Effects of Bed Material and Downstream Flow Depth on the Evolution of Bed in a Right-Angled Open-Channel Confluence
Publication: Journal of Irrigation and Drainage Engineering
Volume 150, Issue 1
Abstract
Effects of bed material and downstream flow depth on bed evolution in a right-angled channel confluence were studied through laboratory experiments. Velocity field, water surface elevation, and bed profile were measured intermittently until the flow attained equilibrium. Sediment discharges at various locations of the confluence were estimated from bed levels. Six prominent bedforms were identified, and their characteristics were quantified. The sediment discharges from different channels were initially high but decreased to approximately zero as the flow attained equilibrium. Downstream flow depth influenced overall sediment transport in the system, including the main features of bed morphology. Overall erosion in the confluence reduced as the particle size of the bed material increased. In addition, the maximum scour depth occurred at the confluence edge, and, due to the sharp corner of the confluence, its location did not change with time. Results from the present experimental study can help validate numerical models and assist in the design of a right-angled confluence.
Practical Applications
This study is related to the hydraulics of man-made confluences with mobile beds and can be useful in the following practical applications. More accurate numerical models to predict maximum scour, bed morphodynamics, and sediment transport in man-made confluences can be developed using the detailed bed profile measurements at different time instants presented in this study. Note that available numerical models use sediment discharge formulas (e.g., Meyer-Peter-Muller, Van Rijn), which are for sediment flows in straight channels. The interplay between the three-dimensional flow field, developed bed shear stress, and sediment discharge can be explored. In addition, A man-made confluence with the mobile bed can be designed with findings from the present study. The bedforms corresponding to equilibrium flow depend on discharge ratio, confluence angle, flow conditions at the exit channel, and bed material characteristics. The major bedforms can be incorporated into the confluence geometry.
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Data Availability Statement
The data of this study are available from the corresponding author upon reasonable request.
Acknowledgments
The authors thank the journal editors and reviewers for their valuable comments and suggestions. The authors also acknowledge the Indian Council of Cultural Relations (ICCR) and the Department of Biotechnology under the Ministry of Science and Technology, Government of India for financial help (Grant/Sanction No. BT/IN/Indo-UK/AMR-Env/03/ST/2020-21, December 11, 2020) and the Indian Institute of Technology Gandhinagar for laboratory and other support.
References
Amy, L., and R. Dorrell. 2022. “Equilibrium sediment transport by dilute turbidity currents: Comparison of competence-based and capacity-based models.” Sedimentology 69 (2): 624–650. https://doi.org/10.1111/sed.12921.
Ashmore, P., and G. Parker. 1983. “Confluence scour in coarse braided streams.” Water Resour. Res. 19 (2): 392–402. https://doi.org/10.1029/WR019i002p00392.
Ashmore, P. E. 1982. “Laboratory modelling of gravel braided stream morphology.” Earth Surf. Process. Landforms 7 (3): 201–225. https://doi.org/10.1002/esp.3290070301.
Balouchi, B., M. R. Nikoo, and J. Adamowski. 2015. “Development of expert systems for the prediction of scour depth under live-bed conditions at river confluences: Application of different types of ANNs and the M5P model tree.” Appl. Soft Comput. J. 34 (Jun): 51–59. https://doi.org/10.1016/j.asoc.2015.04.040.
Best, J. L. 1987. “Flow dynamics at river channel confluences: Implications for sediment transport and bed morphology.” Recent Dev. Fluv. Sedimentol. 1973 (1): 27–35. https://doi.org/10.2110/pec.87.39.0027.
Best, J. L. 1988. “Sediment transport and bed morphology at river channel confluences.” Sedimentology 35 (3): 481–498. https://doi.org/10.1111/j.1365-3091.1988.tb00999.x.
Best, J. L., and B. L. Rhoads. 2008. “Sediment transport, bed morphology and the sedimentology of river channel confluences.” In River confluences, tributaries and the fluvial network, edited by S. Rice, A. Roy, and B. Rhoads, 1–9. Hoboken, NJ: Wiley.
Biron, P., J. L. Best, and A. G. Roy. 1996. “Effects of bed discordance on flow dynamics at open channel confluences.” J. Hydraul. Eng. 122 (12): 676–682. https://doi.org/10.1061/(ASCE)0733-9429(1996)122:12(676).
Biron, P., A. G. Roy, J. L. Best, and C. J. Boyer. 1993. “Bed morphology and sedimentology at the confluence of unequal depth channels.” Geomorphology 8 (2–3): 115–129. https://doi.org/10.1016/0169-555X(93)90032-W.
