长江口工程促淤区的淤积特性分析

Study on deposition characteristics of promoting silting project in the Yangtze Estuary

对长江口南汇东滩工程促淤区的动态淤积特性进行系统分析,结果表明:工程促淤可将原不同地形地貌的滩涂调整为总体近岸高,离岸低,有一定坡度的连续性滩面。在充分促淤的条件下,工程区平均高潮位和纳潮口底高程可近似作为促淤后地形高程分布的范围指标。促淤区的空间分布表现为水深较深处比水深浅处的淤积强度大,水深越深,淤积量越多。各观测点的淤积强度随时间的延长呈递减趋势,一般经过2~3年的工程促淤,淤积厚度不再随促淤历时而有大幅度的增长。南汇东滩0 m等深线以上的促淤工程,在前2~3年的年均淤积强度约为0.2~0.3 m/a;-2 m等深线以上促淤工程,在前2~3的年均淤积强度约为0.5 m/a;-3^-4 m等深线以上促淤工程,前2~3年的年均淤积强度约为1.0 m/a。

Promoting silt deposition usually acts as the first stage during implementation of reclamation project.Located on the mouth bar of the Yangtze River,East Nanhui tidal flat is one of the key areas of development and utilization of tidal flat resources.Terrain data of several promoting silt deposition areas in the East Nanhui tidal flat are collected.Based on these data deposition characteristics and rate are discussed.The tidal-flat area can be adjusted to a continuous slope through promoting silting project.The mean high tide level and the bottom elevation of the tidal inlet can be regarded as the indexes of the elevation distribution after sufficient siltation.Deposition rate is larger in deep water area than in shallow water area.Deposition rate shows a decreasing trend with time.Generally after 2~3 years of engineering siltation,the thickness of siltation becomes very small.The annual deposition rate of the first 2~3 is about0.2 ~0.3 m/a over the 0 m contour line above the East Nanhui tidal flat,while0.5 m/a over the-2m contour line and 1.0 m/a over the-3^-4 m contour line.