Effects of Dam Failure Mechanisms on Downstream Flood Propagation

Abstract

The careful mapping of areas that might potentially be flooded following a dam failure is necessary to understand, reduce and manage the relevant risks. These ones, in turn, strongly depend upon both the dam failure mechanisms and the characteristics of the areas potentially subjected to inundation (i.e. topography, presence of infrastructures, …). Specifically, referring to the embankment dam on Sciaguana River (Sicily, Italy), 2D unsteady flow simulations of the possible dam break due to (a) overtopping or (b) piping failure have been carried out by running the HEC RAS code. The effects of an assigned breach formation and progression mechanisms on flood propagation have been parametrically analysed. Inundation mapping results obtained through the proposed dam failure model have been compared with the potentially flooding areas predicted by the local government Authorities. Some breach prediction methods available in technical literature have been furthermore applied; the corresponding results have been discussed and compared with the numerical (HEC RAS) simulations. The proposed analyses may contribute to a better and more reliable delimitation of the flood hazard areas as well as the definition of relevant mitigation countermeasures.