长江口北支围垦对其水动力影响的数值模拟分析

Numerical simulation analysis of influence of reclamation of north branch in the Yangtze River estuary on hydrodynamic characteristics

20世纪50年代以来,上海市和江苏省两地对长江口北支实施了大规模围垦,使北支河宽大幅度缩窄,地形边界显著改变。在利用MIKE21_FM构建长江口—杭州湾二维垂向平均潮流数学模型,并用实测数据对模型进行验证的基础上,对北支大规模围垦前后的潮流场进行了模拟分析。研究结果表明:大规模围垦后,北支全河段平均高潮潮位抬升,平均低潮潮位降低;中上游河段涨、落潮流速增大,下游入海河段涨、落潮流速减小;南北支涨潮流汇流点上提至南北支交汇的崇头,涨潮动力增强。

The large - scale reclamation projects on north branch of Yangtze River estuary have been conducted by both Shang- hai City and liangsu Province since 1950s, which has narrowed the river channel and changed the terrain boundary greatly. Using MIKE21-FM, a 2D hydrodynamic numerical model of vertical average tidal currents in Yangtze estuary and Hangzhou Bay is es- tablished. Based on the satisfied verification results, the tidal current field of north branch before and after the large - scale recla- mations is simulated. The results show that after the large - scale reclamation, the average high tidal level of the entire river channel of north branch raised, while the average low tidal level declined; the velocity of flood and ebb tide in the middle and up- per reaches increased; however the situation in the lower reaches is quite the opposite ; With hydrodynamic force of the flood tide strengthened, the confluence of flood tide between south and north branches moved up to Chongtou where the South and North Branches converge.