Abstract
The goal of this study was the development of a method of estimating a hydrograph of a mudflow passing through a slit check dam. Past research has shown that a slit check dam makes the hydrograph low. No study, however, has systematically clarified the influence of the sediment concentration and slit width on this effect. Therefore this research began with the clarification of the influence of these factors by flume experiments, and numerical simulations were performed to estimate the hydrograph.
The experiments were performed using a flume with a width of 10 cm, length of 300 cm, and height of 20 cm, set at gradients of 10° and 15° . The experiments were done using four dam models with slit widths of 1 cm, 2.3 cm, 5.3 cm, and 6.7 cm. Two mixtures of sand, Bentonite and water -sediment volumetric concentration of 40% and 20% were used. Each mixture was supplied from the upstream end of the channel at a constant rate with a tube pump. After the flow reached a steady state, one of the dam models was placed in the flume. The results show that the narrower the slit, the lower the discharge and the longer it is constrained. And the higher the sediment concentration, the lower the discharge.
The hydrographs were calculated using continue equation and momentum equation with MacCormack's method. It was assumed that maximum discharge with the specific energy in the upstream of dam model could flow out. The calculations accurately duplicated the experimental results.
