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针对近期长江口南北槽分流口地区出现新的河床冲淤演变情况,对分流口河道尤其北槽入口河段多次实测水文结果进行分析,探讨了分流口河道悬沙输运机制。通过引入输沙机制影响强度尺度参数,得到悬沙输运机制的数学表达形式,并进一步探讨了北槽入口河道产生淤积的原因。结果表明:(1)北槽分流口存在三级输沙机制,且不同输沙机制项在近口段、口中段和口内段各段中影响程度也不相同;(2)分流口泥沙来源于南港河段,在向“南港—北槽”输运过程中,一部分泥沙受到分流潜堤拦截,落淤在潜堤北侧造成九段沙沙头持续淤长;(3)悬沙在口中段受两项输沙机制的共同控制下,跨跃航槽,横向输运。并在输移过程中落淤,最终形成北槽入口局部区域的持续淤积。
In view of the recent evolution of scour and silting in the diversion area of the north-south trough in the Changjiang Estuary, several hydrologic results measured at the inlet of the diversion channel, especially in the north channel were analyzed, and the transport mechanism of suspended sediment in the diversion channel was discussed. The mathematical model of suspended sediment transport mechanism is obtained by introducing the influencing scale parameters of sediment transport mechanism, and the reasons for siltation in the channel of the north trough are also discussed. The results show that: (1) There is a three-stage sediment transport mechanism in the diversion outlets of the north groove, and the influence of different sediment transport mechanisms in the sections near the mouth, middle mouth and inner mouth is different; (2) In the Nankang section, a part of the silt was intercepted by the diversion embankment during the transport to the “Nangang-North Slot”, and siltation was caused on the north side of the submerged-ditch to cause a continuous siltation of the Jiudu section. (3) In the middle section of the mouth, under the common control of the two sediment transport mechanisms, cross-leap navigation slots are transported horizontally. And during the transport process of siltation, the final formation of the northern part of the mouth of the continuous deposition of silt.