长江口水下三角洲演变规律及河势控制初探

The evolution law of underwater delta in the estuary area of the Yangtze River and preliminary study on river regime control

长江河口区水下三角洲的稳定关系着河口区域滩涂湿地的保护、经济社会的发展,研究长江河口区水下三角洲的变化规律,制定相应的控制对策有着重要的意义。基于长江河口区水下三角洲近40年的4个测次的地形资料,采用平面形态与断面形态分析相结合的方法,探讨了长江河口区水下三角洲的变化规律和相应的控制对策。总体来看,受入海沙量减少的影响,长江河口区水下三角洲前缘10~20 m等深线之间的区域冲刷明显。崇明东滩沙体总体变化不大,横沙东滩、南汇边滩在圈围工程影响下,面积有所淤长。横沙浅滩、九段沙窜沟发育,切割洲滩,沙体稳定性受到威胁,建议对横沙浅滩、九段沙实施守护,以控制长江河口区河势稳定。

The stability of the river delta of the Yangtze River estuary area is related to the protection of tidal wetlands in the estuary area,and the development of economy and society.It is of great significance to study the changing laws of the underwater delta in the Yangtze River estuary area and formulate corresponding control measures.Based on the topographical data of four surveys of the underwater delta of the Yangtze River estuary in the past 40 years,the method of combining planar morphology and cross-sectional morphology analysis is used to explore the river regime change law of the underwater delta in the Yangtze River estuary.The corresponding control countermeasures are discussed.Generally speaking,affected by the decrease in the amount of sand entering the sea,the area scour between the 10m-20m contours of the underwater delta front of the Yangtze River estuary is obvious.Chongming Dongtan sand body has little change in general.Hengsha East Beach and Nanhui Bund are affected by the encircling project,and the area is silted.Hengsha shoal and Jiuduan sand channeling ditch develop,cutting the bank and beach,and the stability of the sand body is threatened.It is recommended to guard the Hengsha shoal and Jiuduan sand to control the river regime stability in the estuary of the Yangtze River.