Abstract

Wuqiao reach is located in middle reach of the Yangtze River, south China. After the building up of Wuhan Yangtze Bridge, the main problem in Wuqiao reach is the navigation-obstruction of Hanyang side bar. In order to make clear about the navigation obstruction mechanism of Hanyang side bar, flow characteristics and channel evolution characteristics has been analyzed based on approaches of model experiment and GIS. The velocity distribution, velocity direction, evolution rules of bars and relationships among bars have been analyzed respectively. And colligating the flow characteristics and channel evolution characteristics of Wuqiao reach, the formation cause of Hanyang side bar, the evolution rules of Hanyang side bar intro-year and inter-years, the influence factors to the development of Hanyang side bar and the navigation-obstruction mechanism have been concluded. The suggestion to navigation regulation is finally given. The analysis indicates that the water block produced by channel constriction and bridge pier hinder, the backwater produced by Hanjiang River afflux, the sucking effect of Wuchang deep pool and the decline of right branch induces the formation of Hanyang side bar and the mainstream oblique flow from Qianzhou tail to Wuchang deep pool. As the mainstream variation in different discharge, the intro-year variation of Hanyang side bar presents as scours in flood period and deposits in falling stage and low-water period. The inter-years variation of Hanyang side bar is influenced by the adjustment of bars under different incoming water & sediment conditions. Especially, the shape, top height and tail position of Qianzhou can control the position of oblique flow and further influence the development of Hanyang side bar. So the adjustment of bars dominates Hanyang side bar whether hinders the navigation or not. Based on these recognitions, the navigation regulation in Wuqiao reach should focus on maintenance of Qianzhou ideal shape, adjustment of oblique flow position and enhance of hydrodynamic condition in Hanyang side bar.

Keywords: River Evolution, Navigation-Obstruction, Model Experiment, GIS