352 - Comparison Between TELEMAC-2D/SISYPHE and a Slumping Failure Model to Simulate Breaching of Earthen Embankments

Earthen dams are utilized worldwide for water storage and flood mitigation. Inadequate design and poor maintenance of such structures can result in breaching failures, which may have devastating impacts on both humans and property. Due to a lack of breaching models that fully characterize the breach evolution and failure process, a numerical model was developed in-house at the University of South Carolina. This model captures the spatial and temporal evolution of breaching. It solves the shallow-water equations and sediment mass conservation equation while considering the slumping failure expected in non-cohesive earthen embankments. Widely used free-surface flow models typically focus solely on the flow field by considering a rigid boundary. However, TELEMAC-MASCARET, an open-source solver of free-surface flow developed by several European organizations, contains two modules, TELEMAC-2D/SISYPHE, which can simulate morphodynamic changes in floodplains. The current work aims to compare the simulation of the breaching process in dams due to overtopping by TELEMAC-2D/SISYPHE with that by the in-house model, considering the breach measurements of the Upper Rocky Ford Dam that failed during the historic October 2015 flood in South Carolina. The breach outflow hydrograph and the evolution of breach shape in time and space are compared. Preliminary results indicate that the predictions made by the in-house model compare better with the field results than those made by TELEMAC-2D/SISYPHE. This paves the way to investigate the feasibility of integrating the in-house breaching model with TELEMAC-2D for better prediction of both the embankment breaching process and flood routing simulation.