Abstract: The Yangtze River estuary dam project is affected by the combined effects of Yangtze River runoff, external tides, and waves. The combined action of the Yangtze River runoff and external tides forms the flow along the embankment, over the embankment, and around the embankment around the building, causing local erosion around the building. The wave action is mainly caused by wind, waves, and surges from the open sea, which cause local erosion of the sandy beach surface at the foot of the embankment. This article summarizes the commonly used methods and existing problems for calculating erosion depth, and compares them using multiple methods for calculation. Based on the geological conditions of the engineering site and the overall river regime, numerical simulation research and local physical model tests were conducted on the erosion depth in key areas. The comparison and analysis with the erosion depth calculated by empirical formulas were conducted to ultimately determine the scale of bottom protection and design the bottom protection structure, providing reference for similar projects.