Renmin Zhujiang (Nov 2024)
Numerical Simulation of Hydrodynamic Characteristics of Spur Dikes in Beijiang River and Its Influence on Navigation Safety
Abstract
In order to deeply explore the influence of spur dikes in Beijiang River on navigation safety, this study adopted the calculation model of unstructured-grid finite volume coastal Dcean model (FVCOM), took the mainstream reach of 23 km of Beijiang River in Yingde section as the research area, constructed a three-dimensional hydrodynamic model, and verified the effectiveness of the model through measured data. On this basis, the hydrodynamic characteristics with and without spur dikes were simulated under the assumed constant inlet flow rate of 420 m³/s, and the abrupt bend section in the study area was analyzed. The calculation results show that the spur dike reduces the near-shore flow velocity by 44.6%~90.3%, increases the channel depth by 0~0.2 m, and elevates the mainstream flow velocity by 66.6%~121.8%. In addition, the spur dike converges the lateral mainstream. The degree of swing is reduced by up to 41.6%, and the amplitude of swing is reduced by up to 50.2%, which has a positive effect on the improvement of the navigability of the channel. However, the arrangement of the spur dike also increases some negative effects. For example, the unilateral long spur dikes lead to the increase of the opposite near-shore flow velocity by 73.3%~129.0%, the decrease of the horizontal mainstream curvature of the channel from 784.2 m to 774.5 m, and the decrease of the bending radius of the hydrodynamic axis by 14.0%~36.7%, which may constitute a potential threat to the navigation safety. The results of this study not only reveal the complex role of spur dikes in the hydrodynamic characteristics of a specific river section but also provide an important reference for the analysis of spur dikes on navigation safety in natural channels.
