抄録
It is known that the vertical structure of the river bed of the Chikugo River estuary consists of complex structures of gata-soil and sand. In this study, we develop a new model of bed variation analysis in the river estuaries with complex structures of bed layers, and we clarify the mechanism of bed variation and the amount of sand supply from the Chikugo River estuaries to the Ariake Sea during a flood. In the model, when the rate of volume of gata-soil is larger than the porosity of sand, bed variation are calculated by the GBVC method and continuity equation of sediment which takes into account the sediment discharge of sand and erosion speed of the cohesive material so as to correspond to the volume of gata-soil and sand. This is because the gata-soil has characteristics of the transportation different from sand and mixture of the sand and the gata-soil has great influence on the bed variation.
