NUMERICAL STUDY ON RIVER LEVEE BREACH BY CONSIDERING GRAIN-SIZE DISTRIBUTION OF LEVEE MATERIALS

Abstract

 The overflow breaches of the river levees in large-scale experiments and a historical flood event have been investigated using a process-based model with considering grain-size distribution of levee materials, for evaluating the validity of the numerical model on the hydro-morphodynamic process of river flood, levee failure and inundation. The comparisons between the numerical and experimental results show that the model can reproduce detail processes of levee overtopping, breach deepening and widening, and flood-plain erosion and accretion measured in three different experimental conditions. The multiple grain-size model has an effective advantage in simulation of lateral breaches of the levees exposed to high-velocity flood flows. The application of a real levee-breach event on the Ikarashi River (Japan) in July 2004 shows that the model with detailed hydro-morphological conditions is appropriate for the estimation of final breach width, morphological changes in flood plain, and inundation volume.