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2014年7月11-18日和10月29-31日以多波束测深系统和浅地层剖面仪等先进现场测量仪器对长江口北港河槽进行走航测量,结合人类活动强干扰下的海图水深数据及河槽表层沉积物资料探讨近期长江口北港河槽冲淤变化与微地貌特征。结果表明:在流域来水量变化不明显,来沙量锐减的情况下,近年来长江口河口段中上游河槽整体上处于微冲刷环境,而青草沙水库工程的实施导致北港中段河槽的冲刷程度更甚且冲刷态势向下延伸。2002-2012年北港泥沙净冲刷量为6.54亿m3,平均每年冲刷0.65亿m3。在其冲刷环境的影响下,近期北港河槽底床上除发育平滑床底外,还广泛发育冲沟和凹坑等侵蚀性微地貌,而河槽受到冲刷将导致底沙推移质运动增强,同样有利于沙波微地貌的发育。沙波主要分布在河槽沉积物为细砂的北港中上段底床的大部分区域和拦门沙河段的局部区域。
From July 11-18, 2014 and October 29-31, 2014, we measured the North River channel of the Yangtze River estuary with advanced on-site measuring instruments such as multibeam sounding system and shallow stratum profiler. Combining with the chart of strong human activity interference Water Depth Data and Surface Sediment Data of River Channels Discussion on the Eroscogenic and Microfacies Changes of the North Harbor Fluvial in the Yangtze River Estuary. The results show that the river channel in the middle and upper estuary of Changjiang Estuary is in a micro-scour environment as a whole in recent years with the change of water inflow in the basin is not obvious and the amount of sediment is drastically decreasing. However, the implementation of Qingcaosha Reservoir Project resulted in the erosion of river channel in the middle section of North Harbor Even more erosion situation extends downward. The net sediment scour of North Harbor from 2002 to 2012 was 654 million m3, with an average of 65 million m3 being washed off annually. Under the influence of its scouring environment, in addition to the smooth bed at the bottom of the Beigang River fluvial bed, erosional microfacies such as gully and pits are also widely developed. The scouring of the channel will lead to the enhancement of thrusting movement of the bottom sand, which is also beneficial to Shabo micro-topography development. The sand waves are mainly distributed in most of the upper part of the middle section of the upper part of the North Harbor where the riverbed sediments are fine sand and in the local area of the Shahe section of the barricade.