federico II Open Archive, Naples, Italy.
Nehal, L., Yan, Z. M., Xia, J. H., and Khaldi, A. (2012). “Flow through non-submerged vegetation.” 16th Int. Water Technology Conf., IWTC 16, IWTA, Alexandria, Egypt.
Nepf, H. M. (1999). “Drag, turbulence, and diffusion in flow through emergent vegetation.” Water Resour. Res., 35(2), 479–489.
Pasche, E., and Rouvé, G. (1985). “Overbank flow with vegetatively roughened floodplains.” J. Hydraul. Eng., 1262–1278.
Petryk, S., and Bosmajian, G. (1975). “Analysis of flow through vegetation.” J. Hydraul. Div., 101(7), 871–884.
Pope, S. B. (2000). “Free shear flows.” Turbulent flows, Cambridge Univ. Press, Cambridge, U.K., 139–144.
Rajaratnam, N., and Ahmadi, R. (2010). “Hydraulics of channels with flood-plains.” J. Hydraul. Res., 19(1), 43–60.
Rameshwaran, P., and Shiono, K. (2007). “Quasi two-dimensional model for straight overbank flows through emergent vegetation on floodplains.” J. Hydraul. Res., 45(3), 302–315.
Sanjou, M., Nezu, I., and Itai, K. (2010). “Space-time correlation and momentum exchanges in compound channel flow by simultaneous measurements of two sets of ADVs.” River Flow 2010, CRC Press, Boca Raton, FL, 495–502.
Shiono, K., and Knight, D. W. (1991). “Turbulent open-channel flows with variable depth across the channel.” J. Fluid Meeh., 222, 617–646.
Shiono, K., Takeda, M., Yang, K., Sugihara, Y., and Ishigaki, T. (2012). “Modeling of vegetated rivers for inbank and overbank flows.” Proc., Int. Conf. on Fluvial Hydraulics: River Flow-September 5-7, CRC Press, Boca Raton, FL, 263–269.
Shucksmith, J. D., Boxall, J. B., and Guymer, I. (2012). “Bulk flow resistance in vegetated channels: Analysis of momentum balance approaches based on data obtained in aging live vegetation.” J. Hydraul. Eng., 1624–1635.
Stoesser, T., Kim, S., and Diplas, P. (2010). “Turbulent flow through idealized emergent vegetation.” J. Hydraul. Eng., 1003–1017.
Sun, X., and Shiono, K. (2009). “Flow resistance of one-line emergent vegetation along the floodplain edge of a compound open channel.” Adv. Water Resour., 32(3), 430–438.
Tang, X., and Knight, D. W. (2008). “Lateral depth-averaged velocity distributions and bed shear in rectangular compound channels.” J. Hydraul. Eng., 1337–1342.
Tang, X., Sterling, M., and Knight, D. W. (2010). “A general analytical model for lateral velocity distributions in vegetated channels.” River Flow 2010, CRC Press, Boca Raton, FL, 469–475.
Tanino, Y., and Nepf, H. (2008). “Laboratory investigation of mean drag in a random array of rigid, emergent cylinders.” J. Hydraul. Eng., 34–41.
Terrier, B. (2010). “Flow characteristics in straight compound channels with vegetation along the main channel.” Ph.D. dissertation, Dept. of Civil and Building Engineering, Loughborough Univ., Loughborough, U.K.
Teymourei, E., Barani, G. A., Janfeshan, H., and Dehghanie, A. A. (2013). “Determination of SKM mathematical model for estimation of transverse velocity distribution in compound channels.” J. Basic Appl. Sci. Res., 3(2s), 682–688.
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., 929–936.
Tinoco, R. O., and Cowen, E. A. (2013). “The direct and indirect measurement of boundary stress and drag on individual and complex arrays of elements.” Exp. Fluids, 54(1509), 1–16.
Tominaga, A., and Nezu, I. (1991). “Turbulent structure in compound open-channel flows.” J. Hydraul. Eng., 21–41.
Valyrakis, M., Liu, D., Mcgann, N., Turker, U., and Yagci, O. (2015). “Characterrising the effect of increasing river bank vegetation on the flow field across the channel.” E-Proc., 36th IAHR World Congress 28 June–3 July, 2015, CRC Press, Boca Raton, FL.
van Prooijen, B. C., Battjes, J. A., and Uijttewaal, W. S. J. (2005). “Momentum exchange in straight uniform compound channel flow.” J. Hydraul. Eng., 175–183.
van Prooijen, B. C., and Uijttewaal, W. S. J. (2002). “A linear approach for the evolution of coherent structures in shallow mixing layers.” Phys. Fluids, 14(12), 4105–4114.
Vermaas, D. A., Uijttewaal, W. S. J., and Hoitink, A. J. F. (2011). “Lateral transfer of streamwise momentum caused by a roughness transition across a shallow channel.” Water Resour. Res., 47(2), 1–12.
White, B. L., and Nepf, H. M. (2007). “Shear instability and coherent structures in shallow flow adjacent to a porous layer.” J. Fluid Mech., 593, 1–32.
White, B. L., and Nepf, H. M. (2008). “A vortex-based model of velocity and shear stress in a partially vegetated shallow channel.” Water Resour. Res., 44, W01412.
Wunder, S., Lehmann, B., and Nestmann, F. (2011). “Determination of the drag coefficients of emergent and just submerged willows.” Int. J. River Basin Manage., 9(3–4), 231–236.
Yang, K., Cao, S., and Knight, D. (2007). “Flow patterns in compound channels with vegetated floodplains.” J. Hydraul. Eng., 148–159.
Yang, K., Nie, R., Liu, X., and Cao, S. (2013). “Modeling depth-averaged velocity and boundary shear stress in rectangular compound channels with secondary flows.” J. Hydraul. Eng., 76–83.
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©2017 American Society of Civil Engineers.
History
Received: Mar 21, 2016
Accepted: May 25, 2017
Published online: Sep 13, 2017
Published in print: Nov 1, 2017
Discussion open until: Feb 13, 2018
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