Alternative Method for Determining Manning's Roughness Coefficient Using Two-Point Velocity in Equilibrium and Nonequilibrium Sediment Transport
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Understanding flow resistance equations, such as Manning’s roughness equation, is essential for river design and improvement. Estimating Manning’s roughness coefficient becomes more complicated when sediment transport is involved. This study takes an alternative approach by using velocity profiles to examine how sediment transport affects Manning’s roughness coefficient. To achieve this goal, 1200 velocity profiles with sediment-feeding (SF) and non-sediment-feeding (NSF) flows are evaluated to determine the (composite) Manning’s roughness coefficient. Sediment-feeding flows describe sediment flow under equilibrium conditions, whereas non-sediment-feeding flows represent sediment flow under nonequilibrium conditions. A Sontek 16-MHz Acoustic Doppler Velocimeter is used to measure the velocity (and turbulence) profiles. In addition to the present data, 225 secondary velocity profile data sets are analyzed in this study. The research findings indicate that the composite Manning’s roughness coefficient nco can be determined from Manning’s roughness coefficient nz/B at z/B in the transversal direction, using two points of the velocity profile at y/H = 0.2 and 0.4 in the vertical direction. The differences in the velocity profile shape (u/U) due to sediment feeding, particularly in inner regions (y/H ≤ 0.2), affect the value of nz/B. nco for sediment-feeding flows are generally higher than the cross-section Manning roughness coefficient n. As nco (based on nz/B) is based on the velocity profile, the nco values change with sediment transport. Meanwhile, the n values remain unchanged because the equation variables cannot detect the presence of sediment transport. For non-sediment-feeding flow, the differences in nco with n are 14.80% for a fixed bed (FB) and 18.17% for a movable bed (MB). The differences are even more pronounced for sediment-feeding flow at 33.01% for a fixed bed and 36.52% for a movable bed. The point where nz/B/nco = 1 occurs at z/B = 0.2 from the channel sidewall. This suggests that nz/B, measured at z/B = 0.2 from the channel sidewall, provides a good representation of nco for the section.
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[1] Chow, V. T. (1960). Open-Channel Hydraulics. Ven Te Chow. McGraw-Hill, New York, United States.
[2] W. L. Cowan. (1956). Estimating hydraulic roughness coefficients. Agricultural Engineering, 37(7), 473–475.
[3] Arcement, G. J., & Schneider, V. R. (1989). Guide for selecting Manning's roughness coefficients for natural channels and flood plains (No. 2339). USGPO; For sale by the Books and Open-File Reports Section, US Geological Survey, Reston, United States. doi 10.3133/wsp2339.
[4] Allen, T. G. (2014). A Study of the Variability Versus the Assumed Constancy of Manning's n. Ph.D. Thesis, Utah State University, Logan, United States.
[5] Rad, H. R., Ebrahimian, H., Liaghat, A., Khalaji, F., & Arani, M. S. (2025). Temporal variation of Manning roughness coefficient in furrow irrigation and its relationship with various field parameters. Applied Water Science, 15(1), 7. doi:10.1007/s13201-024-02334-9.
[6] Julien, P. Y. (2016). Gradually Varied Flow. Essentials of hydraulics. Cambridge University Press, Cambridge, United Kingdom. doi:10.1017/9781108907446.011.
[7] Maini, M., Kironoto, B. A., Istiarto, & Rahardjo, A. P. (2024). Evaluating Manning’s Roughness Coefficient for Flows with Equilibrium and Non-equilibrium Sediment Transport. Jordan Journal of Civil Engineering, 18(1), 65–80. doi:10.14525/JJCE.v18i1.06.
[8] Zhang, G. H., Luo, R. T., Cao, Y., Shen, R. C., & Zhang, X. C. (2010). Impacts of sediment load on Manning coefficient in supercritical shallow flow on steep slopes. Hydrological Processes, 24(26), 3909–3914. doi:10.1002/hyp.7892.
[9] Gao, P., & Abrahams, A. D. (2004). Bedload transport resistance in rough open-channel flows. Earth Surface Processes and Landforms, 29(4), 423–435. doi:10.1002/esp.1038.
[10] Campbell, L., McEwan, I., Nikora, V., Pokrajac, D., Gallagher, M., & Manes, C. (2005). Bed-Load Effects on Hydrodynamics of Rough-Bed Open-Channel Flows. Journal of Hydraulic Engineering, 131(7), 576–585. doi:10.1061/(asce)0733-9429(2005)131:7(576).
[11] Bergeron, N. E., & Carbonneau, P. (1999). The effect of sediment concentration on bedload roughness. Hydrological Processes, 13(16), 2583-2589. doi:10.1002/(sici)1099-1085(199911)13:16<2583::aid-hyp939>3.0.co;2-s.
[12] Song, T., Chiew, Y. M., & Chin, C. O. (1998). Effect of Bed-Load Movement on Flow Friction Factor. Journal of Hydraulic Engineering, 124(2), 165–175. doi:10.1061/(asce)0733-9429(1998)124:2(165).
[13] Smart, G. M., & Jaeggi, M. N. R. (1983). Sediment transport on steep slopes. Communications from the Research Institute for Hydraulic Engineering, Hydrology and Glaciology, 64, 91-191.
[14] Nikora, V. I., & Smart, G. M. (1997). Turbulence Characteristics of New Zealand Gravel-Bed Rivers. Journal of Hydraulic Engineering, 123(9), 764–773. doi:10.1061/(asce)0733-9429(1997)123:9(764).
[15] Carbonneau, P. E., & Bergeron, N. E. (2000). The effect of bedload transport on mean and turbulent flow properties. Geomorphology, 35(3–4), 267–278. doi:10.1016/S0169-555X(00)00046-5.
