Abstract
We discuss the prediction of debris flow characteristics and estimation of sediment runoff control using erosion control facilities such as check dams and channel works in an actual mountain torrent based on the results of field survey and numerical analysis. In the Ohzedani River, a tributary of the Sendai River, a very active sediment runoff took place in September 1961 due to the second Muroto typhoon. A one-dimensional numerical simulation is conducted in order to investigate variations in debris flow characteristics along a river reach with erosion control facilities. According to the analytical results, debris flow discharge increases several orders of magnitude compared to water, and that the sediment transport rate varies with river-bed slope and river width. Flow discharge decreases suddenly at the cross section with check dams due to the variation of sediment transport. Flow path is fixed with channel works and it makes a great contribution for the protection against debris flow flooding. The computational condition of river-bed erosion has much effect on these numerical results.
