防城港拦门沙航道的泥沙来源及冲淤规律的研究

防城港位于广西壮族自治区的南部,北部弯的顶部,它是我国南方新建的万旽级重要港口。该港在开发过程中遇到的关键问题之一是外航道有拦门沙,水深只有3.2m,拦门沙开挖以后是否会出现泥沙淤积影响正常通航，对此必须作出科学预测。中国科学院海洋研究所受交通部委托,与交通部广州航道局和广西交通局勘察设计院等单位协作,于1974年至1978年进行了系统的调查研究,并先后提出了《踏勘报告》和《调査研究报告》。根据我们对地质地貌的历史演变、泥沙来源及泥沙运动规律的研究，推测拦门沙开挖后泥沙洄淤量不大,开发前景良好,为该港的建设提供了科学依据。经过将近三年的实践检验,结论基本上符合事实。本文即是在上述报告的基础上撰写的。

STUDY OF THE SOURCE OF SAND AND THE PATTERN OF EROSION-ACCUMULATION AT THE BAR OFF THE FANGCHENG PORT

The evolution and sand source of the bar off the Fangcheng Port was under investigation from 1974-1978, the result of which indicated that this bar is a residue of the delta of the ancient Fangcheng River. Analysing the minerals and grain size, we found that the sand of the bar mainly came from the ancient Fangcheng River, and the sand carried by the present Fangcheng River has little effect on it. By using the methods of the comparative photographic map and calculation of wave and tide energy,silt accumulated on this part of waerway is found to be about 2.1-2.8×104m3 annually.The outer waterway is eroded in winter, and the sand again accumulated in summer. It is supposed that the amount of accumulation will be about 5-10×104m3 annually when the outer waterway is dragged to the depth of 7 m. The above mentioned result has been comfirmed by measurement from 1979-1981.