【摘要】 本文主要讨论了汕头港外拦江沙及其航道洄淤的物质来源。认为外拦江沙的形成和消长,与新津溪输出泥沙以及该处的海洋动力因素的作用密切相关。外拦江沙的物质来源主要是新津溪的入海泥沙,而对浚深航道来说,待狎金浅滩的泥沙本身就是它的直接物质来源。外拦江沙在自然状况下处于准动态平衡,淤积缓慢,但一经浚深,便会出现严重的淤积。为维持—5.5m以下的航道,估计洄淤疏浚量最大为50—60×10~4m~3a。更多还原

【Abstract】 In this paper the sand sources of the bar at the river mouth outside the Shantou Port and the dredged channel are further discussed and the accumulation is calculated roughly based on other’s studies and the data recently acquired. The results revealed that the bar at the river mouth outside Shantou Port just overlaps the modern ebb delta and the delta of the Xinjinxi River based on the ancient longshore bar. The development, growth and decline of it are closely related to the charaeteristies of the sand carried there from Xinjinxi River and by the wave and the tidal current. The bar at the river mouth has turned to be declining after dredging a channel through it according to the sediment patterns. The volume of the sediment is on the decrease from the river mouth to the channel on the bar, and the heavy minerals can be divided into three zones: titanite, magnetite, zircon→epidote, hornblende→biotite in accordance with their specific gravities and shapes. Its properties show that the sand was transported to the river mouth from the Xinjinxi River. Comparison of the historic charts (1907—1979) show that average annual accumulation in this area is about 560,000m~3, that on the east side of the channel accounts for 87.3%. However, accumulation on the west side tends to get faster, indicating that the sand was transported from east to west. Various informations testify that the sand accumulater in the dredged channel is transported from shoal in the east side. At present, the bar of the river mouth is under a dynamic paraequlibrium with a slight accumulation. However, after the channel is dredged, the channel will be silted up gradually by the sand. The volume of the silt deposit is related to the width and depth of the dredged channel. Provided that the channel is 80 m wide and -5.5m deep, the accumulation may be estimated as 500,000—600,000 m~2/a.更多还原