Uncertainties in dam failure modelling with the US NWS BREACH model

This paper draws together experience from using the US NWS BREACH model to simulate dam failure. Several deficiencies in the model have been identified which can lead to substantial uncertainty in prediction of the outflow hydrograph from the dam. There appears to be inconsistency in the transition from piping to overtopping failure and the model can produce unusual hydrograph shapes. The implications for practical application are that flood hazard areas identified by hydrodynamic modelling of the dam breach wave may be significantly in error, particularly in the critical zone close to the dam where risk to life is greatest.