Estuaries like the Yangtze Estuary are influenced by tides and river flows, which can be affected by human activities. A study looked at how tidal waves and river flows interact in the Yangtze Estuary using computer models and data analysis. They found that tides in the coastal area stay the same over time, but in the tidal river, the water level changes seasonally. During the dry season, tides can reach far inland, while in the wet season, they don't go as far. The strength of the tides can vary due to factors like river flow and channel width. The Three Gorges Reservoir affects tides by changing seasonal water discharge, leading to changes in tidal amplitudes in the tidal river.