Author(s): Jun Yan; Zhixian Cao; Huaihan Liu; Zhiyuan Yue; Li Zheng; Zhongmin Fu
Linked Author(s):
Keywords: Numerical model; Central bar protection; Characteristics of flow and sediment; Waterway regulation
Abstract: The central bar is the shoal which located in the central of the river. It generally features with enlarged river width and unstable bed geometry under the fluctuating water level and changing water/sediment conditions. The unstable characteristic often results in adverse impacts on the waterway flow conditions. In order to improve the waterway flow conditions, the protection measures are often required to stabilize the central bars. Two types of protection projects are usually employed, i. e., beach protection project with soft mattress and the fish-bone dike project. The impacts of these central bar protection projects on the waterway flow condition are investigated using a coupled two-dimensional hydrodynamics and sediment transport mathematical model on unstructured triangular mesh. The model is first validated against experimental data and the flow characteristics around the central bar and the bed evolution are reproduced rather well. Then, several cases are carried out under different flow and sediment conditions when the two different types of the central bars protection measures are carried out. The results show that both the soft mattress protection and the fish-bone dike protection can keep the head of central bar from scouring and increase the channel water depth on both sides of the central bar. Moreover, the differences of local scour and deposition characteristics in river-bed and around the structures between the two protection projects are revealed. The results reveal the impact of the central bar protection projects on the waterway flows which facilitates guiding significance to the regulation of the middle and lower reaches of the Yangtze River waterway with shoals and central bars.
Year: 2013