Abstract: Many technical challenges related to hydrological and geological conditions were encountered during construction of large-diameter underwater shield tunnels in the Yangtze River basin due to lack of experience in these areas, especially regarding high water pressure, a shallow overburden and servere erosion conditons. Using the Weisan Road river-crossing tunnel as an example, multi-beam bathymetry-based riverbed monitoring technology is used to take a three-dimensional dynamic measurement of the underwater topography and flow rate and to forecast the staged riverbed erosion condtions based on historical data. With the multi-beam bathymetry-based riverbed monitoring technology, advanced prediction of the hydrological and geological conditions of the underwater shield tunnel is achieved, which provides technical support for the risk control of the shield tunnel.