地形变异条件下长江口南港河段水动力变化

1958—2010年，长江口南港河段河槽断面形态呈“U”型和“W”型交替变化。基于二维潮流数学模型，模拟了1958，1973，1997和2010年长江口地形条件下的水动力变化，进而分析了地形变化对潮波传递和潮流运动的影响。研究表明，南港河段水动力与地形变化密切相关。自1958年以来，南港河段潮差逐渐减小，潮波变形逐渐加剧；潮流与瑞丰沙发展变化联系紧密；1997年，瑞丰沙范围最大时，南港流速平面上呈复式分布，长兴水道为涨潮占优，其他年份，落潮占优，南港主槽始终为落潮占优；南港落潮分流比自1958至1973年明显降低，1973年后趋于稳定，为50%左右，随地形变化较小。

Hydrodynamic changes in south channel of Yangtze River estuary under topographic variation conditions

The river channel section of the south channel of the Yangtze River estuary changed alternately in “U” and “W” shapes from 1958 to 2010. Based on the two-dimensional tidal current mathematical model, the hydrodynamic changes under the topographic conditions of the Yangtze River estuary in 1958, 1973, 1997 and 2010 are respectively simulated, and the impacts of topographic changes on the tidal wave transmission and tidal current movement are analyzed. The research results show that the hydrodynamics in the study area (south channel) is closely related to the topographic variation. The tidal range of the south channel reach has gradually decreased, and the tidal wave deformation has gradually intensified since 1958. The tidal current movement is closely related to the development of the Ruifeng shoal. In 1997 when Ruifeng shoal was the largest, the flow velocity of the south channel was distributed in a double pattern. The Changxing waterway was dominated by the high tide, while the other years were dominated by the ebb tide, and the main channel of the south channel was always dominated by the ebb tide. From 1958 to 1973, the diversion ratio of the ebb tide in the south channel decreased significantly, and stablilized after 1973 to about 50%, with little change with the topography.