The article gives the results of numerical simulation of flood wave routing though an urban riverbed for preliminary evaluation of capacity of its section exposed to strong anthropogenic impact. As a study area the Sudoł Dominikański stream (called also Rozrywka) in the area of Krakow was chosen. The numerical calculations were performed basing on 1-D unsteady flow model built using the MIKE 11 by DHI program. In the model the objects of engineering constructions were included such as: bridges, culverts, piped section and the potential floodplain areas. Due to lack of a gauge stations, the hypothetical waves built basing on the rainfall-runoff model were used as a boundary conditions.