Tracking hydrodynamic variation in a tide-dominant estuary over the past half-century

Tide-dominated estuaries, serving as critical interfaces for land-sea interactions and navigation systems, are experiencing substantial morphodynamic alterations and channel shrinkage due to intensive anthropogenic pressures. This study investigates the spatiotemporal hydrodynamic evolution and its mechanism in the Shiziyang tidal channel (SZY) in the Pearl River Estuary (PRE) through a half-century of data analysis and numerical simulation (Delft-3D FM). Our tracking reveals significant tidal intensification, with tidal ranges at the mouth increasing from 1.60 m in 1955 to 1.79 m in 2016, accompanied by accelerated tidal wave propagation (35.3 % enhancement during 1975 − 2005) and a remarkable shift from tidal damping to amplification. The tidal energy flux amplification exhibited pronounced spatial heterogeneity, with significantly stronger enhancement in the upper reach (99.2 %) compared to the lower reach (24.6 %). Tidal range showed positive correlations with river discharge but remained independent of sediment flux, with channel dredging and port infrastructure emerging as primary amplifiers of tidal dynamics through depth-mediated friction reduction. The dredging-induced channel deepening (46.53 %) and port construction-induced narrowing (66.23 %) collectively enhanced energy flux by 52.32 % through frictional reduction and current modulation (peaking at 233 % variation). The maximum amplification (186.72 %) occurred in the upper reach, primarily driven by its greater channel narrowing (21.42 %). These findings demonstrate how human interventions fundamentally transform tidal channel dynamics in a complex estuary, elucidating the mechanistic responses of tidal systems to anthropogenic forcing.