This article gives the results of developing and testing a system for operational river flood forecasting, which is based on a system of hydrological and hydrodynamic models, as well as ground-observation and satellite data. This system is implemented on the basis of service-oriented architecture. A specific feature of the system is fully automated implementation of the entire modeling cycle—from loading input data to interpreting and visualizing the results and alerting the interested parties. The theoretical basis for coherent functioning of all system components is the qualimetry of models and polymodel complexes developed by the authors. The practical implementation is based on open codes and freeware. The results of testing demonstrate the potential for a wide introduction of such systems in the activities of territorial authorities and emergency services.