Strong currents induced by tidal oscillations have been overlooked in previous flood-risk assessments of the Mekong River. To discuss the potential disaster risk associated with tidal-flow intensification, this study applied ocean tidal modelling to a typical dry season when the tidal regime is predominant compared to the fluvial regime. The model can forecast tidal levels and velocities at a given time and location in the urban area of the Mekong Delta, which is characterized by many tributaries, channels, and low-lying lands, in addition to the main stream of the Mekong River. Numerical simulations revealed that a rapid flow, which could exceed 1 m/s in both the ebb and flood tidal phases, likely occurred along the tributary. Although this study only focused on the tidal regime, such locally intensified flows can be further amplified by a high river discharge or storm surge, having potentially dangerous consequences, such as difficulties in handling ships and small ships being capsized.