Abstract
A 1: 200-scale river course model, corresponding to a section about 1. 7 km long between check dam No. 1 and 2 in the Nougou valley in the upper reaches of the River Ibi, was constructed.
Three series of experiments were performed with this model.
In the first series (Experiment A), three channel bed conditions in the construction order of dam No. 1, 2 and 3, which have been set up in the valley, were made respectively. Experimeltal debris flow was allowed to flush out. The variations in deformation of the channel bed and the mean diameter and sorting coefficient of deposits according to the number of dams were elucidated.
In the second series (Experiment B), we performed experiments under six conditions on the grid-size of dam No. 3, which was a grid-type dam. We clarified the relationship between the grid-size and amount of channel bed deformation and the representative grain-size parameters in the reaches influenced by dam No. 3.
In the third series (Experiment C), another grid-type dam, No. 4, was set up about 210cm upstream from dam No. 3. Under this condition, the debris flow was allowed to flush out. It was revealed that the continuous arrangement of grid-type dams with appropriate grid-size and interval had a synergistic effect on the control of debris flow.
