The river flow capacity is influenced greatly by the Manning roughness coefficient, but the estimate value of Manning roughness coefficients of the previous studies was considered as a constant value in all river cross-sections. Thus, the previous estimate values could not change with the level of river water surface, and could not reflect the influence of Manning roughness coefficients change with the distribution of berms in the river. In order to evaluate the influenced of water surface level due to the berms development, Geographic Information System (GIS) was used to investigate and record the berms distribution of the research region and to digitize them. It would make the combination of GIS and models, convenient to have the most precise in the forward research process.