土桥水道碍航特性突变分析

长江下游土桥水道自1998年开始航道条件恶化,但不同时期碍航特性不同。以1955—2014年土桥水道的实测地形、水文资料及大通站水沙资料为基础,用有序聚类法分析了大通站输沙量的变化特点,以及各类碍航特性变化的原因。结果表明:目前土桥水道碍航特性已从断面形态宽浅及淤沙碍航变为左汊分流比下降,其主要原因是三峡蓄水后大通站水沙过程的变化。该水沙过程不利于左汊分流比的维持,特别是175 m蓄水方案运行后,左汊分流比明显下降,成为影响航道条件的主要因素。

Mutation of navigation-obstructing characteristics in Tuqiao waterway

The navigational condition of Tuqiao waterway has deteriorated since 1998,but the navigation-obstructing characteristics have varied with time.Therefore,this dissertation attempt to delve into the mutation of the navigation-obstructing characteristics.Firstly,it draws on data from the topography and hydrology of Tuqiao as well as the date of water and sediment from Datong hydrological station during 1955 to 2014.Secondly,by using the ordered cluster method it analyzes the changes of sediment discharge of Datong hydrological station,and the reasons of the variations of navigation-obstructing characteristics.The results show that the navigation-obstructing characteristics have changed from the problems of section shape and silty-sand to the declining split ratio of the left branch.The main reason is the changes in the water and sediment process of Datong hydrological station after the impoundment of Three Gorges Reservoir.The new process of water and sediment is detrimental to the maintenance/stabilization in the flow diversion ratio of the left branch,which specially causes a significant decrease in the flow diversion ratio after the operation of 175 m water impoundment scheme,and has become the main reason of the worsening navigational condition.