Numerical modelling of levee breach with an improved slope-failure operator

A new slope-failure operator for bank sediment collapsing is proposed and tested. As compared to traditional operators that mainly depend on geometric parameters, the new operator considers the fact that collapsed sediments should firstly enter into the nearby water flow, and whether the collapsed sediments become part of the nearby bed should depend on the local flow and sediment conditions. Both the improved and traditional operators are implemented into the hydro-sediment-morphodynamic modelling framework. The model with these operators is applied to simulate experimental levee-breaching processes induced by overtopping flows. The model with the improved operator can produce numerical solutions (e.g. breaching shape, discharge) of much better accuracy (e.g. the RMSE for breaching discharge is 0.0024–0.0058 m³ s−1), as compared to the using of the traditional operator (e.g. the RMSE for breaching discharge is 0.0033–0.0087 m³ s−1).