Abstract:Kou’anzhi waterway is an important part in the second phase of the regulation project of 12.5 m deep water channel from Nanjing to mouth in the Yangtze River. According to the measured topographic data in past years,we analyze the riverbed evolution trends in Kou’anzhi waterway and form the treatment thoughts of 12.5 m deep water channel in Kou’anzhi waterway with relevant engineering schemes put forward. Applying the 2-D tidal current and sediment mathematical model,we evaluate the scheme effects. The calculated results reveal that:1)the river regime of Kou’anzhi waterway is steady substantially;2)the transition part shoal exists in the broadening segment of the left branch of Luochengzhou,in which,the channel conditions varies with the hydrological processes;3)the erosion and deposition in Manyusha shoal change frequently in different hydrological years,but the erosion and atrophy are the major prospect of sand variations in Manyusha due to abrupt reduction of the sediment from upstream. Therefore,the essential thoughts of the channel regulation are mainly stabilizing the protective engineering in the head of Luochengzhou and Manyusha shoal,and combining the spur and submerged dike to increase the erosion ability of shallow areas. The objective of 12.5 m deep water channel can be obtained by taking engineering measures.