[16] Zhang, K., Li, N., Fu, S., Mu, H., & Lu, B. (2025). The mechanism of surface cover influences the sediment transport capacity. Journal of Hydrology, 651, 132527. doi:10.1016/j.jhydrol.2024.132527.
[17] Hou, L., & Zhang, H. (2025). Research on the calculation method of frictional resistance in the lower reaches of the Yellow River. Shuili Xuebao/Journal of Hydraulic Engineering, 56(1), 63–72. doi:10.13243/j.cnki.slxb.20240170.
[18] Manning, R. (1891). On the flow of water in open channels and pipes. Transactions, Institution of Civil Engineers of Ireland, 20, 161.
[19] Keulegan, G. H. (1938). Laws of turbulent flow in open channels. Journal of Research of the National Bureau of Standards, 21(6), 707. doi:10.6028/jres.021.039.
[20] Woo, H. S., Julien, P. Y., & Richardson, E. V. (1988). Suspension of Large Concentrations of Sands. Journal of Hydraulic Engineering, 114(8), 888–898. doi:10.1061/(asce)0733-9429(1988)114:8(888).
[21] Van Rijn, L.C. (1993) Principles of Sediment Transport in Rivers, Estuaries and Coastal Areas. Aqua Publications, Amsterdam, Netherelands.
[22] Kironoto, B. A., & Yulistiyanto, B. (2016). The simplified of suspended sediment measurement method for predicting suspended sediment load as a basic of reservoir capacity design as renewable energy resource. International Journal of Renewable Energy Research, 6(1), 315–322. doi:10.20508/ijrer.v6i1.3026.g6788.
[23] Yulistiyanto, B., Kironoto, B., Giarto, B., Kiptiah, M., & Tantowi, M. L. (2019). The Simplified of Suspended Sediment Measurement Method in Natural River (Case study of Kuning River in Yogyakarta, Indonesia). Journal of the Civil Engineering Forum, 5(3), 243. doi:10.22146/jcef.47061.
[24] Kironoto, B. A., Yulistiyanto, B., Giarto, R. B., Kiptiah, M., & Sitinjak, O. E. (2018). The simplified of suspended sediment measurement method for predicting suspended sediment discharge in natural river (case study of Opak River, Yogyakarta, Indonesia). Proceedings - International Association for Hydro-Environment Engineering and Research (IAHR)-Asia Pacific Division (APD) Congress: Multi-Perspective Water for Sustainable Development, IAHR-APD 2018, 1, 273–281.
[25] Einstein, H. A., & El-Samni, E. S. A. (1949). Hydrodynamic forces on a rough wall. Reviews of Modern Physics, 21(3), 520–524. doi:10.1103/RevModPhys.21.520.
[26] Grass, A. J. (1971). Structural features of turbulent flow over smooth and rough boundaries. Journal of Fluid Mechanics, 50(2), 233–255. doi:10.1017/S0022112071002556.
[27] Hinze, J. O. (1959). Turbulence. McGraw-Hill, New York, United States.
[28] Kironoto, B. A., & Graf, W. H. (1994). Turbulence characteristics in rough uniform open-channel flow. Proceedings of the Institution of Civil Engineers: Water, Maritime and Energy, 106(4), 333–344. doi:10.1680/iwtme.1994.27234.
[29] Schlichting, H. (1979) Boundary Layer Theory. 7th Edition, McGraw-Hill, New York, United States. doi:10.1115/1.3240614.
[30] Schlichting, H., & Gersten, K. (2016). Boundary-layer theory. Springer-Verlag, Berlin, Germany. doi:10.1007/978-3-662-52919-5.
[31] Lotter, G. K. (1933). Considerations on hydraulic design of channels with different roughness of walls. Transactions, All-Union Scientific Research Institute of Hydraulic Engineering, Leningrad, 9, 238-241.
[32] Maini, M. (2024). The Effect of Sediment Transport on Manning's Roughness Coefficient in Open Channels. Ph.D. Thesis, Yogyakarta, Indonesia.
[33] Colebrook, C. F., & White, C. M. (1937). the Reduction of Carrying Capacity of Pipes with Age. Journal of the Institution of Civil Engineers, 7(1), 99–118. doi:10.1680/ijoti.1937.14682.
[34] Reynolds, A. J. (1974). Turbulent flows in engineering. John Wiley & Sons, Hoboken, United States.
[35] Nezu, I., & Rodi, W. (1986). Open‐channel Flow Measurements with a Laser Doppler Anemometer. Journal of Hydraulic Engineering, 112(5), 335–355. doi:10.1061/(asce)0733-9429(1986)112:5(335).
[36] Kironoto, B. A. (2008). verage suspended sediment concentration at depth based on 1, 2, and 3 point measurements in open channel uniform flow. Dinamika Teknik Sipil, 8(1), 59-71. (In Indonesian).
[37] Maini, M., Kironoto, B. A., Rahardjo, A. P., & Istiarto. (2023). Flow Characteristics of Equilibrium and Non-Equilibrium Sediment Transport Flows. International Journal of GEOMATE, 25(110), 77–86. doi:10.21660/2023.110.3957.
[38] Maini, M., Kironoto, B. A., Rahardjo, A. P., & Istiarto. (2024). Effect of equilibrium and non-equilibrium sediment transport flows on the shear velocity in an open channel. IOP Conference Series: Earth and Environmental Science. doi:10.1088/1755-1315/1311/1/012013.
[39] Boyer, M. C. (1954). Estimating the Manning coefficient from an average bed roughness in open channels. Eos, Transactions American Geophysical Union, 35(6), 957-961. doi:10.1029/TR035i006p00957.
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