三峡水库蓄水以来关洲汊道形态调整效应的数值模拟

Numerical modelling of effects of channel morphology′s adjustment in Guanzhou inlet after impoundment of the Three Gorge Reservoir

为明晰三峡水库蓄水后关洲汊道形态调整对航道条件的影响,采用平面二维水流数学模型,研究了关洲汊道地形变化与水流运动特征及枯水位的关系。结果表明:关洲汊道左汊冲刷发展引起分流比调整,减弱了其对枯水位的控制作用,下游河道冲刷引起的水位降幅向上游传递作用增强;关洲汊道左汊冲刷还导致其下游芦家河汊道进口断面流速左减右增,增加了鸳鸯港边滩淤积及芦家河石泓的冲刷动力条件,不利于芦家河水道航道条件。为了维护上游枯水位的稳定并保证下游浅滩冲刷动力,应对关洲汊道进行守护,对分流比进行控制。

In order to investigate the effects of channel morphology adjustment on waterway condition in Guan-zhou reach after the impoundment of the Three Gorge Reservoir, 2D hydrodynamic numerical model was used tostudy the relationship between the changes of topography and hydraulic characteristics at low water periods. The re-sults show that the scouring of the left branch arouses the adjustment of diversion ratio, weakens the controlling ef-fects on the low flow water level and enhances the upstream transmission of the water level drop caused by the ero-sion of downstream reach. The scouring of the left branch also leads to the change of the cross section velocity at en-trance of Lujiahe reach. The velocity of the left branch reduces and the right increases. The changes of flow condi-tions cause deposition in Yuanyang sand bar and erosion in right branch of Lujiahe reach, which are harmful to thewaterway conditions of Lujiahe reach. To maintain a stable water level in the upstream and ensure the scouring dy-namic conditions of the downstream shoals, the Guanzhou reach should be protected and the water diversion ratio be-tween the two branches should be controlled.