Although damage resulting from levee breaches is particularly serious, there is a lack of technical data on the mechanism behind the phenomenon. Accordingly, the authors have conducted a series of levee breach experiments which were set up in the Chiyoda experimental flume. In this study, the authors focused on the sedimentation within the flood areas attached next to the experimental levees. The experimental conditions were variety of discharge, levee material, and levee shape. Using the results of the experiments, the authors clarified the relationship between the sediment distributions and the experimental conditions. Then, comparing the volume of breached levee and the accumulated sediment, the origin of the accumulated sediment was examined. The authors also conducted a numerical calculation using Nays2D model and identified the relationship of the plenary velocity distributions and the sediment distributions.
