Study of Riverbed Evolution and Channel Siltation at South Passage of the Yangtze Estuary

Using multiple underwater terrain material and field hydrological observation data,then combining with the surrounding project progress,the recent evolutional process and channel siltation reasons of the South Passage are analyzed.The results show that:1South Passage scours in the upper segment,and deposits in the lower;2the mouth bar of South Passage gets shortened and riverbed gradually raises;3the volume of Jiangya'nansha Shoal increases,and the empennage of the shoal extends to downstream.Preliminary analysis suggests that:the natural deposition extension of Jiangya'nansha Shoal is the primary cause of channel siltation.