Depth averaged numerical simulation of non-cohesive river dike breaching due to overtopping flows

Flood risk assessment is a major concern in urban and industrial areas located along rivers and open channels. These areas are generally protected by fluvial dikes (i.e. dykes, levees) but overtopping flows are often observed on these structures. As a result, a breaching process can be initiated, usually causing dike failure and inundation of the protected areas. The main purpose of this work is to numerically simulate the fluvial dike breaching process and outflow hydrograph. A set of empirical laws and a physically based approach estimating breach expansion are implemented in the two-dimensional depth-averaged module TELEMAC-2D from the TELEMAC-MASCARET suite of solvers. We perform simulations of a field-scale experiment and laboratory flume experiments for non-cohesive fluvial dike breaching due to overtopping flows. Three dimensional (3D) evolving dike geometry and time series of breach outflow and water levels were recorded for this later case. The numerical results are compared against experimental data, highlighting the ability of the modelling approaches to predict the main breach features. © 2020 Taylor & Francis Group, London