Biswal, S. K., P. K. Mohapatra, and K. Muralidhar. 2016. “Hydraulics of combining flow in a right-angled compound open channel junction.” Sadhana–Acad. Proc. Eng. Sci. 41 (1): 97–110. https://doi.org/10.1007/s12046-015-0442-y.
Bombar, G., and A. H. Cardoso. 2020. “Effect of the sediment discharge on the equilibrium bed morphology of movable bed open-channel confluences.” Geomorphology 367 (Oct): 107329. https://doi.org/10.1016/j.geomorph.2020.107329.
Borghei, S., A. Nazari, and A. Daemi. 2004. “Scouring profile at channel junction.” In Proc., Int. Conf. Hydraulics of Dams and River Structures, 327–332. London: CRC Press.
Borghei, S. M., and A. J. Sahebari. 2010. “Local scour at open-channel junctions.” J. Hydraul. Res. 48 (4): 538–542. https://doi.org/10.1080/00221686.2010.492107.
Boyer, C., A. G. Roy, and J. L. Best. 2006. “Dynamics of a river channel confluence with discordant beds: Flow turbulence, bed load sediment transport, and bed morphology.” J. Geophys. Res. Earth Surf. 111 (4): 1–22. https://doi.org/10.1029/2005JF000458.
Bryan, R. B., and N. J. Kuhn. 2002. “Hydraulic conditions in experimental rill confluences and scour in erodible soils.” Water Resour. Res. 38 (5): 1–13. https://doi.org/10.1029/2000WR000140.
Chanson, H. 2004. The hydraulics of open channel flow: An introduction. New York: Elsevier.
Chourasiya, S., P. K. Mohapatra, and S. Tripathi. 2017. “Non-intrusive underwater measurement of mobile bottom surface.” Adv. Water Resour. 104 (Jun): 76–88. https://doi.org/10.1016/j.advwatres.2017.03.009.
Cong, R., and R. Winters. 2011. How does the Kinect work? Belmont, CA: Jameco Electronics.
Fox, R. W., A. T. McDonald, P. J. Pritchard, and J. W. Mitchell. 2018. Introduction to fluid mechanics. New York: Wiley.
Guillén-Ludeña, S. 2015. Hydro-morphodynamics of open-channel confluences with low discharge ratio and dominant tributary sediment supply. Hoboken, NJ: Wiley.
Guillén-Ludeña, S., M. J. Franca, A. H. Cardoso, and A. J. Schleiss. 2015. “Hydro-morphodynamic evolution in a 90° movable bed discordant confluence with low discharge ratio.” Earth Surf. Processes Landforms 40 (14): 1927–1938. https://doi.org/10.1002/esp.3770.
Guillén-Ludeña, S., M. J. Franca, A. H. Cardoso, and A. J. Schleiss. 2016. “Evolution of the hydromorphodynamics of mountain river confluences for varying discharge ratios and junction angles.” Geomorphology 255 (Feb): 1–15. https://doi.org/10.1016/j.geomorph.2015.12.006.
Huang, J., L. J. Weber, and Y. G. Lai. 2002. “In open-channel junctions.” J. Hydraul. Eng. 128 (Mar): 268–280. https://doi.org/10.1061/(ASCE)0733-9429(2002)128:3(268).
Kapula, P. R., B. V. Reddy, B. Sushannth, B. S. Srikar, A. Deekonda, and C. Jyothsna. 2022. “Creating models for 3D printing using Kinect based scanners.” In Proc., 7th Int. Conf. Communication Electronics System ICCES 2022, 261–265. New York: IEEE. https://doi.org/10.1109/ICCES54183.2022.9835787.
Leite Ribeiro, M., K. Blanckaert, A. G. Roy, and A. J. Schleiss. 2012a. “Flow and sediment dynamics in channel confluences.” J. Geophys. Res. Earth Surf. 117 (1): 12. https://doi.org/10.1029/2011JF002171.
Leite Ribeiro, M., K. Blanckaert, A. G. Roy, and A. J. Schleiss. 2012b. “Hydromorphological implications of local tributary widening for river rehabilitation.” Water Resour. Res. 48 (10): 1–19. https://doi.org/10.1029/2011WR011296.
Liu, T. H., L. Chen, and B. Ling Fan. 2012. “Experimental study on flow pattern and sediment transportation at a 90° open-channel confluence.” Int. J. Sediment Res. 27 (2): 178–187. https://doi.org/10.1016/S1001-6279(12)60026-2.
Melville, B. 2008. “The physics of local scour at bridge piers.” In Proc., 4th Int. Conf. Scour Eros, 28–38. Auckland, New Zealand: Univ. of Auckland.
Melville, B. W. 1997. “Pier and abutment scour: Integrated approach.” J. Hydraul. Eng. 123 (2): 125–136. https://doi.org/10.1061/(ASCE)0733-9429(1997)123:2(125).
