Modeling of Breach Volume in the Chiyoda Breach Experiment

Abstract

This study aims to propose a new numerical model for levee breach based on the results of relating experiments. Authors performed large-scale experiments of overtopping levee breach using the Chiyoda experimental flume located on the floodway of an actual river channel. By taking advantage of the scale of the flume, authors monitored the levee breach processes under highly precise hydraulic conditions, and the results showed a correlation between breached volume and shields number. Then authors applied the experimental results to a conventional two-dimensional shallow water with moving bed model, and found some limitations. Next, authors proposed a revised model based on the conventional model by integrating the experimental results into geomechanics, then obtained a fine reproduction result with regard to the levee breach widening during an actual flood of Yabe River in 2013.

Main channel width effects on overtopping-induced non-cohesive fluvial dike breaching

“…Available experimental works have attempted to clarify the role of some parameters on the breach expansion, including main channel inflow and downstream boundary condition (Michelazzo et al, 2018;Rifai et al, 2017), floodplain backwater (i.e. presence of water in the floodplain or leveed area prior to dike breaching) (Rifai et al, 2018), grain size of the dike material (Islam, 2012;Kakinuma et al, 2013;Rifai et al, 2021), fine sediment inducing apparent cohesion in the dike material (Rifai et al, 2021), and dike cross-sectional shape (Schmitz et al, 2021). However, other factors still require investigation, such as the main channel width.…”