292 / 2024-02-29 08:37:09

Three-dimensional modelling and application of large-scale Ω-shaped bank erosion process in the Lower Yangtze River

Bank erosion,three-dimensional modelling,Ω-shaped,Lower Yangtze River,optimization strategies

Bank erosion in the densely populated Lower Yangtze River (LYR) poses a significant threat to riparian residents and industry. Different from general bank erosion types in previous researches, it typically has a Ω shape in the LYR, develops rapidly within a few hours and results in an obvious erosion pond. However, modeling such erosion is challenging due to the continuously changing flow structure within the pond as the bank boundary retreats. Therefore, a three-dimensional model is proposed in the current research, coupling a hydro-and sediment dynamic module with a bank erosion module. The results show that:① The proposed model successfully reproduced the hydraulic conditions and the Ω-shaped bank erosion process in the study reach. The calculated bank erosion area in the tidal reach is around 98,370 m², close to the measured value of 84,060 m²;②The shoulder protection and check dam projects respectively restrict bank foot erosion at the shoulders and reduce the flow velocity within the Ω-shaped bank erosion zone to halt the development of erosion. ③ The proposed optimization strategies include raising the sluice gate elevation by 2.5 m and shifting the location of the shoulder guarding structures towards the main stream by approximately 35 to 63 m. Compared to the pre-optimization scenario, the optimized plan reduces the eroded bank area by 1493m², a reduction of 17.4%, and decreases the maximum flow velocity by an average of approximately 14.5%. Additionally, the area of intense turbulence within the ponds decreases by approximately 12.4%.