Abstract. Previous work on morphodynamic evolution in the Yangtze Estuary (YE) is based on measured historical bathymetries. To evaluate the sensitivity of sand–mud interaction in the estuarine morpho-dynamics, a process-based morphodynamic model, Delft3D, is used to examine the morphodynamic behaviour from 1958 to 1997. Different scenarios concerning sand and mud and their combination are designed systematically. The scenarios considering multiple fractions, and especially with four fractions, improve the hindcasting evolution, suggesting the importance of including both sand and mud fractions and a sediment gradient setting of medium grain.