The morphodynamic evolution of an idealized inlet system is investigated using a 2-D depth-averaged process-based model, incorporating the hydrodynamic equations, Englund-Hansen’s sediment transport formula and the mass conservation equation. The model is given a fixed geometry, impermeable boundaries and uniform sediment grain size, and driven by shore-parallel tidal currents. The results show that the model reproduces major elements of the inlet system, e.g., the evolution of flood / ebb tidal deltas and tidal channels. Equilibrium is reached after several years, with the residual transport gradually decreasing and eventually diminishing. The modeled minimum cross-sectional entrance area of the tidal inlet system is comparable with that calculated with the statistical P-A relationship for tidal inlets along the East China Sea coast. The morphological evolution of the inlet system is controlled by a negative feedback between hydrodynamics, sediment transport and bathymetric changes. The unique flow field of the inlet system, i.e. a jet during the ebb and a radial inflow during the flood, is responsible for the hydrodynamic setting. The evolution rates decrease exponentially with time: the system develops rapidly at an early stage while it slows down at later stages. Temporal changes in hydrodynamics occur in the system; for example, the flood velocity decreases while its duration increases, which weakens the flood domination patterns. The formation of the multi-channel system in the tidal basin is associated with two stages; at the first stage the flood delta is formed and the water depth is reduced, and at the second stage the flood is dissected by a number of tidal channels in which the water depth increases in response to tidal scour. |