Estimation of inflow to inundation area due to levee breach

Abstract

There have been many numerical studies simulating the flood inundation, for which it is of importance to use an inflow to an inundation area as initial and boundary conditions. However, few experimental studies for the inflow estimation have been carried out. In this study, experiments were conducted to estimate an inflow to an inundation area due to levee breach with consideration of breach slope and width. The experiment tank is 30m long and 25m wide, and the channel is 30m long and 5m wide. The flat bed of both the channel and the inundation area are made of cement mortar. The initial water level in the channel was changed from 0.15m to 0.45m with a difference of 0.05m. Each water level was tested for the levee breach widths of 0.5m, 1.0m, 1.5m and 2.0m, and the levee breach slope (V:H) of 1: 0.0, 1: 0.1, 1: 0.3, and 1: 0.5. The experimental results were compared with side weirs, broad-crested weirs and an analytic solution of the dam break flow. From the comparisons, the inflow of the experiments is found to agree with the broad-crested weir flow. In the relationship between an experimental inflow per unit width q and overflow depth h0, the effect of the breach slope and width appears to be insignificant, which consequently results in a single curve of the relationship regardless of the breach slope and width.