Abstract: In the study of branching rivers, flow and sediment diversion ratio is an important factor. The flow and sediment diversion ratio at Fujiangsha river reach in the Yangtze River Estuary was calculated according to in-situ data from 2012 to 2019 by using a 3D tidal-sediment numerical model ECOM-Sed. Result demonstrate that runoff increase in the upstream or tidal range decrease in the downstream would both intensify the imbalance between flow and sediment diversion. The factor of such imbalance is positively correlated with the amount of dredging maintainance of navigation channel. It’s difficult for the 30% discharge in Fubei channel to convey about 40% sediment flux. Such impbalance would result in severe silting in Fubei navigation channel. To alleviate the silting, engineering measures such as lengthening or heightening of the three existing groins at Fujiangsha reach can be taken to reduce the imbalance.

Key words: Yangtze River estuary, Fujiangsha river reach, Fubei channel, diversion ratio between flow and sediment, imbalance