Research on sediment yield and sediment discharge which considers timing of sediment yield

Abstract

A large-scale sediment-related disaster was occurred in the Hime River drainage area in July, 1995. To understand the timing of this sediment movement, the hearing to the person in charge of the local disaster prevention was investigated. As a result, it was occurred the timing of the sediment yield had concentrated around 18 o'clock July 11 in each tributary. But only Nakaya River was occurred the sediment yield in the early morning, July 12. Moreover, the scouring Tsukitsuki gate at the main river was 16 : 00-17 : 00 of the 11 th before the sediment yield of each tributary concentrated, the cause of damage to the building in the vicinity at Hime River spa is due to the sedimentation, and no water discharge increase. The reproduction calculation considered the timing of sediment yield. As a result, the streambed from the No.8 Shita-himekawa bridge point to Ohdokoro River rose in the maximum by about 10 m, and was corresponding to an almost actual phenomenon. As for the variation of riverbed, it has been understood that not only the sediment discharge but also the timing of the sediment yield is greatly related from the tributary.