Sand excavation and waterway regulation in the Pearl River networks have led to a decrease in water levels at hydrological stations. The Sixianjiao Station saw a significant 2.68m drop during floods. Tidal dynamics have increased due to channel volume changes, with tidal differences rising from 0.35m to 0.53m annually. Discharge in river mouths has been redistributed, with increases in Hongqi and Modao River Mouths but decreases in others. These alterations have also caused saline intrusion issues in recent years.