长江口深水航道及横沙东滩促淤圈围对滞流点的影响

Impacts of Yangtze Estuary Deepwater Channel Project and Hengsha East Shoal Siltation and Reclamation Project on Stagnation Point

滞流点位置的变化对河口拦门沙的形成和泥沙淤积具有极大的影响.基于MIKE3软件建立长江口水动力和盐度输运三维数学模型,采用实测资料对模型的潮位、流速、流向和盐度进行验证.运用验证好的数学模型模拟和分析长江口深水航道工程及横沙东滩促淤圈围工程对河口滞流点位置的影响,结果表明,(1)应用改进的近底层平均单宽通量计算公式确定滞流点的位置,验证结果良好,可以用该公式确定滞流点的位置;(2)深水航道工程的建设增大了水深和涨落潮流速,各汊道内落潮流量的增加明显高于涨潮流量的增加,且滞流点均向下游移动;(3)横沙东滩促淤圈围工程建成后,北港滞流点向下游移动约5km,北槽和南槽的滞流点则向上游移动约1km.

Variation of stagnation point has significant influence on mouth bar formation and sediment deposition. A three-dimensional hydrodynamic and salinity transport model based on MIKE 3 which has well been validated through observation data of tidal level, velocity magnitude and direction, and salinity was established to simulate and analyze the movement of the stagnation points caused by the Yangtze estuary deepwater channel project and the Hengsha east shoal siltation and reclamation project. It reveals that, OPosition of stagnation point is determined by an improved bottom average unit-width flux formula, and the verification of stagnation point is good. ②Water depth and current speed has increased after construction of the Yangtze estuary deepwater channel project, the increase of ebb discharge is obviously large than the increase of flood discharge, and stagnation points move downstream in all bifurcations. ③ After the Hengsha east shoal siltation and reclamation project, stagnation point moves about 5 km downstream in the North Channel and moves about 1 km upstream in both North Passage and South Passage.