三峡水库投运后关洲河段河势调整及水沙特性响应研究

Channel Adjustment of Guanzhou Reach and Water and Sediment Response Ater Operation of Three Gorges Reservoir

水库修建投运后,将在一定程度上改变其下游河道的水沙条件,导致下游河床失去原有的动态平衡,其水沙特性也将随着河床冲淤变化而有所响应.本文以紧邻三峡大坝下游、河床冲刷发展较充分的关洲河段为研究对象,采用河道地形、水文资料分析及平面二维数学模型计算等方法,研究水库下游河段受冲刷影响后的河势调整、总流能量损失及水流挟沙力的响应特点.研究结果表明:(1)三峡水库投运后,关洲河段河床经历持续冲刷并逐渐趋于动态平衡,全河段在2006~2010年之间的冲刷幅度达到最大;且微弯分汊段的冲刷量要大于上游顺直段及下游顺直段的冲刷量.(2)在河床持续冲刷的过程中,总流能量损失沿着减小的方向响应;水流挟沙力逐渐减小并趋于与来流含沙量一致.

Due to the operation of water conservancy project in a river,the riverbed downstream will lose its original balance,and the characteristics of water and sediment will change and respond accordingly to the riverbed adjustment.The downstream Guanzhou Reach,which is near the Three Gorges Dam and the riverbed scouring fully developed,is studied by analyzing topographic and hydrological data and a plane 2-D mathematical modeling.The response characteristics of total flow energy loss and sediment carrying capacity to channel adjustment in downstream reaches are explored.Research results show that:(1)After the Three Gorges Reservoir was put into operation,the riverbed in Guanzhou Reach has experienced continuous erosion and gradually tended to dynamic balance,and the scouring amount between 2006 and 2010 in the whole reach reached the maximum,and the erosion amount of the braided reach is larger than that of the straight reach.(2)In the process of continuous riverbed scouring,total flow energy loss will tend to decrease and sediment carrying capacity will gradually decrease and tend to be consistent with the coming sediment concentration of the river.