Impact of Groynes on Hydrodynamics adjacent to a Concave Bank in a Braided River

DOI

10.2991/978-94-6463-672-7_21How to use a DOI?

Keywords

Hydrodynamics; concave bank; groyne; velocity; scour

Abstract

The rivers of Bangladesh, particularly braided rivers, are highly dynamic and susceptible to frequent hydro-morphological changes, such as riverbank erosion, which poses significant challenges to riverbank protection. This persistent issue results in significant land loss and community displacement, prompting substantial investment by the mitigation authority for river management. This study aims to explore the effectiveness of groynes in managing riverbank erosion by analyzing their impact on water flow and scour dynamics. A physical model of a braided river was developed in a laboratory setting, featuring a concave bank with groynes at various spacing-to-length (S/L) ratios (1.0, 2.0, and 3.0). The experiments were conducted using an open-channel flume with sand-leveled beds, simulating flow conditions with an average discharge of 100m3/hour. The results indicate that groynes reduce upstream flow velocity by 91–95%, with gradual decreases downstream. The placement of groynes had minimal effect on overall water depth but significantly influenced flow velocity patterns. Scour measurements revealed that the maximum erosion occurred at the upstream toe of the groynes, with increased spacing between groynes leading to deeper and more extended scour zones. These observations suggest that the interaction between flow dynamics and groyne configurations plays a crucial role in mitigating erosion. The study concludes that optimal groyne spacing, particularly an S/L ratio of 3.0, is necessary to balance flow management and erosion control effectively. These findings provide key insights into designing riverbank protection systems for braided rivers, which are critical for mitigating the adverse effects of erosion on vulnerable communities and ecosystems. The research highlights the importance of strategic planning in hydraulic engineering for sustainable river management, addressing both sediment transport and the evolving challenges posed by river dynamics in Bangladesh.

Copyright

© 2025 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Md. Zakir Hasan
AU  - Rokshana Pervin
AU  - Md. Al-Islam
AU  - Muhammad Saifur Rahmman
PY  - 2025
DA  - 2025/04/04
TI  - Impact of Groynes on Hydrodynamics adjacent to a Concave Bank in a Braided River
BT  - Proceedings of the 1st International Conference on Recent Innovation in Civil Engineering and Architecture for Sustainable Development (IICASD-2024)
PB  - Atlantis Press
SP  - 260
EP  - 270
SN  - 2352-5401
UR  - https://doi.org/10.2991/978-94-6463-672-7_21
DO  - 10.2991/978-94-6463-672-7_21
ID  - Hasan2025
ER  -