Investigation of Flow Hydraulics in Flooded Meandering Rivers under the Effect of Floodplain Width Change

Document Type : Technical paper

Authors

• Mohammad Naghavi ¹
• Mirali Mohammadi ²

¹ Ph.D. in Civil Engineering, Hydraulic Structures, Faculty of Engineering, Urmia University, Urmia, Iran.

² Professor of Civil Engineering, Faculty of Engineering, Urmia University, Urmia, Iran.

10.22067/jwsd.v11i1.2311-1283

Abstract

Flood plains of rivers play a significant role in the transfer of flood discharge. In this research, the vertical distribution of the longitudinal and transverse flow velocities and the amount of discharge passing through different sections of the main channel in flooded meandering rivers under the effect of the change in floodplain width and relative depth were investigated. Because the fact that the width of the floodplain is constantly changing along the river's path, in this article, from the four meandering compound channels with floodplain widths of 3.3, 4.31, 5.32, and 6.33 meters and three relative depths of 0.26, 0.35 and 0.45 were used. The results of the numerical simulation showed that with the increase in the width of the floodplain, the value of longitudinal and transverse flow velocities decreases and these changes in the transverse and longitudinal flow velocities are more noticeable due to the change in the width of the floodplain in the middle sections and above the overflow depth of the main channel, so that with the increase 92% of the width of the floodplain, the value of the maximum transverse and longitudinal flow velocity in the middle section decreases by 21% and 25%, respectively. Also, according to the results of this research, with a 92% increase in the width of the floodplain, the average flow velocity and discharge through different sections of the main channel will decrease by 24% and 33%, respectively.

Keywords

• Meandering Compound Channel
• Longitudinal Velocity
• Transverse Velocity
• Floodplain Width Change
• Numerical Simulation

Main Subjects

• Water Transfer & Hydraulic Structures

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References

نقوی، محمد، محمدی، میرعلی، و مهتابی، قربان. (1398). سرعت جریان در کانال مرکب پیچان تحت تأثیر ضریب خمیدگی. مهندسی عمران مدرس، 19(5)، 208-219. https://mcej.modares.ac.ir/article-16-30266-fa.html
نقوی، محمد، محمدی، میرعلی، و مهتابی، قربان. (1399). شدت آشفتگی و تنش برشی جداره در کانال مرکب پیچان تحت اثر تغییر ضریب خمیدگی. مدل‌سازی در مهندسی، 18(60)، 53-69. doi: 10.22075/JME.2019.18692.1776
نقوی، محمد، محمدی، میرعلی، و مهتابی، قربان. (1400، الف). خصوصیات جریان‌های عرضی در کانال‌های مرکب پیچان. نشریه مهندسی عمران امیرکبیر، 53(8)، 3499-3516. doi: 10.22060/CEEJ.2021.17983.6728
نقوی، محمد، محمدی، میرعلی، و مهتابی، قربان. (1400، ب). تأثیر عمق نسبی سیلاب روی هیدرولیک جریان در کانال‌های مرکب پیچان. نشریه علمی پژوهشی مهندسی آبیاری و آب ایران، 11(3)، 55-78. doi: 10.22125/IWE.2021.128113
نقوی، محمد، محمدی، میرعلی، و مهتابی، قربان. (1403). اثر تراکم سازه‌های حاشیه پیچان‌رودها روی مشخصات جریان در مواقع سیلابی. مدیریت آب و آبیاری، 14(1)، 123-139. doi: 10.22059/JWIM.2023.364637.1101
Ervine, D. A., Willetts, B. B., Sellin, R. H. J., & Lorena, M. (1993). Factors Affecting Conveyance in Meandering Compound Flows. Journal of Hydraulic Engineering, 119(12), 1383-1399. doi: 10.1061/(ASCE)0733-9429(1993)119:12(1383)
Liu, C., Wright, N., Liu, X., & Yang, K. (2014). An analytical model for lateral depth-averaged velocity distributions along a meander in curved compound channels. Advances in Water Resources, 74, 26-43. doi: 10.1016/j.advwatres.2014.08.003
Liu, C., Shan, Y., Liu, X., Yang, K., & Liu, H. (2016). The effect of floodplain grass on the flow character-istics of meandering compound channels. Journal of Hydrology, 542, 1-17. doi: 10.1016/j.jhydrol.2016.07.037
Lyness, J. F., Myers, W. R. C., Cassells, J.  B. C., & O’Sullivan, J. J. (2001). The influence of planform on flow resistance in mobile bed compound channels. Proceedings of the ICE - Water and Maritime Engineering, 148(1), 5-14. doi: 10.1680/wama.148.1.5.40367
Moncho-Esteve, I., Palau-Salvador, G., García-Villalba, M., Muto, Y. and Shiono, K. (2018). A numerical study of the complex flow structure in a compound meandering channel. Advances in Water Resources, 116, 95-116. doi: 10.1016/j.advwatres.2018.03.013
Naghavi, M., Mohammadi, M., & Mahtabi, G. (2022). An experimental evaluation of the blocks in floodplain on hydraulic characteristics of flow in a meandering compound channel. Journal of Hydrology, 612, 127976. doi: 10.1016/j.jhydrol.2022.127976
Naghavi, M., Mohammadi, M., & Mahtabi, G. (2023a). The effect of building arrangement on the flow characteristics in meandering compound channels. Journal of Environmental Management, 331, 117288. doi: 10.1016/j.jenvman.2023.117288
Naghavi, M., Mohammadi, M., Mahtabi, G., & Abraham, J. (2023b). Experimental assessment of velocity and bed shear stress in the main channel of a meandering compound channel with one-sided blocks in floodplain. Journal of Hydrology, 617, 129073. doi: 10.1016/j.jhydrol.2023.129073
Naghavi, M., Mohammadi, M., & Mahtabi, G. (2023c). Transverse Velocities and Vortices in Compound Meandering Channel: Effect of Building Arrangement in the Floodplains. Journal of Hydraulic Structures, 6(3), 66-87. 117288. doi: 10.22055/jhs.2023.45051.1267 
Shan, Y., Liu, X., Yang, K., & Liu, C. (2017). Analytical model for stage-discharge estimation in meander-ing compound channels with submerged flexible vegetation. Advances in Water Resources, 108, 170-183. doi: 10.1016/j.advwatres.2017.07.021
Shan, Y., Huang, S., Liu, C., Guo, Y., & Yang, K. (2018). Prediction of the depth-averaged two-dimensional flow direction along a meander in compound channels. Journal of Hydrology, 565, 318-330. doi: 10.1016/j.jhydrol.2018.08.004
Shiono, K., & Muto, Y. (1998). Complex flow mechanisms in compound meandering channels with overbank flow. Journal of Fluid Mechanics, 376, 221-261. doi: 10.1017/S0022112098002869
Shiono, K., Spooner, J., Chan, T. L., Rameshwaran, P., & Chandler, J. H. (2008). Flow characteristics in meandering channels with non-mobile and mobile beds for overbank flows. Journal of Hydraulic Research, 46(1), 113-132. doi: 10.1080/00221686.2008.9521848
Wormleaton, P. R., Sellin, R. H. J., & Bryant, T. (2004). Conveyance in a two-stage meandering channel with a mobile bed. Journal of Hydraulic Research, 42(5), 493-506. doi: 10.1080/00221686.2004.9641219