AN ANALYSIS OF THE DIFFUSION OF SUSPENDED SEDIMENT DISCHARGED FROM THE CHANGJIANG RIVER BASED ON THE SATELLITE IMAGES
Yun Caixing Cai Mengyi and Wang Baoquan(East China Normal University) (Shanghai Waterway Bureau)
The suspended sediment discharged by the Changjiang River into the sea not only causes direct siltation in the estuarine region, but also affects the nearby continental shelf. This paper proposes to analyse the diffusion of this suspended sediment based on the satellite images. Recent data from Landsat Images reflect that the amount of discharge from the North Channel is greater than that from the North Passage, while the latter is greater than the South Passage. On its way into the sea, the suspended load forms a distinctly step by step diffusion and deposition. The sedimentation may be divided into four stages: muddy stretch, turbid flow, plumes and freshening stream. Owing to the effect of drift and ocean wind current, the direction of diffusion is north-eastward in high flood season and south-eastward in low flood season.Meterological satellite images displayed turbid flow section of about a few tenth of kilometer in width off the coast of Jiangsu and Zhejiang provinces. The diffusion of suspended sediment from Changjiang River can extend from Lusi Sea area to Zhejiang and Fujian Provinces in the south. Particular attention must be called to the fact that there exists a stable turbid current of a width of 50 kilometers between 32°00'-33°00' N. It was formed by the concourse of Huanghai Sea cold mass, Kuroshio tributary and Changjiang freshening stream.