长江下游澄通河段通州沙汊道演变新特征

长江下游澄通河段通州沙汊道为典型的多滩分汊河道,在径潮流共同作用下,河势与航道条件复杂多变。近期该河段实施了一系列河道(航道)整治工程后,通州沙西水道涨落潮流归顺主槽,该水道淤积萎缩态势得到缓解,但疏挖拓展后的水深条件难以维持,西水道将经历整治后的调整平衡过程。东水道局部河势发展趋向不利,其中:龙爪岩上段呈现主流右摆、滩槽交错的特征,右侧洲滩冲刷,滩面串沟依然存在,并有进一步冲刷发展的趋势;龙爪岩下段营船港外边滩冲刷左移,新开沙尾-10 m(高程)潜心滩冲刷,对航道不利。建议及时采取守护东水道右侧洲滩的措施,整治新开沙外滩,并考虑实施通州沙圈围工程,有利于维持洲滩与汊道分流格局长远稳定。

Recent Evolution Features of Tongzhou Shoal Channel in Chengtong Reach of Lower Yangtze River

Tongzhou shoal channel in Chengtong Reach of the lower Yangtze River is a typical bifurcation channel with multiple shoals as well as complex and variable river regime and waterway condition under combined riverine and tidal forcing. After river and waterway regulation projects in recent years, the flooding and ebb currents converged along the main west channel of the Tongzhou Shoal, alleviating the channel’s silting and shrinking. However, the west channel was unable to maintain its water depth after dredging and will adjust and approach to equilibrium, whereas the local river regime of the east channel tended to be unfavorable. The mainstream of upstream segment of the Longzhuayan node moved rightward and the shoals and channels intertwined. The right side of the Tongzhou shoal was scoured, with a trend of further scour along the connecting channels on the Tongzhou shoal. The marginal shoal near the Yingchuan port in the segment downstream the Longzhuayan node was scoured to the left, and the submerged shoals -10 m under the tail of Xinkai shoal was scoured, which is unfavorable to navigation. Measures should be taken to protect the right side of the east channel in time, to renovate the Xinkai shoal, and to consider reclamation of the Tongzhou shoal. Such measures are conducive to maintain the long-term stability of the shoals and the flow diversion pattern of the bifurcation channel.