伶仃洋水沙变化及对铜鼓航道回淤的影响研究

Study on the Variation of Runoff and Sediment in the Lingding and Its Influence on the Back Silting of the Tonggu Channel

铜鼓一期航道回淤量远大于预期,综合伶仃洋岸线变化遥感调查、铜鼓航道实测水文资料分析、数值模拟等多种研究方法,研究铜鼓航道回淤增强成因。结果表明:(1)伶仃洋西滩北侧大面积围垦,使得伶仃洋东西岸潮位横比降增大,径流对伶仃洋中滩、东滩的影响增强;(2)伶仃航道二期及拓宽工程导致伶仃航道潮汐上溯动力增强,对下泄径流有一定的顶托作用,使得东槽净泄量占比增大,在涨潮初期,铜鼓航道涨潮流、暗士敦水道涨潮流与深圳湾下泄流在铜鼓航道北段共同形顺时针环流,使得铜鼓航道北段成为淤积最为严重的区域;(3)收缩型河口湾使得波浪辐聚增强,此前的研究对波流共同作用下局地泥沙悬扬起动后在航道内落淤未充分考虑;(4)频繁的采砂活动导致局部泥沙浓度骤升,伶仃洋内重大工程对铜鼓航道回淤亦有不利影响。

The amount of silt in the first stage of the Tonggu channel is much larger than expected. Synthesized multiple research methods including RS survey of the coastline change of the Lingding Estuary, the hydrological data analysis and numerical simulation of the Tonggu channel, the causes of the aggravation of the Tonggu Channel was studied. The results show that:①large area reclamation in the northwest area of Lingding west shoal amplified the transected water level difference between the east and west territorial waters, which enhanced the impact of fluvial runoff on the middle and the east shoals;②the second stage of the navigation channel project led to the flood tide of the channel enhanced, which enlarged the proportion of drainage of fluvial runoff by east channel. Flood current from Tonggu Channel and Ansidun Water Channel and ebb current compose an clockwise circulation during the beginning of the flood, which made the northern section of the Tonggu Channel become the most severely deposited area;③the contracted estuary made the wave convergence enhanced,previous studies have not fully considered the siltation in the channel after the start of the local sediment suspension under the combined action of the wave current;④continuous sand mining activities increased the concentration of local suspended sediment, and major projects in Lingding Estuary had adverse effects on the back silt of the Tonggu Channel.