The subject of this diploma thesis is a comparison between two river hydraulics modeling approaches, the first one being combined 1D and 2D modeling, and the second one being solely 2D modeling. Both models are located at Bečva river, between its 17,282 and 28,419 river kilometer. The outputs of the simulations are water flow velocity maps, water depth maps, maps that show differences between flood areas calculated in both models, tables comparing channel water surface elevations and schematic long sections. In conclusion of the thesis, the outputs of the simulations are compared.