Author(s): Shampa; Hussain Muhammad Muktadir; Maruf Ahmed; Akm Saiful Islam

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Keywords: Sand-bar; Bank protection structure; Scouring; Ganges; Brahmaputra-Jamun

Abstract: Sand bars are an integral part of the alluvial river's geophysical system due to these rivers' wide sediment availability and varied transport capacity. The sand bar translation considerably influences the stability of the river bank. But while designing the riverbank protection structures (RBPS), the impact of such sand bars is frequently overlooked as the development of such bars is quite uncertain regarding location, amplitude and translation. This study quantifies the localized impact of sand bars on bank protection structures in two types of alluvial rivers- meandering (Ganges) and braided (Brahmaputra-Jamuna). We found that in the case of the Ganges, the maximum flow depth in existing conditions was 34.32 m, while in extreme bar conditions, it was 51.25 m, using satellite image analysis and 2D numerical investigation. The net change after one monsoon flood in the existing conditions was -0.51 m, with a maximum bed scouring of -25.63 m. The extreme condition in the Brahmaputra-Jamuna basin occurred in 2011, when a large compound bar appeared in the study domain. According to our findings, the presence of a sandbar can increase the hydraulic load to RBPS by 47% in the Ganges and 65% in the Brahmaputra-Jamuna. Therefore, when designing the BPS in such rivers, these conditions should be taken into account.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p1424-cd

Year: 2023