Author(s): O. P. Maurya; K. K. Nandi; S. Modalavalasa; S. Dutta

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Keywords: Sinuous channel; Floodplain; Sand mining pit; Bridge pier; Flow-3D; Flow characteristics

Abstract: Anthropogenic activities within the river corridor can have a long-term influence on river health if not managed effectively. Uncontrolled practices of sand mining, a common but aggressive activity can cause severe river bed degradation and, as a result, river incisions, lateral channel instability, and bed armoring. This can further affect the downstream structure such as the bridge pier as well as the morphology of the river. The purpose of this study is to examine, with the help of a numerical model, the impact of a mining pit on the downstream pier and the main channel hydrodynamics if it is present on the flood plain of a sinuous channel. To carry out the study we have considered a meandering channel with two different sinuousness (1.1, 1.25). Additionally, a rectangular mining pit and a downstream circular bridge pier were considered on the flood plains of the channel. The numerical model used for the study was Flow 3D HYDRO with the renormalized group turbulence solver (RNG). As sinuosity increases, the highest zone of streamwise velocity narrows near the mining pit and widens out just downstream of the bridge pier, according to the findings. Near the sand mining pit, the shear layer zone shifted towards the main channel from the near bank. The secondary current at the outer bank near the mining pit is more concentrated in both cases. The channel having more sinuosity has shown a significant change in turbulence kinetic energy (TKE) as compared to the other channel. Additionally, this study can provide insight into the morphodynamics of meandering rivers under different in-channel disturbance conditions and thus be helpful in the proper planning and management of river health.

DOI: https://doi.org/10.26077/4735-1995

Year: 2022