Evolution of the Yangtze River Estuary from 1997 to 2023 and tidal strength feedback simulation

In order to explore the evolution of the Yangtze River Estuary (YRE) and the feedback of tidal strength under strong human intervention, the changes in the shoreline, erosion and deposition patterns, and tidal strength were studied based on YRE bathymetry data from 1997 to 2023, and a scenario simulation of the YRE using a tidal mathematical model was conducted. The results showed that, under the influence of strong human activities from 1997 to 2023, the shoreline of YRE expanded toward the sea, resulting in an average reduction of 2400 m in river width, a decrease of 643.79 km² in water area, an increase of 136 million cubic meters in volume, and an increase of 1.34 m in average water depth. The results also revealed a trend of “river channel narrowing, shoal silting, channels eroding, groove developing, and riverbed deepening.” The tidal strength in the South Branch, South Passage, and the upper part of the North Branch of YRE increased, while the tidal strength in the North Channel, North Passage, and Hengsha Channel decreased. Finally, there was no significant change in the other regions of the YRE. The results of this study can provide useful guidance for the protection and management of YRE, such as river regulation and dike construction.