Melville, B. W., and A. J. Sutherland. 1988. “Design method for local scour at bridge piers.” J. Hydraul. Eng. 114 (10): 1210–1226. https://doi.org/10.1061/(ASCE)0733-9429(1988)114:10(1210).
Mosley, M. P. 1976. “An experimental study of channel confluences.” J. Geol. 84 (5): 535–562. https://doi.org/10.1086/628230.
Nazari-Giglou, A., A. Jabbari-Sahebari, A. Shakibaeinia, and S. M. Borghei. 2014. “An experimental study of sediment transport in channel confluences.” Int. J. Sediment Res. 31 (1): 87–96. https://doi.org/10.1016/j.ijsrc.2014.08.001.
Newcombe, R. A., S. Izadi, O. Hilliges, D. Molyneaux, D. Kim, A. J. Davison, P. Kohli, J. Shotton, S. Hodges, and A. Fitzgibbon. 2011. “KinectFusion: Real-time dense surface mapping and tracking.” In Proc., 2011 10th IEEE Int. Symp. Mixed Augmented Reality, 127–136. New York: IEEE. https://doi.org/10.1109/ISMAR.2011.6092378.
Pandey, A. K., and P. K. Mohapatra. 2021. “Reduction of the flow separation zone at combining open-channel junction by applying alternate suction and blowing.” J. Irrig. Drain. Eng. 147 (10): 1–10. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001611.
Pandey, A. K., and P. K. Mohapatra. 2022. “Three-dimensional numerical simulation of the flood-wave propagation at a combining open-channel junction.” J. Irrig. Drain. Eng. 148 (11): 1–14. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001713.
Pandey, A. K., and P. K. Mohapatra. 2023. “Flow dynamics and pollutant transport at an artificial right-angled open-channel junction with a deformed bed.” J. Hydraul. Eng. 149 (4): 1–17. https://doi.org/10.1061/JHEND8.HYENG-13424.
Pomaska, G. 2013. “Monitoring the deterioration of stone at Mindener Museum’s lapidarium.” Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci. 5 (Sep): 495–500. https://doi.org/10.5194/isprsarchives-xl-5-w2-495-2013.
Ramamurthy, A. S., J. Qu, and D. Vo. 2007. “Numerical and experimental study of dividing open-channel flows.” J. Hydraul. Eng. 133 (10): 1135–1144. https://doi.org/10.1061/(ASCE)0733-9429(2007)133:10(1135).
Safi, W. H., and P. K. Mohapatra. 2023. “Flow past: An artificial channel confluence with mobile bed.” In Proc., World Environment Water Resources Congress 2023, edited by S. Ahmad and R. Murray, 235–244. Reston, VA: ASCE.
Shakibainia, A., M. R. M. Tabatabai, and A. R. Zarrati. 2010. “Three-dimensional numerical study of flow structure in channel confluences.” Can. J. Civ. Eng. 37 (5): 772–781. https://doi.org/10.1139/L10-016.
Shettar, A. S., and K. K. Murthy. 1996. “A numerical study of division of flow in open channels.” J. Hydraul. Res. 34 (5): 651–675. https://doi.org/10.1080/00221689609498464.
Weber, L. J., E. D. Shumate, and N. Mawer. 2001. “Experiments on flow at a 90-degree open channel junction.” J. Hydraul. Eng. 127 (May): 340–350. https://doi.org/10.1061/(ASCE)0733-9429(2001)127:5(340).
Yu, Q., S. Yuan, and C. D. Rennie. 2020. “Experiments on the morphodynamics of open channel confluences: Implications for the accumulation of contaminated sediments.” J. Geophys. Res. Earth Surf. 125 (9): 1–25. https://doi.org/10.1029/2019JF005438.
Yuan, S., H. Tang, Y. Xiao, X. Qiu, and Y. Xia. 2018. “Water flow and sediment transport at open-channel confluences: An experimental study.” J. Hydraul. Res. 56 (3): 333–350. https://doi.org/10.1080/00221686.2017.1354932.
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© 2023 American Society of Civil Engineers.
History
Received: Apr 21, 2023
Accepted: Oct 2, 2023
Published online: Nov 9, 2023
Published in print: Feb 1, 2024
Discussion open until: Apr 9, 2024
ASCE Technical Topics:
- Bed forms
- Bed materials
- Channels (waterway)
- Engineering fundamentals
- Engineering mechanics
- Equilibrium
- Flow measurement
- Hydraulic engineering
- Hydraulic structures
- Measurement (by type)
- River and stream beds
- River engineering
- Rivers and streams
- Sediment
- Sediment transport
- Statics (mechanics)
- Water and water resources
- Waterways
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