长江口口内河段冲淤演变特征及控制因子分析

Processes of decadal morphology and controlling factors of the inner Yangtze Estuary

基于1958-2015年间多个年份实测地形资料,定量分析了长江口口内河段的冲淤演变过程,结果表明:该河段经历了剧烈的河势调整,深槽冲刷、浅滩淤积为主要特征,其中20世纪80年代尤为显著,之后整体河势趋于相对稳定。冲淤量从净淤积向净冲刷转换,与河流来沙量的变化趋势一致,5～15 m水深范围内对来沙量的变化最敏感。洪水事件和特枯水文年对河槽冲淤量的影响同样显著,包括20世纪90年代的连续洪水年、2010年大洪水及2006年特枯水年。

Processes of decadal morphology in the inner Yangtze Estuary are analyzed based on bathymetric data in 1958-2015.Results indicate that the study area experienced remarkable pattern modification with scour along main channels and accretion at shallow shoals,particularly in 1980 s.Channel-shoal pattern evolved towards relatively stable after 1980 s.Sediment volume changes converted from net accretion to net erosion,which is consistent with sediment load variation,and the river bed between 5 m and 15 m was more sensitive.Impacts of river flood events and extremely dry years on the volume changes were also significant,especially the frequent river floods in the 1990 s,river flood in 2010 and extremely low river inputs in 2006.