A multi-resolution treatment method for the analysis of flood submergence of river beaches was ad-vanced.With this method，the flow in rivers was simulated by solving the two-dimensional water equation using finite element method.Drying and wetting judgement was aoopieu olau rates were obtained by simulations. Theer channels.The water surface elevations corresponding to various tow raes were obuanhena py soTmentation andsurface was used to split the high-resolution DEM (digital elevaton moderyio pogtayol .w ne ansed in pratice forregion growing methods were used to recognize the wet and dry areas.1insnmelnia wa1 um) twn-jimansionalthe estuary section of downstream Nandujiang River，during which the low resolution (10m) two-dimensional shallow water numerical simulations were effectively combined with the high resolution local topography (2m). Inthis way，high precision computations were obtained for the submerged area.