STUDY ON TIMELY CHANGE OF RESERVOIR SEDIMENTATION USING RRIS MODEL

Abstract

 Because of the large rainfall event in 2017 around Kisyu area, one of the river named Akatani river was severely damaged. In the most of the mountainous area of the river, debris flow took place. In order to design the river to eliminate future damage of this kind, it is important to properly estimate the sediment transport rate from catchment area. This kind of study are classified as the sediment runoff. For this purpose, the authors proposed the RRIS model, which composed with Rainfall runoff, inundation, and sediment transport. The present study discuss about the case of Kawamata dam, whose sedimentation data are available. In the year of 1982, the Kawamata Dam catchment area experienced severer flood, which involve debris flow. The authors analyzed the timely changed of the sedimentation of the lake of Kawamata. Based on the analysis, large sedimentation are recognized between just after the Debris flow and few years. Thereafter, the sedimentation become much less. The authors tried to simulate this kind of sediment transport process with using RRIS model. The RRIS model simulated sediment-hydraulically reasonable results regarding to the sediment transport rate, riverbed variation, and spatially temporal changes of the bed material distribution. In addition to that, the RRIS model reasonably estimated the volume of sedimentation in the Lake Kawamata.