Abstract: Determining the optimal scale of pump station is a crucial aspect of designing drainage systems in tidal rivers.We constructed a physical model of a tidal river system and conducted experimental investigations on the scales of two pump stations situated at the outlets under selected hydrological boundary conditions and project operational requirements.Our study reveals that:(a) constrained by the river's discharge capacity, a critical scale exists for the pump station, beyond which the water level remains unaffected by further scale increments;(b) the extent of water level reduction due to drainage pumping correlates closely with the proximity of the pump station, with greater proximity resulting in more pronounced water level drops. Building upon these insights and conducting multiple trials, we propose an optimal scale combination for the two pump stations to meet design specifications:80 m³/s for the Wenchong Pump Station situated farther away, and 130 m³/s for the closer Jinzichong Pump Station. This research offers valuable data for optimizing design processes and serves as a reference for similar projects.

Key words: tidal river, scale of drainage pump station, physical model test, water level, rehabilitation project