The topic of natural disaster management -- prediction, prevention, or minimization of their impact is an important topic for scientific research. The advances in computer simulation and highperformance computing in recent years have highly extended the possibilities in this field, and have changed the ways in which natural disaster management systems operate. This paper describes evolution of one such system -- a flood prediction application. The application consists of a set of simulation models, visualization tools, and various support components. During past six years it has evolved from a simple hydraulic modeling scenario into a sophisticated cascade of simulations, using state-of-the art grid, workflow and knowledge management technologies, and is one of the first applications of the SOKU [1]concept in the field of computer simulations.