出水時における土砂の浮遊実態-長良川を例として

抄録

The authors observed the characteristics of suspended sediment in the Nagara River for three years since 1979. The suspended sediment consists of the suspended load and the wash load, and the former grain size composition is related to the bed material and its concentration is governed by the flow rate, the latter turbidity is governed by the upslope supply rate. The authors examined the suspending aspects of both the suspended load and the wash load by using measured field data. Namely, the characters of the suspended load have been examined under the idea of interchangeability with the bed material, and it has been demonstrated that the mean grain size is about 0.2mm to 0.3mm and standard deviation of grain composition is nearly constant. While a generative process of wash load has been examined with a simple mathematical expression, and the results show that the wash load is characterized by the upslope supply sources.