伶仃洋滩槽演变及其发展趋势

Processes and Developing Tendency of Shoals and Channels in Lingdingyang Waters

伶汀洋水面开阔 ,岛屿众多 ;径流来水来沙量大 ,入汇口门多而分布不均匀 ;潮汐弱 ,潮流强弱平面分布不均匀 ,因而造就了当今的三滩两槽的淤积形态。两槽的形成与中滩的发育演变相辅相成 ,随着东、西滩淤积抬高和中滩淤积南移 ,必将导致东槽南段的西南汊进、排水能力不断减小 ;与此同时西槽北端因西滩的挤逼和推移质淤积也将日益萎缩 ,中滩北段漫流日益增强 ,必将导致切滩夺主 ,在伶仃浅滩与拦江沙之间将重新冲开通道。顺应滩槽演变趋势 ,因势利导 ,挖通拦江沙与伶仃浅滩间的沙梗 ,不仅可使伶仃洋航道收“一劳永逸”和事半功倍之效 ,而且还可提高排沙能力 。

In open Lingdingyang water area, there are a large number of islands. The runoff brings a large amount of discharge and sediment. There are many confluent entrances distributed non-uniformly. the tide range is small and the distribution of tidal current strength in plant is non-uniform. All of these cause the present deposited pattern, i. e. three shoals and two channels. Formation of the two channels and development of the middle shoal are supplementing to each other. Along with raising of the east and west shoals and moving to south of the middle shoal, inflow and outflow of the southwest branch located in the southern part of the east channel will be decreased. At the same time, the northern part of the west channel will be declining because of the pressing of west shoal and depositing of bed-load, and the current flowing over the northern part of the middle shoal will be strong. As a result, a new channel will be formed between Lingdingyang shoal and the sand bar by scouring. According to the tendency of the shoals and channels, the sand bank between Lingdingyang shoal and the sand bar should be dredged, by which not only Lingdingyang channel can be improved, but also sediment transport capacity of the waters can be raised.