长江口南北港分汊口控制工程对北港河势的影响

Effect of North-South Channel Bifurcation Control Engineering on the North Channel of Yangtze Estuary

为识别长江口南北港分汊口控制工程对长江口南支北港河势的影响,利用控制长江口北港的两条固定监测断面在2002-2015年间9个年份实测的高分辨率、高精度水下地形数据,通过叠加对比分析,准确识别了剖面的水下地形变化特征。并通过＂相邻年份剖面切面面积差值/剖面长度＂的比值计算了不同年份间剖面地形的平均变化量,作为指示不同年份间剖面地形变化总体特征的指标,反映了剖面地形随时间变化的总体规律。结果表明：近十年来北港河势变化主要受到长江口南北港分汊口控制工程的影响,其影响特征在空间上差异显著,对北港上段（尤其南岸）河势影响明显,而对下段的影响有限（微弱变化主要发生在北岸）;在时间上,北港上段和下段分别在工程竣工4年后和2年后达到稳定状态;2013年后北港河势趋于稳定,南北港分汊口控制工程已发挥显著作用,有利于北港航道开发。

To identify the fluvial process effect of the North-South channel bifurcation Control Priject on the North Channel of Yangtze estuary,the bathymetrical data with high resolution and high precision of two monitoring cross-sections located in the upstream and downstream of North Channel were studied from 2002 to2015. Based on the comparative analysis of these data,together with the calculated ratio of the cut areas and the lengths of the profiles,the fluvial process history of the profiles with time were proposed. Results show that the fluvial process influence of the engineering on the North Channel was quite different in space,as it was remarkable for the upstream channel,especially for nearby the south bank. But the weak impact was limited on the area nearby its north bank of the downstream channel. After the project was completed in 2009,the geomorphology of the upstream and downstream of the North Channel reached steady states in four and two years,respectively. After 2013,the condition of the entire North Channel became stable and conducive for navigation.