Proceedings of the Seventh International Conference on Hydroscience and Engineering, Philadelphia, PA, September 2006. http://hdl.handle.net/1860/732A flood forecasting methodology is presented for a hypothetical dam failure event and possible solutions are proposed that could lead to reduction of flood consequences. During recent years, many methods have been developed with the purpose of achieving a better representation of the processes involved in breaching of a dam. However, no single method, to the best of our knowledge, can be considered to fully represent and predict the breach characteristics with high accuracy. In this study, we estimate the breach characteristics using two separate breach models and compare the resulting peak outflows with the range of peak outflows obtained using the empirical formulations. Despite only 10% difference in the peak outflow values obtained from two breach models, significant discrepancy is observed in timing and shape of the hydrograph. The peak outflow obtained using Hagen’s empirical formula is almost the same as predicted using physically based models. Though the empirical formulations might be useful for ‘rough/fast’ prediction of the peak outflow values, it is not applicable for dam break flood forecasting task, where the knowledge about breach development in time is important. The resulting hydrographs, constituting the upstream boundary condition for the Sobek 1D2D hydrodynamic model led to two different flood progression scenarios at the areas downstream the dam. The difference in timing of the breach outflow hydrographs is preserved during the propagation of the flood wave up to 30km from the dam
