DAM Break Analysis Due to Piping Failure Using HEC-RAS and HEC-GeoRAS

2. Group of Hydrology and Water Resources, Faculty of Engineering, Agostinho Neto University, Angola

Abstract: Angola has been actively building DAMs for the past few decades to meet various infrastructure requirements, but the country has never had a DAM demolished or failed. Based on the result attained from past studies, potential DAM Break scenarios and the ensuing flooding were not given much attention, therefore, the research mainly focusses on the analysis of both cases, by means of the Hydrologic Engineering Center River Analysis System (HEC-RAS), and the analysis of piping failure mode scenario which is frequently associated with dam break cases. For validation and forecasting of the DAM Break failure mode parameters, the hydrograph’s linear Breakout-flow in the structure, located in Cunene Province, for both Froehlich and MacDonald & Langridge-Monopolis formulations was generated at different intervals in HEC-RAS using the empirical equations and numerical models of both Froehlich and MacDonald & Langridge-Monopolis. A high Probable Maximum Flood (PMF) inflow of 8.036 m3/s is used as a reservoir input to determine whether the piping failure was conceivable, estimating that the spillway has demonstrated that it can handle the inundation caused by the PMF, turning the infiltration of the embankment impossible. Additionally, HEC-RAS was used to model piping failure. The resulting Break due to the piping failure was examined, and flood hydrographs were obtained at various cross-sections along the river.