The characteristics of bedload discharge monitored by sediment discharge and hydrological observation at debris flow occurrences and its application for monitoring in mountain river basin

Abstract

The sediment discharge volume is observed with hydrophones and turbid meters at 100 observation stations by Sabo work offices of MLIT. At one of those stations, located in Daiya River, Nikko city, the sediment discharge affected by debris flow was observed during the flooding, 2011. The result of the data analysis seemed that the changing of bedload discharge volume had characteristic trend in comparison with other flooding when debris flow didn't occurred. It is supposed that these trend were caused by the difference of the type of sediment supplying, such as debris flow or riverbed material movement and the riverbed condition especially grain size changing. Therefore these trend can be applied to the river basin monitoring for example occurrence of dangerous sediment discharge caused by debris flow and landslide.