Quantifying Changes in Downstream Flow Characteristics in Sinuous Channels Due to the Series of Floodplain Sand Mining Pits

This study investigates the impact of sand mining pits on downstream flow characteristics within sinuous channels. Three distinct scenarios were analyzed: sinuous channels without mining pits (experimentally at the IIT Guwahati Fluvial Eco-Hydraulic Laboratory and numerically using FLOW-3D HYDRO v1.0 u1), sinuous channels with two mining pits, and sinuous channels with three mining pits (both analyzed numerically). The main aim of this study is to differentiate between downstream flow characteristics in the main sinuous channel with two sand mining pits and those with three mining pits. The study will specifically focus on various flow parameters, including streamwise velocity, secondary current, vorticity, and turbulence intensity. Key findings include a decreasing streamwise velocity magnitude from the inner to the outer bank, with a notable reduction in the core zone of streamwise velocity in scenarios involving mining pits. Additionally, the concentration of secondary currents is lower near the outer bank compared to scenarios with three mining pits. The presence of mining pits intensifies streamwise vorticity near the inner bank and induces clockwise rotation of secondary vorticity in mining pit scenarios. Turbulence intensity is more pronounced near the inner bank in scenarios with mining pits. There is an error range of 18 to 34% when comparing the numerical simulations to the experimental data. These findings provide valuable insights into the hydrodynamic influences on flow within sinuous channels impacted by sand mining pits. Future research could extend this study by incorporating sediment transport models to enhance our understanding of sediment movement in such environments.